diff options
| author | Kees Cook <keescook@chromium.org> | 2017-07-18 15:25:35 -0700 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2017-08-01 12:03:14 -0700 |
| commit | 64701dee4178eb4a771b8b36cd86560f5b0e2460 (patch) | |
| tree | 1a0012699f1c5ba4fb7909eb0db75aaf10168e7a /fs/exec.c | |
| parent | 473d89639db0aaa0799616b397584ba4f58cd8e1 (diff) | |
exec: Use sane stack rlimit under secureexec
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>
Diffstat (limited to 'fs/exec.c')
| -rw-r--r-- | fs/exec.c | 12 |
1 files changed, 12 insertions, 0 deletions
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; |