rtnl: message - read group membership of incoming messages

[elogind.git] / src / libsystemd / sd-rtnl / rtnl-message.c

diff --git a/src/libsystemd/sd-rtnl/rtnl-message.c b/src/libsystemd/sd-rtnl/rtnl-message.c
index 9043c675acbb95877e7f74c2038374c5d6149b69..84b46afb6b1807ed8d2a07d27b469d4c63147480 100644 (file)
--- a/src/libsystemd/sd-rtnl/rtnl-message.c
+++ b/src/libsystemd/sd-rtnl/rtnl-message.c
@@ -290,6 +290,21 @@ int sd_rtnl_message_addr_get_family(sd_rtnl_message *m, unsigned char *family) {
         return 0;
 }
 
+int sd_rtnl_message_addr_get_prefixlen(sd_rtnl_message *m, unsigned char *prefixlen) {
+        struct ifaddrmsg *ifa;
+
+        assert_return(m, -EINVAL);
+        assert_return(m->hdr, -EINVAL);
+        assert_return(rtnl_message_type_is_addr(m->hdr->nlmsg_type), -EINVAL);
+        assert_return(prefixlen, -EINVAL);
+
+        ifa = NLMSG_DATA(m->hdr);
+
+        *prefixlen = ifa->ifa_prefixlen;
+
+        return 0;
+}
+
 int sd_rtnl_message_addr_get_scope(sd_rtnl_message *m, unsigned char *scope) {
         struct ifaddrmsg *ifa;
 
@@ -1083,6 +1098,60 @@ int socket_write_message(sd_rtnl *nl, sd_rtnl_message *m) {
         return k;
 }
 
+static int socket_recv_message(int fd, struct iovec *iov, uint32_t *_group, bool peek) {
+        uint8_t cred_buffer[CMSG_SPACE(sizeof(struct ucred)) +
+                            CMSG_SPACE(sizeof(struct nl_pktinfo))];
+        struct msghdr msg = {
+                .msg_iov = iov,
+                .msg_iovlen = 1,
+                .msg_control = cred_buffer,
+                .msg_controllen = sizeof(cred_buffer),
+        };
+        struct cmsghdr *cmsg;
+        uint32_t group = 0;
+        bool auth = false;
+        int r;
+
+        assert(fd >= 0);
+        assert(iov);
+
+        r = recvmsg(fd, &msg, MSG_TRUNC | (peek ? MSG_PEEK : 0));
+        if (r < 0)
+                /* no data */
+                return (errno == EAGAIN) ? 0 : -errno;
+        else if (r == 0)
+                /* connection was closed by the kernel */
+                return -ECONNRESET;
+
+        for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+                if (cmsg->cmsg_level == SOL_SOCKET &&
+                    cmsg->cmsg_type == SCM_CREDENTIALS &&
+                    cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred))) {
+                        struct ucred *ucred = (void *)CMSG_DATA(cmsg);
+
+                        /* from the kernel */
+                        if (ucred->uid == 0 && ucred->pid == 0)
+                                auth = true;
+                } else if (cmsg->cmsg_level == SOL_NETLINK &&
+                           cmsg->cmsg_type == NETLINK_PKTINFO &&
+                           cmsg->cmsg_len == CMSG_LEN(sizeof(struct nl_pktinfo))) {
+                        struct nl_pktinfo *pktinfo = (void *)CMSG_DATA(cmsg);
+
+                        /* multi-cast group */
+                        group = pktinfo->group;
+                }
+        }
+
+        if (!auth)
+                /* not from the kernel, ignore */
+                return 0;
+
+        if (group)
+                *_group = group;
+
+        return r;
+}
+
 /* On success, the number of bytes received is returned and *ret points to the received message
  * which has a valid header and the correct size.
  * If nothing useful was received 0 is returned.
@@ -1090,16 +1159,9 @@ int socket_write_message(sd_rtnl *nl, sd_rtnl_message *m) {
  */
 int socket_read_message(sd_rtnl *rtnl) {
         _cleanup_rtnl_message_unref_ sd_rtnl_message *first = NULL;
-        uint8_t cred_buffer[CMSG_SPACE(sizeof(struct ucred))];
         struct iovec iov = {};
-        struct msghdr msg = {
-                .msg_iov = &iov,
-                .msg_iovlen = 1,
-                .msg_control = cred_buffer,
-                .msg_controllen = sizeof(cred_buffer),
-        };
-        struct cmsghdr *cmsg;
-        bool auth = false, multi_part = false, done = false;
+        uint32_t group = 0;
+        bool multi_part = false, done = false;
         struct nlmsghdr *new_msg;
         size_t len;
         int r;
@@ -1110,13 +1172,9 @@ int socket_read_message(sd_rtnl *rtnl) {
         assert(rtnl->rbuffer_allocated >= sizeof(struct nlmsghdr));
 
         /* read nothing, just get the pending message size */
-        r = recvmsg(rtnl->fd, &msg, MSG_PEEK | MSG_TRUNC);
-        if (r < 0)
-                /* no data */
-                return (errno == EAGAIN) ? 0 : -errno;
-        else if (r == 0)
-                /* connection was closed by the kernel */
-                return -ECONNRESET;
+        r = socket_recv_message(rtnl->fd, &iov, &group, true);
+        if (r <= 0)
+                return r;
         else
                 len = (size_t)r;
 
@@ -1129,13 +1187,10 @@ int socket_read_message(sd_rtnl *rtnl) {
         iov.iov_base = rtnl->rbuffer;
         iov.iov_len = rtnl->rbuffer_allocated;
 
-        r = recvmsg(rtnl->fd, &msg, MSG_TRUNC);
-        if (r < 0)
-                /* no data */
-                return (errno == EAGAIN) ? 0 : -errno;
-        else if (r == 0)
-                /* connection was closed by the kernel */
-                return -ECONNRESET;
+        /* read the pending message */
+        r = socket_recv_message(rtnl->fd, &iov, &group, false);
+        if (r <= 0)
+                return r;
         else
                 len = (size_t)r;
 
@@ -1143,24 +1198,6 @@ int socket_read_message(sd_rtnl *rtnl) {
                 /* message did not fit in read buffer */
                 return -EIO;
 
-        for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
-                if (cmsg->cmsg_level == SOL_SOCKET &&
-                    cmsg->cmsg_type == SCM_CREDENTIALS &&
-                    cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred))) {
-                        struct ucred *ucred = (void *)CMSG_DATA(cmsg);
-
-                        /* from the kernel */
-                        if (ucred->uid == 0 && ucred->pid == 0) {
-                                auth = true;
-                                break;
-                        }
-                }
-        }
-
-        if (!auth)
-                /* not from the kernel, ignore */
-                return 0;
-
         if (NLMSG_OK(rtnl->rbuffer, len) && rtnl->rbuffer->nlmsg_flags & NLM_F_MULTI) {
                 multi_part = true;