From df0b5a49406763aa4719dfad561a5de8924ecd59 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Tue, 23 Aug 2011 09:37:39 -0400 Subject: security hardening: ensure suid programs have valid stdin/out/err this behavior (opening fds 0-2 for a suid program) is explicitly allowed (but not required) by POSIX to protect badly-written suid programs from clobbering files they later open. this commit does add some cost in startup code, but the availability of auxv and the security flag will be useful elsewhere in the future. in particular auxv is needed for static-linked vdso support, which is still waiting to be committed (sorry nik!) --- src/env/__libc_start_main.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) (limited to 'src/env/__libc_start_main.c') diff --git a/src/env/__libc_start_main.c b/src/env/__libc_start_main.c index 70af77b5..f31222b2 100644 --- a/src/env/__libc_start_main.c +++ b/src/env/__libc_start_main.c @@ -1,21 +1,21 @@ #include "libc.h" -/* Any use of __environ/environ will override this symbol. */ -char **__dummy_environ = (void *)-1; -weak_alias(__dummy_environ, ___environ); +void __init_security(size_t *); int __libc_start_main( int (*main)(int, char **, char **), int argc, char **argv, int (*init)(int, char **, char **), void (*fini)(void), void (*ldso_fini)(void)) { - /* Save the environment if it may be used by libc/application */ - char **envp = argv+argc+1; - if (___environ != (void *)-1) ___environ = envp; + char **envp = argv+argc+1, **auxv = envp; - /* Avoid writing 0 and triggering unnecessary COW */ - if (ldso_fini) libc.ldso_fini = ldso_fini; - if (fini) libc.fini = fini; + __environ = envp; + do auxv++; while (*auxv); + libc.auxv = (void *)++auxv; + libc.ldso_fini = ldso_fini; + libc.fini = fini; + + __init_security((void *)auxv); /* Execute constructors (static) linked into the application */ if (init) init(argc, argv, envp); -- cgit v1.2.1