start: remove procfs pidfd support

We'll only rely on proper anon-inode based pidfd support in the future.
There's no good reason to use the procfs fallback. All the fancy features we
might want to use are only available with anon-inode pidfds.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

diff --git a/src/lxc/start.c b/src/lxc/start.c
index d62acf4bd8a7924c108107d6fc9ff060aa05d326..f085aa60d04eace6cae49e080de5f0d65d043b33 100644 (file)
--- a/src/lxc/start.c
+++ b/src/lxc/start.c
@@ -385,8 +385,6 @@ static int signal_handler(int fd, uint32_t events, void *data,
        if (siginfo.ssi_signo == SIGHUP) {
                if (hdlr->pidfd >= 0)
                        lxc_raw_pidfd_send_signal(hdlr->pidfd, SIGTERM, NULL, 0);
-               else if (hdlr->proc_pidfd >= 0)
-                       lxc_raw_pidfd_send_signal(hdlr->proc_pidfd, SIGTERM, NULL, 0);
                else
                        kill(hdlr->pid, SIGTERM);
                INFO("Killing %d since terminal hung up", hdlr->pid);
@@ -398,9 +396,6 @@ static int signal_handler(int fd, uint32_t events, void *data,
                if (hdlr->pidfd >= 0)
                        lxc_raw_pidfd_send_signal(hdlr->pidfd,
                                                  siginfo.ssi_signo, NULL, 0);
-               else if (hdlr->proc_pidfd >= 0)
-                       lxc_raw_pidfd_send_signal(hdlr->proc_pidfd,
-                                                 siginfo.ssi_signo, NULL, 0);
                else
                        kill(hdlr->pid, siginfo.ssi_signo);
                INFO("Forwarded signal %d to pid %d", siginfo.ssi_signo, hdlr->pid);
@@ -649,8 +644,6 @@ void lxc_zero_handler(struct lxc_handler *handler)
 
        handler->pidfd = -EBADF;
 
-       handler->proc_pidfd = -EBADF;
-
        handler->sigfd = -1;
 
        for (i = 0; i < LXC_NS_MAX; i++)
@@ -674,9 +667,6 @@ void lxc_free_handler(struct lxc_handler *handler)
        if (handler->pidfd >= 0)
                close(handler->pidfd);
 
-       if (handler->proc_pidfd >= 0)
-               close(handler->proc_pidfd);
-
        if (handler->sigfd >= 0)
                close(handler->sigfd);
 
@@ -726,7 +716,6 @@ struct lxc_handler *lxc_init_handler(const char *name, struct lxc_conf *conf,
        handler->monitor_status_fd = -EBADF;
        handler->pinfd = -1;
        handler->pidfd = -EBADF;
-       handler->proc_pidfd = -EBADF;
        handler->sigfd = -EBADF;
        handler->init_died = false;
        handler->state_socket_pair[0] = handler->state_socket_pair[1] = -1;
@@ -1104,8 +1093,6 @@ void lxc_abort(const char *name, struct lxc_handler *handler)
 
        if (handler->pidfd >= 0)
                ret = lxc_raw_pidfd_send_signal(handler->pidfd, SIGKILL, NULL, 0);
-       else if (handler->proc_pidfd >= 0)
-               ret = lxc_raw_pidfd_send_signal(handler->proc_pidfd, SIGKILL, NULL, 0);
        else if (handler->pid > 0)
                ret = kill(handler->pid, SIGKILL);
        if (ret < 0)
@@ -1624,30 +1611,6 @@ static inline int do_share_ns(void *arg)
        return 0;
 }
 
-static int proc_pidfd_open(pid_t pid)
-{
-       __do_close_prot_errno int proc_pidfd = -EBADF;
-       char path[100];
-
-       snprintf(path, sizeof(path), "/proc/%d", pid);
-       proc_pidfd = open(path, O_DIRECTORY | O_RDONLY | O_CLOEXEC);
-       if (proc_pidfd < 0) {
-               SYSERROR("Failed to open %s", path);
-               return -1;
-       }
-
-       /* Test whether we can send signals. */
-       if (lxc_raw_pidfd_send_signal(proc_pidfd, 0, NULL, 0)) {
-               if (errno != ENOSYS)
-                       SYSERROR("Failed to send signal through pidfd");
-               else
-                       INFO("Sending signals through pidfds not supported on this kernel");
-               return -1;
-       }
-
-       return move_fd(proc_pidfd);
-}
-
 /* lxc_spawn() performs crucial setup tasks and clone()s the new process which
  * exec()s the requested container binary.
  * Note that lxc_spawn() runs in the parent namespaces. Any operations performed
@@ -1759,12 +1722,6 @@ static int lxc_spawn(struct lxc_handler *handler)
        }
        TRACE("Cloned child process %d", handler->pid);
 
-       if (handler->pidfd < 0) {
-               handler->proc_pidfd = proc_pidfd_open(handler->pid);
-               if (handler->proc_pidfd < 0 && (errno != ENOSYS))
-                       goto out_delete_net;
-       }
-
        ret = snprintf(pidstr, 20, "%d", handler->pid);
        if (ret < 0 || ret >= 20)
                goto out_delete_net;

diff --git a/src/lxc/start.h b/src/lxc/start.h
index 662ac5570445c96c94f6601f62edd42d0726a4a7..f40b4d661eb13b6735a453f9b22be4bf6dc083cb 100644 (file)
--- a/src/lxc/start.h
+++ b/src/lxc/start.h
@@ -83,12 +83,6 @@ struct lxc_handler {
        /* The child's pidfd. */
        int pidfd;
 
-       /*
-        * File descriptor for the /proc/<pid> directory of the container's
-        * init process.
-        */
-       int proc_pidfd;
-
        /* The grandfather's pid when double-forking. */
        pid_t transient_pid;