nsenter: reuse pidfd for --net-socket

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/sys-utils/nsenter.c b/sys-utils/nsenter.c
index e60cc4d12fb888a0a839d9aa5a2a079803350a9a..183d2675f210a3a901bc0eb7116cee067802231f 100644 (file)
--- a/sys-utils/nsenter.c
+++ b/sys-utils/nsenter.c
@@ -311,19 +311,15 @@ static void enter_namespaces(int pid_fd, int namespaces, bool ignore_errors)
        }
 }
 
-static void open_target_sk_netns(int pid, int sock_fd)
+static void open_target_sk_netns(int pidfd, int sock_fd)
 {
        struct namespace_file *nsfile;
        struct stat sb;
-       int pidfd, sk, nsfd;
+       int sk, nsfd;
 
        nsfile = get_nsfile(CLONE_NEWNET);
        assert(nsfile->nstype);
 
-       pidfd = pidfd_open(pid, 0);
-       if (pidfd < 0)
-               err(EXIT_FAILURE, _("failed to pidfd_open() for %d"), pid);
-
        sk = pidfd_getfd(pidfd, sock_fd, 0);
        if (sk < 0)
                err(EXIT_FAILURE, _("pidfd_getfd(%d, %u)"), pidfd, sock_fd);
@@ -340,7 +336,6 @@ static void open_target_sk_netns(int pid, int sock_fd)
        nsfile->fd = nsfd;
        nsfile->enabled = true;
        close(sk);
-       close(pidfd);
 }
 
 static int get_ns_ino(const char *path, ino_t *ino)
@@ -662,14 +657,16 @@ int main(int argc, char *argv[])
         * Open remaining namespace and directory descriptors.
         */
        namespaces = get_namespaces_without_fd();
-       if (namespaces) {
+       if (namespaces || sock_fd >= 0) {
                if (!namespace_target_pid)
                        errx(EXIT_FAILURE, _("no target PID specified"));
 
                pid_fd = pidfd_open(namespace_target_pid, 0);
                if (pid_fd < 0) {
-                       /* fallback to classic way */
-                       open_namespaces(namespaces);
+                       if (sock_fd >= 0)
+                               err(EXIT_FAILURE, _("failed to pidfd_open() for %d"), namespace_target_pid);
+                       if (namespaces)
+                               open_namespaces(namespaces);    /* fallback */
                }
        }
 
@@ -693,11 +690,8 @@ int main(int argc, char *argv[])
        if (do_user_parent)
                open_parent_user_ns_fd();
 
-       if (sock_fd != -1) {
-               if (!namespace_target_pid)
-                       errx(EXIT_FAILURE, _("--net-socket needs target PID"));
-               open_target_sk_netns(namespace_target_pid, sock_fd);
-       }
+       if (sock_fd >= 0)
+               open_target_sk_netns(pid_fd, sock_fd);
 
        /* All initialized, get final set of namespaces */
        namespaces = get_namespaces();