linux-stable/fs/generic_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

197 lines
4.2 KiB
C

/*
* fs/generic_acl.c
*
* (C) 2005 Andreas Gruenbacher <agruen@suse.de>
*
* This file is released under the GPL.
*/
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/generic_acl.h>
/**
* generic_acl_list - Generic xattr_handler->list() operation
* @ops: Filesystem specific getacl and setacl callbacks
*/
size_t
generic_acl_list(struct inode *inode, struct generic_acl_operations *ops,
int type, char *list, size_t list_size)
{
struct posix_acl *acl;
const char *name;
size_t size;
acl = ops->getacl(inode, type);
if (!acl)
return 0;
posix_acl_release(acl);
switch(type) {
case ACL_TYPE_ACCESS:
name = POSIX_ACL_XATTR_ACCESS;
break;
case ACL_TYPE_DEFAULT:
name = POSIX_ACL_XATTR_DEFAULT;
break;
default:
return 0;
}
size = strlen(name) + 1;
if (list && size <= list_size)
memcpy(list, name, size);
return size;
}
/**
* generic_acl_get - Generic xattr_handler->get() operation
* @ops: Filesystem specific getacl and setacl callbacks
*/
int
generic_acl_get(struct inode *inode, struct generic_acl_operations *ops,
int type, void *buffer, size_t size)
{
struct posix_acl *acl;
int error;
acl = ops->getacl(inode, type);
if (!acl)
return -ENODATA;
error = posix_acl_to_xattr(acl, buffer, size);
posix_acl_release(acl);
return error;
}
/**
* generic_acl_set - Generic xattr_handler->set() operation
* @ops: Filesystem specific getacl and setacl callbacks
*/
int
generic_acl_set(struct inode *inode, struct generic_acl_operations *ops,
int type, const void *value, size_t size)
{
struct posix_acl *acl = NULL;
int error;
if (S_ISLNK(inode->i_mode))
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);
}
if (acl) {
mode_t mode;
error = posix_acl_valid(acl);
if (error)
goto failed;
switch(type) {
case ACL_TYPE_ACCESS:
mode = inode->i_mode;
error = posix_acl_equiv_mode(acl, &mode);
if (error < 0)
goto failed;
inode->i_mode = mode;
if (error == 0) {
posix_acl_release(acl);
acl = NULL;
}
break;
case ACL_TYPE_DEFAULT:
if (!S_ISDIR(inode->i_mode)) {
error = -EINVAL;
goto failed;
}
break;
}
}
ops->setacl(inode, type, acl);
error = 0;
failed:
posix_acl_release(acl);
return error;
}
/**
* generic_acl_init - Take care of acl inheritance at @inode create time
* @ops: Filesystem specific getacl and setacl callbacks
*
* Files created inside a directory with a default ACL inherit the
* directory's default ACL.
*/
int
generic_acl_init(struct inode *inode, struct inode *dir,
struct generic_acl_operations *ops)
{
struct posix_acl *acl = NULL;
mode_t mode = inode->i_mode;
int error;
inode->i_mode = mode & ~current->fs->umask;
if (!S_ISLNK(inode->i_mode))
acl = ops->getacl(dir, ACL_TYPE_DEFAULT);
if (acl) {
struct posix_acl *clone;
if (S_ISDIR(inode->i_mode)) {
clone = posix_acl_clone(acl, GFP_KERNEL);
error = -ENOMEM;
if (!clone)
goto cleanup;
ops->setacl(inode, ACL_TYPE_DEFAULT, clone);
posix_acl_release(clone);
}
clone = posix_acl_clone(acl, GFP_KERNEL);
error = -ENOMEM;
if (!clone)
goto cleanup;
error = posix_acl_create_masq(clone, &mode);
if (error >= 0) {
inode->i_mode = mode;
if (error > 0)
ops->setacl(inode, ACL_TYPE_ACCESS, clone);
}
posix_acl_release(clone);
}
error = 0;
cleanup:
posix_acl_release(acl);
return error;
}
/**
* generic_acl_chmod - change the access acl of @inode upon chmod()
* @ops: FIlesystem specific getacl and setacl callbacks
*
* A chmod also changes the permissions of the owner, group/mask, and
* other ACL entries.
*/
int
generic_acl_chmod(struct inode *inode, struct generic_acl_operations *ops)
{
struct posix_acl *acl, *clone;
int error = 0;
if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
acl = ops->getacl(inode, ACL_TYPE_ACCESS);
if (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)
ops->setacl(inode, ACL_TYPE_ACCESS, clone);
posix_acl_release(clone);
}
return error;
}