From: "Eric W. Biederman" <[email protected]> 3.12-stable review patch. If anyone has any objections, please let me know.
=============== commit 80dd00a23784b384ccea049bfb3f259d3f973b9d upstream. setresuid allows the euid to be set to any of uid, euid, suid, and fsuid. Therefor it is safe to allow an unprivileged user to map their euid and use CAP_SETUID privileged with exactly that uid, as no new credentials can be obtained. I can not find a combination of existing system calls that allows setting uid, euid, suid, and fsuid from the fsuid making the previous use of fsuid for allowing unprivileged mappings a bug. This is part of a fix for CVE-2014-8989. Reviewed-by: Andy Lutomirski <[email protected]> Signed-off-by: "Eric W. Biederman" <[email protected]> Signed-off-by: Jiri Slaby <[email protected]> --- kernel/user_namespace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index a5809c42a1b3..6e495bd672a7 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -805,7 +805,7 @@ static bool new_idmap_permitted(const struct file *file, u32 id = new_map->extent[0].lower_first; if (cap_setid == CAP_SETUID) { kuid_t uid = make_kuid(ns->parent, id); - if (uid_eq(uid, file->f_cred->fsuid)) + if (uid_eq(uid, file->f_cred->euid)) return true; } } -- 2.2.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
