4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kees Cook <keescook@xxxxxxxxxxxx>
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@xxxxxxxxx>
Fixes: e37fdb785a5f ("exec: Use secureexec for setting dumpability")
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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);