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![Christoph Hellwig](/assets/img/avatar_default.png)
This prevents in-memory corruption and possible panics if the on-disk ACL is badly corrupted. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ben Myers <bpm@sgi.com>
422 lines
8.7 KiB
C
422 lines
8.7 KiB
C
/*
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* Copyright (c) 2008, Christoph Hellwig
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* All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "xfs.h"
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#include "xfs_acl.h"
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#include "xfs_attr.h"
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#include "xfs_bmap_btree.h"
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#include "xfs_inode.h"
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#include "xfs_vnodeops.h"
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#include "xfs_trace.h"
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#include <linux/slab.h>
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#include <linux/xattr.h>
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#include <linux/posix_acl_xattr.h>
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/*
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* Locking scheme:
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* - all ACL updates are protected by inode->i_mutex, which is taken before
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* calling into this file.
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*/
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STATIC struct posix_acl *
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xfs_acl_from_disk(struct xfs_acl *aclp)
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{
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struct posix_acl_entry *acl_e;
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struct posix_acl *acl;
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struct xfs_acl_entry *ace;
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int count, i;
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count = be32_to_cpu(aclp->acl_cnt);
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if (count > XFS_ACL_MAX_ENTRIES)
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return ERR_PTR(-EFSCORRUPTED);
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acl = posix_acl_alloc(count, GFP_KERNEL);
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if (!acl)
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return ERR_PTR(-ENOMEM);
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for (i = 0; i < count; i++) {
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acl_e = &acl->a_entries[i];
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ace = &aclp->acl_entry[i];
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/*
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* The tag is 32 bits on disk and 16 bits in core.
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*
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* Because every access to it goes through the core
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* format first this is not a problem.
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*/
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acl_e->e_tag = be32_to_cpu(ace->ae_tag);
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acl_e->e_perm = be16_to_cpu(ace->ae_perm);
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switch (acl_e->e_tag) {
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case ACL_USER:
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case ACL_GROUP:
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acl_e->e_id = be32_to_cpu(ace->ae_id);
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break;
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case ACL_USER_OBJ:
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case ACL_GROUP_OBJ:
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case ACL_MASK:
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case ACL_OTHER:
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acl_e->e_id = ACL_UNDEFINED_ID;
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break;
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default:
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goto fail;
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}
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}
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return acl;
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fail:
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posix_acl_release(acl);
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return ERR_PTR(-EINVAL);
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}
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STATIC void
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xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
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{
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const struct posix_acl_entry *acl_e;
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struct xfs_acl_entry *ace;
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int i;
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aclp->acl_cnt = cpu_to_be32(acl->a_count);
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for (i = 0; i < acl->a_count; i++) {
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ace = &aclp->acl_entry[i];
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acl_e = &acl->a_entries[i];
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ace->ae_tag = cpu_to_be32(acl_e->e_tag);
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ace->ae_id = cpu_to_be32(acl_e->e_id);
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ace->ae_perm = cpu_to_be16(acl_e->e_perm);
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}
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}
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struct posix_acl *
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xfs_get_acl(struct inode *inode, int type)
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{
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struct xfs_inode *ip = XFS_I(inode);
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struct posix_acl *acl;
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struct xfs_acl *xfs_acl;
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int len = sizeof(struct xfs_acl);
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unsigned char *ea_name;
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int error;
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acl = get_cached_acl(inode, type);
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if (acl != ACL_NOT_CACHED)
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return acl;
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trace_xfs_get_acl(ip);
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switch (type) {
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case ACL_TYPE_ACCESS:
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ea_name = SGI_ACL_FILE;
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break;
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case ACL_TYPE_DEFAULT:
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ea_name = SGI_ACL_DEFAULT;
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break;
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default:
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BUG();
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}
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/*
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* If we have a cached ACLs value just return it, not need to
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* go out to the disk.
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*/
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xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
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if (!xfs_acl)
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return ERR_PTR(-ENOMEM);
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error = -xfs_attr_get(ip, ea_name, (unsigned char *)xfs_acl,
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&len, ATTR_ROOT);
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if (error) {
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/*
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* If the attribute doesn't exist make sure we have a negative
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* cache entry, for any other error assume it is transient and
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* leave the cache entry as ACL_NOT_CACHED.
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*/
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if (error == -ENOATTR) {
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acl = NULL;
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goto out_update_cache;
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}
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goto out;
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}
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acl = xfs_acl_from_disk(xfs_acl);
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if (IS_ERR(acl))
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goto out;
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out_update_cache:
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set_cached_acl(inode, type, acl);
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out:
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kfree(xfs_acl);
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return acl;
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}
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STATIC int
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xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
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{
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struct xfs_inode *ip = XFS_I(inode);
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unsigned char *ea_name;
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int error;
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if (S_ISLNK(inode->i_mode))
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return -EOPNOTSUPP;
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switch (type) {
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case ACL_TYPE_ACCESS:
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ea_name = SGI_ACL_FILE;
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break;
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case ACL_TYPE_DEFAULT:
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if (!S_ISDIR(inode->i_mode))
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return acl ? -EACCES : 0;
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ea_name = SGI_ACL_DEFAULT;
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break;
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default:
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return -EINVAL;
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}
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if (acl) {
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struct xfs_acl *xfs_acl;
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int len;
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xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
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if (!xfs_acl)
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return -ENOMEM;
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xfs_acl_to_disk(xfs_acl, acl);
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len = sizeof(struct xfs_acl) -
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(sizeof(struct xfs_acl_entry) *
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(XFS_ACL_MAX_ENTRIES - acl->a_count));
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error = -xfs_attr_set(ip, ea_name, (unsigned char *)xfs_acl,
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len, ATTR_ROOT);
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kfree(xfs_acl);
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} else {
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/*
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* A NULL ACL argument means we want to remove the ACL.
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*/
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error = -xfs_attr_remove(ip, ea_name, ATTR_ROOT);
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/*
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* If the attribute didn't exist to start with that's fine.
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*/
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if (error == -ENOATTR)
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error = 0;
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}
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if (!error)
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set_cached_acl(inode, type, acl);
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return error;
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}
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static int
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xfs_set_mode(struct inode *inode, umode_t mode)
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{
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int error = 0;
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if (mode != inode->i_mode) {
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struct iattr iattr;
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iattr.ia_valid = ATTR_MODE | ATTR_CTIME;
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iattr.ia_mode = mode;
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iattr.ia_ctime = current_fs_time(inode->i_sb);
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error = -xfs_setattr_nonsize(XFS_I(inode), &iattr, XFS_ATTR_NOACL);
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}
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return error;
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}
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static int
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xfs_acl_exists(struct inode *inode, unsigned char *name)
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{
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int len = sizeof(struct xfs_acl);
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return (xfs_attr_get(XFS_I(inode), name, NULL, &len,
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ATTR_ROOT|ATTR_KERNOVAL) == 0);
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}
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int
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posix_acl_access_exists(struct inode *inode)
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{
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return xfs_acl_exists(inode, SGI_ACL_FILE);
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}
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int
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posix_acl_default_exists(struct inode *inode)
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{
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if (!S_ISDIR(inode->i_mode))
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return 0;
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return xfs_acl_exists(inode, SGI_ACL_DEFAULT);
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}
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/*
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* No need for i_mutex because the inode is not yet exposed to the VFS.
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*/
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int
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xfs_inherit_acl(struct inode *inode, struct posix_acl *acl)
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{
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umode_t mode = inode->i_mode;
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int error = 0, inherit = 0;
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if (S_ISDIR(inode->i_mode)) {
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error = xfs_set_acl(inode, ACL_TYPE_DEFAULT, acl);
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if (error)
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goto out;
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}
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error = posix_acl_create(&acl, GFP_KERNEL, &mode);
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if (error < 0)
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return error;
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/*
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* If posix_acl_create returns a positive value we need to
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* inherit a permission that can't be represented using the Unix
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* mode bits and we actually need to set an ACL.
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*/
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if (error > 0)
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inherit = 1;
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error = xfs_set_mode(inode, mode);
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if (error)
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goto out;
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if (inherit)
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error = xfs_set_acl(inode, ACL_TYPE_ACCESS, acl);
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out:
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posix_acl_release(acl);
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return error;
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}
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int
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xfs_acl_chmod(struct inode *inode)
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{
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struct posix_acl *acl;
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int error;
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if (S_ISLNK(inode->i_mode))
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return -EOPNOTSUPP;
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acl = xfs_get_acl(inode, ACL_TYPE_ACCESS);
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if (IS_ERR(acl) || !acl)
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return PTR_ERR(acl);
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error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
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if (error)
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return error;
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error = xfs_set_acl(inode, ACL_TYPE_ACCESS, acl);
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posix_acl_release(acl);
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return error;
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}
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static int
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xfs_xattr_acl_get(struct dentry *dentry, const char *name,
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void *value, size_t size, int type)
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{
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struct posix_acl *acl;
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int error;
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acl = xfs_get_acl(dentry->d_inode, type);
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if (IS_ERR(acl))
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return PTR_ERR(acl);
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if (acl == NULL)
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return -ENODATA;
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error = posix_acl_to_xattr(acl, value, size);
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posix_acl_release(acl);
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return error;
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}
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static int
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xfs_xattr_acl_set(struct dentry *dentry, const char *name,
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const void *value, size_t size, int flags, int type)
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{
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struct inode *inode = dentry->d_inode;
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struct posix_acl *acl = NULL;
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int error = 0;
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if (flags & XATTR_CREATE)
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return -EINVAL;
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if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
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return value ? -EACCES : 0;
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if ((current_fsuid() != inode->i_uid) && !capable(CAP_FOWNER))
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return -EPERM;
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if (!value)
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goto set_acl;
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acl = posix_acl_from_xattr(value, size);
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if (!acl) {
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/*
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* acl_set_file(3) may request that we set default ACLs with
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* zero length -- defend (gracefully) against that here.
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*/
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goto out;
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}
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if (IS_ERR(acl)) {
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error = PTR_ERR(acl);
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goto out;
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}
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error = posix_acl_valid(acl);
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if (error)
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goto out_release;
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error = -EINVAL;
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if (acl->a_count > XFS_ACL_MAX_ENTRIES)
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goto out_release;
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if (type == ACL_TYPE_ACCESS) {
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umode_t mode = inode->i_mode;
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error = posix_acl_equiv_mode(acl, &mode);
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if (error <= 0) {
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posix_acl_release(acl);
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acl = NULL;
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if (error < 0)
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return error;
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}
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error = xfs_set_mode(inode, mode);
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if (error)
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goto out_release;
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}
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set_acl:
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error = xfs_set_acl(inode, type, acl);
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out_release:
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posix_acl_release(acl);
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out:
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return error;
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}
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const struct xattr_handler xfs_xattr_acl_access_handler = {
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.prefix = POSIX_ACL_XATTR_ACCESS,
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.flags = ACL_TYPE_ACCESS,
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.get = xfs_xattr_acl_get,
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.set = xfs_xattr_acl_set,
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};
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const struct xattr_handler xfs_xattr_acl_default_handler = {
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.prefix = POSIX_ACL_XATTR_DEFAULT,
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.flags = ACL_TYPE_DEFAULT,
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.get = xfs_xattr_acl_get,
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.set = xfs_xattr_acl_set,
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};
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