pam: Don't use geteuid() to get uid for authenticated user

Instead we use the 'struct passwd' that we looked up earlier.

This causes issues when the PAM stack is not running as the user
but as root or someone else.

https://bugzilla.gnome.org/show_bug.cgi?id=733418

1 files changed, 16 insertions, 12 deletions

diff --git a/pam/gkr-pam-client.c b/pam/gkr-pam-client.c
index ee175474..16468ddf 100644
--- a/pam/gkr-pam-client.c
+++ b/pam/gkr-pam-client.c
@@ -57,7 +57,8 @@
 #endif
 
 static int
-check_peer_same_uid (int sock)
+check_peer_same_uid (struct passwd *pwd,
+                     int sock)
 {
 	uid_t uid = -1;
 	
@@ -109,12 +110,12 @@ check_peer_same_uid (int sock)
 #else
 	syslog (GKR_LOG_WARN, "Cannot verify that the process to which we are passing the login"
 	        " password is genuinely running as the same user login: not supported on this OS.");
-	uid = geteuid ();
+	uid = pwd->pw_uid;
 	
 	
 #endif
 
-	if (uid != geteuid ()) {
+	if (uid != pwd->pw_uid) {
 		syslog (GKR_LOG_ERR, "The gnome keyring socket is not running with the same "
 		        "credentials as the user login. Disconnecting.");
 		return 0;
@@ -142,7 +143,8 @@ write_credentials_byte (int sock)
 }
 
 static int
-lookup_daemon (const char *control,
+lookup_daemon (struct passwd *pwd,
+               const char *control,
                struct sockaddr_un *addr)
 {
 	struct stat st;
@@ -178,7 +180,7 @@ lookup_daemon (const char *control,
 		return GKD_CONTROL_RESULT_FAILED;
 	}
 	
-	if (st.st_uid != geteuid ()) {
+	if (st.st_uid != pwd->pw_uid) {
 		syslog (GKR_LOG_ERR, "The gnome keyring socket is not owned with the same "
 		        "credentials as the user login: %s", addr->sun_path);
 		return GKD_CONTROL_RESULT_FAILED;
@@ -194,7 +196,8 @@ lookup_daemon (const char *control,
 }
 
 static int
-connect_daemon (struct sockaddr_un *addr,
+connect_daemon (struct passwd *pwd,
+                struct sockaddr_un *addr,
                 int *out_sock)
 {
 	int sock;
@@ -222,7 +225,7 @@ connect_daemon (struct sockaddr_un *addr,
 
 	/* Verify the server is running as the right user */
 	
-	if (check_peer_same_uid (sock) <= 0) {
+	if (check_peer_same_uid (pwd, sock) <= 0) {
 		close (sock);
 		return GKD_CONTROL_RESULT_FAILED;
 	}
@@ -300,7 +303,8 @@ read_part (int fd,
 }
 
 static int
-keyring_daemon_op (struct sockaddr_un *addr,
+keyring_daemon_op (struct passwd *pwd,
+                   struct sockaddr_un *addr,
                    int op,
                    int argc,
                    const char *argv[])
@@ -322,7 +326,7 @@ keyring_daemon_op (struct sockaddr_un *addr,
 	        op == GKD_CONTROL_OP_UNLOCK ||
 	        op == GKD_CONTROL_OP_QUIT);
 
-	ret = connect_daemon (addr, &sock);
+	ret = connect_daemon (pwd, addr, &sock);
 	if (ret != GKD_CONTROL_RESULT_OK)
 		goto done;
 
@@ -413,7 +417,7 @@ gkr_pam_client_run_operation (struct passwd *pwd, const char *control,
 	defchld.sa_handler = SIG_DFL;
 	sigaction (SIGCHLD, &defchld, &oldchld);
 
-	res = lookup_daemon (control, &addr);
+	res = lookup_daemon (pwd, control, &addr);
 	if (res != GKD_CONTROL_RESULT_OK)
 		return res;
 
@@ -421,7 +425,7 @@ gkr_pam_client_run_operation (struct passwd *pwd, const char *control,
 	    pwd->pw_uid == geteuid () && pwd->pw_gid == getegid ()) {
 
 		/* Already running as the right user, simple */
-		res = keyring_daemon_op (&addr, op, argc, argv);
+		res = keyring_daemon_op (pwd, &addr, op, argc, argv);
 		
 	} else {
 		
@@ -442,7 +446,7 @@ gkr_pam_client_run_operation (struct passwd *pwd, const char *control,
 				exit (GKD_CONTROL_RESULT_FAILED);
 			}
 	
-			res = keyring_daemon_op (&addr, op, argc, argv);
+			res = keyring_daemon_op (pwd, &addr, op, argc, argv);
 			exit (res);
 			return 0; /* Never reached */