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Commit 8742f229 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

userns: limit the maximum depth of user_namespace->parent chain 



Ensure that user_namespace->parent chain can't grow too much.
Currently we use the hardroded 32 as limit.

Reported-by: default avatarAndy Lutomirski <luto@amacapital.net>
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 55f5bfd4

include/linux/user_namespace.h

+1 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ struct user_namespace { 
	struct uid_gid_map	projid_map;

	atomic_t		count;

	struct user_namespace	*parent;

	int			level;

	kuid_t			owner;

	kgid_t			group;

	unsigned int		proc_inum;

kernel/user_namespace.c

+4 −0
Original line number Diff line number Diff line
@@ -62,6 +62,9 @@ int create_user_ns(struct cred *new) 
	kgid_t group = new->egid;

	int ret;



	if (parent_ns->level > 32)

		return -EUSERS;



	/*

	 * Verify that we can not violate the policy of which files

	 * may be accessed that is specified by the root directory,
@@ -92,6 +95,7 @@ int create_user_ns(struct cred *new) 
	atomic_set(&ns->count, 1);

	/* Leave the new->user_ns reference with the new user namespace. */

	ns->parent = parent_ns;

	ns->level = parent_ns->level + 1;

	ns->owner = owner;

	ns->group = group;