Use new socket if uid, pid, or gid changes

The gssproxy daemon uses SO_PEERCRED to determine credentials of the
connecting process.  However, these credentials are set only at the time
connect has called.  Therefore they must be reset every time uid or pid
changes.  For completeness, we check gid as well.

Signed-off-by: Robbie Harwood <rharwood@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Closes #27

1 files changed, 22 insertions, 0 deletions

diff --git a/proxy/src/client/gpm_common.c b/proxy/src/client/gpm_common.c
index cb4ccdb..0a54dbc 100644
--- a/proxy/src/client/gpm_common.c
+++ b/proxy/src/client/gpm_common.c
@@ -13,6 +13,12 @@
 struct gpm_ctx {
     pthread_mutex_t lock;
     int fd;
+
+    /* these are only meaningful if fd != -1 */
+    pid_t pid;
+    uid_t uid;
+    gid_t gid;
+
     int next_xid;
 };
 
@@ -93,6 +99,9 @@ done:
         }
     }
     gpmctx->fd = fd;
+    gpmctx->pid = getpid();
+    gpmctx->uid = geteuid();
+    gpmctx->gid = getegid();
     return ret;
 }
 
@@ -120,12 +129,25 @@ static void gpm_close_socket(struct gpm_ctx *gpmctx)
 static int gpm_grab_sock(struct gpm_ctx *gpmctx)
 {
     int ret;
+    pid_t p;
+    uid_t u;
+    gid_t g;
 
     ret = pthread_mutex_lock(&gpmctx->lock);
     if (ret) {
         return ret;
     }
 
+    /* Detect fork / setresuid and friends */
+    p = getpid();
+    u = geteuid();
+    g = getegid();
+
+    if (gpmctx->fd != -1 &&
+        (p != gpmctx->pid || u != gpmctx->uid || g != gpmctx->gid)) {
+        gpm_close_socket(gpmctx);
+    }
+
     if (gpmctx->fd == -1) {
         ret = gpm_open_socket(gpmctx);
     }