From 31a83bd48d9aad2a039565fc39f1a52bd0cdf17d Mon Sep 17 00:00:00 2001 From: Teddy Reed Date: Mon, 10 Feb 2020 21:29:26 -0500 Subject: [PATCH] Fix ordering of setgid and setuid It looks like the code to drop privileges may have been broken via commit 37f0e1f. That commit reverted the correct order from #911, which first drops the gid then the uid. If setuid is called first then the target user may not have the ability to setgid. --- sway/main.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/sway/main.c b/sway/main.c index e0af4a79..d4585f73 100644 --- a/sway/main.c +++ b/sway/main.c @@ -186,12 +186,17 @@ static void log_kernel(void) { static bool drop_permissions(void) { if (getuid() != geteuid() || getgid() != getegid()) { - if (setuid(getuid()) != 0 || setgid(getgid()) != 0) { - sway_log(SWAY_ERROR, "Unable to drop root, refusing to start"); + // Set the gid and uid in the correct order. + if (setgid(getgid()) != 0) { + sway_log(SWAY_ERROR, "Unable to drop root group, refusing to start"); + return false; + } + if (setuid(getuid()) != 0) { + sway_log(SWAY_ERROR, "Unable to drop root user, refusing to start"); return false; } } - if (setuid(0) != -1) { + if (setgid(0) != -1 || setuid(0) != -1) { sway_log(SWAY_ERROR, "Unable to drop root (we shouldn't be able to " "restore it after setuid), refusing to start"); return false;