From 64fa6f059ae0b491fdb52c7375d59774ff9c237a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= Date: Tue, 15 Mar 2022 16:35:47 +0100 Subject: [PATCH] shared/install: do not try to resolve symlinks outside of root directory MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit I linked a file as root, so I had a symlink /root/test.service ← /etc/systemd/system/test.service. To my surpise, when running test-systemctl-enable, it failed with a cryptic EACCES. The previous commit made the logs a bit better. Strace shows that we were trying to follow the symlink without taking --root into account. It seems that this bug was introduced in 66a19d85a533b15ed32f4066ec880b5a8c06babd: before it, we'd do readlink_malloc(), which returned a path relative to root. But we only used that path for checking if the path is in remove_symlinks_to set, which contains relative paths. So if the path was relative, we'd get a false-negative answer, but we didn't go outside of the root. (We need to canonicalize the symlink to get a consistent answer.) But after 66a19 we use chase_symlinks(), without taking root into account which is completely bogus. (cherry picked from commit 40276314afc4fb5c35c6b3da3e6185af6ed3886b) Related: #2082131 --- src/shared/install.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/shared/install.c b/src/shared/install.c index ce045d02be..ad0238ab50 100644 --- a/src/shared/install.c +++ b/src/shared/install.c @@ -612,7 +612,7 @@ static int remove_marked_symlinks_fd( return -ENOMEM; path_simplify(p); - q = chase_symlinks(p, NULL, CHASE_NONEXISTENT, &dest, NULL); + q = chase_symlinks(p, lp->root_dir, CHASE_NONEXISTENT, &dest, NULL); if (q == -ENOENT) continue; if (q < 0) {