| Message ID | 1501545093-56634-11-git-send-email-keescook@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, 31 Jul 2017, Kees Cook wrote: > The examination of "current" to decide dumpability is wrong. This was a > check of and euid/uid (or egid/gid) mismatch in the existing process, > not the newly created one. This appears to stretch back into even the > "history.git" tree. Luckily, dumpability is later set in commit_creds(). > In earlier kernel versions before creds existed, similar checks also > existed late in the exec flow, covering up the mistake as far back as I > could find. > > Note that because the commit_creds() check examines differences of euid, > uid, egid, gid, and capabilities between the old and new creds, it would > look like the setup_new_exec() dumpability test could be entirely removed. > However, the secureexec test may cover a different set of tests (specific > to the LSMs) than what commit_creds() checks for. So, fix this test to > use secureexec (the removed euid tests are redundant to the commoncap > secureexec checks now). > > Cc: David Howells <dhowells@redhat.com> > Signed-off-by: Kees Cook <keescook@chromium.org> > Acked-by: Serge Hallyn <serge@hallyn.com> > --- > fs/exec.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Reviewed-by: James Morris <james.l.morris@oracle.com>
diff --git a/fs/exec.c b/fs/exec.c index f0e8d25eba9f..f9997ea6414e 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1333,7 +1333,7 @@ void setup_new_exec(struct linux_binprm * bprm) current->sas_ss_sp = current->sas_ss_size = 0; - if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid())) + if (!bprm->secureexec) set_dumpable(current->mm, SUID_DUMP_USER); else set_dumpable(current->mm, suid_dumpable);