Ensure statd gets started if required when non-root

user mounts an NFS filesystem.

The first time an NFS filesystem is mounted, we start statd from
/sbin/mount.nfs.  If this first time is a non-root user doing the
 mount, (thanks to e.g.  the 'users' option in /etc/fstab)
then we need to be sure that the 'setuid' status from mount.nfs
is inherited through to rpc.statd so that it runs as root.

There are two places where we loose our setuid status due to the shell
(/bin/sh) discarding.

1/ mount.nfs uses "system" to run /usr/sbin/start-statd.  This runs a
   shell which is likely to drop privileges.  So change that code to use
  'fork' and 'execl' explicitly.
2/ start-statd is a shell script.  To convince the shell to allow the
  program to run in privileged mode, we need to add a "-p" flag.

We could just call setuid(getuid()) at some appropriate time, and it
might be worth doing that as well, however I think that getting
rid of 'system()' is a good idea and once that is done, the
adding of '-p' is trivial and sufficient.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Steve Dickson <steved@redhat.com>

diff --git a/utils/mount/network.c b/utils/mount/network.c
index 2db694d2541bb1a8acfe8d3956bbc14d1de8a84f..806344c399dd92d4f3b5ebe8d8f67ea9099c6061 100644 (file)
--- a/utils/mount/network.c
+++ b/utils/mount/network.c
@@ -36,6 +36,7 @@
 
 #include <sys/types.h>
 #include <sys/socket.h>
+#include <sys/wait.h>
 #include <netinet/in.h>
 #include <rpc/rpc.h>
 #include <rpc/pmap_prot.h>
@@ -705,7 +706,18 @@ int start_statd(void)
 #ifdef START_STATD
        if (stat(START_STATD, &stb) == 0) {
                if (S_ISREG(stb.st_mode) && (stb.st_mode & S_IXUSR)) {
-                       system(START_STATD);
+                       pid_t pid = fork();
+                       switch (pid) {
+                       case 0: /* child */
+                               execl(START_STATD, START_STATD, NULL);
+                               exit(1);
+                       case -1: /* error */
+                               perror("Fork failed");
+                               break;
+                       default: /* parent */
+                               waitpid(pid, NULL,0);
+                               break;
+                       }
                        if (probe_statd())
                                return 1;
                }

diff --git a/utils/statd/start-statd b/utils/statd/start-statd
index 6e7ea04ba9f32e1c84bf1c0e2e70e9d226f7675e..c7805eeaf8d3c185d8755b03b155d0404ac1551b 100644 (file)
--- a/utils/statd/start-statd
+++ b/utils/statd/start-statd
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/sh -p
 # nfsmount calls this script when mounting a filesystem with locking
 # enabled, but when statd does not seem to be running (based on
 # /var/run/rpc.statd.pid).