[Virtio-fs] [PATCH 2/2] virtiofsd: drop all capabilities in the wait parent process
Stefan Hajnoczi
stefanha at redhat.com
Thu Apr 16 16:49:07 UTC 2020
All this process does is wait for its child. No capabilities are
needed.
Signed-off-by: Stefan Hajnoczi <stefanha at redhat.com>
---
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 af97ba1c41..0c3f33b074 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.
*/
@@ -2561,6 +2572,8 @@ 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);
--
2.25.1
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