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

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 <[email protected]> know about it.

From: Kees Cook <[email protected]>
Date: Tue, 2 Jan 2018 15:21:33 -0800
Subject: exec: Weaken dumpability for secureexec

From: Kees Cook <[email protected]>

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

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

@@ -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 [email protected] are

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