/*
* linux/fs/ext2/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/fs.h>
#include "ext2.h"
#include "xattr.h"
#include "acl.h"
/*
* Convert from filesystem to in-memory representation.
*/
static struct posix_acl *
ext2_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(ext2_acl_header))
return ERR_PTR(-EINVAL);
if (((ext2_acl_header *)value)->a_version !=
cpu_to_le32(EXT2_ACL_VERSION))
return ERR_PTR(-EINVAL);
value = (char *)value + sizeof(ext2_acl_header);
count = ext2_acl_count(size);
if (count < 0)
return ERR_PTR(-EINVAL);
if (count == 0)
return NULL;
acl = posix_acl_alloc(count, GFP_KERNEL);
if (!acl)
return ERR_PTR(-ENOMEM);
for (n=0; n < count; n++) {
ext2_acl_entry *entry =
(ext2_acl_entry *)value;
if ((char *)value + sizeof(ext2_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(ext2_acl_entry_short);
acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
break;
case ACL_USER:
case ACL_GROUP:
value = (char *)value + sizeof(ext2_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 *
ext2_acl_to_disk(const struct posix_acl *acl, size_t *size)
{
ext2_acl_header *ext_acl;
char *e;
size_t n;
*size = ext2_acl_size(acl->a_count);
ext_acl = (ext2_acl_header *)kmalloc(sizeof(ext2_acl_header) +
acl->a_count * sizeof(ext2_acl_entry), GFP_KERNEL);
if (!ext_acl)
return ERR_PTR(-ENOMEM);
ext_acl->a_version = cpu_to_le32(EXT2_ACL_VERSION);
e = (char *)ext_acl + sizeof(ext2_acl_header);
for (n=0; n < acl->a_count; n++) {
ext2_acl_entry *entry = (ext2_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(ext2_acl_entry);
break;
case ACL_USER_OBJ:
case ACL_GROUP_OBJ:
case ACL_MASK:
case ACL_OTHER:
e += sizeof(ext2_acl_entry_short);
break;
default:
goto fail;
}
}
return (char *)ext_acl;
fail:
kfree(ext_acl);
return ERR_PTR(-EINVAL);
}
static inline struct posix_acl *
ext2_iget_acl(struct inode *inode, struct posix_acl **i_acl)
{
struct posix_acl *acl = EXT2_ACL_NOT_CACHED;
spin_lock(&inode->i_lock);
if (*i_acl != EXT2_ACL_NOT_CACHED)
acl = posix_acl_dup(*i_acl);
spin_unlock(&inode->i_lock);
return acl;
}
static inline void
ext2_iset_acl(struct inode *inode, struct posix_acl **i_acl,
struct posix_acl *acl)
{
spin_lock(&inode->i_lock);
if (*i_acl != EXT2_ACL_NOT_CACHED)
posix_acl_release(*i_acl);
*i_acl = posix_acl_dup(acl);
spin_unlock(&inode->i_lock);
}
/*
* inode->i_sem: don't care
*/
static struct posix_acl *
ext2_get_acl(struct inode *inode, int type)
{
const size_t max_size = ext2_acl_size(EXT2_ACL_MAX_ENTRIES);
struct ext2_inode_info *ei = EXT2_I(inode);
int name_index;
char *value;
struct posix_acl *acl;
int retval;
if (!test_opt(inode->i_sb, POSIX_ACL))
return 0;
switch(type) {
case ACL_TYPE_ACCESS:
acl = ext2_iget_acl(inode, &ei->i_acl);
if (acl != EXT2_ACL_NOT_CACHED)
return acl;
name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
break;
case ACL_TYPE_DEFAULT:
acl = ext2_iget_acl(inode, &ei->i_default_acl);
if (acl != EXT2_ACL_NOT_CACHED)
return acl;
name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
break;
default:
return ERR_PTR(-EINVAL);
}
value = kmalloc(max_size, GFP_KERNEL);
if (!value)
return ERR_PTR(-ENOMEM);
retval = ext2_xattr_get(inode, name_index, "", value, max_size);
acl = ERR_PTR(retval);
if (retval >= 0)
acl = ext2_acl_from_disk(value, retval);
else if (retval == -ENODATA || retval == -ENOSYS)
acl = NULL;
kfree(value);
if (!IS_ERR(acl)) {
switch(type) {
case ACL_TYPE_ACCESS:
ext2_iset_acl(inode, &ei->i_acl, acl);
break;
case ACL_TYPE_DEFAULT:
ext2_iset_acl(inode, &ei->i_default_acl, acl);
break;
}
}
return acl;
}
/*
* inode->i_sem: down
*/
static int
ext2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
{
struct ext2_inode_info *ei = EXT2_I(inode);
int name_index;
void *value = NULL;
size_t size;
int error;
if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
if (!test_opt(inode->i_sb, POSIX_ACL))
return 0;
switch(type) {
case ACL_TYPE_ACCESS:
name_index = EXT2_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;
mark_inode_dirty(inode);
if (error == 0)
acl = NULL;
}
}
break;
case ACL_TYPE_DEFAULT:
name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
if (!S_ISDIR(inode->i_mode))
return acl ? -EACCES : 0;
break;
default:
return -EINVAL;
}
if (acl) {
if (acl->a_count > EXT2_ACL_MAX_ENTRIES)
return -EINVAL;
value = ext2_acl_to_disk(acl, &size);
if (IS_ERR(value))
return (int)PTR_ERR(value);
}
error = ext2_xattr_set(inode, name_index, "", value, size, 0);
if (value)
kfree(value);
if (!error) {
switch(type) {
case ACL_TYPE_ACCESS:
ext2_iset_acl(inode, &ei->i_acl, acl);
break;
case ACL_TYPE_DEFAULT:
ext2_iset_acl(inode, &ei->i_default_acl, acl);
break;
}
}
return error;
}
/*
* Inode operation permission().
*
* inode->i_sem: don't care
*/
int
ext2_permission(struct inode *inode, int mask, struct nameidata *nd)
{
int mode = inode->i_mode;
/* Nobody gets write access to a read-only fs */
if ((mask & MAY_WRITE) && IS_RDONLY(inode) &&
(S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
return -EROFS;
/* Nobody gets write access to an immutable file */
if ((mask & MAY_WRITE) && IS_IMMUTABLE(inode))
return -EACCES;
if (current->fsuid == inode->i_uid) {
mode >>= 6;
} else if (test_opt(inode->i_sb, POSIX_ACL)) {
struct posix_acl *acl;
/* The access ACL cannot grant access if the group class
permission bits don't contain all requested permissions. */
if (((mode >> 3) & mask & S_IRWXO) != mask)
goto check_groups;
acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
if (acl) {
int error = posix_acl_permission(inode, acl, mask);
posix_acl_release(acl);
if (error == -EACCES)
goto check_capabilities;
return error;
} else
goto check_groups;
} else {
check_groups:
if (in_group_p(inode->i_gid))
mode >>= 3;
}
if ((mode & mask & S_IRWXO) == mask)
return 0;
check_capabilities:
/* Allowed to override Discretionary Access Control? */
if ((mask & (MAY_READ|MAY_WRITE)) || (inode->i_mode & S_IXUGO))
if (capable(CAP_DAC_OVERRIDE))
return 0;
/* Read and search granted if capable(CAP_DAC_READ_SEARCH) */
if (capable(CAP_DAC_READ_SEARCH) && ((mask == MAY_READ) ||
(S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))))
return 0;
return -EACCES;
}
/*
* Initialize the ACLs of a new inode. Called from ext2_new_inode.
*
* dir->i_sem: down
* inode->i_sem: up (access to inode is still exclusive)
*/
int
ext2_init_acl(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 = ext2_get_acl(dir, ACL_TYPE_DEFAULT);
if (IS_ERR(acl))
return PTR_ERR(acl);
}
if (!acl)
inode->i_mode &= ~current->fs->umask;
}
if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
struct posix_acl *clone;
mode_t mode;
if (S_ISDIR(inode->i_mode)) {
error = ext2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
if (error)
goto cleanup;
}
clone = posix_acl_clone(acl, GFP_KERNEL);
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 = ext2_set_acl(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_sem: down
*/
int
ext2_acl_chmod(struct inode *inode)
{
struct posix_acl *acl, *clone;
int error;
if (!test_opt(inode->i_sb, POSIX_ACL))
return 0;
if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
acl = ext2_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)
error = ext2_set_acl(inode, ACL_TYPE_ACCESS, clone);
posix_acl_release(clone);
return error;
}
/*
* Extended attribut handlers
*/
static size_t
ext2_xattr_list_acl_access(char *list, struct inode *inode,
const char *name, int name_len)
{
const size_t size = sizeof(XATTR_NAME_ACL_ACCESS);
if (!test_opt(inode->i_sb, POSIX_ACL))
return 0;
if (list)
memcpy(list, XATTR_NAME_ACL_ACCESS, size);
return size;
}
static size_t
ext2_xattr_list_acl_default(char *list, struct inode *inode,
const char *name, int name_len)
{
const size_t size = sizeof(XATTR_NAME_ACL_DEFAULT);
if (!test_opt(inode->i_sb, POSIX_ACL))
return 0;
if (list)
memcpy(list, XATTR_NAME_ACL_DEFAULT, size);
return size;
}
static int
ext2_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 = ext2_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
ext2_xattr_get_acl_access(struct inode *inode, const char *name,
void *buffer, size_t size)
{
if (strcmp(name, "") != 0)
return -EINVAL;
return ext2_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
}
static int
ext2_xattr_get_acl_default(struct inode *inode, const char *name,
void *buffer, size_t size)
{
if (strcmp(name, "") != 0)
return -EINVAL;
return ext2_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
}
static int
ext2_xattr_set_acl(struct inode *inode, int type, const void *value,
size_t size)
{
struct posix_acl *acl;
int error;
if (!test_opt(inode->i_sb, POSIX_ACL))
return -EOPNOTSUPP;
if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
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;
error = ext2_set_acl(inode, type, acl);
release_and_out:
posix_acl_release(acl);
return error;
}
static int
ext2_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 ext2_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
}
static int
ext2_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 ext2_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
}
struct ext2_xattr_handler ext2_xattr_acl_access_handler = {
.prefix = XATTR_NAME_ACL_ACCESS,
.list = ext2_xattr_list_acl_access,
.get = ext2_xattr_get_acl_access,
.set = ext2_xattr_set_acl_access,
};
struct ext2_xattr_handler ext2_xattr_acl_default_handler = {
.prefix = XATTR_NAME_ACL_DEFAULT,
.list = ext2_xattr_list_acl_default,
.get = ext2_xattr_get_acl_default,
.set = ext2_xattr_set_acl_default,
};
void
exit_ext2_acl(void)
{
ext2_xattr_unregister(EXT2_XATTR_INDEX_POSIX_ACL_ACCESS,
&ext2_xattr_acl_access_handler);
ext2_xattr_unregister(EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT,
&ext2_xattr_acl_default_handler);
}
int __init
init_ext2_acl(void)
{
int error;
error = ext2_xattr_register(EXT2_XATTR_INDEX_POSIX_ACL_ACCESS,
&ext2_xattr_acl_access_handler);
if (error)
goto fail;
error = ext2_xattr_register(EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT,
&ext2_xattr_acl_default_handler);
if (error)
goto fail;
return 0;
fail:
exit_ext2_acl();
return error;
}
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