pppd: Set local and remote IPv6 addresses by one call

Currently local IPv6 address is set by SIOCSIFADDR ioctl and remote peer
address is appended by rtnetlink RTM_NEWADDR/NLM_F_REPLACE call. For
RTM_NEWADDR/NLM_F_REPLACE call it is needed to specify both local + remote
addresses as local address is used for matching to which address needs to
be remote peer address appended. When issuing this call kernel first
removes currently configured local address and then inserts a new pair of
local + remote addresses.

Simplify whole setup by just one rtnetlink RTM_NEWADDR/NLM_F_CREATE call by
inserting pair of local + remote addresses atomically. Therefore calling
SIOCSIFADDR ioctl for local IPv6 address is not used or needed anymore.

Signed-off-by: Pali Rohár <pali@kernel.org>

diff --git a/pppd/sys-linux.c b/pppd/sys-linux.c
index ca0db844018a9c9e31dac56df39e5a8c5939fa3a..3ec7860ff4cd1c5101198f77766b00544b6e9592 100644 (file)
--- a/pppd/sys-linux.c
+++ b/pppd/sys-linux.c
@@ -172,9 +172,9 @@ struct in6_ifreq {
 #endif
 
 #define IN6_LLADDR_FROM_EUI64(sin6, eui64) do {                        \
-       memset(&sin6.s6_addr, 0, sizeof(struct in6_addr));      \
-       sin6.s6_addr16[0] = htons(0xfe80);                      \
-       eui64_copy(eui64, sin6.s6_addr32[2]);                   \
+       memset(&(sin6).s6_addr, 0, sizeof(struct in6_addr));    \
+       (sin6).s6_addr16[0] = htons(0xfe80);                    \
+       eui64_copy(eui64, (sin6).s6_addr32[2]);                 \
        } while (0)
 
 static const eui64_t nulleui64;
@@ -2832,7 +2832,11 @@ int cifaddr (int unit, u_int32_t our_adr, u_int32_t his_adr)
 }
 
 #ifdef INET6
-static int append_peer_ipv6_address(unsigned int iface, struct in6_addr *local_addr, struct in6_addr *remote_addr)
+/********************************************************************
+ *
+ * sif6addr_rtnetlink - Config the interface with both IPv6 link-local addresses via rtnetlink
+ */
+static int sif6addr_rtnetlink(unsigned int iface, eui64_t our_eui64, eui64_t his_eui64)
 {
     struct msghdr msg;
     struct sockaddr_nl sa;
@@ -2841,15 +2845,17 @@ static int append_peer_ipv6_address(unsigned int iface, struct in6_addr *local_a
     struct ifaddrmsg *ifa;
     struct rtattr *local_rta;
     struct rtattr *remote_rta;
-    char buf[NLMSG_LENGTH(sizeof(*ifa) + RTA_LENGTH(sizeof(*local_addr)) + RTA_LENGTH(sizeof(*remote_addr)))];
+    char buf[NLMSG_LENGTH(sizeof(*ifa) + 2*RTA_LENGTH(sizeof(struct in6_addr)))];
     ssize_t nlmsg_len;
     struct nlmsgerr *errmsg;
     int one;
     int fd;
 
     fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
-    if (fd < 0)
+    if (fd < 0) {
+        error("sif6addr_rtnetlink: socket(NETLINK_ROUTE): %m (line %d)", __LINE__);
         return 0;
+    }
 
     /*
      * Tell kernel to not send to us payload of acknowledgment error message.
@@ -2869,6 +2875,7 @@ static int append_peer_ipv6_address(unsigned int iface, struct in6_addr *local_a
     sa.nl_groups = 0;
 
     if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
+        error("sif6addr_rtnetlink: bind(AF_NETLINK): %m (line %d)", __LINE__);
         close(fd);
         return 0;
     }
@@ -2876,9 +2883,9 @@ static int append_peer_ipv6_address(unsigned int iface, struct in6_addr *local_a
     memset(buf, 0, sizeof(buf));
 
     nlmsg = (struct nlmsghdr *)buf;
-    nlmsg->nlmsg_len = NLMSG_LENGTH(sizeof(*ifa) + RTA_LENGTH(sizeof(*local_addr)) + RTA_LENGTH(sizeof(*remote_addr)));
+    nlmsg->nlmsg_len = sizeof(buf);
     nlmsg->nlmsg_type = RTM_NEWADDR;
-    nlmsg->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | NLM_F_REPLACE;
+    nlmsg->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | NLM_F_EXCL | NLM_F_CREATE;
     nlmsg->nlmsg_seq = 1;
     nlmsg->nlmsg_pid = 0;
 
@@ -2890,14 +2897,14 @@ static int append_peer_ipv6_address(unsigned int iface, struct in6_addr *local_a
     ifa->ifa_index = iface;
 
     local_rta = IFA_RTA(ifa);
-    local_rta->rta_len = RTA_LENGTH(sizeof(*local_addr));
+    local_rta->rta_len = RTA_LENGTH(sizeof(struct in6_addr));
     local_rta->rta_type = IFA_LOCAL;
-    memcpy(RTA_DATA(local_rta), local_addr, sizeof(*local_addr));
+    IN6_LLADDR_FROM_EUI64(*(struct in6_addr *)RTA_DATA(local_rta), our_eui64);
 
     remote_rta = (struct rtattr *)((char *)local_rta + local_rta->rta_len);
-    remote_rta->rta_len = RTA_LENGTH(sizeof(*remote_addr));
+    remote_rta->rta_len = RTA_LENGTH(sizeof(struct in6_addr));
     remote_rta->rta_type = IFA_ADDRESS;
-    memcpy(RTA_DATA(remote_rta), remote_addr, sizeof(*remote_addr));
+    IN6_LLADDR_FROM_EUI64(*(struct in6_addr *)RTA_DATA(remote_rta), his_eui64);
 
     memset(&sa, 0, sizeof(sa));
     sa.nl_family = AF_NETLINK;
@@ -2918,6 +2925,7 @@ static int append_peer_ipv6_address(unsigned int iface, struct in6_addr *local_a
     msg.msg_flags = 0;
 
     if (sendmsg(fd, &msg, 0) < 0) {
+        error("sif6addr_rtnetlink: sendmsg(RTM_NEWADDR/NLM_F_CREATE): %m (line %d)", __LINE__);
         close(fd);
         return 0;
     }
@@ -2936,13 +2944,17 @@ static int append_peer_ipv6_address(unsigned int iface, struct in6_addr *local_a
     msg.msg_flags = 0;
 
     nlmsg_len = recvmsg(fd, &msg, 0);
-    close(fd);
 
-    if (nlmsg_len < 0)
+    if (nlmsg_len < 0) {
+        error("sif6addr_rtnetlink: recvmsg(NLM_F_ACK): %m (line %d)", __LINE__);
+        close(fd);
         return 0;
+    }
+
+    close(fd);
 
     if ((size_t)nlmsg_len < sizeof(*nlmsg)) {
-        errno = EINVAL;
+        error("sif6addr_rtnetlink: recvmsg(NLM_F_ACK): Packet too short (line %d)", __LINE__);
         return 0;
     }
 
@@ -2950,23 +2962,24 @@ static int append_peer_ipv6_address(unsigned int iface, struct in6_addr *local_a
 
     /* acknowledgment packet for NLM_F_ACK is NLMSG_ERROR */
     if (nlmsg->nlmsg_type != NLMSG_ERROR) {
-        errno = EINVAL;
+        error("sif6addr_rtnetlink: recvmsg(NLM_F_ACK): Not an acknowledgment packet (line %d)", __LINE__);
         return 0;
     }
 
     if ((size_t)nlmsg_len < NLMSG_LENGTH(sizeof(*errmsg))) {
-        errno = EINVAL;
+        error("sif6addr_rtnetlink: recvmsg(NLM_F_ACK): Packet too short (line %d)", __LINE__);
         return 0;
     }
 
     errmsg = NLMSG_DATA(nlmsg);
 
-    /* error == 0 indicates success */
-    if (errmsg->error == 0)
-        return 1;
+    /* error == 0 indicates success, negative value is errno code */
+    if (errmsg->error != 0) {
+        error("sif6addr_rtnetlink: %s (line %d)", strerror(-errmsg->error), __LINE__);
+        return 0;
+    }
 
-    errno = -errmsg->error;
-    return 0;
+    return 1;
 }
 
 /********************************************************************
@@ -2978,7 +2991,6 @@ int sif6addr (int unit, eui64_t our_eui64, eui64_t his_eui64)
     struct in6_ifreq ifr6;
     struct ifreq ifr;
     struct in6_rtmsg rt6;
-    struct in6_addr remote_addr;
 
     if (sock6_fd < 0) {
        errno = -sock6_fd;
@@ -2992,27 +3004,26 @@ int sif6addr (int unit, eui64_t our_eui64, eui64_t his_eui64)
        return 0;
     }
 
-    /* Local interface */
-    memset(&ifr6, 0, sizeof(ifr6));
-    IN6_LLADDR_FROM_EUI64(ifr6.ifr6_addr, our_eui64);
-    ifr6.ifr6_ifindex = ifr.ifr_ifindex;
-    ifr6.ifr6_prefixlen = 128;
-
-    if (ioctl(sock6_fd, SIOCSIFADDR, &ifr6) < 0) {
-       error("sif6addr: ioctl(SIOCSIFADDR): %m (line %d)", __LINE__);
-       return 0;
-    }
-
     if (kernel_version >= KVERSION(2,1,16)) {
-        /* Set remote peer address (and route for it) */
-        IN6_LLADDR_FROM_EUI64(remote_addr, his_eui64);
-        if (!append_peer_ipv6_address(ifr.ifr_ifindex, &ifr6.ifr6_addr, &remote_addr)) {
-            error("sif6addr: setting remote peer address failed: %m");
+        /* Set both local address and remote peer address (with route for it) via rtnetlink */
+        return sif6addr_rtnetlink(ifr.ifr_ifindex, our_eui64, his_eui64);
+    } else {
+        /* Local interface */
+        memset(&ifr6, 0, sizeof(ifr6));
+        IN6_LLADDR_FROM_EUI64(ifr6.ifr6_addr, our_eui64);
+        ifr6.ifr6_ifindex = ifr.ifr_ifindex;
+        ifr6.ifr6_prefixlen = 128;
+
+        if (ioctl(sock6_fd, SIOCSIFADDR, &ifr6) < 0) {
+            error("sif6addr: ioctl(SIOCSIFADDR): %m (line %d)", __LINE__);
             return 0;
         }
-    }
 
-    if (kernel_version < KVERSION(2,1,16)) {
+        /*
+         * Linux kernel does not provide AF_INET6 ioctl SIOCSIFDSTADDR for
+         * setting remote peer host address, so set only route to remote host.
+         */
+
         /* Route to remote host */
         memset(&rt6, 0, sizeof(rt6));
         IN6_LLADDR_FROM_EUI64(rt6.rtmsg_dst, his_eui64);