Patch "exec: Weaken dumpability for secureexec" has been added to the 4.14-stable tree

Patch "exec: Weaken dumpability for secureexec" has been added to the 4.14-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    exec: Weaken dumpability for secureexec

to the 4.14-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:
     exec-weaken-dumpability-for-secureexec.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From e816c201aed5232171f8eb80b5d46ae6516683b9 Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@chromium.org>
Date: Tue, 2 Jan 2018 15:21:33 -0800
Subject: exec: Weaken dumpability for secureexec

From: Kees Cook <keescook@chromium.org>

commit e816c201aed5232171f8eb80b5d46ae6516683b9 upstream.

This is a logical revert of commit e37fdb785a5f ("exec: Use secureexec
for setting dumpability")

This weakens dumpability back to checking only for uid/gid changes in
current (which is useless), but userspace depends on dumpability not
being tied to secureexec.

  https://bugzilla.redhat.com/show_bug.cgi?id=1528633

Reported-by: Tom Horsley <horsley1953@gmail.com>
Fixes: e37fdb785a5f ("exec: Use secureexec for setting dumpability")
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/exec.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1350,9 +1350,14 @@ void setup_new_exec(struct linux_binprm
 
 	current->sas_ss_sp = current->sas_ss_size = 0;
 
-	/* Figure out dumpability. */
+	/*
+	 * Figure out dumpability. Note that this checking only of current
+	 * is wrong, but userspace depends on it. This should be testing
+	 * bprm->secureexec instead.
+	 */
 	if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP ||
-	    bprm->secureexec)
+	    !(uid_eq(current_euid(), current_uid()) &&
+	      gid_eq(current_egid(), current_gid())))
 		set_dumpable(current->mm, suid_dumpable);
 	else
 		set_dumpable(current->mm, SUID_DUMP_USER);


Patches currently in stable-queue which might be from keescook@chromium.org are

queue-4.14/exec-weaken-dumpability-for-secureexec.patch