From: keescook@chromium.org (Kees Cook)
To: linux-security-module@vger.kernel.org
Subject: [PATCH v5 14/15] exec: Use sane stack rlimit under secureexec
Date: Tue, 1 Aug 2017 12:16:37 -0700 [thread overview]
Message-ID: <1501614998-62619-15-git-send-email-keescook@chromium.org> (raw)
In-Reply-To: <1501614998-62619-1-git-send-email-keescook@chromium.org>
For a secureexec, before memory layout selection has happened, reset the
stack rlimit to something sane to avoid the caller having control over
the resulting layouts.
$ ulimit -s
8192
$ ulimit -s unlimited
$ /bin/sh -c 'ulimit -s'
unlimited
$ sudo /bin/sh -c 'ulimit -s'
8192
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
---
fs/exec.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/fs/exec.c b/fs/exec.c
index 3006c1c24304..3235cbd85efa 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1350,6 +1350,18 @@ void setup_new_exec(struct linux_binprm * bprm)
*/
bprm->secureexec |= bprm->cap_elevated;
+ if (bprm->secureexec) {
+ /*
+ * For secureexec, reset the stack limit to sane default to
+ * avoid bad behavior from the prior rlimits. This has to
+ * happen before arch_pick_mmap_layout(), which examines
+ * RLIMIT_STACK, but after the point of no return to avoid
+ * needing to clean up the change on failure.
+ */
+ if (current->signal->rlim[RLIMIT_STACK].rlim_cur > _STK_LIM)
+ current->signal->rlim[RLIMIT_STACK].rlim_cur = _STK_LIM;
+ }
+
arch_pick_mmap_layout(current->mm);
current->sas_ss_sp = current->sas_ss_size = 0;
--
2.7.4
--
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next prev parent reply other threads:[~2017-08-01 19:16 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-01 19:16 [PATCH v5 00/15] exec: Use sane stack rlimit under secureexec Kees Cook
2017-08-01 19:16 ` [PATCH v5 01/15] exec: Rename bprm->cred_prepared to called_set_creds Kees Cook
2017-08-01 19:16 ` [PATCH v5 02/15] exec: Correct comments about "point of no return" Kees Cook
2017-08-01 19:16 ` [PATCH v5 03/15] binfmt: Introduce secureexec flag Kees Cook
2017-08-01 19:16 ` [PATCH v5 04/15] apparmor: Refactor to remove bprm_secureexec hook Kees Cook
2017-08-01 19:16 ` [PATCH v5 05/15] selinux: " Kees Cook
2017-08-01 19:16 ` [PATCH v5 06/15] smack: " Kees Cook
2017-08-01 19:16 ` [PATCH v5 07/15] commoncap: " Kees Cook
2017-08-01 19:16 ` [PATCH v5 08/15] commoncap: Move cap_elevated calculation into bprm_set_creds Kees Cook
2017-08-01 19:16 ` [PATCH v5 09/15] LSM: drop bprm_secureexec hook Kees Cook
2017-08-01 19:16 ` [PATCH v5 10/15] exec: Use secureexec for setting dumpability Kees Cook
2017-08-01 19:16 ` [PATCH v5 11/15] exec: Use secureexec for clearing pdeath_signal Kees Cook
2017-08-01 19:16 ` [PATCH v5 12/15] smack: Remove redundant pdeath_signal clearing Kees Cook
2017-08-01 19:16 ` [PATCH v5 13/15] exec: Consolidate dumpability logic Kees Cook
2017-08-01 19:16 ` Kees Cook [this message]
2017-08-01 19:16 ` [PATCH v5 15/15] exec: Consolidate pdeath_signal clearing Kees Cook
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