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busybox: fix login applet on selinux

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Currently the system boots up, but is unusable because pressing enter
does not provide login with error:

  login: can't get SID for root

This is happenning, because login.c passes the Linux username directly
to get_default_context(), while libselinux expects an SELinux user
identity, causing the call to fail for users without a matching SELinux
name (e.g., root) and aborting login on SELinux-enabled systems.

Fixes: #19075
Upstream-Status: Submitted [https://lists.busybox.net/pipermail/busybox/2025-April/091407.html]
Signed-off-by: Petr Štetiar <ynezz@true.cz>
Link: https://github.com/openwrt/openwrt/pull/19080
(cherry picked from commit 5809bfaaac)
Link: https://github.com/openwrt/openwrt/pull/19542
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
This commit is contained in:
Petr Štetiar 2025-06-09 15:44:44 +00:00 • committed by Hauke Mehrtens
parent 254f6b2414
commit bfed41cc6a
1 changed files with 51 additions and 0 deletions
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51
package/utils/busybox/patches/600-loginutils-login.c-libselinux-get_default_context-ex.patch Normal file
View file

@ -0,0 +1,51 @@
From 850a6d031039237b0b13d8fab9f10a7cd4752907 Mon Sep 17 00:00:00 2001
From: Dominick Grift <dominick.grift@defensec.nl>
Date: Sat, 5 Apr 2025 13:40:26 +0200
Subject: [PATCH] loginutils/login.c: libselinux get_default_context() expects
seuser
Use getseuserbyname() to get the seuser associated with username and use that
instead with get_default_context()
>From get_default_context.3:
"These functions takes a SELinux user identity that must be defined in the SELinux policy as their input, not a Linux username."
Fixes: #19075
Upstream-Status: Submitted [https://lists.busybox.net/pipermail/busybox/2025-April/091407.html]
Signed-off-by: Dominick Grift <dominick.grift@defensec.nl>
---
loginutils/login.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
--- a/loginutils/login.c
+++ b/loginutils/login.c
@@ -183,12 +183,16 @@ static void die_if_nologin(void)
static void initselinux(char *username, char *full_tty,
security_context_t *user_sid)
{
+ char *seuser = NULL, *level = NULL;
security_context_t old_tty_sid, new_tty_sid;
if (!is_selinux_enabled())
return;
- if (get_default_context(username, NULL, user_sid)) {
+ if (getseuserbyname(username, &seuser, &level)) {
+ bb_error_msg_and_die("can't get seuser for %s", username);
+ }
+ if (get_default_context(seuser, NULL, user_sid)) {
bb_error_msg_and_die("can't get SID for %s", username);
}
if (getfilecon(full_tty, &old_tty_sid) < 0) {
@@ -201,6 +205,11 @@ static void initselinux(char *username,
if (setfilecon(full_tty, new_tty_sid) != 0) {
bb_perror_msg_and_die("chsid(%s, %s) failed", full_tty, new_tty_sid);
}
+
+ if (ENABLE_FEATURE_CLEAN_UP) {
+ free(seuser);
+ free(level);
+ }
}
#endif