From 19dae2c62210862bca0597a48c98f8244f1070aa Mon Sep 17 00:00:00 2001 From: Maria Matejka Date: Tue, 10 Sep 2024 21:58:46 +0200 Subject: [PATCH] Flock: Telnet connection to hypervisor seems to work well --- flock/hypervisor.c | 166 +++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 160 insertions(+), 6 deletions(-) diff --git a/flock/hypervisor.c b/flock/hypervisor.c index b826a046..38aa1ce0 100644 --- a/flock/hypervisor.c +++ b/flock/hypervisor.c @@ -8,6 +8,7 @@ #include "flock/flock.h" +#include #include /** @@ -132,17 +133,87 @@ static struct hypervisor_exposed { /** * Exposed process' parent side (requestor) **/ +static int +hypervisor_telnet_connected(sock *sk, uint size UNUSED) +{ + int fd = accept(sk->fd, NULL, 0); + if (fd < 0) + { + if (errno == EAGAIN) + return 1; + + log(L_ERR "failed to accept telnet connection: %m"); + return 0; + } + + int e = fork(); + if (e < 0) + { + log(L_ERR "failed to fork: %m"); + return 0; + } + + if (e) + { + log(L_INFO "telnet connected"); + close(fd); + return 1; + } + + close(0); + close(1); + close(2); + dup2(fd, 0); + dup2(fd, 1); + + e = execl("/usr/sbin/telnetd", "telnetd", "-E", "/bin/bash", NULL); + log(L_ERR "failed to execl: %m"); + exit(42); +} + static int hypervisor_exposed_parent_rx(sock *sk, uint size UNUSED) { - log(L_INFO "HV EP RX"); - recvmsg(sk->fd, NULL, 0); + int sfd = -1; + 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 e = recvmsg(sk->fd, &m, 0); + + struct cmsghdr *c = CMSG_FIRSTHDR(&m); + memcpy(&sfd, CMSG_DATA(c), sizeof sfd); + + ASSERT_DIE(buf[0] == 0xa1); + ASSERT_DIE(buf[1] == 0x21); + ASSERT_DIE(buf[2] == 0x19); + + 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"); +// hexp_received_telnet(port, sfd); + return 0; } static void -hypervisor_exposed_parent_err(sock *sk UNUSED, int e UNUSED) +hypervisor_exposed_parent_err(sock *sk, int e UNUSED) { + sk_close(sk); } /** @@ -161,9 +232,88 @@ hypervisor_exposed_child_rx(sock *sk, uint size UNUSED) .msg_iovlen = 1, }; int e = recvmsg(sk->fd, &m, 0); - log(L_INFO "HV EC RX %d", e); + if (e != 3) + { + log(L_ERR "Got something strange: %d, %m", e); + return 0; + } - return 0; + /* Only one thing is actually supported for now: opening a listening socket */ + int sfd = socket(AF_INET6, SOCK_STREAM, 0); + if (sfd < 0) + { + log(L_ERR "Failed to socket(): %m"); + return 0; + } + + while (1) + { + u32 r = (random_u32() % (32768-1024) + 1024); + union { + struct sockaddr_in6 sin; + struct sockaddr a; + } sin = { + .sin = { + .sin6_family = AF_INET6, + .sin6_port = htons(r), + .sin6_addr.s6_addr[15] = 1, + }, + }; + + + int e = bind(sfd, &sin.a, sizeof sin); + if (e < 0) + if (errno == EADDRINUSE) + { + log(L_INFO "Tried to bind to %u but already in use", r); + continue; + } else { + log(L_ERR "Failed to bind to %u: %m", r); + close(sfd); + return 0; + } + + e = listen(sfd, 10); + if (e < 0) + { + log(L_ERR "Failed to listen(): %m", e); + close(sfd); + return 0; + } + + log(L_INFO "SUCCESS"); + + byte outbuf[128]; + linpool *lp = lp_new(sk->pool); + struct cbor_writer *cw = cbor_init(outbuf, sizeof outbuf, lp); + cbor_open_block_with_length(cw, 1); + cbor_add_int(cw, -2); + cbor_add_int(cw, r); + struct iovec v = { + .iov_base = outbuf, + .iov_len = cw->pt, + }; + byte cbuf[CMSG_SPACE(sizeof sfd)]; + 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 sfd); + memcpy(CMSG_DATA(c), &sfd, sizeof sfd); + + e = sendmsg(sk->fd, &m, 0); + if (e < 0) + log(L_ERR "Failed to send socket: %m"); + + close(sfd); + + return 0; + } } static void @@ -239,6 +389,7 @@ struct hexp_telnet_port { const char *name; uint hash; uint port; + int fd; }; static struct hexp_telnet { @@ -275,7 +426,10 @@ hexp_get_telnet(sock *s, const char *name) 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) - return hexp_have_telnet(s, p); + if (p->port) + return hexp_have_telnet(s, p); + else + return; /* Waiting for the exposed part */ uint8_t buf[64]; linpool *lp = lp_new(s->pool);