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Diffstat (limited to '')
| -rw-r--r-- | nchan.c | 443 |
1 files changed, 443 insertions, 0 deletions
@@ -0,0 +1,443 @@ +/* $OpenBSD: nchan.c,v 1.74 2022/02/01 23:32:51 djm Exp $ */ +/* + * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "includes.h" + +#include <sys/types.h> +#include <sys/socket.h> + +#include <errno.h> +#include <string.h> +#include <stdarg.h> + +#include "openbsd-compat/sys-queue.h" +#include "ssh2.h" +#include "sshbuf.h" +#include "ssherr.h" +#include "packet.h" +#include "channels.h" +#include "compat.h" +#include "log.h" + +/* + * SSH Protocol 1.5 aka New Channel Protocol + * Thanks to Martina, Axel and everyone who left Erlangen, leaving me bored. + * Written by Markus Friedl in October 1999 + * + * Protocol versions 1.3 and 1.5 differ in the handshake protocol used for the + * tear down of channels: + * + * 1.3: strict request-ack-protocol: + * CLOSE -> + * <- CLOSE_CONFIRM + * + * 1.5: uses variations of: + * IEOF -> + * <- OCLOSE + * <- IEOF + * OCLOSE -> + * i.e. both sides have to close the channel + * + * 2.0: the EOF messages are optional + * + * See the debugging output from 'ssh -v' and 'sshd -d' of + * ssh-1.2.27 as an example. + * + */ + +/* functions manipulating channel states */ +/* + * EVENTS update channel input/output states execute ACTIONS + */ +/* + * ACTIONS: should never update the channel states + */ +static void chan_send_eof2(struct ssh *, Channel *); +static void chan_send_eow2(struct ssh *, Channel *); + +/* helper */ +static void chan_shutdown_write(struct ssh *, Channel *); +static void chan_shutdown_read(struct ssh *, Channel *); +static void chan_shutdown_extended_read(struct ssh *, Channel *); + +static const char * const ostates[] = { + "open", "drain", "wait_ieof", "closed", +}; +static const char * const istates[] = { + "open", "drain", "wait_oclose", "closed", +}; + +static void +chan_set_istate(Channel *c, u_int next) +{ + if (c->istate > CHAN_INPUT_CLOSED || next > CHAN_INPUT_CLOSED) + fatal("chan_set_istate: bad state %d -> %d", c->istate, next); + debug2("channel %d: input %s -> %s", c->self, istates[c->istate], + istates[next]); + c->istate = next; +} + +static void +chan_set_ostate(Channel *c, u_int next) +{ + if (c->ostate > CHAN_OUTPUT_CLOSED || next > CHAN_OUTPUT_CLOSED) + fatal("chan_set_ostate: bad state %d -> %d", c->ostate, next); + debug2("channel %d: output %s -> %s", c->self, ostates[c->ostate], + ostates[next]); + c->ostate = next; +} + +void +chan_read_failed(struct ssh *ssh, Channel *c) +{ + debug2("channel %d: read failed", c->self); + switch (c->istate) { + case CHAN_INPUT_OPEN: + chan_shutdown_read(ssh, c); + chan_set_istate(c, CHAN_INPUT_WAIT_DRAIN); + break; + default: + error("channel %d: chan_read_failed for istate %d", + c->self, c->istate); + break; + } +} + +void +chan_ibuf_empty(struct ssh *ssh, Channel *c) +{ + debug2("channel %d: ibuf empty", c->self); + if (sshbuf_len(c->input)) { + error("channel %d: chan_ibuf_empty for non empty buffer", + c->self); + return; + } + switch (c->istate) { + case CHAN_INPUT_WAIT_DRAIN: + if (!(c->flags & (CHAN_CLOSE_SENT|CHAN_LOCAL))) + chan_send_eof2(ssh, c); + chan_set_istate(c, CHAN_INPUT_CLOSED); + break; + default: + error("channel %d: chan_ibuf_empty for istate %d", + c->self, c->istate); + break; + } +} + +void +chan_obuf_empty(struct ssh *ssh, Channel *c) +{ + debug2("channel %d: obuf empty", c->self); + if (sshbuf_len(c->output)) { + error("channel %d: chan_obuf_empty for non empty buffer", + c->self); + return; + } + switch (c->ostate) { + case CHAN_OUTPUT_WAIT_DRAIN: + chan_shutdown_write(ssh, c); + chan_set_ostate(c, CHAN_OUTPUT_CLOSED); + break; + default: + error("channel %d: internal error: obuf_empty for ostate %d", + c->self, c->ostate); + break; + } +} + +void +chan_rcvd_eow(struct ssh *ssh, Channel *c) +{ + debug2("channel %d: rcvd eow", c->self); + switch (c->istate) { + case CHAN_INPUT_OPEN: + chan_shutdown_read(ssh, c); + chan_set_istate(c, CHAN_INPUT_CLOSED); + break; + } +} + +static void +chan_send_eof2(struct ssh *ssh, Channel *c) +{ + int r; + + debug2("channel %d: send eof", c->self); + switch (c->istate) { + case CHAN_INPUT_WAIT_DRAIN: + if (!c->have_remote_id) + fatal_f("channel %d: no remote_id", c->self); + if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_EOF)) != 0 || + (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || + (r = sshpkt_send(ssh)) != 0) + fatal_fr(r, "send CHANNEL_EOF"); + c->flags |= CHAN_EOF_SENT; + break; + default: + error("channel %d: cannot send eof for istate %d", + c->self, c->istate); + break; + } +} + +static void +chan_send_close2(struct ssh *ssh, Channel *c) +{ + int r; + + debug2("channel %d: send close", c->self); + if (c->ostate != CHAN_OUTPUT_CLOSED || + c->istate != CHAN_INPUT_CLOSED) { + error("channel %d: cannot send close for istate/ostate %d/%d", + c->self, c->istate, c->ostate); + } else if (c->flags & CHAN_CLOSE_SENT) { + error("channel %d: already sent close", c->self); + } else { + if (!c->have_remote_id) + fatal_f("channel %d: no remote_id", c->self); + if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_CLOSE)) != 0 || + (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || + (r = sshpkt_send(ssh)) != 0) + fatal_fr(r, "send CHANNEL_EOF"); + c->flags |= CHAN_CLOSE_SENT; + } +} + +static void +chan_send_eow2(struct ssh *ssh, Channel *c) +{ + int r; + + debug2("channel %d: send eow", c->self); + if (c->ostate == CHAN_OUTPUT_CLOSED) { + error("channel %d: must not sent eow on closed output", + c->self); + return; + } + if (!(ssh->compat & SSH_NEW_OPENSSH)) + return; + if (!c->have_remote_id) + fatal_f("channel %d: no remote_id", c->self); + if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_REQUEST)) != 0 || + (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || + (r = sshpkt_put_cstring(ssh, "eow@openssh.com")) != 0 || + (r = sshpkt_put_u8(ssh, 0)) != 0 || + (r = sshpkt_send(ssh)) != 0) + fatal_fr(r, "send CHANNEL_EOF"); +} + +/* shared */ + +void +chan_rcvd_ieof(struct ssh *ssh, Channel *c) +{ + debug2("channel %d: rcvd eof", c->self); + c->flags |= CHAN_EOF_RCVD; + if (c->ostate == CHAN_OUTPUT_OPEN) + chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); + if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN && + sshbuf_len(c->output) == 0 && + !CHANNEL_EFD_OUTPUT_ACTIVE(c)) + chan_obuf_empty(ssh, c); +} + +void +chan_rcvd_oclose(struct ssh *ssh, Channel *c) +{ + debug2("channel %d: rcvd close", c->self); + if (!(c->flags & CHAN_LOCAL)) { + if (c->flags & CHAN_CLOSE_RCVD) + error("channel %d: protocol error: close rcvd twice", + c->self); + c->flags |= CHAN_CLOSE_RCVD; + } + if (c->type == SSH_CHANNEL_LARVAL) { + /* tear down larval channels immediately */ + chan_set_ostate(c, CHAN_OUTPUT_CLOSED); + chan_set_istate(c, CHAN_INPUT_CLOSED); + return; + } + switch (c->ostate) { + case CHAN_OUTPUT_OPEN: + /* + * wait until a data from the channel is consumed if a CLOSE + * is received + */ + chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); + break; + } + switch (c->istate) { + case CHAN_INPUT_OPEN: + chan_shutdown_read(ssh, c); + chan_shutdown_extended_read(ssh, c); + chan_set_istate(c, CHAN_INPUT_CLOSED); + break; + case CHAN_INPUT_WAIT_DRAIN: + if (!(c->flags & CHAN_LOCAL)) + chan_send_eof2(ssh, c); + chan_shutdown_extended_read(ssh, c); + chan_set_istate(c, CHAN_INPUT_CLOSED); + break; + } +} + +void +chan_write_failed(struct ssh *ssh, Channel *c) +{ + debug2("channel %d: write failed", c->self); + switch (c->ostate) { + case CHAN_OUTPUT_OPEN: + case CHAN_OUTPUT_WAIT_DRAIN: + chan_shutdown_write(ssh, c); + if (strcmp(c->ctype, "session") == 0) + chan_send_eow2(ssh, c); + chan_set_ostate(c, CHAN_OUTPUT_CLOSED); + break; + default: + error("channel %d: chan_write_failed for ostate %d", + c->self, c->ostate); + break; + } +} + +void +chan_mark_dead(struct ssh *ssh, Channel *c) +{ + c->type = SSH_CHANNEL_ZOMBIE; +} + +int +chan_is_dead(struct ssh *ssh, Channel *c, int do_send) +{ + if (c->type == SSH_CHANNEL_ZOMBIE) { + debug2("channel %d: zombie", c->self); + return 1; + } + if (c->istate != CHAN_INPUT_CLOSED || c->ostate != CHAN_OUTPUT_CLOSED) + return 0; + if ((ssh->compat & SSH_BUG_EXTEOF) && + c->extended_usage == CHAN_EXTENDED_WRITE && + c->efd != -1 && + sshbuf_len(c->extended) > 0) { + debug2("channel %d: active efd: %d len %zu", + c->self, c->efd, sshbuf_len(c->extended)); + return 0; + } + if (c->flags & CHAN_LOCAL) { + debug2("channel %d: is dead (local)", c->self); + return 1; + } + if (!(c->flags & CHAN_CLOSE_SENT)) { + if (do_send) { + chan_send_close2(ssh, c); + } else { + /* channel would be dead if we sent a close */ + if (c->flags & CHAN_CLOSE_RCVD) { + debug2("channel %d: almost dead", + c->self); + return 1; + } + } + } + if ((c->flags & CHAN_CLOSE_SENT) && + (c->flags & CHAN_CLOSE_RCVD)) { + debug2("channel %d: is dead", c->self); + return 1; + } + return 0; +} + +/* helper */ +static void +chan_shutdown_write(struct ssh *ssh, Channel *c) +{ + sshbuf_reset(c->output); + if (c->type == SSH_CHANNEL_LARVAL) + return; + /* shutdown failure is allowed if write failed already */ + debug2_f("channel %d: (i%d o%d sock %d wfd %d efd %d [%s])", + c->self, c->istate, c->ostate, c->sock, c->wfd, c->efd, + channel_format_extended_usage(c)); + if (c->sock != -1) { + if (shutdown(c->sock, SHUT_WR) == -1) { + debug2_f("channel %d: shutdown() failed for " + "fd %d [i%d o%d]: %.100s", c->self, c->sock, + c->istate, c->ostate, strerror(errno)); + } + } else { + if (channel_close_fd(ssh, c, &c->wfd) < 0) { + logit_f("channel %d: close() failed for " + "fd %d [i%d o%d]: %.100s", c->self, c->wfd, + c->istate, c->ostate, strerror(errno)); + } + } +} + +static void +chan_shutdown_read(struct ssh *ssh, Channel *c) +{ + if (c->type == SSH_CHANNEL_LARVAL) + return; + debug2_f("channel %d: (i%d o%d sock %d wfd %d efd %d [%s])", + c->self, c->istate, c->ostate, c->sock, c->rfd, c->efd, + channel_format_extended_usage(c)); + if (c->sock != -1) { + /* + * shutdown(sock, SHUT_READ) may return ENOTCONN if the + * write side has been closed already. (bug on Linux) + * HP-UX may return ENOTCONN also. + */ + if (shutdown(c->sock, SHUT_RD) == -1 && errno != ENOTCONN) { + error_f("channel %d: shutdown() failed for " + "fd %d [i%d o%d]: %.100s", c->self, c->sock, + c->istate, c->ostate, strerror(errno)); + } + } else { + if (channel_close_fd(ssh, c, &c->rfd) < 0) { + logit_f("channel %d: close() failed for " + "fd %d [i%d o%d]: %.100s", c->self, c->rfd, + c->istate, c->ostate, strerror(errno)); + } + } +} + +static void +chan_shutdown_extended_read(struct ssh *ssh, Channel *c) +{ + if (c->type == SSH_CHANNEL_LARVAL || c->efd == -1) + return; + if (c->extended_usage != CHAN_EXTENDED_READ && + c->extended_usage != CHAN_EXTENDED_IGNORE) + return; + debug_f("channel %d: (i%d o%d sock %d wfd %d efd %d [%s])", + c->self, c->istate, c->ostate, c->sock, c->rfd, c->efd, + channel_format_extended_usage(c)); + if (channel_close_fd(ssh, c, &c->efd) < 0) { + logit_f("channel %d: close() failed for " + "extended fd %d [i%d o%d]: %.100s", c->self, c->efd, + c->istate, c->ostate, strerror(errno)); + } +} |