From c043ae5b2ef2e1e437bf738bbf522799c6213230 Mon Sep 17 00:00:00 2001 From: Krzysztof Nowicki Date: Thu, 30 Nov 2017 11:59:29 +0100 Subject: [PATCH] Fix SELinux labels in cgroup filesystem root directory (#7496) When using SELinux with legacy cgroups the tmpfs on /sys/fs/cgroup is by default labelled as tmpfs_t. This label is also inherited by the "cpu" and "cpuacct" symbolic links. Unfortunately the policy expects them to be labelled as cgroup_t, which is used for all the actual cgroup filesystems. Failure to do so results in a stream of denials. This state cannot be fixed reliably when the cgroup filesystem structure is set-up as the SELinux policy is not yet loaded at this moment. It also cannot be fixed later as the root of the cgroup filesystem is remounted read-only. In order to fix it the root of the cgroup filesystem needs to be temporary remounted read-write, relabelled and remounted back read-only. (cherry picked from commit 8739f23e3c26bbf8b0296421578e56daa63cbf4b) --- src/core/mount-setup.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/src/core/mount-setup.c b/src/core/mount-setup.c index 521545e5c..7a2cae4a3 100644 --- a/src/core/mount-setup.c +++ b/src/core/mount-setup.c @@ -363,14 +363,22 @@ int mount_setup(bool loaded_policy) { usec_t before_relabel, after_relabel; char timespan[FORMAT_TIMESPAN_MAX]; + mkdir_label("/run/systemd/policy-relabelling", 0755); before_relabel = now(CLOCK_MONOTONIC); nftw("/dev", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL); nftw("/run", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL); + /* Temporarily remount the root cgroup filesystem to give it a proper label. */ + (void) mount(NULL, "/sys/fs/cgroup", NULL, MS_REMOUNT, NULL); + label_fix("/sys/fs/cgroup", false, false); + nftw("/sys/fs/cgroup", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL); + (void) mount(NULL, "/sys/fs/cgroup", NULL, MS_REMOUNT|MS_RDONLY, NULL); + after_relabel = now(CLOCK_MONOTONIC); - log_info("Relabelled /dev and /run in %s.", + mkdir_label("/run/systemd/policy-relabelled", 0755); + log_info("Relabelled /dev, /run and /sys/fs/cgroup in %s.", format_timespan(timespan, sizeof(timespan), after_relabel - before_relabel, 0)); } #endif