linux/fs/ext4/acl.c
Linus Torvalds 1d5ccd1c42 ext[234]: move over to 'check_acl' permission model
Don't implement per-filesystem 'extX_permission()' functions that have
to be called for every path component operation, and instead just expose
the actual ACL checking so that the VFS layer can now do it for us.

Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-08 11:09:04 -07:00

499 lines
11 KiB
C

/*
* linux/fs/ext4/acl.c
*
* Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
*/
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/capability.h>
#include <linux/fs.h>
#include "ext4_jbd2.h"
#include "ext4.h"
#include "xattr.h"
#include "acl.h"
/*
* Convert from filesystem to in-memory representation.
*/
static struct posix_acl *
ext4_acl_from_disk(const void *value, size_t size)
{
const char *end = (char *)value + size;
int n, count;
struct posix_acl *acl;
if (!value)
return NULL;
if (size < sizeof(ext4_acl_header))
return ERR_PTR(-EINVAL);
if (((ext4_acl_header *)value)->a_version !=
cpu_to_le32(EXT4_ACL_VERSION))
return ERR_PTR(-EINVAL);
value = (char *)value + sizeof(ext4_acl_header);
count = ext4_acl_count(size);
if (count < 0)
return ERR_PTR(-EINVAL);
if (count == 0)
return NULL;
acl = posix_acl_alloc(count, GFP_NOFS);
if (!acl)
return ERR_PTR(-ENOMEM);
for (n = 0; n < count; n++) {
ext4_acl_entry *entry =
(ext4_acl_entry *)value;
if ((char *)value + sizeof(ext4_acl_entry_short) > end)
goto fail;
acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
switch (acl->a_entries[n].e_tag) {
case ACL_USER_OBJ:
case ACL_GROUP_OBJ:
case ACL_MASK:
case ACL_OTHER:
value = (char *)value +
sizeof(ext4_acl_entry_short);
acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
break;
case ACL_USER:
case ACL_GROUP:
value = (char *)value + sizeof(ext4_acl_entry);
if ((char *)value > end)
goto fail;
acl->a_entries[n].e_id =
le32_to_cpu(entry->e_id);
break;
default:
goto fail;
}
}
if (value != end)
goto fail;
return acl;
fail:
posix_acl_release(acl);
return ERR_PTR(-EINVAL);
}
/*
* Convert from in-memory to filesystem representation.
*/
static void *
ext4_acl_to_disk(const struct posix_acl *acl, size_t *size)
{
ext4_acl_header *ext_acl;
char *e;
size_t n;
*size = ext4_acl_size(acl->a_count);
ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count *
sizeof(ext4_acl_entry), GFP_NOFS);
if (!ext_acl)
return ERR_PTR(-ENOMEM);
ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION);
e = (char *)ext_acl + sizeof(ext4_acl_header);
for (n = 0; n < acl->a_count; n++) {
ext4_acl_entry *entry = (ext4_acl_entry *)e;
entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag);
entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
switch (acl->a_entries[n].e_tag) {
case ACL_USER:
case ACL_GROUP:
entry->e_id = cpu_to_le32(acl->a_entries[n].e_id);
e += sizeof(ext4_acl_entry);
break;
case ACL_USER_OBJ:
case ACL_GROUP_OBJ:
case ACL_MASK:
case ACL_OTHER:
e += sizeof(ext4_acl_entry_short);
break;
default:
goto fail;
}
}
return (char *)ext_acl;
fail:
kfree(ext_acl);
return ERR_PTR(-EINVAL);
}
/*
* Inode operation get_posix_acl().
*
* inode->i_mutex: don't care
*/
static struct posix_acl *
ext4_get_acl(struct inode *inode, int type)
{
int name_index;
char *value = NULL;
struct posix_acl *acl;
int retval;
if (!test_opt(inode->i_sb, POSIX_ACL))
return NULL;
acl = get_cached_acl(inode, type);
if (acl != ACL_NOT_CACHED)
return acl;
switch (type) {
case ACL_TYPE_ACCESS:
name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
break;
case ACL_TYPE_DEFAULT:
name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
break;
default:
BUG();
}
retval = ext4_xattr_get(inode, name_index, "", NULL, 0);
if (retval > 0) {
value = kmalloc(retval, GFP_NOFS);
if (!value)
return ERR_PTR(-ENOMEM);
retval = ext4_xattr_get(inode, name_index, "", value, retval);
}
if (retval > 0)
acl = ext4_acl_from_disk(value, retval);
else if (retval == -ENODATA || retval == -ENOSYS)
acl = NULL;
else
acl = ERR_PTR(retval);
kfree(value);
if (!IS_ERR(acl))
set_cached_acl(inode, type, acl);
return acl;
}
/*
* Set the access or default ACL of an inode.
*
* inode->i_mutex: down unless called from ext4_new_inode
*/
static int
ext4_set_acl(handle_t *handle, struct inode *inode, int type,
struct posix_acl *acl)
{
int name_index;
void *value = NULL;
size_t size = 0;
int error;
if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
switch (type) {
case ACL_TYPE_ACCESS:
name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
if (acl) {
mode_t mode = inode->i_mode;
error = posix_acl_equiv_mode(acl, &mode);
if (error < 0)
return error;
else {
inode->i_mode = mode;
ext4_mark_inode_dirty(handle, inode);
if (error == 0)
acl = NULL;
}
}
break;
case ACL_TYPE_DEFAULT:
name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
if (!S_ISDIR(inode->i_mode))
return acl ? -EACCES : 0;
break;
default:
return -EINVAL;
}
if (acl) {
value = ext4_acl_to_disk(acl, &size);
if (IS_ERR(value))
return (int)PTR_ERR(value);
}
error = ext4_xattr_set_handle(handle, inode, name_index, "",
value, size, 0);
kfree(value);
if (!error)
set_cached_acl(inode, type, acl);
return error;
}
int
ext4_check_acl(struct inode *inode, int mask)
{
struct posix_acl *acl = ext4_get_acl(inode, ACL_TYPE_ACCESS);
if (IS_ERR(acl))
return PTR_ERR(acl);
if (acl) {
int error = posix_acl_permission(inode, acl, mask);
posix_acl_release(acl);
return error;
}
return -EAGAIN;
}
/*
* Initialize the ACLs of a new inode. Called from ext4_new_inode.
*
* dir->i_mutex: down
* inode->i_mutex: up (access to inode is still exclusive)
*/
int
ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
{
struct posix_acl *acl = NULL;
int error = 0;
if (!S_ISLNK(inode->i_mode)) {
if (test_opt(dir->i_sb, POSIX_ACL)) {
acl = ext4_get_acl(dir, ACL_TYPE_DEFAULT);
if (IS_ERR(acl))
return PTR_ERR(acl);
}
if (!acl)
inode->i_mode &= ~current_umask();
}
if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
struct posix_acl *clone;
mode_t mode;
if (S_ISDIR(inode->i_mode)) {
error = ext4_set_acl(handle, inode,
ACL_TYPE_DEFAULT, acl);
if (error)
goto cleanup;
}
clone = posix_acl_clone(acl, GFP_NOFS);
error = -ENOMEM;
if (!clone)
goto cleanup;
mode = inode->i_mode;
error = posix_acl_create_masq(clone, &mode);
if (error >= 0) {
inode->i_mode = mode;
if (error > 0) {
/* This is an extended ACL */
error = ext4_set_acl(handle, inode,
ACL_TYPE_ACCESS, clone);
}
}
posix_acl_release(clone);
}
cleanup:
posix_acl_release(acl);
return error;
}
/*
* Does chmod for an inode that may have an Access Control List. The
* inode->i_mode field must be updated to the desired value by the caller
* before calling this function.
* Returns 0 on success, or a negative error number.
*
* We change the ACL rather than storing some ACL entries in the file
* mode permission bits (which would be more efficient), because that
* would break once additional permissions (like ACL_APPEND, ACL_DELETE
* for directories) are added. There are no more bits available in the
* file mode.
*
* inode->i_mutex: down
*/
int
ext4_acl_chmod(struct inode *inode)
{
struct posix_acl *acl, *clone;
int error;
if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
if (!test_opt(inode->i_sb, POSIX_ACL))
return 0;
acl = ext4_get_acl(inode, ACL_TYPE_ACCESS);
if (IS_ERR(acl) || !acl)
return PTR_ERR(acl);
clone = posix_acl_clone(acl, GFP_KERNEL);
posix_acl_release(acl);
if (!clone)
return -ENOMEM;
error = posix_acl_chmod_masq(clone, inode->i_mode);
if (!error) {
handle_t *handle;
int retries = 0;
retry:
handle = ext4_journal_start(inode,
EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
if (IS_ERR(handle)) {
error = PTR_ERR(handle);
ext4_std_error(inode->i_sb, error);
goto out;
}
error = ext4_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
ext4_journal_stop(handle);
if (error == -ENOSPC &&
ext4_should_retry_alloc(inode->i_sb, &retries))
goto retry;
}
out:
posix_acl_release(clone);
return error;
}
/*
* Extended attribute handlers
*/
static size_t
ext4_xattr_list_acl_access(struct inode *inode, char *list, size_t list_len,
const char *name, size_t name_len)
{
const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
if (!test_opt(inode->i_sb, POSIX_ACL))
return 0;
if (list && size <= list_len)
memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
return size;
}
static size_t
ext4_xattr_list_acl_default(struct inode *inode, char *list, size_t list_len,
const char *name, size_t name_len)
{
const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
if (!test_opt(inode->i_sb, POSIX_ACL))
return 0;
if (list && size <= list_len)
memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
return size;
}
static int
ext4_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
{
struct posix_acl *acl;
int error;
if (!test_opt(inode->i_sb, POSIX_ACL))
return -EOPNOTSUPP;
acl = ext4_get_acl(inode, type);
if (IS_ERR(acl))
return PTR_ERR(acl);
if (acl == NULL)
return -ENODATA;
error = posix_acl_to_xattr(acl, buffer, size);
posix_acl_release(acl);
return error;
}
static int
ext4_xattr_get_acl_access(struct inode *inode, const char *name,
void *buffer, size_t size)
{
if (strcmp(name, "") != 0)
return -EINVAL;
return ext4_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
}
static int
ext4_xattr_get_acl_default(struct inode *inode, const char *name,
void *buffer, size_t size)
{
if (strcmp(name, "") != 0)
return -EINVAL;
return ext4_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
}
static int
ext4_xattr_set_acl(struct inode *inode, int type, const void *value,
size_t size)
{
handle_t *handle;
struct posix_acl *acl;
int error, retries = 0;
if (!test_opt(inode->i_sb, POSIX_ACL))
return -EOPNOTSUPP;
if (!is_owner_or_cap(inode))
return -EPERM;
if (value) {
acl = posix_acl_from_xattr(value, size);
if (IS_ERR(acl))
return PTR_ERR(acl);
else if (acl) {
error = posix_acl_valid(acl);
if (error)
goto release_and_out;
}
} else
acl = NULL;
retry:
handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
if (IS_ERR(handle))
return PTR_ERR(handle);
error = ext4_set_acl(handle, inode, type, acl);
ext4_journal_stop(handle);
if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
goto retry;
release_and_out:
posix_acl_release(acl);
return error;
}
static int
ext4_xattr_set_acl_access(struct inode *inode, const char *name,
const void *value, size_t size, int flags)
{
if (strcmp(name, "") != 0)
return -EINVAL;
return ext4_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
}
static int
ext4_xattr_set_acl_default(struct inode *inode, const char *name,
const void *value, size_t size, int flags)
{
if (strcmp(name, "") != 0)
return -EINVAL;
return ext4_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
}
struct xattr_handler ext4_xattr_acl_access_handler = {
.prefix = POSIX_ACL_XATTR_ACCESS,
.list = ext4_xattr_list_acl_access,
.get = ext4_xattr_get_acl_access,
.set = ext4_xattr_set_acl_access,
};
struct xattr_handler ext4_xattr_acl_default_handler = {
.prefix = POSIX_ACL_XATTR_DEFAULT,
.list = ext4_xattr_list_acl_default,
.get = ext4_xattr_get_acl_default,
.set = ext4_xattr_set_acl_default,
};