From 32c08acba3d938ec2fa4f9d2ff8160bbe05a20cb Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Wed, 30 Mar 2016 17:27:32 +0200 Subject: [PATCH] sulogin: remove suid paranoia code, explain why it's not necessary function old new delta sulogin_main 325 270 -55 Signed-off-by: Denys Vlasenko --- loginutils/sulogin.c | 22 +++++++++------------- 1 file changed, 9 insertions(+), 13 deletions(-) diff --git a/loginutils/sulogin.c b/loginutils/sulogin.c index d2ac1f65d..33f078ae7 100644 --- a/loginutils/sulogin.c +++ b/loginutils/sulogin.c @@ -32,6 +32,14 @@ int sulogin_main(int argc UNUSED_PARAM, char **argv) struct passwd *pwd; const char *shell; + /* Note: sulogin is not a suid app. It is meant to be run by init + * for single user / emergency mode. init starts it as root. + * Normal users (potentially malisious ones) can only run it under + * their UID, therefore no paranoia here is warranted: + * $LD_LIBRARY_PATH in env, TTY = /dev/sda + * are no more dangerous here than in e.g. cp applet. + */ + logmode = LOGMODE_BOTH; openlog(applet_name, 0, LOG_AUTH); @@ -47,18 +55,9 @@ int sulogin_main(int argc UNUSED_PARAM, char **argv) dup(0); } - /* Malicious use like "sulogin /dev/sda"? */ - if (!isatty(0) || !isatty(1) || !isatty(2)) { - logmode = LOGMODE_SYSLOG; - bb_error_msg_and_die("not a tty"); - } - - /* Clear dangerous stuff, set PATH */ - sanitize_env_if_suid(); - pwd = getpwuid(0); if (!pwd) { - goto auth_error; + bb_error_msg_and_die("no password entry for root"); } while (1) { @@ -92,7 +91,4 @@ int sulogin_main(int argc UNUSED_PARAM, char **argv) /* Exec login shell with no additional parameters. Never returns. */ run_shell(shell, 1, NULL, NULL); - - auth_error: - bb_error_msg_and_die("no password entry for root"); }