72 lines
2.3 KiB
Diff
72 lines
2.3 KiB
Diff
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From d9c09138d91566af49ef8179d9995c84294e2486 Mon Sep 17 00:00:00 2001
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From: Kaarle Ritvanen <kaarle.ritvanen@datakunkku.fi>
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Date: Thu, 5 Nov 2015 16:27:36 +0200
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Subject: [PATCH 10/12] su: FEATURE_SU_NULLOK_SECURE
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When this feature is enabled, blank passwords are not accepted by su
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unless the user is on a secure TTY defined in /etc/securetty. This
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resembles the default PAM configuration of some Linux distros which
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specify the nullok_secure option for pam_unix.so.
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---
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loginutils/su.c | 18 +++++++++++++-----
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1 file changed, 13 insertions(+), 5 deletions(-)
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diff --git a/loginutils/su.c b/loginutils/su.c
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index 24ffbde86..086445243 100644
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--- a/loginutils/su.c
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+++ b/loginutils/su.c
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@@ -24,6 +24,11 @@
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//config: bool "Enable su to check user's shell to be listed in /etc/shells"
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//config: depends on SU
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//config: default y
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+//config:config FEATURE_SU_NULLOK_SECURE
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+//config: bool "Disallow blank passwords from TTYs other than specified in /etc/securetty"
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+//config: depends on SU
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+//config: default n
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+
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//applet:/* Needs to be run by root or be suid root - needs to change uid and gid: */
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//applet:IF_SU(APPLET(su, BB_DIR_BIN, BB_SUID_REQUIRE))
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@@ -76,6 +81,7 @@ int su_main(int argc UNUSED_PARAM, char **argv)
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struct passwd *pw;
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uid_t cur_uid = getuid();
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const char *tty;
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+ int allow_blank = 1;
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#if ENABLE_FEATURE_UTMP
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char user_buf[64];
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#endif
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@@ -100,6 +106,12 @@ int su_main(int argc UNUSED_PARAM, char **argv)
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argv++;
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}
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+ tty = xmalloc_ttyname(STDIN_FILENO);
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+ if (!tty) tty = "none";
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+ tty = skip_dev_pfx(tty);
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+
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+ if (ENABLE_FEATURE_SU_NULLOK_SECURE) allow_blank = check_securetty(tty);
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+
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if (ENABLE_FEATURE_SU_SYSLOG) {
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/* The utmp entry (via getlogin) is probably the best way to
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* identify the user, especially if someone su's from a su-shell.
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@@ -113,16 +125,12 @@ int su_main(int argc UNUSED_PARAM, char **argv)
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pw = getpwuid(cur_uid);
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old_user = pw ? xstrdup(pw->pw_name) : "";
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}
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- tty = xmalloc_ttyname(2);
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- if (!tty) {
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- tty = "none";
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- }
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openlog(applet_name, 0, LOG_AUTH);
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}
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pw = xgetpwnam(opt_username);
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- if (cur_uid == 0 || ask_and_check_password(pw) > 0) {
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+ if (cur_uid == 0 || ask_and_check_password_extended(pw, 0, allow_blank, "Password: ") > 0) {
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if (ENABLE_FEATURE_SU_SYSLOG)
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syslog(LOG_NOTICE, "%c %s %s:%s",
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'+', tty, old_user, opt_username);
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--
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2.11.0
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