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linux/fs/jffs2/acl.c
Eric W. Biederman 5f3a4a28ec userns: Pass a userns parameter into posix_acl_to_xattr and posix_acl_from_xattr 
- Pass the user namespace the uid and gid values in the xattr are stored
   in into posix_acl_from_xattr.

 - Pass the user namespace kuid and kgid values should be converted into
   when storing uid and gid values in an xattr in posix_acl_to_xattr.

- Modify all callers of posix_acl_from_xattr and posix_acl_to_xattr to
  pass in &init_user_ns.

In the short term this change is not strictly needed but it makes the
code clearer.  In the longer term this change is necessary to be able to
mount filesystems outside of the initial user namespace that natively
store posix acls in the linux xattr format.

Cc: Theodore Tso <tytso@mit.edu>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-09-18 01:01:35 -07:00

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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.
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#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);
if (size < 4 * sizeof(struct jffs2_acl_entry_short)) {
if (size % sizeof(struct jffs2_acl_entry_short))
return -1;
return size / sizeof(struct jffs2_acl_entry_short);
} else {
s = size - 4 * sizeof(struct jffs2_acl_entry_short);
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);
}
struct posix_acl *jffs2_get_acl(struct inode *inode, int type)
{
struct posix_acl *acl;
char *value = NULL;
int rc, xprefix;
acl = get_cached_acl(inode, type);
if (acl != ACL_NOT_CACHED)
return acl;
switch (type) {
case ACL_TYPE_ACCESS:
xprefix = JFFS2_XPREFIX_ACL_ACCESS;
break;
case ACL_TYPE_DEFAULT:
xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
break;
default:
BUG();
}
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))
set_cached_acl(inode, type, acl);
return acl;
}
static int __jffs2_set_acl(struct inode *inode, int xprefix, struct posix_acl *acl)
{
char *value = NULL;
size_t size = 0;
int rc;
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;
kfree(value);
return rc;
}
static int jffs2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
{
int rc, xprefix;
if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
switch (type) {
case ACL_TYPE_ACCESS:
xprefix = JFFS2_XPREFIX_ACL_ACCESS;
if (acl) {
umode_t mode = inode->i_mode;
rc = posix_acl_equiv_mode(acl, &mode);
if (rc < 0)
return rc;
if (inode->i_mode != mode) {
struct iattr attr;
attr.ia_valid = ATTR_MODE | ATTR_CTIME;
attr.ia_mode = mode;
attr.ia_ctime = CURRENT_TIME_SEC;
rc = jffs2_do_setattr(inode, &attr);
if (rc < 0)
return rc;
}
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;
}
rc = __jffs2_set_acl(inode, xprefix, acl);
if (!rc)
set_cached_acl(inode, type, acl);
return rc;
}
int jffs2_init_acl_pre(struct inode *dir_i, struct inode *inode, umode_t *i_mode)
{
struct posix_acl *acl;
int rc;
cache_no_acl(inode);
if (S_ISLNK(*i_mode))
return 0; /* Symlink always has no-ACL */
acl = jffs2_get_acl(dir_i, ACL_TYPE_DEFAULT);
if (IS_ERR(acl))
return PTR_ERR(acl);
if (!acl) {
*i_mode &= ~current_umask();
} else {
if (S_ISDIR(*i_mode))
set_cached_acl(inode, ACL_TYPE_DEFAULT, acl);
rc = posix_acl_create(&acl, GFP_KERNEL, i_mode);
if (rc < 0)
return rc;
if (rc > 0)
set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
posix_acl_release(acl);
}
return 0;
}
int jffs2_init_acl_post(struct inode *inode)
{
int rc;
if (inode->i_default_acl) {
rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_DEFAULT, inode->i_default_acl);
if (rc)
return rc;
}
if (inode->i_acl) {
rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_ACCESS, inode->i_acl);
if (rc)
return rc;
}
return 0;
}
int jffs2_acl_chmod(struct inode *inode)
{
struct posix_acl *acl;
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);
rc = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
if (rc)
return rc;
rc = jffs2_set_acl(inode, ACL_TYPE_ACCESS, acl);
posix_acl_release(acl);
return rc;
}
static size_t jffs2_acl_access_listxattr(struct dentry *dentry, char *list,
size_t list_size, const char *name, size_t name_len, int type)
{
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 dentry *dentry, char *list,
size_t list_size, const char *name, size_t name_len, int type)
{
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 dentry *dentry, const char *name,
void *buffer, size_t size, int type)
{
struct posix_acl *acl;
int rc;
if (name[0] != '\0')
return -EINVAL;
acl = jffs2_get_acl(dentry->d_inode, type);
if (IS_ERR(acl))
return PTR_ERR(acl);
if (!acl)
return -ENODATA;
rc = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
posix_acl_release(acl);
return rc;
}
static int jffs2_acl_setxattr(struct dentry *dentry, const char *name,
const void *value, size_t size, int flags, int type)
{
struct posix_acl *acl;
int rc;
if (name[0] != '\0')
return -EINVAL;
if (!inode_owner_or_capable(dentry->d_inode))
return -EPERM;
if (value) {
acl = posix_acl_from_xattr(&init_user_ns, 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(dentry->d_inode, type, acl);
out:
posix_acl_release(acl);
return rc;
}
const struct xattr_handler jffs2_acl_access_xattr_handler = {
.prefix = POSIX_ACL_XATTR_ACCESS,
.flags = ACL_TYPE_DEFAULT,
.list = jffs2_acl_access_listxattr,
.get = jffs2_acl_getxattr,
.set = jffs2_acl_setxattr,
};
const struct xattr_handler jffs2_acl_default_xattr_handler = {
.prefix = POSIX_ACL_XATTR_DEFAULT,
.flags = ACL_TYPE_DEFAULT,
.list = jffs2_acl_default_listxattr,
.get = jffs2_acl_getxattr,
.set = jffs2_acl_setxattr,
};
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