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linux-next/fs/orangefs/acl.c
Jan Kara 073931017b posix_acl: Clear SGID bit when setting file permissions
When file permissions are modified via chmod(2) and the user is not in
the owning group or capable of CAP_FSETID, the setgid bit is cleared in
inode_change_ok().  Setting a POSIX ACL via setxattr(2) sets the file
permissions as well as the new ACL, but doesn't clear the setgid bit in
a similar way; this allows to bypass the check in chmod(2).  Fix that.

References: CVE-2016-7097
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2016-09-22 10:55:32 +02:00

168 lines
4.1 KiB
C

/*
* (C) 2001 Clemson University and The University of Chicago
*
* See COPYING in top-level directory.
*/
#include "protocol.h"
#include "orangefs-kernel.h"
#include "orangefs-bufmap.h"
#include <linux/posix_acl_xattr.h>
#include <linux/fs_struct.h>
struct posix_acl *orangefs_get_acl(struct inode *inode, int type)
{
struct posix_acl *acl;
int ret;
char *key = NULL, *value = NULL;
switch (type) {
case ACL_TYPE_ACCESS:
key = XATTR_NAME_POSIX_ACL_ACCESS;
break;
case ACL_TYPE_DEFAULT:
key = XATTR_NAME_POSIX_ACL_DEFAULT;
break;
default:
gossip_err("orangefs_get_acl: bogus value of type %d\n", type);
return ERR_PTR(-EINVAL);
}
/*
* Rather than incurring a network call just to determine the exact
* length of the attribute, I just allocate a max length to save on
* the network call. Conceivably, we could pass NULL to
* orangefs_inode_getxattr() to probe the length of the value, but
* I don't do that for now.
*/
value = kmalloc(ORANGEFS_MAX_XATTR_VALUELEN, GFP_KERNEL);
if (value == NULL)
return ERR_PTR(-ENOMEM);
gossip_debug(GOSSIP_ACL_DEBUG,
"inode %pU, key %s, type %d\n",
get_khandle_from_ino(inode),
key,
type);
ret = orangefs_inode_getxattr(inode, key, value,
ORANGEFS_MAX_XATTR_VALUELEN);
/* if the key exists, convert it to an in-memory rep */
if (ret > 0) {
acl = posix_acl_from_xattr(&init_user_ns, value, ret);
} else if (ret == -ENODATA || ret == -ENOSYS) {
acl = NULL;
} else {
gossip_err("inode %pU retrieving acl's failed with error %d\n",
get_khandle_from_ino(inode),
ret);
acl = ERR_PTR(ret);
}
/* kfree(NULL) is safe, so don't worry if value ever got used */
kfree(value);
return acl;
}
int orangefs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
{
struct orangefs_inode_s *orangefs_inode = ORANGEFS_I(inode);
int error = 0;
void *value = NULL;
size_t size = 0;
const char *name = NULL;
switch (type) {
case ACL_TYPE_ACCESS:
name = XATTR_NAME_POSIX_ACL_ACCESS;
if (acl) {
umode_t mode;
error = posix_acl_update_mode(inode, &mode, &acl);
if (error) {
gossip_err("%s: posix_acl_update_mode err: %d\n",
__func__,
error);
return error;
}
if (inode->i_mode != mode)
SetModeFlag(orangefs_inode);
inode->i_mode = mode;
mark_inode_dirty_sync(inode);
}
break;
case ACL_TYPE_DEFAULT:
name = XATTR_NAME_POSIX_ACL_DEFAULT;
break;
default:
gossip_err("%s: invalid type %d!\n", __func__, type);
return -EINVAL;
}
gossip_debug(GOSSIP_ACL_DEBUG,
"%s: inode %pU, key %s type %d\n",
__func__, get_khandle_from_ino(inode),
name,
type);
if (acl) {
size = posix_acl_xattr_size(acl->a_count);
value = kmalloc(size, GFP_KERNEL);
if (!value)
return -ENOMEM;
error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
if (error < 0)
goto out;
}
gossip_debug(GOSSIP_ACL_DEBUG,
"%s: name %s, value %p, size %zd, acl %p\n",
__func__, name, value, size, acl);
/*
* Go ahead and set the extended attribute now. NOTE: Suppose acl
* was NULL, then value will be NULL and size will be 0 and that
* will xlate to a removexattr. However, we don't want removexattr
* complain if attributes does not exist.
*/
error = orangefs_inode_setxattr(inode, name, value, size, 0);
out:
kfree(value);
if (!error)
set_cached_acl(inode, type, acl);
return error;
}
int orangefs_init_acl(struct inode *inode, struct inode *dir)
{
struct orangefs_inode_s *orangefs_inode = ORANGEFS_I(inode);
struct posix_acl *default_acl, *acl;
umode_t mode = inode->i_mode;
int error = 0;
ClearModeFlag(orangefs_inode);
error = posix_acl_create(dir, &mode, &default_acl, &acl);
if (error)
return error;
if (default_acl) {
error = orangefs_set_acl(inode, default_acl, ACL_TYPE_DEFAULT);
posix_acl_release(default_acl);
}
if (acl) {
if (!error)
error = orangefs_set_acl(inode, acl, ACL_TYPE_ACCESS);
posix_acl_release(acl);
}
/* If mode of the inode was changed, then do a forcible ->setattr */
if (mode != inode->i_mode) {
SetModeFlag(orangefs_inode);
inode->i_mode = mode;
orangefs_flush_inode(inode);
}
return error;
}