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linux/fs/jffs2/acl.c
Satyam Sharma 3bd858ab1c Introduce is_owner_or_cap() to wrap CAP_FOWNER use with fsuid check 
Introduce is_owner_or_cap() macro in fs.h, and convert over relevant
users to it. This is done because we want to avoid bugs in the future
where we check for only effective fsuid of the current task against a
file's owning uid, without simultaneously checking for CAP_FOWNER as
well, thus violating its semantics.
[ XFS uses special macros and structures, and in general looked ...
untouchable, so we leave it alone -- but it has been looked over. ]

The (current->fsuid != inode->i_uid) check in generic_permission() and
exec_permission_lite() is left alone, because those operations are
covered by CAP_DAC_OVERRIDE and CAP_DAC_READ_SEARCH. Similarly operations
falling under the purview of CAP_CHOWN and CAP_LEASE are also left alone.

Signed-off-by: Satyam Sharma <ssatyam@cse.iitk.ac.in>
Cc: Al Viro <viro@ftp.linux.org.uk>
Acked-by: Serge E. Hallyn <serge@hallyn.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17 12:00:03 -07:00

487 lines
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/*
* JFFS2 -- Journalling Flash File System, Version 2.
*
* Copyright © 2006 NEC Corporation
*
* Created by KaiGai Kohei <kaigai@ak.jp.nec.com>
*
* For licensing information, see the file 'LICENCE' in this directory.
*
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/time.h>
#include <linux/crc32.h>
#include <linux/jffs2.h>
#include <linux/xattr.h>
#include <linux/posix_acl_xattr.h>
#include <linux/mtd/mtd.h>
#include "nodelist.h"
static size_t jffs2_acl_size(int count)
{
if (count <= 4) {
return sizeof(struct jffs2_acl_header)
+ count * sizeof(struct jffs2_acl_entry_short);
} else {
return sizeof(struct jffs2_acl_header)
+ 4 * sizeof(struct jffs2_acl_entry_short)
+ (count - 4) * sizeof(struct jffs2_acl_entry);
}
}
static int jffs2_acl_count(size_t size)
{
size_t s;
size -= sizeof(struct jffs2_acl_header);
s = size - 4 * sizeof(struct jffs2_acl_entry_short);
if (s < 0) {
if (size % sizeof(struct jffs2_acl_entry_short))
return -1;
return size / sizeof(struct jffs2_acl_entry_short);
} else {
if (s % sizeof(struct jffs2_acl_entry))
return -1;
return s / sizeof(struct jffs2_acl_entry) + 4;
}
}
static struct posix_acl *jffs2_acl_from_medium(void *value, size_t size)
{
void *end = value + size;
struct jffs2_acl_header *header = value;
struct jffs2_acl_entry *entry;
struct posix_acl *acl;
uint32_t ver;
int i, count;
if (!value)
return NULL;
if (size < sizeof(struct jffs2_acl_header))
return ERR_PTR(-EINVAL);
ver = je32_to_cpu(header->a_version);
if (ver != JFFS2_ACL_VERSION) {
JFFS2_WARNING("Invalid ACL version. (=%u)\n", ver);
return ERR_PTR(-EINVAL);
}
value += sizeof(struct jffs2_acl_header);
count = jffs2_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 (i=0; i < count; i++) {
entry = value;
if (value + sizeof(struct jffs2_acl_entry_short) > end)
goto fail;
acl->a_entries[i].e_tag = je16_to_cpu(entry->e_tag);
acl->a_entries[i].e_perm = je16_to_cpu(entry->e_perm);
switch (acl->a_entries[i].e_tag) {
case ACL_USER_OBJ:
case ACL_GROUP_OBJ:
case ACL_MASK:
case ACL_OTHER:
value += sizeof(struct jffs2_acl_entry_short);
acl->a_entries[i].e_id = ACL_UNDEFINED_ID;
break;
case ACL_USER:
case ACL_GROUP:
value += sizeof(struct jffs2_acl_entry);
if (value > end)
goto fail;
acl->a_entries[i].e_id = je32_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);
}
static void *jffs2_acl_to_medium(const struct posix_acl *acl, size_t *size)
{
struct jffs2_acl_header *header;
struct jffs2_acl_entry *entry;
void *e;
size_t i;
*size = jffs2_acl_size(acl->a_count);
header = kmalloc(sizeof(*header) + acl->a_count * sizeof(*entry), GFP_KERNEL);
if (!header)
return ERR_PTR(-ENOMEM);
header->a_version = cpu_to_je32(JFFS2_ACL_VERSION);
e = header + 1;
for (i=0; i < acl->a_count; i++) {
entry = e;
entry->e_tag = cpu_to_je16(acl->a_entries[i].e_tag);
entry->e_perm = cpu_to_je16(acl->a_entries[i].e_perm);
switch(acl->a_entries[i].e_tag) {
case ACL_USER:
case ACL_GROUP:
entry->e_id = cpu_to_je32(acl->a_entries[i].e_id);
e += sizeof(struct jffs2_acl_entry);
break;
case ACL_USER_OBJ:
case ACL_GROUP_OBJ:
case ACL_MASK:
case ACL_OTHER:
e += sizeof(struct jffs2_acl_entry_short);
break;
default:
goto fail;
}
}
return header;
fail:
kfree(header);
return ERR_PTR(-EINVAL);
}
static struct posix_acl *jffs2_iget_acl(struct inode *inode, struct posix_acl **i_acl)
{
struct posix_acl *acl = JFFS2_ACL_NOT_CACHED;
spin_lock(&inode->i_lock);
if (*i_acl != JFFS2_ACL_NOT_CACHED)
acl = posix_acl_dup(*i_acl);
spin_unlock(&inode->i_lock);
return acl;
}
static void jffs2_iset_acl(struct inode *inode, struct posix_acl **i_acl, struct posix_acl *acl)
{
spin_lock(&inode->i_lock);
if (*i_acl != JFFS2_ACL_NOT_CACHED)
posix_acl_release(*i_acl);
*i_acl = posix_acl_dup(acl);
spin_unlock(&inode->i_lock);
}
static struct posix_acl *jffs2_get_acl(struct inode *inode, int type)
{
struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
struct posix_acl *acl;
char *value = NULL;
int rc, xprefix;
switch (type) {
case ACL_TYPE_ACCESS:
acl = jffs2_iget_acl(inode, &f->i_acl_access);
if (acl != JFFS2_ACL_NOT_CACHED)
return acl;
xprefix = JFFS2_XPREFIX_ACL_ACCESS;
break;
case ACL_TYPE_DEFAULT:
acl = jffs2_iget_acl(inode, &f->i_acl_default);
if (acl != JFFS2_ACL_NOT_CACHED)
return acl;
xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
break;
default:
return ERR_PTR(-EINVAL);
}
rc = do_jffs2_getxattr(inode, xprefix, "", NULL, 0);
if (rc > 0) {
value = kmalloc(rc, GFP_KERNEL);
if (!value)
return ERR_PTR(-ENOMEM);
rc = do_jffs2_getxattr(inode, xprefix, "", value, rc);
}
if (rc > 0) {
acl = jffs2_acl_from_medium(value, rc);
} else if (rc == -ENODATA || rc == -ENOSYS) {
acl = NULL;
} else {
acl = ERR_PTR(rc);
}
if (value)
kfree(value);
if (!IS_ERR(acl)) {
switch (type) {
case ACL_TYPE_ACCESS:
jffs2_iset_acl(inode, &f->i_acl_access, acl);
break;
case ACL_TYPE_DEFAULT:
jffs2_iset_acl(inode, &f->i_acl_default, acl);
break;
}
}
return acl;
}
static int jffs2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
{
struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
size_t size = 0;
char *value = NULL;
int rc, xprefix;
if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
switch (type) {
case ACL_TYPE_ACCESS:
xprefix = JFFS2_XPREFIX_ACL_ACCESS;
if (acl) {
mode_t mode = inode->i_mode;
rc = posix_acl_equiv_mode(acl, &mode);
if (rc < 0)
return rc;
if (inode->i_mode != mode) {
inode->i_mode = mode;
jffs2_dirty_inode(inode);
}
if (rc == 0)
acl = NULL;
}
break;
case ACL_TYPE_DEFAULT:
xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
if (!S_ISDIR(inode->i_mode))
return acl ? -EACCES : 0;
break;
default:
return -EINVAL;
}
if (acl) {
value = jffs2_acl_to_medium(acl, &size);
if (IS_ERR(value))
return PTR_ERR(value);
}
rc = do_jffs2_setxattr(inode, xprefix, "", value, size, 0);
if (!value && rc == -ENODATA)
rc = 0;
if (value)
kfree(value);
if (!rc) {
switch(type) {
case ACL_TYPE_ACCESS:
jffs2_iset_acl(inode, &f->i_acl_access, acl);
break;
case ACL_TYPE_DEFAULT:
jffs2_iset_acl(inode, &f->i_acl_default, acl);
break;
}
}
return rc;
}
static int jffs2_check_acl(struct inode *inode, int mask)
{
struct posix_acl *acl;
int rc;
acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
if (IS_ERR(acl))
return PTR_ERR(acl);
if (acl) {
rc = posix_acl_permission(inode, acl, mask);
posix_acl_release(acl);
return rc;
}
return -EAGAIN;
}
int jffs2_permission(struct inode *inode, int mask, struct nameidata *nd)
{
return generic_permission(inode, mask, jffs2_check_acl);
}
int jffs2_init_acl(struct inode *inode, struct inode *dir)
{
struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
struct posix_acl *acl = NULL, *clone;
mode_t mode;
int rc = 0;
f->i_acl_access = JFFS2_ACL_NOT_CACHED;
f->i_acl_default = JFFS2_ACL_NOT_CACHED;
if (!S_ISLNK(inode->i_mode)) {
acl = jffs2_get_acl(dir, ACL_TYPE_DEFAULT);
if (IS_ERR(acl))
return PTR_ERR(acl);
if (!acl)
inode->i_mode &= ~current->fs->umask;
}
if (acl) {
if (S_ISDIR(inode->i_mode)) {
rc = jffs2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
if (rc)
goto cleanup;
}
clone = posix_acl_clone(acl, GFP_KERNEL);
rc = -ENOMEM;
if (!clone)
goto cleanup;
mode = inode->i_mode;
rc = posix_acl_create_masq(clone, &mode);
if (rc >= 0) {
inode->i_mode = mode;
if (rc > 0)
rc = jffs2_set_acl(inode, ACL_TYPE_ACCESS, clone);
}
posix_acl_release(clone);
}
cleanup:
posix_acl_release(acl);
return rc;
}
void jffs2_clear_acl(struct jffs2_inode_info *f)
{
if (f->i_acl_access && f->i_acl_access != JFFS2_ACL_NOT_CACHED) {
posix_acl_release(f->i_acl_access);
f->i_acl_access = JFFS2_ACL_NOT_CACHED;
}
if (f->i_acl_default && f->i_acl_default != JFFS2_ACL_NOT_CACHED) {
posix_acl_release(f->i_acl_default);
f->i_acl_default = JFFS2_ACL_NOT_CACHED;
}
}
int jffs2_acl_chmod(struct inode *inode)
{
struct posix_acl *acl, *clone;
int rc;
if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
acl = jffs2_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;
rc = posix_acl_chmod_masq(clone, inode->i_mode);
if (!rc)
rc = jffs2_set_acl(inode, ACL_TYPE_ACCESS, clone);
posix_acl_release(clone);
return rc;
}
static size_t jffs2_acl_access_listxattr(struct inode *inode, char *list, size_t list_size,
const char *name, size_t name_len)
{
const int retlen = sizeof(POSIX_ACL_XATTR_ACCESS);
if (list && retlen <= list_size)
strcpy(list, POSIX_ACL_XATTR_ACCESS);
return retlen;
}
static size_t jffs2_acl_default_listxattr(struct inode *inode, char *list, size_t list_size,
const char *name, size_t name_len)
{
const int retlen = sizeof(POSIX_ACL_XATTR_DEFAULT);
if (list && retlen <= list_size)
strcpy(list, POSIX_ACL_XATTR_DEFAULT);
return retlen;
}
static int jffs2_acl_getxattr(struct inode *inode, int type, void *buffer, size_t size)
{
struct posix_acl *acl;
int rc;
acl = jffs2_get_acl(inode, type);
if (IS_ERR(acl))
return PTR_ERR(acl);
if (!acl)
return -ENODATA;
rc = posix_acl_to_xattr(acl, buffer, size);
posix_acl_release(acl);
return rc;
}
static int jffs2_acl_access_getxattr(struct inode *inode, const char *name, void *buffer, size_t size)
{
if (name[0] != '\0')
return -EINVAL;
return jffs2_acl_getxattr(inode, ACL_TYPE_ACCESS, buffer, size);
}
static int jffs2_acl_default_getxattr(struct inode *inode, const char *name, void *buffer, size_t size)
{
if (name[0] != '\0')
return -EINVAL;
return jffs2_acl_getxattr(inode, ACL_TYPE_DEFAULT, buffer, size);
}
static int jffs2_acl_setxattr(struct inode *inode, int type, const void *value, size_t size)
{
struct posix_acl *acl;
int rc;
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);
if (acl) {
rc = posix_acl_valid(acl);
if (rc)
goto out;
}
} else {
acl = NULL;
}
rc = jffs2_set_acl(inode, type, acl);
out:
posix_acl_release(acl);
return rc;
}
static int jffs2_acl_access_setxattr(struct inode *inode, const char *name,
const void *buffer, size_t size, int flags)
{
if (name[0] != '\0')
return -EINVAL;
return jffs2_acl_setxattr(inode, ACL_TYPE_ACCESS, buffer, size);
}
static int jffs2_acl_default_setxattr(struct inode *inode, const char *name,
const void *buffer, size_t size, int flags)
{
if (name[0] != '\0')
return -EINVAL;
return jffs2_acl_setxattr(inode, ACL_TYPE_DEFAULT, buffer, size);
}
struct xattr_handler jffs2_acl_access_xattr_handler = {
.prefix = POSIX_ACL_XATTR_ACCESS,
.list = jffs2_acl_access_listxattr,
.get = jffs2_acl_access_getxattr,
.set = jffs2_acl_access_setxattr,
};
struct xattr_handler jffs2_acl_default_xattr_handler = {
.prefix = POSIX_ACL_XATTR_DEFAULT,
.list = jffs2_acl_default_listxattr,
.get = jffs2_acl_default_getxattr,
.set = jffs2_acl_default_setxattr,
};
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