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teigland pushed a commit to branch master in repository sanlock.
The following commit(s) were added to refs/heads/master by this push: new af09f3d lockfile: Keep lockfile owned by root af09f3d is described below
commit af09f3d9a5a8c2cfcd364f3b3e26333f3472d825 Author: Nir Soffer nsoffer@redhat.com AuthorDate: Fri Nov 30 00:03:19 2018 +0200
lockfile: Keep lockfile owned by root
On Fedora 28, sanlock fails to create the lockfile before dropping privileges, because /run/sanlock is owned by sanlock, and selinux disables DAC_OVERRIDE.
To allow root to create the lockfile before dropping privileges /run/sanlock is owned by group root, and group writable. Since sanlock never write to the lockfile after dropping privileges, keep the lockfile owned by root.
Here are /run/sanlock permissions with this change:
$ ls -lhdZ /run/sanlock drwxrwxr-x. 2 sanlock root system_u:object_r:sanlock_var_run_t:s0 80 Nov 29 23:07 /run/sanlock
$ ls -lhZ /run/sanlock total 4.0K -rw-r--r--. 1 root root system_u:object_r:sanlock_var_run_t:s0 5 Nov 29 23:07 sanlock.pid srw-rw----. 1 sanlock sanlock system_u:object_r:sanlock_var_run_t:s0 0 Nov 29 23:07 sanlock.sock
Signed-off-by: Nir Soffer nsoffer@redhat.com --- src/lockfile.c | 12 ++++-------- src/main.c | 6 +++++- 2 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/src/lockfile.c b/src/lockfile.c index 5a2518e..cffaaff 100644 --- a/src/lockfile.c +++ b/src/lockfile.c @@ -36,7 +36,10 @@ int lockfile(const char *dir, const char *name, int uid, int gid) mode_t old_umask; int fd, rv;
- old_umask = umask(0022); + /* Make rundir group writable, allowing creation of the lockfile when + * starting as root. */ + + old_umask = umask(0002); rv = mkdir(dir, 0775); if (rv < 0 && errno != EEXIST) { umask(old_umask); @@ -89,13 +92,6 @@ int lockfile(const char *dir, const char *name, int uid, int gid) goto fail; }
- rv = fchown(fd, uid, gid); - if (rv < 0) { - log_error("lockfile fchown error %s: %s", - path, strerror(errno)); - goto fail; - } - return fd; fail: close(fd); diff --git a/src/main.c b/src/main.c index b3898e2..9538cc5 100644 --- a/src/main.c +++ b/src/main.c @@ -1682,8 +1682,12 @@ static int do_daemon(void) if (!privileged) log_warn("Running in unprivileged mode");
+ /* If we run as root, make run_dir owned by root, so we can create the + * lockfile when selinux disables DAC_OVERRIDE. + * See https://danwalsh.livejournal.com/79643.html */
- fd = lockfile(run_dir, SANLK_LOCKFILE_NAME, com.uid, com.gid); + fd = lockfile(run_dir, SANLK_LOCKFILE_NAME, com.uid, + privileged ? 0 : com.gid); if (fd < 0) { close_logging(); return fd;