fill missing netdev fields for unprivileged containers

lxc-user-nic now returns the names of the interfaces and
unpriv_assign_nic function parses that information to fill
missing netdev->veth_attr.pair and netdev->name.

With this patch get_running_config_item started to provide
correct information;

>>> import lxc; c = lxc.Container("rubik"); c.get_running_config_item("lxc.network.0.name"); c.get_running_config_item("lxc.network.0.veth.pair");
'eth0'
'veth9MT2L4'
>>>

and lxc-info started to show network stats;

lxc-info -n rubik
Name:           rubik
State:          RUNNING
PID:            23061
IP:             10.0.3.233
CPU use:        3.86 seconds
BlkIO use:      88.00 KiB
Memory use:     6.53 MiB
KMem use:       0 bytes
Link:           veth9MT2L4
 TX bytes:      3.45 KiB
 RX bytes:      8.83 KiB
 Total bytes:   12.29 KiB

Signed-off-by: S.Çağlar Onur <caglar@10ur.org>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

diff --git a/src/lxc/conf.c b/src/lxc/conf.c
index e5df68bffe8a0c57a5b9fad1d1447f615da3910c..10f46aef15b207f25a6a979822d3f6be199fc686 100644 (file)
--- a/src/lxc/conf.c
+++ b/src/lxc/conf.c
@@ -3014,6 +3014,10 @@ void lxc_delete_network(struct lxc_handler *handler)
 static int unpriv_assign_nic(struct lxc_netdev *netdev, pid_t pid)
 {
        pid_t child;
+       int bytes, pipefd[2];
+       char *token, *saveptr = NULL;
+       /* lxc-user-nic returns "interface_name:interface_name" format */
+       char buffer[IFNAMSIZ*2 + 1];
 
        if (netdev->type != LXC_NET_VETH) {
                ERROR("nic type %d not support for unprivileged use",
@@ -3021,23 +3025,66 @@ static int unpriv_assign_nic(struct lxc_netdev *netdev, pid_t pid)
                return -1;
        }
 
+       if(pipe(pipefd) < 0) {
+               SYSERROR("pipe failed");
+               return -1;
+       }
+
        if ((child = fork()) < 0) {
                SYSERROR("fork");
+               close(pipefd[0]);
+               close(pipefd[1]);
+               return -1;
+       }
+
+       if (child == 0) { // child
+               /* close the read-end of the pipe */
+               close(pipefd[0]);
+               /* redirect the stdout to write-end of the pipe */
+               dup2(pipefd[1], STDOUT_FILENO);
+               /* close the write-end of the pipe */
+               close(pipefd[0]);
+
+               // Call lxc-user-nic pid type bridge
+               char pidstr[20];
+               char *args[] = {LXC_USERNIC_PATH, pidstr, "veth", netdev->link, netdev->name, NULL };
+               snprintf(pidstr, 19, "%lu", (unsigned long) pid);
+               pidstr[19] = '\0';
+               execvp(args[0], args);
+               SYSERROR("execvp lxc-user-nic");
+               exit(1);
+       }
+
+       /* close the write-end of the pipe */
+       close(pipefd[1]);
+
+       bytes = read(pipefd[0], &buffer, IFNAMSIZ*2 + 1);
+       if (bytes < 0) {
+               SYSERROR("read failed");
+       }
+       buffer[bytes - 1] = '\0';
+
+       if (wait_for_pid(child) != 0) {
+               close(pipefd[0]);
                return -1;
        }
 
-       if (child > 0)
-               return wait_for_pid(child);
+       /* close the read-end of the pipe */
+       close(pipefd[0]);
+
+       /* fill netdev->name field */
+       token = strtok_r(buffer, ":", &saveptr);
+       if (!token)
+               return -1;
+       netdev->name = strdup(token);
 
-       // Call lxc-user-nic pid type bridge
+       /* fill netdev->veth_attr.pair field */
+       token = strtok_r(NULL, ":", &saveptr);
+       if (!token)
+               return -1;
+       netdev->priv.veth_attr.pair = strdup(token);
 
-       char pidstr[20];
-       char *args[] = {LXC_USERNIC_PATH, pidstr, "veth", netdev->link, netdev->name, NULL };
-       snprintf(pidstr, 19, "%lu", (unsigned long) pid);
-       pidstr[19] = '\0';
-       execvp(args[0], args);
-       SYSERROR("execvp lxc-user-nic");
-       exit(1);
+       return 0;
 }
 
 int lxc_assign_network(struct lxc_list *network, pid_t pid)

diff --git a/src/lxc/lxc_user_nic.c b/src/lxc/lxc_user_nic.c
index a2f0c96b90297ba43bfdda8979051098e34e2f0d..ce7917725ec110f53057ee9f52372276341ddfd5 100644 (file)
--- a/src/lxc/lxc_user_nic.c
+++ b/src/lxc/lxc_user_nic.c
@@ -599,5 +599,7 @@ int main(int argc, char *argv[])
                exit(1);
        }
 
+       // write the name of the interface pair to the stdout - like eth0:veth9MT2L4
+       fprintf(stdout, "%s:%s\n", vethname, nicname);
        exit(0);
 }