From 66502bbca37ca7a3bfa57e82cfc03b89a7a11eae Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Thu, 16 Apr 2020 17:49:07 +0100 Subject: [PATCH] virtiofsd: drop all capabilities in the wait parent process MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit All this process does is wait for its child. No capabilities are needed. Signed-off-by: Stefan Hajnoczi Reviewed-by: Philippe Mathieu-Daudé Signed-off-by: Dr. David Alan Gilbert --- tools/virtiofsd/passthrough_ll.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index e49650b63d..3ba1d90984 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -2530,6 +2530,17 @@ static void print_capabilities(void) printf("}\n"); } +/* + * Drop all Linux capabilities because the wait parent process only needs to + * sit in waitpid(2) and terminate. + */ +static void setup_wait_parent_capabilities(void) +{ + capng_setpid(syscall(SYS_gettid)); + capng_clear(CAPNG_SELECT_BOTH); + capng_apply(CAPNG_SELECT_BOTH); +} + /* * Move to a new mount, net, and pid namespaces to isolate this process. */ @@ -2563,6 +2574,8 @@ static void setup_namespaces(struct lo_data *lo, struct fuse_session *se) pid_t waited; int wstatus; + setup_wait_parent_capabilities(); + /* The parent waits for the child */ do { waited = waitpid(child, &wstatus, 0);