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165 lines
4.4 KiB
165 lines
4.4 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* getroot.c: get the root dentry for an NFS mount |
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* |
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* Copyright (C) 2006 Red Hat, Inc. All Rights Reserved. |
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* Written by David Howells ([email protected]) |
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*/ |
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#include <linux/module.h> |
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#include <linux/init.h> |
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#include <linux/time.h> |
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#include <linux/kernel.h> |
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#include <linux/mm.h> |
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#include <linux/string.h> |
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#include <linux/stat.h> |
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#include <linux/errno.h> |
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#include <linux/unistd.h> |
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#include <linux/sunrpc/clnt.h> |
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#include <linux/sunrpc/stats.h> |
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#include <linux/nfs_fs.h> |
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#include <linux/nfs_mount.h> |
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#include <linux/lockd/bind.h> |
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#include <linux/seq_file.h> |
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#include <linux/mount.h> |
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#include <linux/vfs.h> |
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#include <linux/namei.h> |
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#include <linux/security.h> |
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#include <linux/uaccess.h> |
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#include "internal.h" |
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#define NFSDBG_FACILITY NFSDBG_CLIENT |
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/* |
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* Set the superblock root dentry. |
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* Note that this function frees the inode in case of error. |
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*/ |
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static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *inode) |
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{ |
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/* The mntroot acts as the dummy root dentry for this superblock */ |
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if (sb->s_root == NULL) { |
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sb->s_root = d_make_root(inode); |
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if (sb->s_root == NULL) |
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return -ENOMEM; |
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ihold(inode); |
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/* |
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* Ensure that this dentry is invisible to d_find_alias(). |
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* Otherwise, it may be spliced into the tree by |
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* d_splice_alias if a parent directory from the same |
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* filesystem gets mounted at a later time. |
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* This again causes shrink_dcache_for_umount_subtree() to |
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* Oops, since the test for IS_ROOT() will fail. |
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*/ |
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spin_lock(&d_inode(sb->s_root)->i_lock); |
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spin_lock(&sb->s_root->d_lock); |
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hlist_del_init(&sb->s_root->d_u.d_alias); |
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spin_unlock(&sb->s_root->d_lock); |
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spin_unlock(&d_inode(sb->s_root)->i_lock); |
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} |
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return 0; |
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} |
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/* |
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* get an NFS2/NFS3 root dentry from the root filehandle |
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*/ |
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int nfs_get_root(struct super_block *s, struct fs_context *fc) |
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{ |
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struct nfs_fs_context *ctx = nfs_fc2context(fc); |
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struct nfs_server *server = NFS_SB(s); |
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struct nfs_fsinfo fsinfo; |
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struct dentry *root; |
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struct inode *inode; |
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char *name; |
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int error = -ENOMEM; |
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unsigned long kflags = 0, kflags_out = 0; |
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name = kstrdup(fc->source, GFP_KERNEL); |
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if (!name) |
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goto out; |
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/* get the actual root for this mount */ |
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fsinfo.fattr = nfs_alloc_fattr(); |
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if (fsinfo.fattr == NULL) |
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goto out_name; |
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fsinfo.fattr->label = nfs4_label_alloc(server, GFP_KERNEL); |
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if (IS_ERR(fsinfo.fattr->label)) |
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goto out_fattr; |
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error = server->nfs_client->rpc_ops->getroot(server, ctx->mntfh, &fsinfo); |
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if (error < 0) { |
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dprintk("nfs_get_root: getattr error = %d\n", -error); |
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nfs_errorf(fc, "NFS: Couldn't getattr on root"); |
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goto out_label; |
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} |
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inode = nfs_fhget(s, ctx->mntfh, fsinfo.fattr, NULL); |
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if (IS_ERR(inode)) { |
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dprintk("nfs_get_root: get root inode failed\n"); |
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error = PTR_ERR(inode); |
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nfs_errorf(fc, "NFS: Couldn't get root inode"); |
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goto out_label; |
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} |
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error = nfs_superblock_set_dummy_root(s, inode); |
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if (error != 0) |
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goto out_label; |
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/* root dentries normally start off anonymous and get spliced in later |
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* if the dentry tree reaches them; however if the dentry already |
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* exists, we'll pick it up at this point and use it as the root |
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*/ |
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root = d_obtain_root(inode); |
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if (IS_ERR(root)) { |
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dprintk("nfs_get_root: get root dentry failed\n"); |
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error = PTR_ERR(root); |
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nfs_errorf(fc, "NFS: Couldn't get root dentry"); |
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goto out_label; |
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} |
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security_d_instantiate(root, inode); |
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spin_lock(&root->d_lock); |
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if (IS_ROOT(root) && !root->d_fsdata && |
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!(root->d_flags & DCACHE_NFSFS_RENAMED)) { |
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root->d_fsdata = name; |
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name = NULL; |
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} |
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spin_unlock(&root->d_lock); |
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fc->root = root; |
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if (NFS_SB(s)->caps & NFS_CAP_SECURITY_LABEL) |
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kflags |= SECURITY_LSM_NATIVE_LABELS; |
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if (ctx->clone_data.sb) { |
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if (d_inode(fc->root)->i_fop != &nfs_dir_operations) { |
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error = -ESTALE; |
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goto error_splat_root; |
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} |
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/* clone lsm security options from the parent to the new sb */ |
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error = security_sb_clone_mnt_opts(ctx->clone_data.sb, |
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s, kflags, &kflags_out); |
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} else { |
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error = security_sb_set_mnt_opts(s, fc->security, |
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kflags, &kflags_out); |
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} |
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if (error) |
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goto error_splat_root; |
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if (NFS_SB(s)->caps & NFS_CAP_SECURITY_LABEL && |
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!(kflags_out & SECURITY_LSM_NATIVE_LABELS)) |
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NFS_SB(s)->caps &= ~NFS_CAP_SECURITY_LABEL; |
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nfs_setsecurity(inode, fsinfo.fattr, fsinfo.fattr->label); |
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error = 0; |
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out_label: |
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nfs4_label_free(fsinfo.fattr->label); |
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out_fattr: |
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nfs_free_fattr(fsinfo.fattr); |
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out_name: |
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kfree(name); |
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out: |
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return error; |
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error_splat_root: |
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dput(fc->root); |
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fc->root = NULL; |
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goto out_label; |
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}
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