Flock: telnet to machines

flock/container.c

@@ -8,6 +8,7 @@
 #include <poll.h>
 #include <sched.h>
 #include <stdlib.h>
+#include <sys/mount.h>
 #include <sys/wait.h>
 #include <unistd.h>
 
@@ -73,6 +74,39 @@ container_poweroff(int fd, int sig)
   exit(0);
 }
 
+static void
+container_zombie(void)
+{
+  zombie = 0;
+  log(L_INFO "Zombie elimination routine invoked.");
+  while (1) {
+    int status;
+    pid_t p = waitpid(-1, &status, WNOHANG);
+
+    if (p < 0)
+    {
+      if (errno != ECHILD)
+	log(L_ERR "Zombie elimination failed: %m");
+      return;
+    }
+
+    if (p == 0)
+      return;
+
+    const char *coreinfo = WCOREDUMP(status) ? " (core dumped)" : "";
+
+    if (WIFEXITED(status))
+      log(L_INFO "Process %d ended with status %d%s", p, WEXITSTATUS(status), coreinfo);
+    else if (WIFSIGNALED(status))
+      log(L_INFO "Process %d exited by signal %d (%s)%s", p, WTERMSIG(status), strsignal(WTERMSIG(status)), coreinfo);
+    else
+      log(L_ERR "Process %d exited with a strange status %d", p, status);
+  }
+}
+
+
+#define SYSCALL(x, ...)	({ int e = x(__VA_ARGS__); if (e < 0) die("Failed to run %s at %s:%d: %m", #x, __FILE__, __LINE__); e; })
+
 static void
 container_mainloop(int fd)
 {
@@ -82,6 +116,10 @@ container_mainloop(int fd)
   signal(SIGINT, container_poweroff_sighandler);
   signal(SIGCHLD, container_child_sighandler);
 
+  /* Remounting proc to reflect the new PID namespace */
+  SYSCALL(mount, "none", "/", NULL, MS_REC | MS_PRIVATE, NULL);
+  SYSCALL(mount, "proc", "/proc", "proc", MS_NOSUID | MS_NODEV | MS_NOEXEC, NULL);
+
   /* TODO: mount overlayfs and chroot */
   while (1)
   {
@@ -95,13 +133,31 @@ container_mainloop(int fd)
 
     int res = ppoll(&pfd, 1, NULL, &newmask);
 
+    if ((res < 0) && (errno != EINTR))
+      log(L_INFO "ppoll returned -1: %m");
+
     if (poweroff)
       container_poweroff(fd, poweroff);
 
+    if (zombie)
+      container_zombie();
+
     if (pfd.revents & POLLIN)
     {
-      byte buf[128];
+      int sfd = -1;
-      ssize_t sz = read(fd, buf, sizeof buf);
+      byte buf[128], cbuf[CMSG_SPACE(sizeof sfd)];
+      struct iovec v = {
+	.iov_base = buf,
+	.iov_len = sizeof buf,
+      };
+      struct msghdr m = {
+	.msg_iov = &v,
+	.msg_iovlen = 1,
+	.msg_control = &cbuf,
+	.msg_controllen = sizeof cbuf,
+      };
+
+      int sz = recvmsg(fd, &m, 0);
       if (sz < 0)
       {
 	log(L_ERR "error reading data from control socket: %m");
@@ -116,11 +172,47 @@ container_mainloop(int fd)
 	  container_poweroff(fd, 0);
 	  break;
 
-      }
+	case 0x21:
-    }
+	  ASSERT_DIE(buf[2] == 0xf6);
+	  struct cmsghdr *c = CMSG_FIRSTHDR(&m);
+	  memcpy(&sfd, CMSG_DATA(c), sizeof sfd);
 
-    /* TODO: check for telnet socket */
+	  int e = fork();
-    log(L_INFO "woken up, res %d (%m)!", res);
+	  if (e < 0) bug("Cannot fork: %m");
+	  if (e == 0) {
+	    int fd = accept(sfd, NULL, 0);
+	    if (fd < 0)
+	    {
+	      log(L_ERR "failed to accept telnet connection: %m");
+	      exit(1);
+	    }
+	    log(L_INFO "telnet connected");
+
+	    close(0);
+	    close(1);
+	    close(2);
+
+	    dup2(fd, 0);
+	    dup2(fd, 1);
+
+	    /* Unblock signals */
+	    sigset_t newmask;
+	    sigemptyset(&newmask);
+	    sigprocmask(SIG_SETMASK, &newmask, NULL);
+
+	    /* Exec the telnet */
+	    e = execl("/usr/sbin/telnetd", "telnetd", "-E", "/bin/bash", NULL);
+	    log(L_ERR "failed to execl: %m");
+	    exit(42);
+	  }
+	  close(sfd);
+	  break;
+
+	default:
+	  log(L_ERR "unknown command on control socket: %d", buf[1]);
+	  break;
+      }
+    }
   }
 }
 
@@ -356,6 +448,14 @@ crt_err(sock *s, int err UNUSED)
   crt->ccc = NULL;
 }
 
+int
+container_ctl_fd(const char *name)
+{
+  uint h = mem_hash(name, strlen(name));
+  struct container_runtime *crt = HASH_FIND(hcf.hash, CRT, name, h);
+  return (crt && crt->s) ? crt->s->fd : -1;
+}
+
 static void
 container_created(callback *cb)
 {

flock/ctl.c

@@ -186,16 +186,21 @@ hcs_parse(struct cbor_parser_context *ctx, const byte *buf, s64 size)
 	    break;
 
 	  case 3: /* telnet listener open */
-	    if ((ctx->type != 7) || (ctx->value != 22))
+	    if ((ctx->type == 7) && (ctx->value == 22))
-	      CBOR_PARSER_ERROR("Expected null, got %u-%u", ctx->type, ctx->value);
+	    {
-	    /* TODO: allow this also for machines */
-
-	    log(L_INFO "Requested telnet open");
-
 	      hexp_get_telnet(ctx->sock, NULL);
-
 	      ctx->major_state = 1;
 	      break;
+	    }
+
+	    else if (ctx->type != 3)
+	      CBOR_PARSER_ERROR("Expected null or string, got %u-%u", ctx->type, ctx->value);
+
+	    ASSERT_DIE(!ctx->target_buf);
+	    ctx->cfg.cf.name = ctx->target_buf = lp_alloc(ctx->lp, ctx->value + 1);
+	    ctx->target_len = ctx->value;
+
+	    break;
 
 	  case 4: /* telnet listener close */
 	    if ((ctx->type != 7) || (ctx->value != 22))
@@ -364,6 +369,11 @@ hcs_parse(struct cbor_parser_context *ctx, const byte *buf, s64 size)
 	/* Read completely! */
 	switch (ctx->major_state)
 	{
+	  case 3:
+	    hexp_get_telnet(ctx->sock, ctx->cfg.cf.name);
+	    ctx->major_state = 1;
+	    break;
+
 	  case 5:
 	    /* Actually not this one */
 	    CBOR_PARSER_ERROR("NOT IMPLEMENTED YET");

flock/flock-cli

@@ -105,6 +105,12 @@ def container_stop(hypervisor: str, name: str):
     for k,v in msg(hypervisor, { 4: { 0: name, }}).items():
         print(k,v)
 
+@handler
+def container_telnet(hypervisor: str, name: str):
+    for k,v in msg(hypervisor, { 1: name}).items():
+        assert(k == -2)
+        os.execlp("telnet", "telnet", "localhost", str(v))
+
 try:
     binname = sys.argv.pop(0)
 except Exception as e:

flock/flock.h

@@ -48,6 +48,7 @@ union flock_machine_config {
 
 void hypervisor_container_request(sock *s, const char *name, const char *basedir, const char *workdir);
 void hypervisor_container_shutdown(sock *s, const char *name);
+int container_ctl_fd(const char *name);
 
 extern event reboot_event, poweroff_event;
 extern event_list shutdown_event_list;

flock/hypervisor.c

@@ -127,6 +127,8 @@ static struct hypervisor_exposed {
   pool *p;
   sock *s;
   struct birdloop *loop;
+  const char *port_name;
+  sock *port_sreq;
 } he;
 
 /**
@@ -136,7 +138,6 @@ static struct hypervisor_exposed {
 static void hexp_received_telnet(void *);
 struct hexp_received_telnet {
   event e;
-  struct hexp_telnet_port *p;
   int fd;
   u16 port;
 };
@@ -165,6 +166,7 @@ hypervisor_telnet_connected(sock *sk, uint size UNUSED)
   {
     log(L_INFO "telnet connected");
     close(fd);
+    sk_close(sk);
     return 1;
   }
 
@@ -214,20 +216,12 @@ hypervisor_exposed_parent_rx(sock *sk, uint size UNUSED)
   u16 port = ntohs(*((u16 *) &buf[3]));
   log(L_INFO "RX %d bytes, fd %d, port %u", e, sfd, port);
 
-  sock *skl = sk_new(sk->pool);
-  skl->type = SK_MAGIC;
-  skl->rx_hook = hypervisor_telnet_connected;
-  skl->fd = sfd;
-  if (sk_open(skl, sk->loop) < 0)
-    bug("Telnet listener: sk_open failed");
-
   struct hexp_received_telnet *hrt = mb_allocz(he.p, sizeof *hrt);
   *hrt = (struct hexp_received_telnet) {
     .e = {
       .hook = hexp_received_telnet,
       .data = hrt,
     },
-    .p = sk->data,
     .port = port,
     .fd = sfd,
   };
@@ -413,86 +407,20 @@ hypervisor_exposed_fork(void)
  * Hypervisor's mapping between external ports and names
  */
 
-#define HEXP_TELNET_KEY(tp)	tp->name, tp->hash
-#define HEXP_TELNET_NEXT(tp)	tp->next
-#define HEXP_TELNET_EQ(a,h,b,i)	((h) == (i)) && (!(a) && !(b) || !strcmp(a,b))
-#define HEXP_TELNET_FN(a,h)	h
-
-#define TLIST_PREFIX hexp_telnet_requestor
-#define TLIST_TYPE struct hexp_telnet_requestor
-#define TLIST_ITEM n
-struct hexp_telnet_requestor {
-  TLIST_DEFAULT_NODE;
-  sock *s;
-  struct cbor_parser_context *ctx;
-};
-
-#define TLIST_WANT_ADD_TAIL
-#include "lib/tlists.h"
-
 static void
 hexp_sock_err(sock *s, int err UNUSED)
 {
-  struct hexp_telnet_requestor *req = s->data;
+  ASSERT_DIE(s == he.port_sreq);
-  s->data = req->ctx;
+  he.port_name = NULL;
-
+  he.port_sreq = NULL;
-  hexp_telnet_requestor_rem_node(hexp_telnet_requestor_enlisted(req), req);
-}
-
-struct hexp_telnet_port {
-  struct hexp_telnet_port *next;
-  const char *name;
-  uint hash;
-  uint port;
-
-  TLIST_LIST(hexp_telnet_requestor) requestors;
-  int fd;
-};
-
-static struct hexp_telnet {
-  pool *pool;
-  HASH(struct hexp_telnet_port) port_hash;
-} hexp_telnet;
-
-static void
-hexp_init_telnet(void)
-{
-  pool *p = rp_new(hcs_pool, hcs_pool->domain, "Hypervisor exposed telnets");
-  hexp_telnet.pool = p;
-  HASH_INIT(hexp_telnet.port_hash, p, 6);
-}
-
-static void
-hexp_have_telnet(sock *s, struct hexp_telnet_port *p)
-{
-  struct linpool *lp = lp_new(s->pool);
-  struct cbor_writer *cw = cbor_init(s->tbuf, s->tbsize, lp);
-  cbor_open_block_with_length(cw, 1);
-  cbor_add_int(cw, -2);
-  cbor_add_int(cw, p->port);
-  sk_send(s, cw->pt);
-  rfree(lp);
 }
 
 void
 hexp_get_telnet(sock *s, const char *name)
 {
-  if (!hexp_telnet.pool)
+  ASSERT_DIE(!he.port_name);
-    hexp_init_telnet();
+  he.port_name = name ?: "";
-
+  he.port_sreq = s;
-  uint h = name ? mem_hash(name, strlen(name)) : 0;
-  struct hexp_telnet_port *p = HASH_FIND(hexp_telnet.port_hash, HEXP_TELNET, name, h);
-  if (p && p->port)
-    return hexp_have_telnet(s, p);
-  else if (!p)
-  {
-    he.s->data = p = mb_alloc(hcs_pool, sizeof *p);
-    *p = (struct hexp_telnet_port) {
-      .name = name,
-      .hash = h,
-      .fd = -1,
-    };
-    HASH_INSERT(hexp_telnet.port_hash, HEXP_TELNET, p);
 
   uint8_t buf[64];
   linpool *lp = lp_new(s->pool);
@@ -501,53 +429,86 @@ hexp_get_telnet(sock *s, const char *name)
   cbor_add_int(cw, 1);
   cw->cbor[cw->pt++] = 0xf6;
 
-    struct iovec v = {
+  int e = write(he.s->fd, buf, cw->pt);
-      .iov_base = buf,
-      .iov_len = cw->pt,
-    };
-    struct msghdr m = {
-      .msg_iov = &v,
-      .msg_iovlen = 1,
-    };
-
-    int e = sendmsg(he.s->fd, &m, 0);
   if (e != cw->pt)
-      bug("sendmsg error handling not implemented, got %d (%m)", e);
+    bug("write error handling not implemented, got %d (%m)", e);
 
   rfree(lp);
-  }
 
   s->err_paused = hexp_sock_err;
   sk_pause_rx(s->loop, s);
-
-  struct hexp_telnet_requestor *req = mb_allocz(hcs_pool, sizeof *req);
-  req->s = s;
-  req->ctx = s->data;
-  s->data = req;
-  hexp_telnet_requestor_add_tail(&p->requestors, req);
 }
 
 static void hexp_received_telnet(void *_data)
 {
   struct hexp_received_telnet *hrt = _data;
 
-  ASSERT_DIE(!hrt->p->port);
+  ASSERT_DIE(he.port_name);
-  hrt->p->port = hrt->port;
+  const char *name = he.port_name;
-  hrt->p->fd = hrt->fd;
+  he.port_name = NULL;
 
+  sock *s = he.port_sreq;
+  he.port_sreq = NULL;
+
+  if (name[0])
+  {
+    /* Transferring the received listening socket to the container */
+    int fd = container_ctl_fd(name);
+
+    /* TODO: unduplicate this code */
     byte outbuf[128];
     linpool *lp = lp_new(hcs_pool);
     struct cbor_writer *cw = cbor_init(outbuf, sizeof outbuf, lp);
     cbor_open_block_with_length(cw, 1);
     cbor_add_int(cw, -2);
+    write_item(cw, 7, 22);
+    struct iovec v = {
+      .iov_base = outbuf,
+      .iov_len = cw->pt,
+    };
+    byte cbuf[CMSG_SPACE(sizeof hrt->fd)];
+    struct msghdr m = {
+      .msg_iov = &v,
+      .msg_iovlen = 1,
+      .msg_control = &cbuf,
+      .msg_controllen = sizeof cbuf,
+    };
+    struct cmsghdr *c = CMSG_FIRSTHDR(&m);
+    c->cmsg_level = SOL_SOCKET;
+    c->cmsg_type = SCM_RIGHTS;
+    c->cmsg_len = CMSG_LEN(sizeof hrt->fd);
+    memcpy(CMSG_DATA(c), &hrt->fd, sizeof hrt->fd);
+
+    int e = sendmsg(fd, &m, 0);
+    if (e < 0)
+      log(L_ERR "Failed to send socket: %m");
+
+    close(hrt->fd);
+  }
+  else
+  {
+    /* Opening listener here */
+
+    sock *skl = sk_new(hcs_pool);
+    skl->type = SK_MAGIC;
+    skl->rx_hook = hypervisor_telnet_connected;
+    skl->data = skl;
+    skl->fd = hrt->fd;
+    if (sk_open(skl, hcs_loop) < 0)
+      bug("Telnet listener: sk_open failed");
+  }
+
+  if (s)
+  {
+    linpool *lp = lp_new(hcs_pool);
+    struct cbor_writer *cw = cbor_init(s->tbuf, s->tbsize, lp);
+    cbor_open_block_with_length(cw, 1);
+    cbor_add_int(cw, -2);
     cbor_add_int(cw, hrt->port);
 
-  WALK_TLIST_DELSAFE(hexp_telnet_requestor, r, &hrt->p->requestors)
+    sk_send(s, cw->pt);
-  {
+    sk_resume_rx(hcs_loop, s);
-    sk_resume_rx(r->s->loop, r->s);
+    rfree(lp);
-    memcpy(r->s->tbuf, outbuf, cw->pt);
-    sk_send(r->s, cw->pt);
-    hexp_telnet_requestor_rem_node(&hrt->p->requestors, r);
   }
 
   birdloop_enter(he.loop);