X-Git-Url: http://git.meshlink.io/?a=blobdiff_plain;f=avahi-core%2Fnetlink.c;h=5050801de831eebe5f9457723bfbd4e1fa690848;hb=c7ecad8fa467b8be2b34064020e2c541c480645e;hp=11961b764f866b795a4d4e3fc2fee8865090c99f;hpb=004678718ef36a4257856350bde7f93ad3141b9a;p=catta

diff --git a/avahi-core/netlink.c b/avahi-core/netlink.c
index 11961b7..5050801 100644
--- a/avahi-core/netlink.c
+++ b/avahi-core/netlink.c
@@ -46,44 +46,64 @@ struct AvahiNetlink {
 };
 
 int avahi_netlink_work(AvahiNetlink *nl, int block) {
+    ssize_t bytes;
+    struct msghdr smsg;
+    struct cmsghdr *cmsg;
+    struct ucred *cred;
+    struct iovec iov;
+    struct nlmsghdr *p;
+    char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
+    
     assert(nl);
 
-    for (;;) {
-        ssize_t bytes;
-        struct nlmsghdr *p;
+    iov.iov_base = nl->buffer;
+    iov.iov_len = nl->buffer_length;
 
-        for (;;) {
-            if ((bytes = recv(nl->fd, nl->buffer, nl->buffer_length, block ? 0 : MSG_DONTWAIT)) < 0) {
+    smsg.msg_name = NULL;
+    smsg.msg_namelen = 0;
+    smsg.msg_iov = &iov;
+    smsg.msg_iovlen = 1;
+    smsg.msg_control = cred_msg;
+    smsg.msg_controllen = sizeof(cred_msg);
+    smsg.msg_flags = (block ? 0 : MSG_DONTWAIT);
 
-                if (errno == EAGAIN || errno == EINTR)
-                    return 0;
-                
-                avahi_log_error(__FILE__": recv() failed: %s", strerror(errno));
-                return -1;
-            }
+    if ((bytes = recvmsg(nl->fd, &smsg, 0)) < 0) {
+        if (errno == EAGAIN || errno == EINTR)
+            return 0;
+        
+        avahi_log_error(__FILE__": recvmsg() failed: %s", strerror(errno));
+        return -1;
+    }
 
-            break;
-        }
+    cmsg = CMSG_FIRSTHDR(&smsg);
 
-        p = (struct nlmsghdr *) nl->buffer;
-        
-        if (nl->callback) {
-            for (; bytes > 0; p = NLMSG_NEXT(p, bytes)) {
-                if (!NLMSG_OK(p, (size_t) bytes)) {
-                    avahi_log_warn(__FILE__": packet truncated");
-                    return -1;
-                }
-
-                nl->callback(nl, p, nl->userdata);
-            }
-        }
+    if (!cmsg || cmsg->cmsg_type != SCM_CREDENTIALS) {
+        avahi_log_warn("No sender credentials received, ignoring data.");
+        return -1;
+    }
 
-        if (block)
-            return 1;
+    cred = (struct ucred*) CMSG_DATA(cmsg);
+
+    if (cred->uid != 0)
+        return -1;
+
+    p = (struct nlmsghdr *) nl->buffer;
+    
+    assert(nl->callback);
+    
+    for (; bytes > 0; p = NLMSG_NEXT(p, bytes)) {
+        if (!NLMSG_OK(p, (size_t) bytes)) {
+            avahi_log_warn(__FILE__": packet truncated");
+            return -1;
+        }
+        
+        nl->callback(nl, p, nl->userdata);
     }
+    
+    return 0;
 }
 
-static void socket_event(AvahiWatch *w, int fd, AvahiWatchEvent event, void *userdata) {
+static void socket_event(AvahiWatch *w, int fd, AVAHI_GCC_UNUSED AvahiWatchEvent event, void *userdata) {
     AvahiNetlink *nl = userdata;
 
     assert(w);
@@ -95,6 +115,7 @@ static void socket_event(AvahiWatch *w, int fd, AvahiWatchEvent event, void *use
 
 AvahiNetlink *avahi_netlink_new(const AvahiPoll *poll_api, uint32_t groups, void (*cb) (AvahiNetlink *nl, struct nlmsghdr *n, void* userdata), void* userdata) {
     int fd = -1;
+    const int on = 1;
     struct sockaddr_nl addr;
     AvahiNetlink *nl = NULL;
 
@@ -116,6 +137,11 @@ AvahiNetlink *avahi_netlink_new(const AvahiPoll *poll_api, uint32_t groups, void
         goto fail;
     }
 
+    if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0) {
+        avahi_log_error(__FILE__": SO_PASSCRED: %s", strerror(errno));
+        goto fail;
+    }
+
     if (!(nl = avahi_new(AvahiNetlink, 1))) {
         avahi_log_error(__FILE__": avahi_new() failed.");
         goto fail;