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![Nick Piggin](/assets/img/avatar_default.png)
This simple implementation just checks for no ACLs on the inode, and if so, then the rcu-walk may proceed, otherwise fail it. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
481 lines
11 KiB
C
481 lines
11 KiB
C
/*
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* linux/fs/ext3/acl.c
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*
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* Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
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*/
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/capability.h>
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#include <linux/fs.h>
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#include <linux/ext3_jbd.h>
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#include <linux/ext3_fs.h>
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#include "xattr.h"
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#include "acl.h"
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/*
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* Convert from filesystem to in-memory representation.
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*/
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static struct posix_acl *
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ext3_acl_from_disk(const void *value, size_t size)
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{
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const char *end = (char *)value + size;
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int n, count;
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struct posix_acl *acl;
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if (!value)
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return NULL;
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if (size < sizeof(ext3_acl_header))
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return ERR_PTR(-EINVAL);
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if (((ext3_acl_header *)value)->a_version !=
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cpu_to_le32(EXT3_ACL_VERSION))
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return ERR_PTR(-EINVAL);
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value = (char *)value + sizeof(ext3_acl_header);
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count = ext3_acl_count(size);
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if (count < 0)
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return ERR_PTR(-EINVAL);
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if (count == 0)
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return NULL;
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acl = posix_acl_alloc(count, GFP_NOFS);
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if (!acl)
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return ERR_PTR(-ENOMEM);
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for (n=0; n < count; n++) {
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ext3_acl_entry *entry =
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(ext3_acl_entry *)value;
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if ((char *)value + sizeof(ext3_acl_entry_short) > end)
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goto fail;
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acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
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acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
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switch(acl->a_entries[n].e_tag) {
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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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value = (char *)value +
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sizeof(ext3_acl_entry_short);
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acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
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break;
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case ACL_USER:
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case ACL_GROUP:
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value = (char *)value + sizeof(ext3_acl_entry);
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if ((char *)value > end)
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goto fail;
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acl->a_entries[n].e_id =
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le32_to_cpu(entry->e_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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if (value != end)
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goto fail;
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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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/*
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* Convert from in-memory to filesystem representation.
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*/
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static void *
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ext3_acl_to_disk(const struct posix_acl *acl, size_t *size)
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{
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ext3_acl_header *ext_acl;
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char *e;
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size_t n;
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*size = ext3_acl_size(acl->a_count);
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ext_acl = kmalloc(sizeof(ext3_acl_header) + acl->a_count *
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sizeof(ext3_acl_entry), GFP_NOFS);
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if (!ext_acl)
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return ERR_PTR(-ENOMEM);
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ext_acl->a_version = cpu_to_le32(EXT3_ACL_VERSION);
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e = (char *)ext_acl + sizeof(ext3_acl_header);
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for (n=0; n < acl->a_count; n++) {
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ext3_acl_entry *entry = (ext3_acl_entry *)e;
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entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag);
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entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
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switch(acl->a_entries[n].e_tag) {
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case ACL_USER:
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case ACL_GROUP:
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entry->e_id =
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cpu_to_le32(acl->a_entries[n].e_id);
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e += sizeof(ext3_acl_entry);
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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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e += sizeof(ext3_acl_entry_short);
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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 (char *)ext_acl;
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fail:
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kfree(ext_acl);
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return ERR_PTR(-EINVAL);
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}
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/*
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* Inode operation get_posix_acl().
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*
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* inode->i_mutex: don't care
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*/
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static struct posix_acl *
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ext3_get_acl(struct inode *inode, int type)
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{
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int name_index;
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char *value = NULL;
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struct posix_acl *acl;
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int retval;
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if (!test_opt(inode->i_sb, POSIX_ACL))
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return NULL;
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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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switch (type) {
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case ACL_TYPE_ACCESS:
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name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
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break;
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case ACL_TYPE_DEFAULT:
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name_index = EXT3_XATTR_INDEX_POSIX_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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retval = ext3_xattr_get(inode, name_index, "", NULL, 0);
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if (retval > 0) {
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value = kmalloc(retval, GFP_NOFS);
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if (!value)
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return ERR_PTR(-ENOMEM);
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retval = ext3_xattr_get(inode, name_index, "", value, retval);
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}
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if (retval > 0)
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acl = ext3_acl_from_disk(value, retval);
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else if (retval == -ENODATA || retval == -ENOSYS)
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acl = NULL;
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else
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acl = ERR_PTR(retval);
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kfree(value);
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if (!IS_ERR(acl))
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set_cached_acl(inode, type, acl);
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return acl;
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}
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/*
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* Set the access or default ACL of an inode.
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*
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* inode->i_mutex: down unless called from ext3_new_inode
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*/
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static int
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ext3_set_acl(handle_t *handle, struct inode *inode, int type,
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struct posix_acl *acl)
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{
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int name_index;
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void *value = NULL;
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size_t size = 0;
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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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name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
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if (acl) {
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mode_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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return error;
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else {
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inode->i_mode = mode;
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inode->i_ctime = CURRENT_TIME_SEC;
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ext3_mark_inode_dirty(handle, inode);
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if (error == 0)
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acl = NULL;
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}
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}
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break;
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case ACL_TYPE_DEFAULT:
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name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
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if (!S_ISDIR(inode->i_mode))
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return acl ? -EACCES : 0;
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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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value = ext3_acl_to_disk(acl, &size);
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if (IS_ERR(value))
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return (int)PTR_ERR(value);
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}
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error = ext3_xattr_set_handle(handle, inode, name_index, "",
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value, size, 0);
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kfree(value);
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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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int
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ext3_check_acl(struct inode *inode, int mask, unsigned int flags)
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{
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struct posix_acl *acl;
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if (flags & IPERM_FLAG_RCU) {
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if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
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return -ECHILD;
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return -EAGAIN;
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}
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acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
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if (IS_ERR(acl))
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return PTR_ERR(acl);
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if (acl) {
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int error = posix_acl_permission(inode, acl, mask);
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posix_acl_release(acl);
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return error;
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}
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return -EAGAIN;
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}
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/*
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* Initialize the ACLs of a new inode. Called from ext3_new_inode.
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*
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* dir->i_mutex: down
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* inode->i_mutex: up (access to inode is still exclusive)
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*/
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int
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ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
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{
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struct posix_acl *acl = NULL;
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int error = 0;
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if (!S_ISLNK(inode->i_mode)) {
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if (test_opt(dir->i_sb, POSIX_ACL)) {
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acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
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if (IS_ERR(acl))
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return PTR_ERR(acl);
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}
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if (!acl)
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inode->i_mode &= ~current_umask();
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}
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if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
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struct posix_acl *clone;
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mode_t mode;
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if (S_ISDIR(inode->i_mode)) {
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error = ext3_set_acl(handle, inode,
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ACL_TYPE_DEFAULT, acl);
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if (error)
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goto cleanup;
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}
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clone = posix_acl_clone(acl, GFP_NOFS);
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error = -ENOMEM;
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if (!clone)
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goto cleanup;
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mode = inode->i_mode;
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error = posix_acl_create_masq(clone, &mode);
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if (error >= 0) {
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inode->i_mode = mode;
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if (error > 0) {
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/* This is an extended ACL */
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error = ext3_set_acl(handle, inode,
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ACL_TYPE_ACCESS, clone);
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}
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}
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posix_acl_release(clone);
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}
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cleanup:
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posix_acl_release(acl);
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return error;
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}
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/*
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* Does chmod for an inode that may have an Access Control List. The
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* inode->i_mode field must be updated to the desired value by the caller
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* before calling this function.
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* Returns 0 on success, or a negative error number.
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*
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* We change the ACL rather than storing some ACL entries in the file
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* mode permission bits (which would be more efficient), because that
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* would break once additional permissions (like ACL_APPEND, ACL_DELETE
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* for directories) are added. There are no more bits available in the
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* file mode.
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*
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* inode->i_mutex: down
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*/
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int
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ext3_acl_chmod(struct inode *inode)
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{
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struct posix_acl *acl, *clone;
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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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if (!test_opt(inode->i_sb, POSIX_ACL))
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return 0;
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acl = ext3_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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clone = posix_acl_clone(acl, GFP_KERNEL);
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posix_acl_release(acl);
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if (!clone)
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return -ENOMEM;
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error = posix_acl_chmod_masq(clone, inode->i_mode);
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if (!error) {
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handle_t *handle;
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int retries = 0;
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retry:
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handle = ext3_journal_start(inode,
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EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
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if (IS_ERR(handle)) {
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error = PTR_ERR(handle);
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ext3_std_error(inode->i_sb, error);
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goto out;
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}
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error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
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ext3_journal_stop(handle);
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if (error == -ENOSPC &&
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ext3_should_retry_alloc(inode->i_sb, &retries))
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goto retry;
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}
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out:
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posix_acl_release(clone);
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return error;
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}
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/*
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* Extended attribute handlers
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*/
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static size_t
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ext3_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len,
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const char *name, size_t name_len, int type)
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{
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const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
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if (!test_opt(dentry->d_sb, POSIX_ACL))
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return 0;
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if (list && size <= list_len)
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memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
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return size;
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}
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static size_t
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ext3_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len,
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const char *name, size_t name_len, int type)
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{
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const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
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if (!test_opt(dentry->d_sb, POSIX_ACL))
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return 0;
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if (list && size <= list_len)
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memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
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return size;
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}
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static int
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ext3_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
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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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if (strcmp(name, "") != 0)
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return -EINVAL;
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if (!test_opt(dentry->d_sb, POSIX_ACL))
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return -EOPNOTSUPP;
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acl = ext3_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, buffer, 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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ext3_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
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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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handle_t *handle;
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struct posix_acl *acl;
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int error, retries = 0;
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if (strcmp(name, "") != 0)
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return -EINVAL;
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if (!test_opt(inode->i_sb, POSIX_ACL))
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return -EOPNOTSUPP;
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if (!is_owner_or_cap(inode))
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return -EPERM;
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if (value) {
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acl = posix_acl_from_xattr(value, size);
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if (IS_ERR(acl))
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return PTR_ERR(acl);
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else if (acl) {
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error = posix_acl_valid(acl);
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if (error)
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goto release_and_out;
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}
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} else
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acl = NULL;
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retry:
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handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
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if (IS_ERR(handle))
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return PTR_ERR(handle);
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error = ext3_set_acl(handle, inode, type, acl);
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ext3_journal_stop(handle);
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if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
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goto retry;
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release_and_out:
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posix_acl_release(acl);
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return error;
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}
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const struct xattr_handler ext3_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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.list = ext3_xattr_list_acl_access,
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.get = ext3_xattr_get_acl,
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.set = ext3_xattr_set_acl,
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};
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const struct xattr_handler ext3_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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.list = ext3_xattr_list_acl_default,
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.get = ext3_xattr_get_acl,
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.set = ext3_xattr_set_acl,
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};
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