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2218 lines
54 KiB
2218 lines
54 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* |
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* Copyright (C) 2011 Novell Inc. |
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*/ |
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|
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#include <uapi/linux/magic.h> |
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#include <linux/fs.h> |
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#include <linux/namei.h> |
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#include <linux/xattr.h> |
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#include <linux/mount.h> |
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#include <linux/parser.h> |
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#include <linux/module.h> |
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#include <linux/statfs.h> |
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#include <linux/seq_file.h> |
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#include <linux/posix_acl_xattr.h> |
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#include <linux/exportfs.h> |
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#include "overlayfs.h" |
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|
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MODULE_AUTHOR("Miklos Szeredi <[email protected]>"); |
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MODULE_DESCRIPTION("Overlay filesystem"); |
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MODULE_LICENSE("GPL"); |
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|
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|
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struct ovl_dir_cache; |
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|
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#define OVL_MAX_STACK 500 |
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|
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static bool ovl_redirect_dir_def = IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR); |
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module_param_named(redirect_dir, ovl_redirect_dir_def, bool, 0644); |
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MODULE_PARM_DESC(redirect_dir, |
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"Default to on or off for the redirect_dir feature"); |
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|
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static bool ovl_redirect_always_follow = |
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IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW); |
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module_param_named(redirect_always_follow, ovl_redirect_always_follow, |
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bool, 0644); |
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MODULE_PARM_DESC(redirect_always_follow, |
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"Follow redirects even if redirect_dir feature is turned off"); |
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|
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static bool ovl_index_def = IS_ENABLED(CONFIG_OVERLAY_FS_INDEX); |
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module_param_named(index, ovl_index_def, bool, 0644); |
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MODULE_PARM_DESC(index, |
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"Default to on or off for the inodes index feature"); |
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|
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static bool ovl_nfs_export_def = IS_ENABLED(CONFIG_OVERLAY_FS_NFS_EXPORT); |
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module_param_named(nfs_export, ovl_nfs_export_def, bool, 0644); |
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MODULE_PARM_DESC(nfs_export, |
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"Default to on or off for the NFS export feature"); |
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|
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static bool ovl_xino_auto_def = IS_ENABLED(CONFIG_OVERLAY_FS_XINO_AUTO); |
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module_param_named(xino_auto, ovl_xino_auto_def, bool, 0644); |
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MODULE_PARM_DESC(xino_auto, |
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"Auto enable xino feature"); |
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|
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static void ovl_entry_stack_free(struct ovl_entry *oe) |
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{ |
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unsigned int i; |
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|
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for (i = 0; i < oe->numlower; i++) |
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dput(oe->lowerstack[i].dentry); |
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} |
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|
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static bool ovl_metacopy_def = IS_ENABLED(CONFIG_OVERLAY_FS_METACOPY); |
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module_param_named(metacopy, ovl_metacopy_def, bool, 0644); |
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MODULE_PARM_DESC(metacopy, |
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"Default to on or off for the metadata only copy up feature"); |
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|
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static void ovl_dentry_release(struct dentry *dentry) |
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{ |
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struct ovl_entry *oe = dentry->d_fsdata; |
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|
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if (oe) { |
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ovl_entry_stack_free(oe); |
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kfree_rcu(oe, rcu); |
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} |
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} |
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|
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static struct dentry *ovl_d_real(struct dentry *dentry, |
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const struct inode *inode) |
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{ |
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struct dentry *real = NULL, *lower; |
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|
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/* It's an overlay file */ |
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if (inode && d_inode(dentry) == inode) |
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return dentry; |
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|
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if (!d_is_reg(dentry)) { |
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if (!inode || inode == d_inode(dentry)) |
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return dentry; |
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goto bug; |
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} |
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|
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real = ovl_dentry_upper(dentry); |
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if (real && (inode == d_inode(real))) |
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return real; |
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|
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if (real && !inode && ovl_has_upperdata(d_inode(dentry))) |
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return real; |
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|
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lower = ovl_dentry_lowerdata(dentry); |
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if (!lower) |
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goto bug; |
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real = lower; |
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|
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/* Handle recursion */ |
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real = d_real(real, inode); |
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|
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if (!inode || inode == d_inode(real)) |
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return real; |
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bug: |
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WARN(1, "%s(%pd4, %s:%lu): real dentry (%p/%lu) not found\n", |
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__func__, dentry, inode ? inode->i_sb->s_id : "NULL", |
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inode ? inode->i_ino : 0, real, |
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real && d_inode(real) ? d_inode(real)->i_ino : 0); |
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return dentry; |
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} |
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|
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static int ovl_revalidate_real(struct dentry *d, unsigned int flags, bool weak) |
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{ |
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int ret = 1; |
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|
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if (weak) { |
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if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) |
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ret = d->d_op->d_weak_revalidate(d, flags); |
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} else if (d->d_flags & DCACHE_OP_REVALIDATE) { |
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ret = d->d_op->d_revalidate(d, flags); |
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if (!ret) { |
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if (!(flags & LOOKUP_RCU)) |
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d_invalidate(d); |
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ret = -ESTALE; |
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} |
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} |
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return ret; |
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} |
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|
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static int ovl_dentry_revalidate_common(struct dentry *dentry, |
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unsigned int flags, bool weak) |
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{ |
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struct ovl_entry *oe = dentry->d_fsdata; |
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struct dentry *upper; |
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unsigned int i; |
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int ret = 1; |
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|
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upper = ovl_dentry_upper(dentry); |
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if (upper) |
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ret = ovl_revalidate_real(upper, flags, weak); |
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|
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for (i = 0; ret > 0 && i < oe->numlower; i++) { |
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ret = ovl_revalidate_real(oe->lowerstack[i].dentry, flags, |
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weak); |
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} |
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return ret; |
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} |
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static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags) |
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{ |
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return ovl_dentry_revalidate_common(dentry, flags, false); |
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} |
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static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags) |
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{ |
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return ovl_dentry_revalidate_common(dentry, flags, true); |
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} |
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static const struct dentry_operations ovl_dentry_operations = { |
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.d_release = ovl_dentry_release, |
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.d_real = ovl_d_real, |
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.d_revalidate = ovl_dentry_revalidate, |
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.d_weak_revalidate = ovl_dentry_weak_revalidate, |
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}; |
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static struct kmem_cache *ovl_inode_cachep; |
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|
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static struct inode *ovl_alloc_inode(struct super_block *sb) |
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{ |
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struct ovl_inode *oi = kmem_cache_alloc(ovl_inode_cachep, GFP_KERNEL); |
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if (!oi) |
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return NULL; |
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oi->cache = NULL; |
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oi->redirect = NULL; |
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oi->version = 0; |
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oi->flags = 0; |
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oi->__upperdentry = NULL; |
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oi->lower = NULL; |
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oi->lowerdata = NULL; |
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mutex_init(&oi->lock); |
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return &oi->vfs_inode; |
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} |
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static void ovl_free_inode(struct inode *inode) |
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{ |
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struct ovl_inode *oi = OVL_I(inode); |
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kfree(oi->redirect); |
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mutex_destroy(&oi->lock); |
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kmem_cache_free(ovl_inode_cachep, oi); |
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} |
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static void ovl_destroy_inode(struct inode *inode) |
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{ |
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struct ovl_inode *oi = OVL_I(inode); |
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dput(oi->__upperdentry); |
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iput(oi->lower); |
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if (S_ISDIR(inode->i_mode)) |
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ovl_dir_cache_free(inode); |
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else |
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iput(oi->lowerdata); |
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} |
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static void ovl_free_fs(struct ovl_fs *ofs) |
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{ |
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struct vfsmount **mounts; |
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unsigned i; |
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iput(ofs->workbasedir_trap); |
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iput(ofs->indexdir_trap); |
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iput(ofs->workdir_trap); |
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dput(ofs->whiteout); |
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dput(ofs->indexdir); |
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dput(ofs->workdir); |
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if (ofs->workdir_locked) |
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ovl_inuse_unlock(ofs->workbasedir); |
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dput(ofs->workbasedir); |
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if (ofs->upperdir_locked) |
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ovl_inuse_unlock(ovl_upper_mnt(ofs)->mnt_root); |
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/* Hack! Reuse ofs->layers as a vfsmount array before freeing it */ |
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mounts = (struct vfsmount **) ofs->layers; |
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for (i = 0; i < ofs->numlayer; i++) { |
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iput(ofs->layers[i].trap); |
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mounts[i] = ofs->layers[i].mnt; |
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} |
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kern_unmount_array(mounts, ofs->numlayer); |
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kfree(ofs->layers); |
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for (i = 0; i < ofs->numfs; i++) |
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free_anon_bdev(ofs->fs[i].pseudo_dev); |
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kfree(ofs->fs); |
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kfree(ofs->config.lowerdir); |
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kfree(ofs->config.upperdir); |
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kfree(ofs->config.workdir); |
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kfree(ofs->config.redirect_mode); |
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if (ofs->creator_cred) |
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put_cred(ofs->creator_cred); |
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kfree(ofs); |
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} |
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static void ovl_put_super(struct super_block *sb) |
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{ |
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struct ovl_fs *ofs = sb->s_fs_info; |
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ovl_free_fs(ofs); |
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} |
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/* Sync real dirty inodes in upper filesystem (if it exists) */ |
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static int ovl_sync_fs(struct super_block *sb, int wait) |
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{ |
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struct ovl_fs *ofs = sb->s_fs_info; |
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struct super_block *upper_sb; |
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int ret; |
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ret = ovl_sync_status(ofs); |
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/* |
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* We have to always set the err, because the return value isn't |
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* checked in syncfs, and instead indirectly return an error via |
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* the sb's writeback errseq, which VFS inspects after this call. |
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*/ |
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if (ret < 0) { |
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errseq_set(&sb->s_wb_err, -EIO); |
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return -EIO; |
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} |
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if (!ret) |
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return ret; |
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|
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/* |
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* Not called for sync(2) call or an emergency sync (SB_I_SKIP_SYNC). |
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* All the super blocks will be iterated, including upper_sb. |
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* |
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* If this is a syncfs(2) call, then we do need to call |
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* sync_filesystem() on upper_sb, but enough if we do it when being |
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* called with wait == 1. |
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*/ |
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if (!wait) |
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return 0; |
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upper_sb = ovl_upper_mnt(ofs)->mnt_sb; |
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down_read(&upper_sb->s_umount); |
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ret = sync_filesystem(upper_sb); |
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up_read(&upper_sb->s_umount); |
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return ret; |
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} |
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|
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/** |
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* ovl_statfs |
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* @sb: The overlayfs super block |
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* @buf: The struct kstatfs to fill in with stats |
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* |
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* Get the filesystem statistics. As writes always target the upper layer |
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* filesystem pass the statfs to the upper filesystem (if it exists) |
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*/ |
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static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf) |
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{ |
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struct ovl_fs *ofs = dentry->d_sb->s_fs_info; |
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struct dentry *root_dentry = dentry->d_sb->s_root; |
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struct path path; |
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int err; |
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ovl_path_real(root_dentry, &path); |
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err = vfs_statfs(&path, buf); |
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if (!err) { |
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buf->f_namelen = ofs->namelen; |
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buf->f_type = OVERLAYFS_SUPER_MAGIC; |
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} |
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return err; |
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} |
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|
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/* Will this overlay be forced to mount/remount ro? */ |
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static bool ovl_force_readonly(struct ovl_fs *ofs) |
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{ |
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return (!ovl_upper_mnt(ofs) || !ofs->workdir); |
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} |
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|
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static const char *ovl_redirect_mode_def(void) |
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{ |
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return ovl_redirect_dir_def ? "on" : "off"; |
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} |
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|
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static const char * const ovl_xino_str[] = { |
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"off", |
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"auto", |
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"on", |
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}; |
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static inline int ovl_xino_def(void) |
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{ |
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return ovl_xino_auto_def ? OVL_XINO_AUTO : OVL_XINO_OFF; |
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} |
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|
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/** |
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* ovl_show_options |
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* |
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* Prints the mount options for a given superblock. |
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* Returns zero; does not fail. |
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*/ |
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static int ovl_show_options(struct seq_file *m, struct dentry *dentry) |
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{ |
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struct super_block *sb = dentry->d_sb; |
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struct ovl_fs *ofs = sb->s_fs_info; |
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|
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seq_show_option(m, "lowerdir", ofs->config.lowerdir); |
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if (ofs->config.upperdir) { |
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seq_show_option(m, "upperdir", ofs->config.upperdir); |
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seq_show_option(m, "workdir", ofs->config.workdir); |
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} |
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if (ofs->config.default_permissions) |
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seq_puts(m, ",default_permissions"); |
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if (strcmp(ofs->config.redirect_mode, ovl_redirect_mode_def()) != 0) |
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seq_printf(m, ",redirect_dir=%s", ofs->config.redirect_mode); |
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if (ofs->config.index != ovl_index_def) |
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seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off"); |
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if (!ofs->config.uuid) |
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seq_puts(m, ",uuid=off"); |
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if (ofs->config.nfs_export != ovl_nfs_export_def) |
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seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ? |
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"on" : "off"); |
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if (ofs->config.xino != ovl_xino_def() && !ovl_same_fs(sb)) |
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seq_printf(m, ",xino=%s", ovl_xino_str[ofs->config.xino]); |
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if (ofs->config.metacopy != ovl_metacopy_def) |
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seq_printf(m, ",metacopy=%s", |
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ofs->config.metacopy ? "on" : "off"); |
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if (ofs->config.ovl_volatile) |
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seq_puts(m, ",volatile"); |
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if (ofs->config.userxattr) |
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seq_puts(m, ",userxattr"); |
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return 0; |
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} |
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|
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static int ovl_remount(struct super_block *sb, int *flags, char *data) |
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{ |
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struct ovl_fs *ofs = sb->s_fs_info; |
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struct super_block *upper_sb; |
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int ret = 0; |
|
|
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if (!(*flags & SB_RDONLY) && ovl_force_readonly(ofs)) |
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return -EROFS; |
|
|
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if (*flags & SB_RDONLY && !sb_rdonly(sb)) { |
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upper_sb = ovl_upper_mnt(ofs)->mnt_sb; |
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if (ovl_should_sync(ofs)) { |
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down_read(&upper_sb->s_umount); |
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ret = sync_filesystem(upper_sb); |
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up_read(&upper_sb->s_umount); |
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} |
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} |
|
|
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return ret; |
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} |
|
|
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static const struct super_operations ovl_super_operations = { |
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.alloc_inode = ovl_alloc_inode, |
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.free_inode = ovl_free_inode, |
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.destroy_inode = ovl_destroy_inode, |
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.drop_inode = generic_delete_inode, |
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.put_super = ovl_put_super, |
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.sync_fs = ovl_sync_fs, |
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.statfs = ovl_statfs, |
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.show_options = ovl_show_options, |
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.remount_fs = ovl_remount, |
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}; |
|
|
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enum { |
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OPT_LOWERDIR, |
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OPT_UPPERDIR, |
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OPT_WORKDIR, |
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OPT_DEFAULT_PERMISSIONS, |
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OPT_REDIRECT_DIR, |
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OPT_INDEX_ON, |
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OPT_INDEX_OFF, |
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OPT_UUID_ON, |
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OPT_UUID_OFF, |
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OPT_NFS_EXPORT_ON, |
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OPT_USERXATTR, |
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OPT_NFS_EXPORT_OFF, |
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OPT_XINO_ON, |
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OPT_XINO_OFF, |
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OPT_XINO_AUTO, |
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OPT_METACOPY_ON, |
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OPT_METACOPY_OFF, |
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OPT_VOLATILE, |
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OPT_ERR, |
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}; |
|
|
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static const match_table_t ovl_tokens = { |
|
{OPT_LOWERDIR, "lowerdir=%s"}, |
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{OPT_UPPERDIR, "upperdir=%s"}, |
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{OPT_WORKDIR, "workdir=%s"}, |
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{OPT_DEFAULT_PERMISSIONS, "default_permissions"}, |
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{OPT_REDIRECT_DIR, "redirect_dir=%s"}, |
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{OPT_INDEX_ON, "index=on"}, |
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{OPT_INDEX_OFF, "index=off"}, |
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{OPT_USERXATTR, "userxattr"}, |
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{OPT_UUID_ON, "uuid=on"}, |
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{OPT_UUID_OFF, "uuid=off"}, |
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{OPT_NFS_EXPORT_ON, "nfs_export=on"}, |
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{OPT_NFS_EXPORT_OFF, "nfs_export=off"}, |
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{OPT_XINO_ON, "xino=on"}, |
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{OPT_XINO_OFF, "xino=off"}, |
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{OPT_XINO_AUTO, "xino=auto"}, |
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{OPT_METACOPY_ON, "metacopy=on"}, |
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{OPT_METACOPY_OFF, "metacopy=off"}, |
|
{OPT_VOLATILE, "volatile"}, |
|
{OPT_ERR, NULL} |
|
}; |
|
|
|
static char *ovl_next_opt(char **s) |
|
{ |
|
char *sbegin = *s; |
|
char *p; |
|
|
|
if (sbegin == NULL) |
|
return NULL; |
|
|
|
for (p = sbegin; *p; p++) { |
|
if (*p == '\\') { |
|
p++; |
|
if (!*p) |
|
break; |
|
} else if (*p == ',') { |
|
*p = '\0'; |
|
*s = p + 1; |
|
return sbegin; |
|
} |
|
} |
|
*s = NULL; |
|
return sbegin; |
|
} |
|
|
|
static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode) |
|
{ |
|
if (strcmp(mode, "on") == 0) { |
|
config->redirect_dir = true; |
|
/* |
|
* Does not make sense to have redirect creation without |
|
* redirect following. |
|
*/ |
|
config->redirect_follow = true; |
|
} else if (strcmp(mode, "follow") == 0) { |
|
config->redirect_follow = true; |
|
} else if (strcmp(mode, "off") == 0) { |
|
if (ovl_redirect_always_follow) |
|
config->redirect_follow = true; |
|
} else if (strcmp(mode, "nofollow") != 0) { |
|
pr_err("bad mount option \"redirect_dir=%s\"\n", |
|
mode); |
|
return -EINVAL; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
static int ovl_parse_opt(char *opt, struct ovl_config *config) |
|
{ |
|
char *p; |
|
int err; |
|
bool metacopy_opt = false, redirect_opt = false; |
|
bool nfs_export_opt = false, index_opt = false; |
|
|
|
config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL); |
|
if (!config->redirect_mode) |
|
return -ENOMEM; |
|
|
|
while ((p = ovl_next_opt(&opt)) != NULL) { |
|
int token; |
|
substring_t args[MAX_OPT_ARGS]; |
|
|
|
if (!*p) |
|
continue; |
|
|
|
token = match_token(p, ovl_tokens, args); |
|
switch (token) { |
|
case OPT_UPPERDIR: |
|
kfree(config->upperdir); |
|
config->upperdir = match_strdup(&args[0]); |
|
if (!config->upperdir) |
|
return -ENOMEM; |
|
break; |
|
|
|
case OPT_LOWERDIR: |
|
kfree(config->lowerdir); |
|
config->lowerdir = match_strdup(&args[0]); |
|
if (!config->lowerdir) |
|
return -ENOMEM; |
|
break; |
|
|
|
case OPT_WORKDIR: |
|
kfree(config->workdir); |
|
config->workdir = match_strdup(&args[0]); |
|
if (!config->workdir) |
|
return -ENOMEM; |
|
break; |
|
|
|
case OPT_DEFAULT_PERMISSIONS: |
|
config->default_permissions = true; |
|
break; |
|
|
|
case OPT_REDIRECT_DIR: |
|
kfree(config->redirect_mode); |
|
config->redirect_mode = match_strdup(&args[0]); |
|
if (!config->redirect_mode) |
|
return -ENOMEM; |
|
redirect_opt = true; |
|
break; |
|
|
|
case OPT_INDEX_ON: |
|
config->index = true; |
|
index_opt = true; |
|
break; |
|
|
|
case OPT_INDEX_OFF: |
|
config->index = false; |
|
index_opt = true; |
|
break; |
|
|
|
case OPT_UUID_ON: |
|
config->uuid = true; |
|
break; |
|
|
|
case OPT_UUID_OFF: |
|
config->uuid = false; |
|
break; |
|
|
|
case OPT_NFS_EXPORT_ON: |
|
config->nfs_export = true; |
|
nfs_export_opt = true; |
|
break; |
|
|
|
case OPT_NFS_EXPORT_OFF: |
|
config->nfs_export = false; |
|
nfs_export_opt = true; |
|
break; |
|
|
|
case OPT_XINO_ON: |
|
config->xino = OVL_XINO_ON; |
|
break; |
|
|
|
case OPT_XINO_OFF: |
|
config->xino = OVL_XINO_OFF; |
|
break; |
|
|
|
case OPT_XINO_AUTO: |
|
config->xino = OVL_XINO_AUTO; |
|
break; |
|
|
|
case OPT_METACOPY_ON: |
|
config->metacopy = true; |
|
metacopy_opt = true; |
|
break; |
|
|
|
case OPT_METACOPY_OFF: |
|
config->metacopy = false; |
|
metacopy_opt = true; |
|
break; |
|
|
|
case OPT_VOLATILE: |
|
config->ovl_volatile = true; |
|
break; |
|
|
|
case OPT_USERXATTR: |
|
config->userxattr = true; |
|
break; |
|
|
|
default: |
|
pr_err("unrecognized mount option \"%s\" or missing value\n", |
|
p); |
|
return -EINVAL; |
|
} |
|
} |
|
|
|
/* Workdir/index are useless in non-upper mount */ |
|
if (!config->upperdir) { |
|
if (config->workdir) { |
|
pr_info("option \"workdir=%s\" is useless in a non-upper mount, ignore\n", |
|
config->workdir); |
|
kfree(config->workdir); |
|
config->workdir = NULL; |
|
} |
|
if (config->index && index_opt) { |
|
pr_info("option \"index=on\" is useless in a non-upper mount, ignore\n"); |
|
index_opt = false; |
|
} |
|
config->index = false; |
|
} |
|
|
|
if (!config->upperdir && config->ovl_volatile) { |
|
pr_info("option \"volatile\" is meaningless in a non-upper mount, ignoring it.\n"); |
|
config->ovl_volatile = false; |
|
} |
|
|
|
err = ovl_parse_redirect_mode(config, config->redirect_mode); |
|
if (err) |
|
return err; |
|
|
|
/* |
|
* This is to make the logic below simpler. It doesn't make any other |
|
* difference, since config->redirect_dir is only used for upper. |
|
*/ |
|
if (!config->upperdir && config->redirect_follow) |
|
config->redirect_dir = true; |
|
|
|
/* Resolve metacopy -> redirect_dir dependency */ |
|
if (config->metacopy && !config->redirect_dir) { |
|
if (metacopy_opt && redirect_opt) { |
|
pr_err("conflicting options: metacopy=on,redirect_dir=%s\n", |
|
config->redirect_mode); |
|
return -EINVAL; |
|
} |
|
if (redirect_opt) { |
|
/* |
|
* There was an explicit redirect_dir=... that resulted |
|
* in this conflict. |
|
*/ |
|
pr_info("disabling metacopy due to redirect_dir=%s\n", |
|
config->redirect_mode); |
|
config->metacopy = false; |
|
} else { |
|
/* Automatically enable redirect otherwise. */ |
|
config->redirect_follow = config->redirect_dir = true; |
|
} |
|
} |
|
|
|
/* Resolve nfs_export -> index dependency */ |
|
if (config->nfs_export && !config->index) { |
|
if (!config->upperdir && config->redirect_follow) { |
|
pr_info("NFS export requires \"redirect_dir=nofollow\" on non-upper mount, falling back to nfs_export=off.\n"); |
|
config->nfs_export = false; |
|
} else if (nfs_export_opt && index_opt) { |
|
pr_err("conflicting options: nfs_export=on,index=off\n"); |
|
return -EINVAL; |
|
} else if (index_opt) { |
|
/* |
|
* There was an explicit index=off that resulted |
|
* in this conflict. |
|
*/ |
|
pr_info("disabling nfs_export due to index=off\n"); |
|
config->nfs_export = false; |
|
} else { |
|
/* Automatically enable index otherwise. */ |
|
config->index = true; |
|
} |
|
} |
|
|
|
/* Resolve nfs_export -> !metacopy dependency */ |
|
if (config->nfs_export && config->metacopy) { |
|
if (nfs_export_opt && metacopy_opt) { |
|
pr_err("conflicting options: nfs_export=on,metacopy=on\n"); |
|
return -EINVAL; |
|
} |
|
if (metacopy_opt) { |
|
/* |
|
* There was an explicit metacopy=on that resulted |
|
* in this conflict. |
|
*/ |
|
pr_info("disabling nfs_export due to metacopy=on\n"); |
|
config->nfs_export = false; |
|
} else { |
|
/* |
|
* There was an explicit nfs_export=on that resulted |
|
* in this conflict. |
|
*/ |
|
pr_info("disabling metacopy due to nfs_export=on\n"); |
|
config->metacopy = false; |
|
} |
|
} |
|
|
|
|
|
/* Resolve userxattr -> !redirect && !metacopy dependency */ |
|
if (config->userxattr) { |
|
if (config->redirect_follow && redirect_opt) { |
|
pr_err("conflicting options: userxattr,redirect_dir=%s\n", |
|
config->redirect_mode); |
|
return -EINVAL; |
|
} |
|
if (config->metacopy && metacopy_opt) { |
|
pr_err("conflicting options: userxattr,metacopy=on\n"); |
|
return -EINVAL; |
|
} |
|
/* |
|
* Silently disable default setting of redirect and metacopy. |
|
* This shall be the default in the future as well: these |
|
* options must be explicitly enabled if used together with |
|
* userxattr. |
|
*/ |
|
config->redirect_dir = config->redirect_follow = false; |
|
config->metacopy = false; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
#define OVL_WORKDIR_NAME "work" |
|
#define OVL_INDEXDIR_NAME "index" |
|
|
|
static struct dentry *ovl_workdir_create(struct ovl_fs *ofs, |
|
const char *name, bool persist) |
|
{ |
|
struct inode *dir = ofs->workbasedir->d_inode; |
|
struct vfsmount *mnt = ovl_upper_mnt(ofs); |
|
struct dentry *work; |
|
int err; |
|
bool retried = false; |
|
|
|
inode_lock_nested(dir, I_MUTEX_PARENT); |
|
retry: |
|
work = lookup_one_len(name, ofs->workbasedir, strlen(name)); |
|
|
|
if (!IS_ERR(work)) { |
|
struct iattr attr = { |
|
.ia_valid = ATTR_MODE, |
|
.ia_mode = S_IFDIR | 0, |
|
}; |
|
|
|
if (work->d_inode) { |
|
err = -EEXIST; |
|
if (retried) |
|
goto out_dput; |
|
|
|
if (persist) |
|
goto out_unlock; |
|
|
|
retried = true; |
|
err = ovl_workdir_cleanup(dir, mnt, work, 0); |
|
dput(work); |
|
if (err == -EINVAL) { |
|
work = ERR_PTR(err); |
|
goto out_unlock; |
|
} |
|
goto retry; |
|
} |
|
|
|
work = ovl_create_real(dir, work, OVL_CATTR(attr.ia_mode)); |
|
err = PTR_ERR(work); |
|
if (IS_ERR(work)) |
|
goto out_err; |
|
|
|
/* |
|
* Try to remove POSIX ACL xattrs from workdir. We are good if: |
|
* |
|
* a) success (there was a POSIX ACL xattr and was removed) |
|
* b) -ENODATA (there was no POSIX ACL xattr) |
|
* c) -EOPNOTSUPP (POSIX ACL xattrs are not supported) |
|
* |
|
* There are various other error values that could effectively |
|
* mean that the xattr doesn't exist (e.g. -ERANGE is returned |
|
* if the xattr name is too long), but the set of filesystems |
|
* allowed as upper are limited to "normal" ones, where checking |
|
* for the above two errors is sufficient. |
|
*/ |
|
err = vfs_removexattr(&init_user_ns, work, |
|
XATTR_NAME_POSIX_ACL_DEFAULT); |
|
if (err && err != -ENODATA && err != -EOPNOTSUPP) |
|
goto out_dput; |
|
|
|
err = vfs_removexattr(&init_user_ns, work, |
|
XATTR_NAME_POSIX_ACL_ACCESS); |
|
if (err && err != -ENODATA && err != -EOPNOTSUPP) |
|
goto out_dput; |
|
|
|
/* Clear any inherited mode bits */ |
|
inode_lock(work->d_inode); |
|
err = notify_change(&init_user_ns, work, &attr, NULL); |
|
inode_unlock(work->d_inode); |
|
if (err) |
|
goto out_dput; |
|
} else { |
|
err = PTR_ERR(work); |
|
goto out_err; |
|
} |
|
out_unlock: |
|
inode_unlock(dir); |
|
return work; |
|
|
|
out_dput: |
|
dput(work); |
|
out_err: |
|
pr_warn("failed to create directory %s/%s (errno: %i); mounting read-only\n", |
|
ofs->config.workdir, name, -err); |
|
work = NULL; |
|
goto out_unlock; |
|
} |
|
|
|
static void ovl_unescape(char *s) |
|
{ |
|
char *d = s; |
|
|
|
for (;; s++, d++) { |
|
if (*s == '\\') |
|
s++; |
|
*d = *s; |
|
if (!*s) |
|
break; |
|
} |
|
} |
|
|
|
static int ovl_mount_dir_noesc(const char *name, struct path *path) |
|
{ |
|
int err = -EINVAL; |
|
|
|
if (!*name) { |
|
pr_err("empty lowerdir\n"); |
|
goto out; |
|
} |
|
err = kern_path(name, LOOKUP_FOLLOW, path); |
|
if (err) { |
|
pr_err("failed to resolve '%s': %i\n", name, err); |
|
goto out; |
|
} |
|
err = -EINVAL; |
|
if (ovl_dentry_weird(path->dentry)) { |
|
pr_err("filesystem on '%s' not supported\n", name); |
|
goto out_put; |
|
} |
|
if (mnt_user_ns(path->mnt) != &init_user_ns) { |
|
pr_err("idmapped layers are currently not supported\n"); |
|
goto out_put; |
|
} |
|
if (!d_is_dir(path->dentry)) { |
|
pr_err("'%s' not a directory\n", name); |
|
goto out_put; |
|
} |
|
return 0; |
|
|
|
out_put: |
|
path_put_init(path); |
|
out: |
|
return err; |
|
} |
|
|
|
static int ovl_mount_dir(const char *name, struct path *path) |
|
{ |
|
int err = -ENOMEM; |
|
char *tmp = kstrdup(name, GFP_KERNEL); |
|
|
|
if (tmp) { |
|
ovl_unescape(tmp); |
|
err = ovl_mount_dir_noesc(tmp, path); |
|
|
|
if (!err && path->dentry->d_flags & DCACHE_OP_REAL) { |
|
pr_err("filesystem on '%s' not supported as upperdir\n", |
|
tmp); |
|
path_put_init(path); |
|
err = -EINVAL; |
|
} |
|
kfree(tmp); |
|
} |
|
return err; |
|
} |
|
|
|
static int ovl_check_namelen(struct path *path, struct ovl_fs *ofs, |
|
const char *name) |
|
{ |
|
struct kstatfs statfs; |
|
int err = vfs_statfs(path, &statfs); |
|
|
|
if (err) |
|
pr_err("statfs failed on '%s'\n", name); |
|
else |
|
ofs->namelen = max(ofs->namelen, statfs.f_namelen); |
|
|
|
return err; |
|
} |
|
|
|
static int ovl_lower_dir(const char *name, struct path *path, |
|
struct ovl_fs *ofs, int *stack_depth) |
|
{ |
|
int fh_type; |
|
int err; |
|
|
|
err = ovl_mount_dir_noesc(name, path); |
|
if (err) |
|
return err; |
|
|
|
err = ovl_check_namelen(path, ofs, name); |
|
if (err) |
|
return err; |
|
|
|
*stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth); |
|
|
|
/* |
|
* The inodes index feature and NFS export need to encode and decode |
|
* file handles, so they require that all layers support them. |
|
*/ |
|
fh_type = ovl_can_decode_fh(path->dentry->d_sb); |
|
if ((ofs->config.nfs_export || |
|
(ofs->config.index && ofs->config.upperdir)) && !fh_type) { |
|
ofs->config.index = false; |
|
ofs->config.nfs_export = false; |
|
pr_warn("fs on '%s' does not support file handles, falling back to index=off,nfs_export=off.\n", |
|
name); |
|
} |
|
/* |
|
* Decoding origin file handle is required for persistent st_ino. |
|
* Without persistent st_ino, xino=auto falls back to xino=off. |
|
*/ |
|
if (ofs->config.xino == OVL_XINO_AUTO && |
|
ofs->config.upperdir && !fh_type) { |
|
ofs->config.xino = OVL_XINO_OFF; |
|
pr_warn("fs on '%s' does not support file handles, falling back to xino=off.\n", |
|
name); |
|
} |
|
|
|
/* Check if lower fs has 32bit inode numbers */ |
|
if (fh_type != FILEID_INO32_GEN) |
|
ofs->xino_mode = -1; |
|
|
|
return 0; |
|
} |
|
|
|
/* Workdir should not be subdir of upperdir and vice versa */ |
|
static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir) |
|
{ |
|
bool ok = false; |
|
|
|
if (workdir != upperdir) { |
|
ok = (lock_rename(workdir, upperdir) == NULL); |
|
unlock_rename(workdir, upperdir); |
|
} |
|
return ok; |
|
} |
|
|
|
static unsigned int ovl_split_lowerdirs(char *str) |
|
{ |
|
unsigned int ctr = 1; |
|
char *s, *d; |
|
|
|
for (s = d = str;; s++, d++) { |
|
if (*s == '\\') { |
|
s++; |
|
} else if (*s == ':') { |
|
*d = '\0'; |
|
ctr++; |
|
continue; |
|
} |
|
*d = *s; |
|
if (!*s) |
|
break; |
|
} |
|
return ctr; |
|
} |
|
|
|
static int __maybe_unused |
|
ovl_posix_acl_xattr_get(const struct xattr_handler *handler, |
|
struct dentry *dentry, struct inode *inode, |
|
const char *name, void *buffer, size_t size) |
|
{ |
|
return ovl_xattr_get(dentry, inode, handler->name, buffer, size); |
|
} |
|
|
|
static int __maybe_unused |
|
ovl_posix_acl_xattr_set(const struct xattr_handler *handler, |
|
struct user_namespace *mnt_userns, |
|
struct dentry *dentry, struct inode *inode, |
|
const char *name, const void *value, |
|
size_t size, int flags) |
|
{ |
|
struct dentry *workdir = ovl_workdir(dentry); |
|
struct inode *realinode = ovl_inode_real(inode); |
|
struct posix_acl *acl = NULL; |
|
int err; |
|
|
|
/* Check that everything is OK before copy-up */ |
|
if (value) { |
|
acl = posix_acl_from_xattr(&init_user_ns, value, size); |
|
if (IS_ERR(acl)) |
|
return PTR_ERR(acl); |
|
} |
|
err = -EOPNOTSUPP; |
|
if (!IS_POSIXACL(d_inode(workdir))) |
|
goto out_acl_release; |
|
if (!realinode->i_op->set_acl) |
|
goto out_acl_release; |
|
if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) { |
|
err = acl ? -EACCES : 0; |
|
goto out_acl_release; |
|
} |
|
err = -EPERM; |
|
if (!inode_owner_or_capable(&init_user_ns, inode)) |
|
goto out_acl_release; |
|
|
|
posix_acl_release(acl); |
|
|
|
/* |
|
* Check if sgid bit needs to be cleared (actual setacl operation will |
|
* be done with mounter's capabilities and so that won't do it for us). |
|
*/ |
|
if (unlikely(inode->i_mode & S_ISGID) && |
|
handler->flags == ACL_TYPE_ACCESS && |
|
!in_group_p(inode->i_gid) && |
|
!capable_wrt_inode_uidgid(&init_user_ns, inode, CAP_FSETID)) { |
|
struct iattr iattr = { .ia_valid = ATTR_KILL_SGID }; |
|
|
|
err = ovl_setattr(&init_user_ns, dentry, &iattr); |
|
if (err) |
|
return err; |
|
} |
|
|
|
err = ovl_xattr_set(dentry, inode, handler->name, value, size, flags); |
|
return err; |
|
|
|
out_acl_release: |
|
posix_acl_release(acl); |
|
return err; |
|
} |
|
|
|
static int ovl_own_xattr_get(const struct xattr_handler *handler, |
|
struct dentry *dentry, struct inode *inode, |
|
const char *name, void *buffer, size_t size) |
|
{ |
|
return -EOPNOTSUPP; |
|
} |
|
|
|
static int ovl_own_xattr_set(const struct xattr_handler *handler, |
|
struct user_namespace *mnt_userns, |
|
struct dentry *dentry, struct inode *inode, |
|
const char *name, const void *value, |
|
size_t size, int flags) |
|
{ |
|
return -EOPNOTSUPP; |
|
} |
|
|
|
static int ovl_other_xattr_get(const struct xattr_handler *handler, |
|
struct dentry *dentry, struct inode *inode, |
|
const char *name, void *buffer, size_t size) |
|
{ |
|
return ovl_xattr_get(dentry, inode, name, buffer, size); |
|
} |
|
|
|
static int ovl_other_xattr_set(const struct xattr_handler *handler, |
|
struct user_namespace *mnt_userns, |
|
struct dentry *dentry, struct inode *inode, |
|
const char *name, const void *value, |
|
size_t size, int flags) |
|
{ |
|
return ovl_xattr_set(dentry, inode, name, value, size, flags); |
|
} |
|
|
|
static const struct xattr_handler __maybe_unused |
|
ovl_posix_acl_access_xattr_handler = { |
|
.name = XATTR_NAME_POSIX_ACL_ACCESS, |
|
.flags = ACL_TYPE_ACCESS, |
|
.get = ovl_posix_acl_xattr_get, |
|
.set = ovl_posix_acl_xattr_set, |
|
}; |
|
|
|
static const struct xattr_handler __maybe_unused |
|
ovl_posix_acl_default_xattr_handler = { |
|
.name = XATTR_NAME_POSIX_ACL_DEFAULT, |
|
.flags = ACL_TYPE_DEFAULT, |
|
.get = ovl_posix_acl_xattr_get, |
|
.set = ovl_posix_acl_xattr_set, |
|
}; |
|
|
|
static const struct xattr_handler ovl_own_trusted_xattr_handler = { |
|
.prefix = OVL_XATTR_TRUSTED_PREFIX, |
|
.get = ovl_own_xattr_get, |
|
.set = ovl_own_xattr_set, |
|
}; |
|
|
|
static const struct xattr_handler ovl_own_user_xattr_handler = { |
|
.prefix = OVL_XATTR_USER_PREFIX, |
|
.get = ovl_own_xattr_get, |
|
.set = ovl_own_xattr_set, |
|
}; |
|
|
|
static const struct xattr_handler ovl_other_xattr_handler = { |
|
.prefix = "", /* catch all */ |
|
.get = ovl_other_xattr_get, |
|
.set = ovl_other_xattr_set, |
|
}; |
|
|
|
static const struct xattr_handler *ovl_trusted_xattr_handlers[] = { |
|
#ifdef CONFIG_FS_POSIX_ACL |
|
&ovl_posix_acl_access_xattr_handler, |
|
&ovl_posix_acl_default_xattr_handler, |
|
#endif |
|
&ovl_own_trusted_xattr_handler, |
|
&ovl_other_xattr_handler, |
|
NULL |
|
}; |
|
|
|
static const struct xattr_handler *ovl_user_xattr_handlers[] = { |
|
#ifdef CONFIG_FS_POSIX_ACL |
|
&ovl_posix_acl_access_xattr_handler, |
|
&ovl_posix_acl_default_xattr_handler, |
|
#endif |
|
&ovl_own_user_xattr_handler, |
|
&ovl_other_xattr_handler, |
|
NULL |
|
}; |
|
|
|
static int ovl_setup_trap(struct super_block *sb, struct dentry *dir, |
|
struct inode **ptrap, const char *name) |
|
{ |
|
struct inode *trap; |
|
int err; |
|
|
|
trap = ovl_get_trap_inode(sb, dir); |
|
err = PTR_ERR_OR_ZERO(trap); |
|
if (err) { |
|
if (err == -ELOOP) |
|
pr_err("conflicting %s path\n", name); |
|
return err; |
|
} |
|
|
|
*ptrap = trap; |
|
return 0; |
|
} |
|
|
|
/* |
|
* Determine how we treat concurrent use of upperdir/workdir based on the |
|
* index feature. This is papering over mount leaks of container runtimes, |
|
* for example, an old overlay mount is leaked and now its upperdir is |
|
* attempted to be used as a lower layer in a new overlay mount. |
|
*/ |
|
static int ovl_report_in_use(struct ovl_fs *ofs, const char *name) |
|
{ |
|
if (ofs->config.index) { |
|
pr_err("%s is in-use as upperdir/workdir of another mount, mount with '-o index=off' to override exclusive upperdir protection.\n", |
|
name); |
|
return -EBUSY; |
|
} else { |
|
pr_warn("%s is in-use as upperdir/workdir of another mount, accessing files from both mounts will result in undefined behavior.\n", |
|
name); |
|
return 0; |
|
} |
|
} |
|
|
|
static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs, |
|
struct ovl_layer *upper_layer, struct path *upperpath) |
|
{ |
|
struct vfsmount *upper_mnt; |
|
int err; |
|
|
|
err = ovl_mount_dir(ofs->config.upperdir, upperpath); |
|
if (err) |
|
goto out; |
|
|
|
/* Upperdir path should not be r/o */ |
|
if (__mnt_is_readonly(upperpath->mnt)) { |
|
pr_err("upper fs is r/o, try multi-lower layers mount\n"); |
|
err = -EINVAL; |
|
goto out; |
|
} |
|
|
|
err = ovl_check_namelen(upperpath, ofs, ofs->config.upperdir); |
|
if (err) |
|
goto out; |
|
|
|
err = ovl_setup_trap(sb, upperpath->dentry, &upper_layer->trap, |
|
"upperdir"); |
|
if (err) |
|
goto out; |
|
|
|
upper_mnt = clone_private_mount(upperpath); |
|
err = PTR_ERR(upper_mnt); |
|
if (IS_ERR(upper_mnt)) { |
|
pr_err("failed to clone upperpath\n"); |
|
goto out; |
|
} |
|
|
|
/* Don't inherit atime flags */ |
|
upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME); |
|
upper_layer->mnt = upper_mnt; |
|
upper_layer->idx = 0; |
|
upper_layer->fsid = 0; |
|
|
|
/* |
|
* Inherit SB_NOSEC flag from upperdir. |
|
* |
|
* This optimization changes behavior when a security related attribute |
|
* (suid/sgid/security.*) is changed on an underlying layer. This is |
|
* okay because we don't yet have guarantees in that case, but it will |
|
* need careful treatment once we want to honour changes to underlying |
|
* filesystems. |
|
*/ |
|
if (upper_mnt->mnt_sb->s_flags & SB_NOSEC) |
|
sb->s_flags |= SB_NOSEC; |
|
|
|
if (ovl_inuse_trylock(ovl_upper_mnt(ofs)->mnt_root)) { |
|
ofs->upperdir_locked = true; |
|
} else { |
|
err = ovl_report_in_use(ofs, "upperdir"); |
|
if (err) |
|
goto out; |
|
} |
|
|
|
err = 0; |
|
out: |
|
return err; |
|
} |
|
|
|
/* |
|
* Returns 1 if RENAME_WHITEOUT is supported, 0 if not supported and |
|
* negative values if error is encountered. |
|
*/ |
|
static int ovl_check_rename_whiteout(struct dentry *workdir) |
|
{ |
|
struct inode *dir = d_inode(workdir); |
|
struct dentry *temp; |
|
struct dentry *dest; |
|
struct dentry *whiteout; |
|
struct name_snapshot name; |
|
int err; |
|
|
|
inode_lock_nested(dir, I_MUTEX_PARENT); |
|
|
|
temp = ovl_create_temp(workdir, OVL_CATTR(S_IFREG | 0)); |
|
err = PTR_ERR(temp); |
|
if (IS_ERR(temp)) |
|
goto out_unlock; |
|
|
|
dest = ovl_lookup_temp(workdir); |
|
err = PTR_ERR(dest); |
|
if (IS_ERR(dest)) { |
|
dput(temp); |
|
goto out_unlock; |
|
} |
|
|
|
/* Name is inline and stable - using snapshot as a copy helper */ |
|
take_dentry_name_snapshot(&name, temp); |
|
err = ovl_do_rename(dir, temp, dir, dest, RENAME_WHITEOUT); |
|
if (err) { |
|
if (err == -EINVAL) |
|
err = 0; |
|
goto cleanup_temp; |
|
} |
|
|
|
whiteout = lookup_one_len(name.name.name, workdir, name.name.len); |
|
err = PTR_ERR(whiteout); |
|
if (IS_ERR(whiteout)) |
|
goto cleanup_temp; |
|
|
|
err = ovl_is_whiteout(whiteout); |
|
|
|
/* Best effort cleanup of whiteout and temp file */ |
|
if (err) |
|
ovl_cleanup(dir, whiteout); |
|
dput(whiteout); |
|
|
|
cleanup_temp: |
|
ovl_cleanup(dir, temp); |
|
release_dentry_name_snapshot(&name); |
|
dput(temp); |
|
dput(dest); |
|
|
|
out_unlock: |
|
inode_unlock(dir); |
|
|
|
return err; |
|
} |
|
|
|
static struct dentry *ovl_lookup_or_create(struct dentry *parent, |
|
const char *name, umode_t mode) |
|
{ |
|
size_t len = strlen(name); |
|
struct dentry *child; |
|
|
|
inode_lock_nested(parent->d_inode, I_MUTEX_PARENT); |
|
child = lookup_one_len(name, parent, len); |
|
if (!IS_ERR(child) && !child->d_inode) |
|
child = ovl_create_real(parent->d_inode, child, |
|
OVL_CATTR(mode)); |
|
inode_unlock(parent->d_inode); |
|
dput(parent); |
|
|
|
return child; |
|
} |
|
|
|
/* |
|
* Creates $workdir/work/incompat/volatile/dirty file if it is not already |
|
* present. |
|
*/ |
|
static int ovl_create_volatile_dirty(struct ovl_fs *ofs) |
|
{ |
|
unsigned int ctr; |
|
struct dentry *d = dget(ofs->workbasedir); |
|
static const char *const volatile_path[] = { |
|
OVL_WORKDIR_NAME, "incompat", "volatile", "dirty" |
|
}; |
|
const char *const *name = volatile_path; |
|
|
|
for (ctr = ARRAY_SIZE(volatile_path); ctr; ctr--, name++) { |
|
d = ovl_lookup_or_create(d, *name, ctr > 1 ? S_IFDIR : S_IFREG); |
|
if (IS_ERR(d)) |
|
return PTR_ERR(d); |
|
} |
|
dput(d); |
|
return 0; |
|
} |
|
|
|
static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs, |
|
struct path *workpath) |
|
{ |
|
struct vfsmount *mnt = ovl_upper_mnt(ofs); |
|
struct dentry *temp, *workdir; |
|
bool rename_whiteout; |
|
bool d_type; |
|
int fh_type; |
|
int err; |
|
|
|
err = mnt_want_write(mnt); |
|
if (err) |
|
return err; |
|
|
|
workdir = ovl_workdir_create(ofs, OVL_WORKDIR_NAME, false); |
|
err = PTR_ERR(workdir); |
|
if (IS_ERR_OR_NULL(workdir)) |
|
goto out; |
|
|
|
ofs->workdir = workdir; |
|
|
|
err = ovl_setup_trap(sb, ofs->workdir, &ofs->workdir_trap, "workdir"); |
|
if (err) |
|
goto out; |
|
|
|
/* |
|
* Upper should support d_type, else whiteouts are visible. Given |
|
* workdir and upper are on same fs, we can do iterate_dir() on |
|
* workdir. This check requires successful creation of workdir in |
|
* previous step. |
|
*/ |
|
err = ovl_check_d_type_supported(workpath); |
|
if (err < 0) |
|
goto out; |
|
|
|
d_type = err; |
|
if (!d_type) |
|
pr_warn("upper fs needs to support d_type.\n"); |
|
|
|
/* Check if upper/work fs supports O_TMPFILE */ |
|
temp = ovl_do_tmpfile(ofs->workdir, S_IFREG | 0); |
|
ofs->tmpfile = !IS_ERR(temp); |
|
if (ofs->tmpfile) |
|
dput(temp); |
|
else |
|
pr_warn("upper fs does not support tmpfile.\n"); |
|
|
|
|
|
/* Check if upper/work fs supports RENAME_WHITEOUT */ |
|
err = ovl_check_rename_whiteout(ofs->workdir); |
|
if (err < 0) |
|
goto out; |
|
|
|
rename_whiteout = err; |
|
if (!rename_whiteout) |
|
pr_warn("upper fs does not support RENAME_WHITEOUT.\n"); |
|
|
|
/* |
|
* Check if upper/work fs supports (trusted|user).overlay.* xattr |
|
*/ |
|
err = ovl_do_setxattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE, "0", 1); |
|
if (err) { |
|
ofs->noxattr = true; |
|
if (ofs->config.index || ofs->config.metacopy) { |
|
ofs->config.index = false; |
|
ofs->config.metacopy = false; |
|
pr_warn("upper fs does not support xattr, falling back to index=off,metacopy=off.\n"); |
|
} |
|
/* |
|
* xattr support is required for persistent st_ino. |
|
* Without persistent st_ino, xino=auto falls back to xino=off. |
|
*/ |
|
if (ofs->config.xino == OVL_XINO_AUTO) { |
|
ofs->config.xino = OVL_XINO_OFF; |
|
pr_warn("upper fs does not support xattr, falling back to xino=off.\n"); |
|
} |
|
err = 0; |
|
} else { |
|
ovl_do_removexattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE); |
|
} |
|
|
|
/* |
|
* We allowed sub-optimal upper fs configuration and don't want to break |
|
* users over kernel upgrade, but we never allowed remote upper fs, so |
|
* we can enforce strict requirements for remote upper fs. |
|
*/ |
|
if (ovl_dentry_remote(ofs->workdir) && |
|
(!d_type || !rename_whiteout || ofs->noxattr)) { |
|
pr_err("upper fs missing required features.\n"); |
|
err = -EINVAL; |
|
goto out; |
|
} |
|
|
|
/* |
|
* For volatile mount, create a incompat/volatile/dirty file to keep |
|
* track of it. |
|
*/ |
|
if (ofs->config.ovl_volatile) { |
|
err = ovl_create_volatile_dirty(ofs); |
|
if (err < 0) { |
|
pr_err("Failed to create volatile/dirty file.\n"); |
|
goto out; |
|
} |
|
} |
|
|
|
/* Check if upper/work fs supports file handles */ |
|
fh_type = ovl_can_decode_fh(ofs->workdir->d_sb); |
|
if (ofs->config.index && !fh_type) { |
|
ofs->config.index = false; |
|
pr_warn("upper fs does not support file handles, falling back to index=off.\n"); |
|
} |
|
|
|
/* Check if upper fs has 32bit inode numbers */ |
|
if (fh_type != FILEID_INO32_GEN) |
|
ofs->xino_mode = -1; |
|
|
|
/* NFS export of r/w mount depends on index */ |
|
if (ofs->config.nfs_export && !ofs->config.index) { |
|
pr_warn("NFS export requires \"index=on\", falling back to nfs_export=off.\n"); |
|
ofs->config.nfs_export = false; |
|
} |
|
out: |
|
mnt_drop_write(mnt); |
|
return err; |
|
} |
|
|
|
static int ovl_get_workdir(struct super_block *sb, struct ovl_fs *ofs, |
|
struct path *upperpath) |
|
{ |
|
int err; |
|
struct path workpath = { }; |
|
|
|
err = ovl_mount_dir(ofs->config.workdir, &workpath); |
|
if (err) |
|
goto out; |
|
|
|
err = -EINVAL; |
|
if (upperpath->mnt != workpath.mnt) { |
|
pr_err("workdir and upperdir must reside under the same mount\n"); |
|
goto out; |
|
} |
|
if (!ovl_workdir_ok(workpath.dentry, upperpath->dentry)) { |
|
pr_err("workdir and upperdir must be separate subtrees\n"); |
|
goto out; |
|
} |
|
|
|
ofs->workbasedir = dget(workpath.dentry); |
|
|
|
if (ovl_inuse_trylock(ofs->workbasedir)) { |
|
ofs->workdir_locked = true; |
|
} else { |
|
err = ovl_report_in_use(ofs, "workdir"); |
|
if (err) |
|
goto out; |
|
} |
|
|
|
err = ovl_setup_trap(sb, ofs->workbasedir, &ofs->workbasedir_trap, |
|
"workdir"); |
|
if (err) |
|
goto out; |
|
|
|
err = ovl_make_workdir(sb, ofs, &workpath); |
|
|
|
out: |
|
path_put(&workpath); |
|
|
|
return err; |
|
} |
|
|
|
static int ovl_get_indexdir(struct super_block *sb, struct ovl_fs *ofs, |
|
struct ovl_entry *oe, struct path *upperpath) |
|
{ |
|
struct vfsmount *mnt = ovl_upper_mnt(ofs); |
|
struct dentry *indexdir; |
|
int err; |
|
|
|
err = mnt_want_write(mnt); |
|
if (err) |
|
return err; |
|
|
|
/* Verify lower root is upper root origin */ |
|
err = ovl_verify_origin(ofs, upperpath->dentry, |
|
oe->lowerstack[0].dentry, true); |
|
if (err) { |
|
pr_err("failed to verify upper root origin\n"); |
|
goto out; |
|
} |
|
|
|
/* index dir will act also as workdir */ |
|
iput(ofs->workdir_trap); |
|
ofs->workdir_trap = NULL; |
|
dput(ofs->workdir); |
|
ofs->workdir = NULL; |
|
indexdir = ovl_workdir_create(ofs, OVL_INDEXDIR_NAME, true); |
|
if (IS_ERR(indexdir)) { |
|
err = PTR_ERR(indexdir); |
|
} else if (indexdir) { |
|
ofs->indexdir = indexdir; |
|
ofs->workdir = dget(indexdir); |
|
|
|
err = ovl_setup_trap(sb, ofs->indexdir, &ofs->indexdir_trap, |
|
"indexdir"); |
|
if (err) |
|
goto out; |
|
|
|
/* |
|
* Verify upper root is exclusively associated with index dir. |
|
* Older kernels stored upper fh in ".overlay.origin" |
|
* xattr. If that xattr exists, verify that it is a match to |
|
* upper dir file handle. In any case, verify or set xattr |
|
* ".overlay.upper" to indicate that index may have |
|
* directory entries. |
|
*/ |
|
if (ovl_check_origin_xattr(ofs, ofs->indexdir)) { |
|
err = ovl_verify_set_fh(ofs, ofs->indexdir, |
|
OVL_XATTR_ORIGIN, |
|
upperpath->dentry, true, false); |
|
if (err) |
|
pr_err("failed to verify index dir 'origin' xattr\n"); |
|
} |
|
err = ovl_verify_upper(ofs, ofs->indexdir, upperpath->dentry, |
|
true); |
|
if (err) |
|
pr_err("failed to verify index dir 'upper' xattr\n"); |
|
|
|
/* Cleanup bad/stale/orphan index entries */ |
|
if (!err) |
|
err = ovl_indexdir_cleanup(ofs); |
|
} |
|
if (err || !ofs->indexdir) |
|
pr_warn("try deleting index dir or mounting with '-o index=off' to disable inodes index.\n"); |
|
|
|
out: |
|
mnt_drop_write(mnt); |
|
return err; |
|
} |
|
|
|
static bool ovl_lower_uuid_ok(struct ovl_fs *ofs, const uuid_t *uuid) |
|
{ |
|
unsigned int i; |
|
|
|
if (!ofs->config.nfs_export && !ovl_upper_mnt(ofs)) |
|
return true; |
|
|
|
/* |
|
* We allow using single lower with null uuid for index and nfs_export |
|
* for example to support those features with single lower squashfs. |
|
* To avoid regressions in setups of overlay with re-formatted lower |
|
* squashfs, do not allow decoding origin with lower null uuid unless |
|
* user opted-in to one of the new features that require following the |
|
* lower inode of non-dir upper. |
|
*/ |
|
if (!ofs->config.index && !ofs->config.metacopy && |
|
ofs->config.xino != OVL_XINO_ON && |
|
uuid_is_null(uuid)) |
|
return false; |
|
|
|
for (i = 0; i < ofs->numfs; i++) { |
|
/* |
|
* We use uuid to associate an overlay lower file handle with a |
|
* lower layer, so we can accept lower fs with null uuid as long |
|
* as all lower layers with null uuid are on the same fs. |
|
* if we detect multiple lower fs with the same uuid, we |
|
* disable lower file handle decoding on all of them. |
|
*/ |
|
if (ofs->fs[i].is_lower && |
|
uuid_equal(&ofs->fs[i].sb->s_uuid, uuid)) { |
|
ofs->fs[i].bad_uuid = true; |
|
return false; |
|
} |
|
} |
|
return true; |
|
} |
|
|
|
/* Get a unique fsid for the layer */ |
|
static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path) |
|
{ |
|
struct super_block *sb = path->mnt->mnt_sb; |
|
unsigned int i; |
|
dev_t dev; |
|
int err; |
|
bool bad_uuid = false; |
|
bool warn = false; |
|
|
|
for (i = 0; i < ofs->numfs; i++) { |
|
if (ofs->fs[i].sb == sb) |
|
return i; |
|
} |
|
|
|
if (!ovl_lower_uuid_ok(ofs, &sb->s_uuid)) { |
|
bad_uuid = true; |
|
if (ofs->config.xino == OVL_XINO_AUTO) { |
|
ofs->config.xino = OVL_XINO_OFF; |
|
warn = true; |
|
} |
|
if (ofs->config.index || ofs->config.nfs_export) { |
|
ofs->config.index = false; |
|
ofs->config.nfs_export = false; |
|
warn = true; |
|
} |
|
if (warn) { |
|
pr_warn("%s uuid detected in lower fs '%pd2', falling back to xino=%s,index=off,nfs_export=off.\n", |
|
uuid_is_null(&sb->s_uuid) ? "null" : |
|
"conflicting", |
|
path->dentry, ovl_xino_str[ofs->config.xino]); |
|
} |
|
} |
|
|
|
err = get_anon_bdev(&dev); |
|
if (err) { |
|
pr_err("failed to get anonymous bdev for lowerpath\n"); |
|
return err; |
|
} |
|
|
|
ofs->fs[ofs->numfs].sb = sb; |
|
ofs->fs[ofs->numfs].pseudo_dev = dev; |
|
ofs->fs[ofs->numfs].bad_uuid = bad_uuid; |
|
|
|
return ofs->numfs++; |
|
} |
|
|
|
static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, |
|
struct path *stack, unsigned int numlower, |
|
struct ovl_layer *layers) |
|
{ |
|
int err; |
|
unsigned int i; |
|
|
|
err = -ENOMEM; |
|
ofs->fs = kcalloc(numlower + 1, sizeof(struct ovl_sb), GFP_KERNEL); |
|
if (ofs->fs == NULL) |
|
goto out; |
|
|
|
/* idx/fsid 0 are reserved for upper fs even with lower only overlay */ |
|
ofs->numfs++; |
|
|
|
/* |
|
* All lower layers that share the same fs as upper layer, use the same |
|
* pseudo_dev as upper layer. Allocate fs[0].pseudo_dev even for lower |
|
* only overlay to simplify ovl_fs_free(). |
|
* is_lower will be set if upper fs is shared with a lower layer. |
|
*/ |
|
err = get_anon_bdev(&ofs->fs[0].pseudo_dev); |
|
if (err) { |
|
pr_err("failed to get anonymous bdev for upper fs\n"); |
|
goto out; |
|
} |
|
|
|
if (ovl_upper_mnt(ofs)) { |
|
ofs->fs[0].sb = ovl_upper_mnt(ofs)->mnt_sb; |
|
ofs->fs[0].is_lower = false; |
|
} |
|
|
|
for (i = 0; i < numlower; i++) { |
|
struct vfsmount *mnt; |
|
struct inode *trap; |
|
int fsid; |
|
|
|
err = fsid = ovl_get_fsid(ofs, &stack[i]); |
|
if (err < 0) |
|
goto out; |
|
|
|
/* |
|
* Check if lower root conflicts with this overlay layers before |
|
* checking if it is in-use as upperdir/workdir of "another" |
|
* mount, because we do not bother to check in ovl_is_inuse() if |
|
* the upperdir/workdir is in fact in-use by our |
|
* upperdir/workdir. |
|
*/ |
|
err = ovl_setup_trap(sb, stack[i].dentry, &trap, "lowerdir"); |
|
if (err) |
|
goto out; |
|
|
|
if (ovl_is_inuse(stack[i].dentry)) { |
|
err = ovl_report_in_use(ofs, "lowerdir"); |
|
if (err) { |
|
iput(trap); |
|
goto out; |
|
} |
|
} |
|
|
|
mnt = clone_private_mount(&stack[i]); |
|
err = PTR_ERR(mnt); |
|
if (IS_ERR(mnt)) { |
|
pr_err("failed to clone lowerpath\n"); |
|
iput(trap); |
|
goto out; |
|
} |
|
|
|
/* |
|
* Make lower layers R/O. That way fchmod/fchown on lower file |
|
* will fail instead of modifying lower fs. |
|
*/ |
|
mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME; |
|
|
|
layers[ofs->numlayer].trap = trap; |
|
layers[ofs->numlayer].mnt = mnt; |
|
layers[ofs->numlayer].idx = ofs->numlayer; |
|
layers[ofs->numlayer].fsid = fsid; |
|
layers[ofs->numlayer].fs = &ofs->fs[fsid]; |
|
ofs->numlayer++; |
|
ofs->fs[fsid].is_lower = true; |
|
} |
|
|
|
/* |
|
* When all layers on same fs, overlay can use real inode numbers. |
|
* With mount option "xino=<on|auto>", mounter declares that there are |
|
* enough free high bits in underlying fs to hold the unique fsid. |
|
* If overlayfs does encounter underlying inodes using the high xino |
|
* bits reserved for fsid, it emits a warning and uses the original |
|
* inode number or a non persistent inode number allocated from a |
|
* dedicated range. |
|
*/ |
|
if (ofs->numfs - !ovl_upper_mnt(ofs) == 1) { |
|
if (ofs->config.xino == OVL_XINO_ON) |
|
pr_info("\"xino=on\" is useless with all layers on same fs, ignore.\n"); |
|
ofs->xino_mode = 0; |
|
} else if (ofs->config.xino == OVL_XINO_OFF) { |
|
ofs->xino_mode = -1; |
|
} else if (ofs->xino_mode < 0) { |
|
/* |
|
* This is a roundup of number of bits needed for encoding |
|
* fsid, where fsid 0 is reserved for upper fs (even with |
|
* lower only overlay) +1 extra bit is reserved for the non |
|
* persistent inode number range that is used for resolving |
|
* xino lower bits overflow. |
|
*/ |
|
BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 30); |
|
ofs->xino_mode = ilog2(ofs->numfs - 1) + 2; |
|
} |
|
|
|
if (ofs->xino_mode > 0) { |
|
pr_info("\"xino\" feature enabled using %d upper inode bits.\n", |
|
ofs->xino_mode); |
|
} |
|
|
|
err = 0; |
|
out: |
|
return err; |
|
} |
|
|
|
static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb, |
|
const char *lower, unsigned int numlower, |
|
struct ovl_fs *ofs, struct ovl_layer *layers) |
|
{ |
|
int err; |
|
struct path *stack = NULL; |
|
unsigned int i; |
|
struct ovl_entry *oe; |
|
|
|
if (!ofs->config.upperdir && numlower == 1) { |
|
pr_err("at least 2 lowerdir are needed while upperdir nonexistent\n"); |
|
return ERR_PTR(-EINVAL); |
|
} |
|
|
|
stack = kcalloc(numlower, sizeof(struct path), GFP_KERNEL); |
|
if (!stack) |
|
return ERR_PTR(-ENOMEM); |
|
|
|
err = -EINVAL; |
|
for (i = 0; i < numlower; i++) { |
|
err = ovl_lower_dir(lower, &stack[i], ofs, &sb->s_stack_depth); |
|
if (err) |
|
goto out_err; |
|
|
|
lower = strchr(lower, '\0') + 1; |
|
} |
|
|
|
err = -EINVAL; |
|
sb->s_stack_depth++; |
|
if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { |
|
pr_err("maximum fs stacking depth exceeded\n"); |
|
goto out_err; |
|
} |
|
|
|
err = ovl_get_layers(sb, ofs, stack, numlower, layers); |
|
if (err) |
|
goto out_err; |
|
|
|
err = -ENOMEM; |
|
oe = ovl_alloc_entry(numlower); |
|
if (!oe) |
|
goto out_err; |
|
|
|
for (i = 0; i < numlower; i++) { |
|
oe->lowerstack[i].dentry = dget(stack[i].dentry); |
|
oe->lowerstack[i].layer = &ofs->layers[i+1]; |
|
} |
|
|
|
out: |
|
for (i = 0; i < numlower; i++) |
|
path_put(&stack[i]); |
|
kfree(stack); |
|
|
|
return oe; |
|
|
|
out_err: |
|
oe = ERR_PTR(err); |
|
goto out; |
|
} |
|
|
|
/* |
|
* Check if this layer root is a descendant of: |
|
* - another layer of this overlayfs instance |
|
* - upper/work dir of any overlayfs instance |
|
*/ |
|
static int ovl_check_layer(struct super_block *sb, struct ovl_fs *ofs, |
|
struct dentry *dentry, const char *name, |
|
bool is_lower) |
|
{ |
|
struct dentry *next = dentry, *parent; |
|
int err = 0; |
|
|
|
if (!dentry) |
|
return 0; |
|
|
|
parent = dget_parent(next); |
|
|
|
/* Walk back ancestors to root (inclusive) looking for traps */ |
|
while (!err && parent != next) { |
|
if (is_lower && ovl_lookup_trap_inode(sb, parent)) { |
|
err = -ELOOP; |
|
pr_err("overlapping %s path\n", name); |
|
} else if (ovl_is_inuse(parent)) { |
|
err = ovl_report_in_use(ofs, name); |
|
} |
|
next = parent; |
|
parent = dget_parent(next); |
|
dput(next); |
|
} |
|
|
|
dput(parent); |
|
|
|
return err; |
|
} |
|
|
|
/* |
|
* Check if any of the layers or work dirs overlap. |
|
*/ |
|
static int ovl_check_overlapping_layers(struct super_block *sb, |
|
struct ovl_fs *ofs) |
|
{ |
|
int i, err; |
|
|
|
if (ovl_upper_mnt(ofs)) { |
|
err = ovl_check_layer(sb, ofs, ovl_upper_mnt(ofs)->mnt_root, |
|
"upperdir", false); |
|
if (err) |
|
return err; |
|
|
|
/* |
|
* Checking workbasedir avoids hitting ovl_is_inuse(parent) of |
|
* this instance and covers overlapping work and index dirs, |
|
* unless work or index dir have been moved since created inside |
|
* workbasedir. In that case, we already have their traps in |
|
* inode cache and we will catch that case on lookup. |
|
*/ |
|
err = ovl_check_layer(sb, ofs, ofs->workbasedir, "workdir", |
|
false); |
|
if (err) |
|
return err; |
|
} |
|
|
|
for (i = 1; i < ofs->numlayer; i++) { |
|
err = ovl_check_layer(sb, ofs, |
|
ofs->layers[i].mnt->mnt_root, |
|
"lowerdir", true); |
|
if (err) |
|
return err; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
static struct dentry *ovl_get_root(struct super_block *sb, |
|
struct dentry *upperdentry, |
|
struct ovl_entry *oe) |
|
{ |
|
struct dentry *root; |
|
struct ovl_path *lowerpath = &oe->lowerstack[0]; |
|
unsigned long ino = d_inode(lowerpath->dentry)->i_ino; |
|
int fsid = lowerpath->layer->fsid; |
|
struct ovl_inode_params oip = { |
|
.upperdentry = upperdentry, |
|
.lowerpath = lowerpath, |
|
}; |
|
|
|
root = d_make_root(ovl_new_inode(sb, S_IFDIR, 0)); |
|
if (!root) |
|
return NULL; |
|
|
|
root->d_fsdata = oe; |
|
|
|
if (upperdentry) { |
|
/* Root inode uses upper st_ino/i_ino */ |
|
ino = d_inode(upperdentry)->i_ino; |
|
fsid = 0; |
|
ovl_dentry_set_upper_alias(root); |
|
if (ovl_is_impuredir(sb, upperdentry)) |
|
ovl_set_flag(OVL_IMPURE, d_inode(root)); |
|
} |
|
|
|
/* Root is always merge -> can have whiteouts */ |
|
ovl_set_flag(OVL_WHITEOUTS, d_inode(root)); |
|
ovl_dentry_set_flag(OVL_E_CONNECTED, root); |
|
ovl_set_upperdata(d_inode(root)); |
|
ovl_inode_init(d_inode(root), &oip, ino, fsid); |
|
ovl_dentry_update_reval(root, upperdentry, DCACHE_OP_WEAK_REVALIDATE); |
|
|
|
return root; |
|
} |
|
|
|
static int ovl_fill_super(struct super_block *sb, void *data, int silent) |
|
{ |
|
struct path upperpath = { }; |
|
struct dentry *root_dentry; |
|
struct ovl_entry *oe; |
|
struct ovl_fs *ofs; |
|
struct ovl_layer *layers; |
|
struct cred *cred; |
|
char *splitlower = NULL; |
|
unsigned int numlower; |
|
int err; |
|
|
|
err = -EIO; |
|
if (WARN_ON(sb->s_user_ns != current_user_ns())) |
|
goto out; |
|
|
|
sb->s_d_op = &ovl_dentry_operations; |
|
|
|
err = -ENOMEM; |
|
ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL); |
|
if (!ofs) |
|
goto out; |
|
|
|
err = -ENOMEM; |
|
ofs->creator_cred = cred = prepare_creds(); |
|
if (!cred) |
|
goto out_err; |
|
|
|
/* Is there a reason anyone would want not to share whiteouts? */ |
|
ofs->share_whiteout = true; |
|
|
|
ofs->config.index = ovl_index_def; |
|
ofs->config.uuid = true; |
|
ofs->config.nfs_export = ovl_nfs_export_def; |
|
ofs->config.xino = ovl_xino_def(); |
|
ofs->config.metacopy = ovl_metacopy_def; |
|
err = ovl_parse_opt((char *) data, &ofs->config); |
|
if (err) |
|
goto out_err; |
|
|
|
err = -EINVAL; |
|
if (!ofs->config.lowerdir) { |
|
if (!silent) |
|
pr_err("missing 'lowerdir'\n"); |
|
goto out_err; |
|
} |
|
|
|
err = -ENOMEM; |
|
splitlower = kstrdup(ofs->config.lowerdir, GFP_KERNEL); |
|
if (!splitlower) |
|
goto out_err; |
|
|
|
err = -EINVAL; |
|
numlower = ovl_split_lowerdirs(splitlower); |
|
if (numlower > OVL_MAX_STACK) { |
|
pr_err("too many lower directories, limit is %d\n", |
|
OVL_MAX_STACK); |
|
goto out_err; |
|
} |
|
|
|
err = -ENOMEM; |
|
layers = kcalloc(numlower + 1, sizeof(struct ovl_layer), GFP_KERNEL); |
|
if (!layers) |
|
goto out_err; |
|
|
|
ofs->layers = layers; |
|
/* Layer 0 is reserved for upper even if there's no upper */ |
|
ofs->numlayer = 1; |
|
|
|
sb->s_stack_depth = 0; |
|
sb->s_maxbytes = MAX_LFS_FILESIZE; |
|
atomic_long_set(&ofs->last_ino, 1); |
|
/* Assume underlaying fs uses 32bit inodes unless proven otherwise */ |
|
if (ofs->config.xino != OVL_XINO_OFF) { |
|
ofs->xino_mode = BITS_PER_LONG - 32; |
|
if (!ofs->xino_mode) { |
|
pr_warn("xino not supported on 32bit kernel, falling back to xino=off.\n"); |
|
ofs->config.xino = OVL_XINO_OFF; |
|
} |
|
} |
|
|
|
/* alloc/destroy_inode needed for setting up traps in inode cache */ |
|
sb->s_op = &ovl_super_operations; |
|
|
|
if (ofs->config.upperdir) { |
|
struct super_block *upper_sb; |
|
|
|
err = -EINVAL; |
|
if (!ofs->config.workdir) { |
|
pr_err("missing 'workdir'\n"); |
|
goto out_err; |
|
} |
|
|
|
err = ovl_get_upper(sb, ofs, &layers[0], &upperpath); |
|
if (err) |
|
goto out_err; |
|
|
|
upper_sb = ovl_upper_mnt(ofs)->mnt_sb; |
|
if (!ovl_should_sync(ofs)) { |
|
ofs->errseq = errseq_sample(&upper_sb->s_wb_err); |
|
if (errseq_check(&upper_sb->s_wb_err, ofs->errseq)) { |
|
err = -EIO; |
|
pr_err("Cannot mount volatile when upperdir has an unseen error. Sync upperdir fs to clear state.\n"); |
|
goto out_err; |
|
} |
|
} |
|
|
|
err = ovl_get_workdir(sb, ofs, &upperpath); |
|
if (err) |
|
goto out_err; |
|
|
|
if (!ofs->workdir) |
|
sb->s_flags |= SB_RDONLY; |
|
|
|
sb->s_stack_depth = upper_sb->s_stack_depth; |
|
sb->s_time_gran = upper_sb->s_time_gran; |
|
} |
|
oe = ovl_get_lowerstack(sb, splitlower, numlower, ofs, layers); |
|
err = PTR_ERR(oe); |
|
if (IS_ERR(oe)) |
|
goto out_err; |
|
|
|
/* If the upper fs is nonexistent, we mark overlayfs r/o too */ |
|
if (!ovl_upper_mnt(ofs)) |
|
sb->s_flags |= SB_RDONLY; |
|
|
|
if (!ofs->config.uuid && ofs->numfs > 1) { |
|
pr_warn("The uuid=off requires a single fs for lower and upper, falling back to uuid=on.\n"); |
|
ofs->config.uuid = true; |
|
} |
|
|
|
if (!ovl_force_readonly(ofs) && ofs->config.index) { |
|
err = ovl_get_indexdir(sb, ofs, oe, &upperpath); |
|
if (err) |
|
goto out_free_oe; |
|
|
|
/* Force r/o mount with no index dir */ |
|
if (!ofs->indexdir) |
|
sb->s_flags |= SB_RDONLY; |
|
} |
|
|
|
err = ovl_check_overlapping_layers(sb, ofs); |
|
if (err) |
|
goto out_free_oe; |
|
|
|
/* Show index=off in /proc/mounts for forced r/o mount */ |
|
if (!ofs->indexdir) { |
|
ofs->config.index = false; |
|
if (ovl_upper_mnt(ofs) && ofs->config.nfs_export) { |
|
pr_warn("NFS export requires an index dir, falling back to nfs_export=off.\n"); |
|
ofs->config.nfs_export = false; |
|
} |
|
} |
|
|
|
if (ofs->config.metacopy && ofs->config.nfs_export) { |
|
pr_warn("NFS export is not supported with metadata only copy up, falling back to nfs_export=off.\n"); |
|
ofs->config.nfs_export = false; |
|
} |
|
|
|
if (ofs->config.nfs_export) |
|
sb->s_export_op = &ovl_export_operations; |
|
|
|
/* Never override disk quota limits or use reserved space */ |
|
cap_lower(cred->cap_effective, CAP_SYS_RESOURCE); |
|
|
|
sb->s_magic = OVERLAYFS_SUPER_MAGIC; |
|
sb->s_xattr = ofs->config.userxattr ? ovl_user_xattr_handlers : |
|
ovl_trusted_xattr_handlers; |
|
sb->s_fs_info = ofs; |
|
sb->s_flags |= SB_POSIXACL; |
|
sb->s_iflags |= SB_I_SKIP_SYNC; |
|
|
|
err = -ENOMEM; |
|
root_dentry = ovl_get_root(sb, upperpath.dentry, oe); |
|
if (!root_dentry) |
|
goto out_free_oe; |
|
|
|
mntput(upperpath.mnt); |
|
kfree(splitlower); |
|
|
|
sb->s_root = root_dentry; |
|
|
|
return 0; |
|
|
|
out_free_oe: |
|
ovl_entry_stack_free(oe); |
|
kfree(oe); |
|
out_err: |
|
kfree(splitlower); |
|
path_put(&upperpath); |
|
ovl_free_fs(ofs); |
|
out: |
|
return err; |
|
} |
|
|
|
static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags, |
|
const char *dev_name, void *raw_data) |
|
{ |
|
return mount_nodev(fs_type, flags, raw_data, ovl_fill_super); |
|
} |
|
|
|
static struct file_system_type ovl_fs_type = { |
|
.owner = THIS_MODULE, |
|
.name = "overlay", |
|
.fs_flags = FS_USERNS_MOUNT, |
|
.mount = ovl_mount, |
|
.kill_sb = kill_anon_super, |
|
}; |
|
MODULE_ALIAS_FS("overlay"); |
|
|
|
static void ovl_inode_init_once(void *foo) |
|
{ |
|
struct ovl_inode *oi = foo; |
|
|
|
inode_init_once(&oi->vfs_inode); |
|
} |
|
|
|
static int __init ovl_init(void) |
|
{ |
|
int err; |
|
|
|
ovl_inode_cachep = kmem_cache_create("ovl_inode", |
|
sizeof(struct ovl_inode), 0, |
|
(SLAB_RECLAIM_ACCOUNT| |
|
SLAB_MEM_SPREAD|SLAB_ACCOUNT), |
|
ovl_inode_init_once); |
|
if (ovl_inode_cachep == NULL) |
|
return -ENOMEM; |
|
|
|
err = ovl_aio_request_cache_init(); |
|
if (!err) { |
|
err = register_filesystem(&ovl_fs_type); |
|
if (!err) |
|
return 0; |
|
|
|
ovl_aio_request_cache_destroy(); |
|
} |
|
kmem_cache_destroy(ovl_inode_cachep); |
|
|
|
return err; |
|
} |
|
|
|
static void __exit ovl_exit(void) |
|
{ |
|
unregister_filesystem(&ovl_fs_type); |
|
|
|
/* |
|
* Make sure all delayed rcu free inodes are flushed before we |
|
* destroy cache. |
|
*/ |
|
rcu_barrier(); |
|
kmem_cache_destroy(ovl_inode_cachep); |
|
ovl_aio_request_cache_destroy(); |
|
} |
|
|
|
module_init(ovl_init); |
|
module_exit(ovl_exit);
|
|
|