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linux/fs/jffs2/acl.c
Christian Brauner 700b794052
fs: port acl to mnt_idmap 
Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-19 09:24:28 +01:00

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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);
break;
case ACL_USER:
value += sizeof(struct jffs2_acl_entry);
if (value > end)
goto fail;
acl->a_entries[i].e_uid =
make_kuid(&init_user_ns,
je32_to_cpu(entry->e_id));
break;
case ACL_GROUP:
value += sizeof(struct jffs2_acl_entry);
if (value > end)
goto fail;
acl->a_entries[i].e_gid =
make_kgid(&init_user_ns,
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(struct_size(header, a_entries, acl->a_count),
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++) {
const struct posix_acl_entry *acl_e = &acl->a_entries[i];
entry = e;
entry->e_tag = cpu_to_je16(acl_e->e_tag);
entry->e_perm = cpu_to_je16(acl_e->e_perm);
switch(acl_e->e_tag) {
case ACL_USER:
entry->e_id = cpu_to_je32(
from_kuid(&init_user_ns, acl_e->e_uid));
e += sizeof(struct jffs2_acl_entry);
break;
case ACL_GROUP:
entry->e_id = cpu_to_je32(
from_kgid(&init_user_ns, acl_e->e_gid));
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, bool rcu)
{
struct posix_acl *acl;
char *value = NULL;
int rc, xprefix;
if (rcu)
return ERR_PTR(-ECHILD);
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);
}
kfree(value);
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;
}
int jffs2_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
struct posix_acl *acl, int type)
{
int rc, xprefix;
struct inode *inode = d_inode(dentry);
switch (type) {
case ACL_TYPE_ACCESS:
xprefix = JFFS2_XPREFIX_ACL_ACCESS;
if (acl) {
umode_t mode;
rc = posix_acl_update_mode(&nop_mnt_idmap, inode, &mode,
&acl);
if (rc)
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(inode);
rc = jffs2_do_setattr(inode, &attr);
if (rc < 0)
return rc;
}
}
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 *default_acl, *acl;
int rc;
cache_no_acl(inode);
rc = posix_acl_create(dir_i, i_mode, &default_acl, &acl);
if (rc)
return rc;
if (default_acl) {
set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
posix_acl_release(default_acl);
}
if (acl) {
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;
}
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