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1254 lines
33 KiB
1254 lines
33 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Copyright (C) 2002,2003 by Andreas Gruenbacher <[email protected]> |
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* |
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* Fixes from William Schumacher incorporated on 15 March 2001. |
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* (Reported by Charles Bertsch, <[email protected]>). |
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*/ |
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|
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/* |
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* This file contains generic functions for manipulating |
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* POSIX 1003.1e draft standard 17 ACLs. |
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*/ |
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|
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#include <linux/kernel.h> |
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#include <linux/slab.h> |
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#include <linux/atomic.h> |
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#include <linux/fs.h> |
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#include <linux/sched.h> |
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#include <linux/cred.h> |
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#include <linux/posix_acl.h> |
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#include <linux/posix_acl_xattr.h> |
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#include <linux/xattr.h> |
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#include <linux/export.h> |
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#include <linux/user_namespace.h> |
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#include <linux/namei.h> |
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#include <linux/mnt_idmapping.h> |
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#include <linux/iversion.h> |
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|
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static struct posix_acl **acl_by_type(struct inode *inode, int type) |
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{ |
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switch (type) { |
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case ACL_TYPE_ACCESS: |
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return &inode->i_acl; |
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case ACL_TYPE_DEFAULT: |
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return &inode->i_default_acl; |
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default: |
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BUG(); |
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} |
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} |
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|
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struct posix_acl *get_cached_acl(struct inode *inode, int type) |
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{ |
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struct posix_acl **p = acl_by_type(inode, type); |
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struct posix_acl *acl; |
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|
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for (;;) { |
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rcu_read_lock(); |
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acl = rcu_dereference(*p); |
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if (!acl || is_uncached_acl(acl) || |
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refcount_inc_not_zero(&acl->a_refcount)) |
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break; |
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rcu_read_unlock(); |
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cpu_relax(); |
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} |
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rcu_read_unlock(); |
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return acl; |
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} |
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EXPORT_SYMBOL(get_cached_acl); |
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|
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struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type) |
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{ |
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struct posix_acl *acl = rcu_dereference(*acl_by_type(inode, type)); |
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|
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if (acl == ACL_DONT_CACHE) { |
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struct posix_acl *ret; |
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|
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ret = inode->i_op->get_acl(inode, type, LOOKUP_RCU); |
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if (!IS_ERR(ret)) |
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acl = ret; |
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} |
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|
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return acl; |
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} |
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EXPORT_SYMBOL(get_cached_acl_rcu); |
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|
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void set_cached_acl(struct inode *inode, int type, struct posix_acl *acl) |
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{ |
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struct posix_acl **p = acl_by_type(inode, type); |
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struct posix_acl *old; |
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|
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old = xchg(p, posix_acl_dup(acl)); |
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if (!is_uncached_acl(old)) |
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posix_acl_release(old); |
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} |
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EXPORT_SYMBOL(set_cached_acl); |
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|
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static void __forget_cached_acl(struct posix_acl **p) |
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{ |
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struct posix_acl *old; |
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|
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old = xchg(p, ACL_NOT_CACHED); |
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if (!is_uncached_acl(old)) |
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posix_acl_release(old); |
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} |
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|
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void forget_cached_acl(struct inode *inode, int type) |
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{ |
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__forget_cached_acl(acl_by_type(inode, type)); |
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} |
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EXPORT_SYMBOL(forget_cached_acl); |
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|
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void forget_all_cached_acls(struct inode *inode) |
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{ |
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__forget_cached_acl(&inode->i_acl); |
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__forget_cached_acl(&inode->i_default_acl); |
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} |
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EXPORT_SYMBOL(forget_all_cached_acls); |
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|
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struct posix_acl *get_acl(struct inode *inode, int type) |
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{ |
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void *sentinel; |
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struct posix_acl **p; |
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struct posix_acl *acl; |
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|
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/* |
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* The sentinel is used to detect when another operation like |
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* set_cached_acl() or forget_cached_acl() races with get_acl(). |
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* It is guaranteed that is_uncached_acl(sentinel) is true. |
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*/ |
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|
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acl = get_cached_acl(inode, type); |
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if (!is_uncached_acl(acl)) |
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return acl; |
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|
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if (!IS_POSIXACL(inode)) |
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return NULL; |
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|
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sentinel = uncached_acl_sentinel(current); |
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p = acl_by_type(inode, type); |
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|
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/* |
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* If the ACL isn't being read yet, set our sentinel. Otherwise, the |
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* current value of the ACL will not be ACL_NOT_CACHED and so our own |
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* sentinel will not be set; another task will update the cache. We |
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* could wait for that other task to complete its job, but it's easier |
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* to just call ->get_acl to fetch the ACL ourself. (This is going to |
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* be an unlikely race.) |
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*/ |
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cmpxchg(p, ACL_NOT_CACHED, sentinel); |
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|
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/* |
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* Normally, the ACL returned by ->get_acl will be cached. |
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* A filesystem can prevent that by calling |
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* forget_cached_acl(inode, type) in ->get_acl. |
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* |
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* If the filesystem doesn't have a get_acl() function at all, we'll |
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* just create the negative cache entry. |
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*/ |
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if (!inode->i_op->get_acl) { |
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set_cached_acl(inode, type, NULL); |
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return NULL; |
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} |
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acl = inode->i_op->get_acl(inode, type, false); |
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|
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if (IS_ERR(acl)) { |
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/* |
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* Remove our sentinel so that we don't block future attempts |
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* to cache the ACL. |
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*/ |
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cmpxchg(p, sentinel, ACL_NOT_CACHED); |
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return acl; |
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} |
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|
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/* |
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* Cache the result, but only if our sentinel is still in place. |
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*/ |
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posix_acl_dup(acl); |
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if (unlikely(cmpxchg(p, sentinel, acl) != sentinel)) |
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posix_acl_release(acl); |
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return acl; |
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} |
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EXPORT_SYMBOL(get_acl); |
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|
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/* |
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* Init a fresh posix_acl |
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*/ |
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void |
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posix_acl_init(struct posix_acl *acl, int count) |
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{ |
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refcount_set(&acl->a_refcount, 1); |
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acl->a_count = count; |
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} |
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EXPORT_SYMBOL(posix_acl_init); |
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|
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/* |
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* Allocate a new ACL with the specified number of entries. |
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*/ |
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struct posix_acl * |
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posix_acl_alloc(int count, gfp_t flags) |
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{ |
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const size_t size = sizeof(struct posix_acl) + |
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count * sizeof(struct posix_acl_entry); |
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struct posix_acl *acl = kmalloc(size, flags); |
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if (acl) |
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posix_acl_init(acl, count); |
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return acl; |
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} |
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EXPORT_SYMBOL(posix_acl_alloc); |
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|
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/* |
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* Clone an ACL. |
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*/ |
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struct posix_acl * |
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posix_acl_clone(const struct posix_acl *acl, gfp_t flags) |
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{ |
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struct posix_acl *clone = NULL; |
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|
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if (acl) { |
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int size = sizeof(struct posix_acl) + acl->a_count * |
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sizeof(struct posix_acl_entry); |
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clone = kmemdup(acl, size, flags); |
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if (clone) |
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refcount_set(&clone->a_refcount, 1); |
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} |
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return clone; |
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} |
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EXPORT_SYMBOL_GPL(posix_acl_clone); |
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|
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/* |
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* Check if an acl is valid. Returns 0 if it is, or -E... otherwise. |
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*/ |
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int |
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posix_acl_valid(struct user_namespace *user_ns, const struct posix_acl *acl) |
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{ |
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const struct posix_acl_entry *pa, *pe; |
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int state = ACL_USER_OBJ; |
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int needs_mask = 0; |
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|
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FOREACH_ACL_ENTRY(pa, acl, pe) { |
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if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE)) |
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return -EINVAL; |
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switch (pa->e_tag) { |
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case ACL_USER_OBJ: |
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if (state == ACL_USER_OBJ) { |
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state = ACL_USER; |
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break; |
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} |
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return -EINVAL; |
|
|
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case ACL_USER: |
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if (state != ACL_USER) |
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return -EINVAL; |
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if (!kuid_has_mapping(user_ns, pa->e_uid)) |
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return -EINVAL; |
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needs_mask = 1; |
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break; |
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|
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case ACL_GROUP_OBJ: |
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if (state == ACL_USER) { |
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state = ACL_GROUP; |
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break; |
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} |
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return -EINVAL; |
|
|
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case ACL_GROUP: |
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if (state != ACL_GROUP) |
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return -EINVAL; |
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if (!kgid_has_mapping(user_ns, pa->e_gid)) |
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return -EINVAL; |
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needs_mask = 1; |
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break; |
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|
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case ACL_MASK: |
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if (state != ACL_GROUP) |
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return -EINVAL; |
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state = ACL_OTHER; |
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break; |
|
|
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case ACL_OTHER: |
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if (state == ACL_OTHER || |
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(state == ACL_GROUP && !needs_mask)) { |
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state = 0; |
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break; |
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} |
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return -EINVAL; |
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|
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default: |
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return -EINVAL; |
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} |
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} |
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if (state == 0) |
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return 0; |
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return -EINVAL; |
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} |
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EXPORT_SYMBOL(posix_acl_valid); |
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|
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/* |
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* Returns 0 if the acl can be exactly represented in the traditional |
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* file mode permission bits, or else 1. Returns -E... on error. |
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*/ |
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int |
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posix_acl_equiv_mode(const struct posix_acl *acl, umode_t *mode_p) |
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{ |
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const struct posix_acl_entry *pa, *pe; |
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umode_t mode = 0; |
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int not_equiv = 0; |
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|
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/* |
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* A null ACL can always be presented as mode bits. |
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*/ |
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if (!acl) |
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return 0; |
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|
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FOREACH_ACL_ENTRY(pa, acl, pe) { |
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switch (pa->e_tag) { |
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case ACL_USER_OBJ: |
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mode |= (pa->e_perm & S_IRWXO) << 6; |
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break; |
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case ACL_GROUP_OBJ: |
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mode |= (pa->e_perm & S_IRWXO) << 3; |
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break; |
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case ACL_OTHER: |
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mode |= pa->e_perm & S_IRWXO; |
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break; |
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case ACL_MASK: |
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mode = (mode & ~S_IRWXG) | |
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((pa->e_perm & S_IRWXO) << 3); |
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not_equiv = 1; |
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break; |
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case ACL_USER: |
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case ACL_GROUP: |
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not_equiv = 1; |
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break; |
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default: |
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return -EINVAL; |
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} |
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} |
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if (mode_p) |
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*mode_p = (*mode_p & ~S_IRWXUGO) | mode; |
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return not_equiv; |
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} |
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EXPORT_SYMBOL(posix_acl_equiv_mode); |
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|
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/* |
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* Create an ACL representing the file mode permission bits of an inode. |
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*/ |
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struct posix_acl * |
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posix_acl_from_mode(umode_t mode, gfp_t flags) |
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{ |
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struct posix_acl *acl = posix_acl_alloc(3, flags); |
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if (!acl) |
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return ERR_PTR(-ENOMEM); |
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|
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acl->a_entries[0].e_tag = ACL_USER_OBJ; |
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acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6; |
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|
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acl->a_entries[1].e_tag = ACL_GROUP_OBJ; |
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acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3; |
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|
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acl->a_entries[2].e_tag = ACL_OTHER; |
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acl->a_entries[2].e_perm = (mode & S_IRWXO); |
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return acl; |
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} |
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EXPORT_SYMBOL(posix_acl_from_mode); |
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|
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/* |
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* Return 0 if current is granted want access to the inode |
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* by the acl. Returns -E... otherwise. |
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*/ |
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int |
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posix_acl_permission(struct user_namespace *mnt_userns, struct inode *inode, |
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const struct posix_acl *acl, int want) |
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{ |
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const struct posix_acl_entry *pa, *pe, *mask_obj; |
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struct user_namespace *fs_userns = i_user_ns(inode); |
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int found = 0; |
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vfsuid_t vfsuid; |
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vfsgid_t vfsgid; |
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|
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want &= MAY_READ | MAY_WRITE | MAY_EXEC; |
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|
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FOREACH_ACL_ENTRY(pa, acl, pe) { |
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switch(pa->e_tag) { |
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case ACL_USER_OBJ: |
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/* (May have been checked already) */ |
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vfsuid = i_uid_into_vfsuid(mnt_userns, inode); |
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if (vfsuid_eq_kuid(vfsuid, current_fsuid())) |
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goto check_perm; |
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break; |
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case ACL_USER: |
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vfsuid = make_vfsuid(mnt_userns, fs_userns, |
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pa->e_uid); |
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if (vfsuid_eq_kuid(vfsuid, current_fsuid())) |
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goto mask; |
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break; |
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case ACL_GROUP_OBJ: |
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vfsgid = i_gid_into_vfsgid(mnt_userns, inode); |
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if (vfsgid_in_group_p(vfsgid)) { |
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found = 1; |
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if ((pa->e_perm & want) == want) |
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goto mask; |
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} |
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break; |
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case ACL_GROUP: |
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vfsgid = make_vfsgid(mnt_userns, fs_userns, |
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pa->e_gid); |
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if (vfsgid_in_group_p(vfsgid)) { |
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found = 1; |
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if ((pa->e_perm & want) == want) |
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goto mask; |
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} |
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break; |
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case ACL_MASK: |
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break; |
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case ACL_OTHER: |
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if (found) |
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return -EACCES; |
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else |
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goto check_perm; |
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default: |
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return -EIO; |
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} |
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} |
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return -EIO; |
|
|
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mask: |
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for (mask_obj = pa+1; mask_obj != pe; mask_obj++) { |
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if (mask_obj->e_tag == ACL_MASK) { |
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if ((pa->e_perm & mask_obj->e_perm & want) == want) |
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return 0; |
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return -EACCES; |
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} |
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} |
|
|
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check_perm: |
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if ((pa->e_perm & want) == want) |
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return 0; |
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return -EACCES; |
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} |
|
|
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/* |
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* Modify acl when creating a new inode. The caller must ensure the acl is |
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* only referenced once. |
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* |
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* mode_p initially must contain the mode parameter to the open() / creat() |
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* system calls. All permissions that are not granted by the acl are removed. |
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* The permissions in the acl are changed to reflect the mode_p parameter. |
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*/ |
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static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p) |
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{ |
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struct posix_acl_entry *pa, *pe; |
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struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL; |
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umode_t mode = *mode_p; |
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int not_equiv = 0; |
|
|
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/* assert(atomic_read(acl->a_refcount) == 1); */ |
|
|
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FOREACH_ACL_ENTRY(pa, acl, pe) { |
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switch(pa->e_tag) { |
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case ACL_USER_OBJ: |
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pa->e_perm &= (mode >> 6) | ~S_IRWXO; |
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mode &= (pa->e_perm << 6) | ~S_IRWXU; |
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break; |
|
|
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case ACL_USER: |
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case ACL_GROUP: |
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not_equiv = 1; |
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break; |
|
|
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case ACL_GROUP_OBJ: |
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group_obj = pa; |
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break; |
|
|
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case ACL_OTHER: |
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pa->e_perm &= mode | ~S_IRWXO; |
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mode &= pa->e_perm | ~S_IRWXO; |
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break; |
|
|
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case ACL_MASK: |
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mask_obj = pa; |
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not_equiv = 1; |
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break; |
|
|
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default: |
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return -EIO; |
|
} |
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} |
|
|
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if (mask_obj) { |
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mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO; |
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mode &= (mask_obj->e_perm << 3) | ~S_IRWXG; |
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} else { |
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if (!group_obj) |
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return -EIO; |
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group_obj->e_perm &= (mode >> 3) | ~S_IRWXO; |
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mode &= (group_obj->e_perm << 3) | ~S_IRWXG; |
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} |
|
|
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*mode_p = (*mode_p & ~S_IRWXUGO) | mode; |
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return not_equiv; |
|
} |
|
|
|
/* |
|
* Modify the ACL for the chmod syscall. |
|
*/ |
|
static int __posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode) |
|
{ |
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struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL; |
|
struct posix_acl_entry *pa, *pe; |
|
|
|
/* assert(atomic_read(acl->a_refcount) == 1); */ |
|
|
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FOREACH_ACL_ENTRY(pa, acl, pe) { |
|
switch(pa->e_tag) { |
|
case ACL_USER_OBJ: |
|
pa->e_perm = (mode & S_IRWXU) >> 6; |
|
break; |
|
|
|
case ACL_USER: |
|
case ACL_GROUP: |
|
break; |
|
|
|
case ACL_GROUP_OBJ: |
|
group_obj = pa; |
|
break; |
|
|
|
case ACL_MASK: |
|
mask_obj = pa; |
|
break; |
|
|
|
case ACL_OTHER: |
|
pa->e_perm = (mode & S_IRWXO); |
|
break; |
|
|
|
default: |
|
return -EIO; |
|
} |
|
} |
|
|
|
if (mask_obj) { |
|
mask_obj->e_perm = (mode & S_IRWXG) >> 3; |
|
} else { |
|
if (!group_obj) |
|
return -EIO; |
|
group_obj->e_perm = (mode & S_IRWXG) >> 3; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
int |
|
__posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p) |
|
{ |
|
struct posix_acl *clone = posix_acl_clone(*acl, gfp); |
|
int err = -ENOMEM; |
|
if (clone) { |
|
err = posix_acl_create_masq(clone, mode_p); |
|
if (err < 0) { |
|
posix_acl_release(clone); |
|
clone = NULL; |
|
} |
|
} |
|
posix_acl_release(*acl); |
|
*acl = clone; |
|
return err; |
|
} |
|
EXPORT_SYMBOL(__posix_acl_create); |
|
|
|
int |
|
__posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode) |
|
{ |
|
struct posix_acl *clone = posix_acl_clone(*acl, gfp); |
|
int err = -ENOMEM; |
|
if (clone) { |
|
err = __posix_acl_chmod_masq(clone, mode); |
|
if (err) { |
|
posix_acl_release(clone); |
|
clone = NULL; |
|
} |
|
} |
|
posix_acl_release(*acl); |
|
*acl = clone; |
|
return err; |
|
} |
|
EXPORT_SYMBOL(__posix_acl_chmod); |
|
|
|
/** |
|
* posix_acl_chmod - chmod a posix acl |
|
* |
|
* @mnt_userns: user namespace of the mount @inode was found from |
|
* @inode: inode to check permissions on |
|
* @mode: the new mode of @inode |
|
* |
|
* If the inode has been found through an idmapped mount the user namespace of |
|
* the vfsmount must be passed through @mnt_userns. This function will then |
|
* take care to map the inode according to @mnt_userns before checking |
|
* permissions. On non-idmapped mounts or if permission checking is to be |
|
* performed on the raw inode simply passs init_user_ns. |
|
*/ |
|
int |
|
posix_acl_chmod(struct user_namespace *mnt_userns, struct inode *inode, |
|
umode_t mode) |
|
{ |
|
struct posix_acl *acl; |
|
int ret = 0; |
|
|
|
if (!IS_POSIXACL(inode)) |
|
return 0; |
|
if (!inode->i_op->set_acl) |
|
return -EOPNOTSUPP; |
|
|
|
acl = get_acl(inode, ACL_TYPE_ACCESS); |
|
if (IS_ERR_OR_NULL(acl)) { |
|
if (acl == ERR_PTR(-EOPNOTSUPP)) |
|
return 0; |
|
return PTR_ERR(acl); |
|
} |
|
|
|
ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode); |
|
if (ret) |
|
return ret; |
|
ret = inode->i_op->set_acl(mnt_userns, inode, acl, ACL_TYPE_ACCESS); |
|
posix_acl_release(acl); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL(posix_acl_chmod); |
|
|
|
int |
|
posix_acl_create(struct inode *dir, umode_t *mode, |
|
struct posix_acl **default_acl, struct posix_acl **acl) |
|
{ |
|
struct posix_acl *p; |
|
struct posix_acl *clone; |
|
int ret; |
|
|
|
*acl = NULL; |
|
*default_acl = NULL; |
|
|
|
if (S_ISLNK(*mode) || !IS_POSIXACL(dir)) |
|
return 0; |
|
|
|
p = get_acl(dir, ACL_TYPE_DEFAULT); |
|
if (!p || p == ERR_PTR(-EOPNOTSUPP)) { |
|
*mode &= ~current_umask(); |
|
return 0; |
|
} |
|
if (IS_ERR(p)) |
|
return PTR_ERR(p); |
|
|
|
ret = -ENOMEM; |
|
clone = posix_acl_clone(p, GFP_NOFS); |
|
if (!clone) |
|
goto err_release; |
|
|
|
ret = posix_acl_create_masq(clone, mode); |
|
if (ret < 0) |
|
goto err_release_clone; |
|
|
|
if (ret == 0) |
|
posix_acl_release(clone); |
|
else |
|
*acl = clone; |
|
|
|
if (!S_ISDIR(*mode)) |
|
posix_acl_release(p); |
|
else |
|
*default_acl = p; |
|
|
|
return 0; |
|
|
|
err_release_clone: |
|
posix_acl_release(clone); |
|
err_release: |
|
posix_acl_release(p); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(posix_acl_create); |
|
|
|
/** |
|
* posix_acl_update_mode - update mode in set_acl |
|
* @mnt_userns: user namespace of the mount @inode was found from |
|
* @inode: target inode |
|
* @mode_p: mode (pointer) for update |
|
* @acl: acl pointer |
|
* |
|
* Update the file mode when setting an ACL: compute the new file permission |
|
* bits based on the ACL. In addition, if the ACL is equivalent to the new |
|
* file mode, set *@acl to NULL to indicate that no ACL should be set. |
|
* |
|
* As with chmod, clear the setgid bit if the caller is not in the owning group |
|
* or capable of CAP_FSETID (see inode_change_ok). |
|
* |
|
* If the inode has been found through an idmapped mount the user namespace of |
|
* the vfsmount must be passed through @mnt_userns. This function will then |
|
* take care to map the inode according to @mnt_userns before checking |
|
* permissions. On non-idmapped mounts or if permission checking is to be |
|
* performed on the raw inode simply passs init_user_ns. |
|
* |
|
* Called from set_acl inode operations. |
|
*/ |
|
int posix_acl_update_mode(struct user_namespace *mnt_userns, |
|
struct inode *inode, umode_t *mode_p, |
|
struct posix_acl **acl) |
|
{ |
|
umode_t mode = inode->i_mode; |
|
int error; |
|
|
|
error = posix_acl_equiv_mode(*acl, &mode); |
|
if (error < 0) |
|
return error; |
|
if (error == 0) |
|
*acl = NULL; |
|
if (!vfsgid_in_group_p(i_gid_into_vfsgid(mnt_userns, inode)) && |
|
!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID)) |
|
mode &= ~S_ISGID; |
|
*mode_p = mode; |
|
return 0; |
|
} |
|
EXPORT_SYMBOL(posix_acl_update_mode); |
|
|
|
/* |
|
* Fix up the uids and gids in posix acl extended attributes in place. |
|
*/ |
|
static int posix_acl_fix_xattr_common(const void *value, size_t size) |
|
{ |
|
const struct posix_acl_xattr_header *header = value; |
|
int count; |
|
|
|
if (!header) |
|
return -EINVAL; |
|
if (size < sizeof(struct posix_acl_xattr_header)) |
|
return -EINVAL; |
|
if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION)) |
|
return -EOPNOTSUPP; |
|
|
|
count = posix_acl_xattr_count(size); |
|
if (count < 0) |
|
return -EINVAL; |
|
if (count == 0) |
|
return 0; |
|
|
|
return count; |
|
} |
|
|
|
void posix_acl_getxattr_idmapped_mnt(struct user_namespace *mnt_userns, |
|
const struct inode *inode, |
|
void *value, size_t size) |
|
{ |
|
struct posix_acl_xattr_header *header = value; |
|
struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end; |
|
struct user_namespace *fs_userns = i_user_ns(inode); |
|
int count; |
|
vfsuid_t vfsuid; |
|
vfsgid_t vfsgid; |
|
kuid_t uid; |
|
kgid_t gid; |
|
|
|
if (no_idmapping(mnt_userns, i_user_ns(inode))) |
|
return; |
|
|
|
count = posix_acl_fix_xattr_common(value, size); |
|
if (count <= 0) |
|
return; |
|
|
|
for (end = entry + count; entry != end; entry++) { |
|
switch (le16_to_cpu(entry->e_tag)) { |
|
case ACL_USER: |
|
uid = make_kuid(&init_user_ns, le32_to_cpu(entry->e_id)); |
|
vfsuid = make_vfsuid(mnt_userns, fs_userns, uid); |
|
entry->e_id = cpu_to_le32(from_kuid(&init_user_ns, |
|
vfsuid_into_kuid(vfsuid))); |
|
break; |
|
case ACL_GROUP: |
|
gid = make_kgid(&init_user_ns, le32_to_cpu(entry->e_id)); |
|
vfsgid = make_vfsgid(mnt_userns, fs_userns, gid); |
|
entry->e_id = cpu_to_le32(from_kgid(&init_user_ns, |
|
vfsgid_into_kgid(vfsgid))); |
|
break; |
|
default: |
|
break; |
|
} |
|
} |
|
} |
|
|
|
static void posix_acl_fix_xattr_userns( |
|
struct user_namespace *to, struct user_namespace *from, |
|
void *value, size_t size) |
|
{ |
|
struct posix_acl_xattr_header *header = value; |
|
struct posix_acl_xattr_entry *entry = (void *)(header + 1), *end; |
|
int count; |
|
kuid_t uid; |
|
kgid_t gid; |
|
|
|
count = posix_acl_fix_xattr_common(value, size); |
|
if (count <= 0) |
|
return; |
|
|
|
for (end = entry + count; entry != end; entry++) { |
|
switch(le16_to_cpu(entry->e_tag)) { |
|
case ACL_USER: |
|
uid = make_kuid(from, le32_to_cpu(entry->e_id)); |
|
entry->e_id = cpu_to_le32(from_kuid(to, uid)); |
|
break; |
|
case ACL_GROUP: |
|
gid = make_kgid(from, le32_to_cpu(entry->e_id)); |
|
entry->e_id = cpu_to_le32(from_kgid(to, gid)); |
|
break; |
|
default: |
|
break; |
|
} |
|
} |
|
} |
|
|
|
void posix_acl_fix_xattr_from_user(void *value, size_t size) |
|
{ |
|
struct user_namespace *user_ns = current_user_ns(); |
|
if (user_ns == &init_user_ns) |
|
return; |
|
posix_acl_fix_xattr_userns(&init_user_ns, user_ns, value, size); |
|
} |
|
|
|
void posix_acl_fix_xattr_to_user(void *value, size_t size) |
|
{ |
|
struct user_namespace *user_ns = current_user_ns(); |
|
if (user_ns == &init_user_ns) |
|
return; |
|
posix_acl_fix_xattr_userns(user_ns, &init_user_ns, value, size); |
|
} |
|
|
|
/** |
|
* make_posix_acl - convert POSIX ACLs from uapi to VFS format using the |
|
* provided callbacks to map ACL_{GROUP,USER} entries into the |
|
* appropriate format |
|
* @mnt_userns: the mount's idmapping |
|
* @fs_userns: the filesystem's idmapping |
|
* @value: the uapi representation of POSIX ACLs |
|
* @size: the size of @void |
|
* @uid_cb: callback to use for mapping the uid stored in ACL_USER entries |
|
* @gid_cb: callback to use for mapping the gid stored in ACL_GROUP entries |
|
* |
|
* The make_posix_acl() helper is an abstraction to translate from uapi format |
|
* into the VFS format allowing the caller to specific callbacks to map |
|
* ACL_{GROUP,USER} entries into the expected format. This is used in |
|
* posix_acl_from_xattr() and vfs_set_acl_prepare() and avoids pointless code |
|
* duplication. |
|
* |
|
* Return: Allocated struct posix_acl on success, NULL for a valid header but |
|
* without actual POSIX ACL entries, or ERR_PTR() encoded error code. |
|
*/ |
|
static struct posix_acl *make_posix_acl(struct user_namespace *mnt_userns, |
|
struct user_namespace *fs_userns, const void *value, size_t size, |
|
kuid_t (*uid_cb)(struct user_namespace *, struct user_namespace *, |
|
const struct posix_acl_xattr_entry *), |
|
kgid_t (*gid_cb)(struct user_namespace *, struct user_namespace *, |
|
const struct posix_acl_xattr_entry *)) |
|
{ |
|
const struct posix_acl_xattr_header *header = value; |
|
const struct posix_acl_xattr_entry *entry = (const void *)(header + 1), *end; |
|
int count; |
|
struct posix_acl *acl; |
|
struct posix_acl_entry *acl_e; |
|
|
|
count = posix_acl_fix_xattr_common(value, size); |
|
if (count < 0) |
|
return ERR_PTR(count); |
|
if (count == 0) |
|
return NULL; |
|
|
|
acl = posix_acl_alloc(count, GFP_NOFS); |
|
if (!acl) |
|
return ERR_PTR(-ENOMEM); |
|
acl_e = acl->a_entries; |
|
|
|
for (end = entry + count; entry != end; acl_e++, entry++) { |
|
acl_e->e_tag = le16_to_cpu(entry->e_tag); |
|
acl_e->e_perm = le16_to_cpu(entry->e_perm); |
|
|
|
switch(acl_e->e_tag) { |
|
case ACL_USER_OBJ: |
|
case ACL_GROUP_OBJ: |
|
case ACL_MASK: |
|
case ACL_OTHER: |
|
break; |
|
|
|
case ACL_USER: |
|
acl_e->e_uid = uid_cb(mnt_userns, fs_userns, entry); |
|
if (!uid_valid(acl_e->e_uid)) |
|
goto fail; |
|
break; |
|
case ACL_GROUP: |
|
acl_e->e_gid = gid_cb(mnt_userns, fs_userns, entry); |
|
if (!gid_valid(acl_e->e_gid)) |
|
goto fail; |
|
break; |
|
|
|
default: |
|
goto fail; |
|
} |
|
} |
|
return acl; |
|
|
|
fail: |
|
posix_acl_release(acl); |
|
return ERR_PTR(-EINVAL); |
|
} |
|
|
|
/** |
|
* vfs_set_acl_prepare_kuid - map ACL_USER uid according to mount- and |
|
* filesystem idmapping |
|
* @mnt_userns: the mount's idmapping |
|
* @fs_userns: the filesystem's idmapping |
|
* @e: a ACL_USER entry in POSIX ACL uapi format |
|
* |
|
* The uid stored as ACL_USER entry in @e is a kuid_t stored as a raw {g,u}id |
|
* value. The vfs_set_acl_prepare_kuid() will recover the kuid_t through |
|
* KUIDT_INIT() and then map it according to the idmapped mount. The resulting |
|
* kuid_t is the value which the filesystem can map up into a raw backing store |
|
* id in the filesystem's idmapping. |
|
* |
|
* This is used in vfs_set_acl_prepare() to generate the proper VFS |
|
* representation of POSIX ACLs with ACL_USER entries during setxattr(). |
|
* |
|
* Return: A kuid in @fs_userns for the uid stored in @e. |
|
*/ |
|
static inline kuid_t |
|
vfs_set_acl_prepare_kuid(struct user_namespace *mnt_userns, |
|
struct user_namespace *fs_userns, |
|
const struct posix_acl_xattr_entry *e) |
|
{ |
|
kuid_t kuid = KUIDT_INIT(le32_to_cpu(e->e_id)); |
|
return from_vfsuid(mnt_userns, fs_userns, VFSUIDT_INIT(kuid)); |
|
} |
|
|
|
/** |
|
* vfs_set_acl_prepare_kgid - map ACL_GROUP gid according to mount- and |
|
* filesystem idmapping |
|
* @mnt_userns: the mount's idmapping |
|
* @fs_userns: the filesystem's idmapping |
|
* @e: a ACL_GROUP entry in POSIX ACL uapi format |
|
* |
|
* The gid stored as ACL_GROUP entry in @e is a kgid_t stored as a raw {g,u}id |
|
* value. The vfs_set_acl_prepare_kgid() will recover the kgid_t through |
|
* KGIDT_INIT() and then map it according to the idmapped mount. The resulting |
|
* kgid_t is the value which the filesystem can map up into a raw backing store |
|
* id in the filesystem's idmapping. |
|
* |
|
* This is used in vfs_set_acl_prepare() to generate the proper VFS |
|
* representation of POSIX ACLs with ACL_GROUP entries during setxattr(). |
|
* |
|
* Return: A kgid in @fs_userns for the gid stored in @e. |
|
*/ |
|
static inline kgid_t |
|
vfs_set_acl_prepare_kgid(struct user_namespace *mnt_userns, |
|
struct user_namespace *fs_userns, |
|
const struct posix_acl_xattr_entry *e) |
|
{ |
|
kgid_t kgid = KGIDT_INIT(le32_to_cpu(e->e_id)); |
|
return from_vfsgid(mnt_userns, fs_userns, VFSGIDT_INIT(kgid)); |
|
} |
|
|
|
/** |
|
* vfs_set_acl_prepare - convert POSIX ACLs from uapi to VFS format taking |
|
* mount and filesystem idmappings into account |
|
* @mnt_userns: the mount's idmapping |
|
* @fs_userns: the filesystem's idmapping |
|
* @value: the uapi representation of POSIX ACLs |
|
* @size: the size of @void |
|
* |
|
* When setting POSIX ACLs with ACL_{GROUP,USER} entries they need to be |
|
* mapped according to the relevant mount- and filesystem idmapping. It is |
|
* important that the ACL_{GROUP,USER} entries in struct posix_acl will be |
|
* mapped into k{g,u}id_t that are supposed to be mapped up in the filesystem |
|
* idmapping. This is crucial since the resulting struct posix_acl might be |
|
* cached filesystem wide. The vfs_set_acl_prepare() function will take care to |
|
* perform all necessary idmappings. |
|
* |
|
* Note, that since basically forever the {g,u}id values encoded as |
|
* ACL_{GROUP,USER} entries in the uapi POSIX ACLs passed via @value contain |
|
* values that have been mapped according to the caller's idmapping. In other |
|
* words, POSIX ACLs passed in uapi format as @value during setxattr() contain |
|
* {g,u}id values in their ACL_{GROUP,USER} entries that should actually have |
|
* been stored as k{g,u}id_t. |
|
* |
|
* This means, vfs_set_acl_prepare() needs to first recover the k{g,u}id_t by |
|
* calling K{G,U}IDT_INIT(). Afterwards they can be interpreted as vfs{g,u}id_t |
|
* through from_vfs{g,u}id() to account for any idmapped mounts. The |
|
* vfs_set_acl_prepare_k{g,u}id() helpers will take care to generate the |
|
* correct k{g,u}id_t. |
|
* |
|
* The filesystem will then receive the POSIX ACLs ready to be cached |
|
* filesystem wide and ready to be written to the backing store taking the |
|
* filesystem's idmapping into account. |
|
* |
|
* Return: Allocated struct posix_acl on success, NULL for a valid header but |
|
* without actual POSIX ACL entries, or ERR_PTR() encoded error code. |
|
*/ |
|
struct posix_acl *vfs_set_acl_prepare(struct user_namespace *mnt_userns, |
|
struct user_namespace *fs_userns, |
|
const void *value, size_t size) |
|
{ |
|
return make_posix_acl(mnt_userns, fs_userns, value, size, |
|
vfs_set_acl_prepare_kuid, |
|
vfs_set_acl_prepare_kgid); |
|
} |
|
EXPORT_SYMBOL(vfs_set_acl_prepare); |
|
|
|
/** |
|
* posix_acl_from_xattr_kuid - map ACL_USER uid into filesystem idmapping |
|
* @mnt_userns: unused |
|
* @fs_userns: the filesystem's idmapping |
|
* @e: a ACL_USER entry in POSIX ACL uapi format |
|
* |
|
* Map the uid stored as ACL_USER entry in @e into the filesystem's idmapping. |
|
* This is used in posix_acl_from_xattr() to generate the proper VFS |
|
* representation of POSIX ACLs with ACL_USER entries. |
|
* |
|
* Return: A kuid in @fs_userns for the uid stored in @e. |
|
*/ |
|
static inline kuid_t |
|
posix_acl_from_xattr_kuid(struct user_namespace *mnt_userns, |
|
struct user_namespace *fs_userns, |
|
const struct posix_acl_xattr_entry *e) |
|
{ |
|
return make_kuid(fs_userns, le32_to_cpu(e->e_id)); |
|
} |
|
|
|
/** |
|
* posix_acl_from_xattr_kgid - map ACL_GROUP gid into filesystem idmapping |
|
* @mnt_userns: unused |
|
* @fs_userns: the filesystem's idmapping |
|
* @e: a ACL_GROUP entry in POSIX ACL uapi format |
|
* |
|
* Map the gid stored as ACL_GROUP entry in @e into the filesystem's idmapping. |
|
* This is used in posix_acl_from_xattr() to generate the proper VFS |
|
* representation of POSIX ACLs with ACL_GROUP entries. |
|
* |
|
* Return: A kgid in @fs_userns for the gid stored in @e. |
|
*/ |
|
static inline kgid_t |
|
posix_acl_from_xattr_kgid(struct user_namespace *mnt_userns, |
|
struct user_namespace *fs_userns, |
|
const struct posix_acl_xattr_entry *e) |
|
{ |
|
return make_kgid(fs_userns, le32_to_cpu(e->e_id)); |
|
} |
|
|
|
/** |
|
* posix_acl_from_xattr - convert POSIX ACLs from backing store to VFS format |
|
* @fs_userns: the filesystem's idmapping |
|
* @value: the uapi representation of POSIX ACLs |
|
* @size: the size of @void |
|
* |
|
* Filesystems that store POSIX ACLs in the unaltered uapi format should use |
|
* posix_acl_from_xattr() when reading them from the backing store and |
|
* converting them into the struct posix_acl VFS format. The helper is |
|
* specifically intended to be called from the ->get_acl() inode operation. |
|
* |
|
* The posix_acl_from_xattr() function will map the raw {g,u}id values stored |
|
* in ACL_{GROUP,USER} entries into the filesystem idmapping in @fs_userns. The |
|
* posix_acl_from_xattr_k{g,u}id() helpers will take care to generate the |
|
* correct k{g,u}id_t. The returned struct posix_acl can be cached. |
|
* |
|
* Note that posix_acl_from_xattr() does not take idmapped mounts into account. |
|
* If it did it calling is from the ->get_acl() inode operation would return |
|
* POSIX ACLs mapped according to an idmapped mount which would mean that the |
|
* value couldn't be cached for the filesystem. Idmapped mounts are taken into |
|
* account on the fly during permission checking or right at the VFS - |
|
* userspace boundary before reporting them to the user. |
|
* |
|
* Return: Allocated struct posix_acl on success, NULL for a valid header but |
|
* without actual POSIX ACL entries, or ERR_PTR() encoded error code. |
|
*/ |
|
struct posix_acl * |
|
posix_acl_from_xattr(struct user_namespace *fs_userns, |
|
const void *value, size_t size) |
|
{ |
|
return make_posix_acl(&init_user_ns, fs_userns, value, size, |
|
posix_acl_from_xattr_kuid, |
|
posix_acl_from_xattr_kgid); |
|
} |
|
EXPORT_SYMBOL (posix_acl_from_xattr); |
|
|
|
/* |
|
* Convert from in-memory to extended attribute representation. |
|
*/ |
|
int |
|
posix_acl_to_xattr(struct user_namespace *user_ns, const struct posix_acl *acl, |
|
void *buffer, size_t size) |
|
{ |
|
struct posix_acl_xattr_header *ext_acl = buffer; |
|
struct posix_acl_xattr_entry *ext_entry; |
|
int real_size, n; |
|
|
|
real_size = posix_acl_xattr_size(acl->a_count); |
|
if (!buffer) |
|
return real_size; |
|
if (real_size > size) |
|
return -ERANGE; |
|
|
|
ext_entry = (void *)(ext_acl + 1); |
|
ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION); |
|
|
|
for (n=0; n < acl->a_count; n++, ext_entry++) { |
|
const struct posix_acl_entry *acl_e = &acl->a_entries[n]; |
|
ext_entry->e_tag = cpu_to_le16(acl_e->e_tag); |
|
ext_entry->e_perm = cpu_to_le16(acl_e->e_perm); |
|
switch(acl_e->e_tag) { |
|
case ACL_USER: |
|
ext_entry->e_id = |
|
cpu_to_le32(from_kuid(user_ns, acl_e->e_uid)); |
|
break; |
|
case ACL_GROUP: |
|
ext_entry->e_id = |
|
cpu_to_le32(from_kgid(user_ns, acl_e->e_gid)); |
|
break; |
|
default: |
|
ext_entry->e_id = cpu_to_le32(ACL_UNDEFINED_ID); |
|
break; |
|
} |
|
} |
|
return real_size; |
|
} |
|
EXPORT_SYMBOL (posix_acl_to_xattr); |
|
|
|
static int |
|
posix_acl_xattr_get(const struct xattr_handler *handler, |
|
struct dentry *unused, struct inode *inode, |
|
const char *name, void *value, size_t size) |
|
{ |
|
struct posix_acl *acl; |
|
int error; |
|
|
|
if (!IS_POSIXACL(inode)) |
|
return -EOPNOTSUPP; |
|
if (S_ISLNK(inode->i_mode)) |
|
return -EOPNOTSUPP; |
|
|
|
acl = get_acl(inode, handler->flags); |
|
if (IS_ERR(acl)) |
|
return PTR_ERR(acl); |
|
if (acl == NULL) |
|
return -ENODATA; |
|
|
|
error = posix_acl_to_xattr(&init_user_ns, acl, value, size); |
|
posix_acl_release(acl); |
|
|
|
return error; |
|
} |
|
|
|
int |
|
set_posix_acl(struct user_namespace *mnt_userns, struct inode *inode, |
|
int type, struct posix_acl *acl) |
|
{ |
|
if (!IS_POSIXACL(inode)) |
|
return -EOPNOTSUPP; |
|
if (!inode->i_op->set_acl) |
|
return -EOPNOTSUPP; |
|
|
|
if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) |
|
return acl ? -EACCES : 0; |
|
if (!inode_owner_or_capable(mnt_userns, inode)) |
|
return -EPERM; |
|
|
|
if (acl) { |
|
int ret = posix_acl_valid(inode->i_sb->s_user_ns, acl); |
|
if (ret) |
|
return ret; |
|
} |
|
return inode->i_op->set_acl(mnt_userns, inode, acl, type); |
|
} |
|
EXPORT_SYMBOL(set_posix_acl); |
|
|
|
static int |
|
posix_acl_xattr_set(const struct xattr_handler *handler, |
|
struct user_namespace *mnt_userns, |
|
struct dentry *unused, struct inode *inode, |
|
const char *name, const void *value, size_t size, |
|
int flags) |
|
{ |
|
struct posix_acl *acl = NULL; |
|
int ret; |
|
|
|
if (value) { |
|
/* |
|
* By the time we end up here the {g,u}ids stored in |
|
* ACL_{GROUP,USER} have already been mapped according to the |
|
* caller's idmapping. The vfs_set_acl_prepare() helper will |
|
* recover them and take idmapped mounts into account. The |
|
* filesystem will receive the POSIX ACLs in the correct |
|
* format ready to be cached or written to the backing store |
|
* taking the filesystem idmapping into account. |
|
*/ |
|
acl = vfs_set_acl_prepare(mnt_userns, i_user_ns(inode), |
|
value, size); |
|
if (IS_ERR(acl)) |
|
return PTR_ERR(acl); |
|
} |
|
ret = set_posix_acl(mnt_userns, inode, handler->flags, acl); |
|
posix_acl_release(acl); |
|
return ret; |
|
} |
|
|
|
static bool |
|
posix_acl_xattr_list(struct dentry *dentry) |
|
{ |
|
return IS_POSIXACL(d_backing_inode(dentry)); |
|
} |
|
|
|
const struct xattr_handler posix_acl_access_xattr_handler = { |
|
.name = XATTR_NAME_POSIX_ACL_ACCESS, |
|
.flags = ACL_TYPE_ACCESS, |
|
.list = posix_acl_xattr_list, |
|
.get = posix_acl_xattr_get, |
|
.set = posix_acl_xattr_set, |
|
}; |
|
EXPORT_SYMBOL_GPL(posix_acl_access_xattr_handler); |
|
|
|
const struct xattr_handler posix_acl_default_xattr_handler = { |
|
.name = XATTR_NAME_POSIX_ACL_DEFAULT, |
|
.flags = ACL_TYPE_DEFAULT, |
|
.list = posix_acl_xattr_list, |
|
.get = posix_acl_xattr_get, |
|
.set = posix_acl_xattr_set, |
|
}; |
|
EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler); |
|
|
|
int simple_set_acl(struct user_namespace *mnt_userns, struct inode *inode, |
|
struct posix_acl *acl, int type) |
|
{ |
|
int error; |
|
|
|
if (type == ACL_TYPE_ACCESS) { |
|
error = posix_acl_update_mode(mnt_userns, inode, |
|
&inode->i_mode, &acl); |
|
if (error) |
|
return error; |
|
} |
|
|
|
inode->i_ctime = current_time(inode); |
|
if (IS_I_VERSION(inode)) |
|
inode_inc_iversion(inode); |
|
set_cached_acl(inode, type, acl); |
|
return 0; |
|
} |
|
|
|
int simple_acl_create(struct inode *dir, struct inode *inode) |
|
{ |
|
struct posix_acl *default_acl, *acl; |
|
int error; |
|
|
|
error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl); |
|
if (error) |
|
return error; |
|
|
|
set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl); |
|
set_cached_acl(inode, ACL_TYPE_ACCESS, acl); |
|
|
|
if (default_acl) |
|
posix_acl_release(default_acl); |
|
if (acl) |
|
posix_acl_release(acl); |
|
return 0; |
|
}
|
|
|