X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fcommon%2Funix.c;h=3490af6e7d584d237d38ec6532d7b1fd93bcf1b1;hp=41525b69170a2c10bfcbdf2401f22936e576d058;hb=b3f35e021305afc1a40b9f3637c77595f38d6df2;hpb=56f0bc67599b5438a4b68bdbec596aaaa39b2e7e

diff --git a/src/common/unix.c b/src/common/unix.c
index 41525b691..3490af6e7 100644
--- a/src/common/unix.c
+++ b/src/common/unix.c
@@ -385,7 +385,7 @@ ssize_t lttcomm_send_fds_unix_sock(int sock, const int *fds, size_t nb_fd)
 	char dummy = 0;
 
 	memset(&msg, 0, sizeof(msg));
-	memset(tmp, 0, CMSG_SPACE(sizeof_fds) * sizeof(char));
+	memset(tmp, 0, sizeof(tmp));
 
 	if (nb_fd > LTTCOMM_MAX_SEND_FDS)
 		return -EINVAL;
@@ -397,6 +397,7 @@ ssize_t lttcomm_send_fds_unix_sock(int sock, const int *fds, size_t nb_fd)
 	if (!cmptr) {
 		return -1;
 	}
+
 	cmptr->cmsg_level = SOL_SOCKET;
 	cmptr->cmsg_type = SCM_RIGHTS;
 	cmptr->cmsg_len = CMSG_LEN(sizeof_fds);
@@ -439,7 +440,9 @@ ssize_t lttcomm_recv_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 	ssize_t ret = 0;
 	struct cmsghdr *cmsg;
 	size_t sizeof_fds = nb_fd * sizeof(int);
-	char recv_fd[CMSG_SPACE(sizeof_fds)];
+
+	/* Account for the struct ucred cmsg in the buffer size */
+	char recv_buf[CMSG_SPACE(sizeof_fds) + CMSG_SPACE(sizeof(struct ucred))];
 	struct msghdr msg;
 	char dummy;
 
@@ -450,8 +453,15 @@ ssize_t lttcomm_recv_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 	iov[0].iov_len = 1;
 	msg.msg_iov = iov;
 	msg.msg_iovlen = 1;
-	msg.msg_control = recv_fd;
-	msg.msg_controllen = sizeof(recv_fd);
+
+	cmsg = (struct cmsghdr *) recv_buf;
+	cmsg->cmsg_len = CMSG_LEN(sizeof_fds);
+	cmsg->cmsg_level = SOL_SOCKET;
+	cmsg->cmsg_type = SCM_RIGHTS;
+
+	msg.msg_control = cmsg;
+	msg.msg_controllen = CMSG_LEN(sizeof(recv_buf));
+	msg.msg_flags = 0;
 
 	do {
 		ret = recvmsg(sock, &msg, 0);
@@ -460,35 +470,63 @@ ssize_t lttcomm_recv_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 		PERROR("recvmsg fds");
 		goto end;
 	}
+
 	if (ret != 1) {
 		fprintf(stderr, "Error: Received %zd bytes, expected %d\n",
 				ret, 1);
 		goto end;
 	}
+
 	if (msg.msg_flags & MSG_CTRUNC) {
 		fprintf(stderr, "Error: Control message truncated.\n");
 		ret = -1;
 		goto end;
 	}
-	cmsg = CMSG_FIRSTHDR(&msg);
-	if (!cmsg) {
-		fprintf(stderr, "Error: Invalid control message header\n");
-		ret = -1;
-		goto end;
-	}
-	if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) {
-		fprintf(stderr, "Didn't received any fd\n");
-		ret = -1;
-		goto end;
-	}
-	if (cmsg->cmsg_len != CMSG_LEN(sizeof_fds)) {
-		fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
-				(size_t) cmsg->cmsg_len, (size_t) CMSG_LEN(sizeof_fds));
-		ret = -1;
-		goto end;
+
+	/*
+	 * If the socket was configured with SO_PASSCRED, the kernel will add a
+	 * control message (cmsg) to the ancillary data of the unix socket. We
+	 * need to expect a cmsg of the SCM_CREDENTIALS as the first control
+	 * message.
+	 */
+	for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+		if (!cmsg) {
+			fprintf(stderr, "Error: Invalid control message header\n");
+			ret = -1;
+			goto end;
+		}
+		if (cmsg->cmsg_level != SOL_SOCKET) {
+			fprintf(stderr, "Error: The socket needs to be of type SOL_SOCKET\n");
+			ret = -1;
+			goto end;
+		}
+		if (cmsg->cmsg_type == SCM_RIGHTS) {
+			/*
+			 * We found the controle message for file descriptors,
+			 * now copy the fds to the fds ptr and return success.
+			 */
+			if (cmsg->cmsg_len != CMSG_LEN(sizeof_fds)) {
+				fprintf(stderr, "Error: Received %zu bytes of"
+					"ancillary data for FDs, expected %zu\n",
+					(size_t) cmsg->cmsg_len,
+					(size_t) CMSG_LEN(sizeof_fds));
+				ret = -1;
+				goto end;
+			}
+			memcpy(fds, CMSG_DATA(cmsg), sizeof_fds);
+			ret = sizeof_fds;
+			goto end;
+		}
+		if (cmsg->cmsg_type == SCM_CREDENTIALS) {
+			/*
+			 * Expect credentials to be sent when expecting fds even
+			 * if no credential were include in the send(). The
+			 * kernel adds them...
+			 */
+			fprintf(stderr, "Received creds... continuing\n");
+			ret = -1;
+		}
 	}
-	memcpy(fds, CMSG_DATA(cmsg), sizeof_fds);
-	ret = sizeof_fds;
 end:
 	return ret;
 }