12a4f9afe
Denys Vlasenko
2017-07-10
Subject
libbb: do not die if setgid/setuid(real_id) on startup fails
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Commit Diff GitHub →
libbb/appletlib.c+15 -2
| @@ -681,8 +681,21 @@ static void check_suid(int applet_no) | |
| if (geteuid()) | |
| bb_error_msg_and_die("must be suid to work properly"); | |
| } else if (APPLET_SUID(applet_no) == BB_SUID_DROP) { | |
| - | xsetgid(rgid); /* drop all privileges */ |
| - | xsetuid(ruid); |
| + | /* |
| + | * Drop all privileges. |
| + | * |
| + | * Don't check for errors: in normal use, they are impossible, |
| + | * and in special cases, exiting is harmful. Example: |
| + | * 'unshare --user' when user's shell is also from busybox. |
| + | * |
| + | * 'unshare --user' creates a new user namespace without any |
| + | * uid mappings. Thus, busybox binary is setuid nobody:nogroup |
| + | * within the namespace, as that is the only user. However, |
| + | * since no uids are mapped, calls to setgid/setuid |
| + | * fail (even though they would do nothing). |
| + | */ |
| + | setgid(rgid); |
| + | setuid(ruid); |
| } | |
| # if ENABLE_FEATURE_SUID_CONFIG | |
| ret: ; | |