This is a note to let you know that I've just added the patch titled userns: Check euid no fsuid when establishing an unprivileged uid mapping to the 3.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: userns-check-euid-no-fsuid-when-establishing-an-unprivileged-uid-mapping.patch and it can be found in the queue-3.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 80dd00a23784b384ccea049bfb3f259d3f973b9d Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Date: Fri, 5 Dec 2014 18:26:30 -0600 Subject: userns: Check euid no fsuid when establishing an unprivileged uid mapping From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> 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 <luto@xxxxxxxxxxxxxx> Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/user_namespace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -811,7 +811,7 @@ static bool new_idmap_permitted(const st 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; } } Patches currently in stable-queue which might be from ebiederm@xxxxxxxxxxxx are queue-3.14/mnt-update-unprivileged-remount-test.patch queue-3.14/mnt-fix-a-memory-stomp-in-umount.patch queue-3.14/userns-check-euid-no-fsuid-when-establishing-an-unprivileged-uid-mapping.patch queue-3.14/mnt-implicitly-add-mnt_nodev-on-remount-when-it-was-implicitly-added-by-mount.patch queue-3.14/userns-don-t-allow-unprivileged-creation-of-gid-mappings.patch queue-3.14/userns-rename-id_map_mutex-to-userns_state_mutex.patch queue-3.14/userns-add-a-knob-to-disable-setgroups-on-a-per-user-namespace-basis.patch queue-3.14/userns-allow-setting-gid_maps-without-privilege-when-setgroups-is-disabled.patch queue-3.14/userns-don-t-allow-setgroups-until-a-gid-mapping-has-been-setablished.patch queue-3.14/groups-consolidate-the-setgroups-permission-checks.patch queue-3.14/userns-only-allow-the-creator-of-the-userns-unprivileged-mappings.patch queue-3.14/userns-document-what-the-invariant-required-for-safe-unprivileged-mappings.patch queue-3.14/umount-disallow-unprivileged-mount-force.patch queue-3.14/userns-unbreak-the-unprivileged-remount-tests.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html