From: Aurelien DARRAGON <adarragon@haproxy.com>
Date: Tue, 29 Oct 2024 10:38:11 +0000 (+0100)
Subject: MEDIUM: sock: also restore effective unix family in get_{src,dst}()
X-Git-Tag: v3.1-dev11~30
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d879bf6600f4518f974766340e0d55ae83484f1e;p=thirdparty%2Fhaproxy.git

MEDIUM: sock: also restore effective unix family in get_{src,dst}()

As in previous commit, let's push the logic a bit further in order to
properly restore the effective UNIX socket type when leveraging
get_src() and get_dst() sock functions, since they rely on getpeername()
and getsockname() under the hood, both of which will actually loose the
effective family and return AF_UNIX for all our custom UNIX sockets.

To do this, add sock_restore_unix_family() helper function from the logic
implemented in the previous commit, and call this function from get_src()
and get_dst() in case of unix socket prior to returning.
---

diff --git a/src/sock.c b/src/sock.c
index 423a92534d..203e3a0e2c 100644
--- a/src/sock.c
+++ b/src/sock.c
@@ -385,6 +385,28 @@ void sock_unbind(struct receiver *rx)
 	rx->fd = -1;
 }
 
+/* restore effective family for UNIX type sockets if needed. Indeed since
+ * kernel doesn't know about custom UNIX families (internal to HAproxy),
+ * they lost when leveraging syscalls such as getsockname() or getpeername().
+ *
+ * This function guesses the effective family by analyzing address and address
+ * length as returned by getsockname() and getpeername() calls.
+ */
+static void sock_restore_unix_family(struct sockaddr_un *un, socklen_t socklen)
+{
+	BUG_ON(un->sun_family != AF_UNIX);
+
+	if (un->sun_path[0]); // regular UNIX socket, not a custom family
+	else if (socklen == sizeof(*un))
+		un->sun_family = AF_CUST_ABNS;
+	else {
+		/* not all struct sockaddr_un space is used..
+		 * (sun_path is partially filled)
+		 */
+		un->sun_family = AF_CUST_ABNSZ;
+	}
+}
+
 /*
  * Retrieves the source address for the socket <fd>, with <dir> indicating
  * if we're a listener (=0) or an initiator (!=0). It returns 0 in case of
@@ -393,10 +415,19 @@ void sock_unbind(struct receiver *rx)
  */
 int sock_get_src(int fd, struct sockaddr *sa, socklen_t salen, int dir)
 {
+	int ret;
+
 	if (dir)
-		return getsockname(fd, sa, &salen);
+		ret = getsockname(fd, sa, &salen);
 	else
-		return getpeername(fd, sa, &salen);
+		ret = getpeername(fd, sa, &salen);
+
+	if (ret)
+		return ret;
+	if (sa->sa_family == AF_UNIX)
+		sock_restore_unix_family((struct sockaddr_un *)sa, salen);
+
+	return ret;
 }
 
 /*
@@ -407,10 +438,19 @@ int sock_get_src(int fd, struct sockaddr *sa, socklen_t salen, int dir)
  */
 int sock_get_dst(int fd, struct sockaddr *sa, socklen_t salen, int dir)
 {
+	int ret;
+
 	if (dir)
-		return getpeername(fd, sa, &salen);
+		ret = getpeername(fd, sa, &salen);
 	else
-		return getsockname(fd, sa, &salen);
+		ret = getsockname(fd, sa, &salen);
+
+	if (ret)
+		return ret;
+	if (sa->sa_family == AF_UNIX)
+		sock_restore_unix_family((struct sockaddr_un *)sa, salen);
+
+	return ret;
 }
 
 /* Try to retrieve exported sockets from worker at CLI <unixsocket>. These
@@ -601,20 +641,10 @@ int sock_get_old_sockets(const char *unixsocket)
 			continue;
 		}
 		if (xfer_sock->addr.ss_family == AF_UNIX) {
-			const struct sockaddr_un *un = (const struct sockaddr_un *)&xfer_sock->addr;
-
 			/* restore effective family if needed, because getsockname()
 			 * only knows about real families:
 			 */
-			if (un->sun_path[0]); // regular UNIX socket, not a custom family
-			else if (socklen == sizeof(*un))
-				xfer_sock->addr.ss_family = AF_CUST_ABNS;
-			else {
-				/* not all struct sockaddr_un space is used..
-				 * (sun_path is partially filled)
-				 */
-				xfer_sock->addr.ss_family = AF_CUST_ABNSZ;
-			}
+			sock_restore_unix_family((struct sockaddr_un *)&xfer_sock->addr, socklen);
 		}