linux/fs/hfsplus/posix_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

138 lines
2.8 KiB
C

/*
* linux/fs/hfsplus/posix_acl.c
*
* Vyacheslav Dubeyko <slava@dubeyko.com>
*
* Handler for Posix Access Control Lists (ACLs) support.
*/
#include "hfsplus_fs.h"
#include "xattr.h"
#include "acl.h"
struct posix_acl *hfsplus_get_posix_acl(struct inode *inode, int type)
{
struct posix_acl *acl;
char *xattr_name;
char *value = NULL;
ssize_t size;
hfs_dbg(ACL_MOD, "[%s]: ino %lu\n", __func__, inode->i_ino);
switch (type) {
case ACL_TYPE_ACCESS:
xattr_name = XATTR_NAME_POSIX_ACL_ACCESS;
break;
case ACL_TYPE_DEFAULT:
xattr_name = XATTR_NAME_POSIX_ACL_DEFAULT;
break;
default:
return ERR_PTR(-EINVAL);
}
size = __hfsplus_getxattr(inode, xattr_name, NULL, 0);
if (size > 0) {
value = (char *)hfsplus_alloc_attr_entry();
if (unlikely(!value))
return ERR_PTR(-ENOMEM);
size = __hfsplus_getxattr(inode, xattr_name, value, size);
}
if (size > 0)
acl = posix_acl_from_xattr(&init_user_ns, value, size);
else if (size == -ENODATA)
acl = NULL;
else
acl = ERR_PTR(size);
hfsplus_destroy_attr_entry((hfsplus_attr_entry *)value);
return acl;
}
int hfsplus_set_posix_acl(struct inode *inode, struct posix_acl *acl,
int type)
{
int err;
char *xattr_name;
size_t size = 0;
char *value = NULL;
hfs_dbg(ACL_MOD, "[%s]: ino %lu\n", __func__, inode->i_ino);
switch (type) {
case ACL_TYPE_ACCESS:
xattr_name = XATTR_NAME_POSIX_ACL_ACCESS;
if (acl) {
err = posix_acl_update_mode(inode, &inode->i_mode, &acl);
if (err)
return err;
}
err = 0;
break;
case ACL_TYPE_DEFAULT:
xattr_name = XATTR_NAME_POSIX_ACL_DEFAULT;
if (!S_ISDIR(inode->i_mode))
return acl ? -EACCES : 0;
break;
default:
return -EINVAL;
}
if (acl) {
size = posix_acl_xattr_size(acl->a_count);
if (unlikely(size > HFSPLUS_MAX_INLINE_DATA_SIZE))
return -ENOMEM;
value = (char *)hfsplus_alloc_attr_entry();
if (unlikely(!value))
return -ENOMEM;
err = posix_acl_to_xattr(&init_user_ns, acl, value, size);
if (unlikely(err < 0))
goto end_set_acl;
}
err = __hfsplus_setxattr(inode, xattr_name, value, size, 0);
end_set_acl:
hfsplus_destroy_attr_entry((hfsplus_attr_entry *)value);
if (!err)
set_cached_acl(inode, type, acl);
return err;
}
int hfsplus_init_posix_acl(struct inode *inode, struct inode *dir)
{
int err = 0;
struct posix_acl *default_acl, *acl;
hfs_dbg(ACL_MOD,
"[%s]: ino %lu, dir->ino %lu\n",
__func__, inode->i_ino, dir->i_ino);
if (S_ISLNK(inode->i_mode))
return 0;
err = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
if (err)
return err;
if (default_acl) {
err = hfsplus_set_posix_acl(inode, default_acl,
ACL_TYPE_DEFAULT);
posix_acl_release(default_acl);
}
if (acl) {
if (!err)
err = hfsplus_set_posix_acl(inode, acl,
ACL_TYPE_ACCESS);
posix_acl_release(acl);
}
return err;
}