Mercurial > dropbear
view svr-x11fwd.c @ 1306:34e6127ef02e
merge fixes from PuTTY import.c
toint() from misc.c
(revids are from hggit conversion)
changeset: 4620:60a336a6c85c
user: Simon Tatham <[email protected]>
date: Thu Feb 25 20:26:33 2016 +0000
files: import.c
description:
Fix potential segfaults in reading OpenSSH's ASN.1 key format.
The length coming back from ber_read_id_len might have overflowed, so
treat it as potentially negative. Also, while I'm here, accumulate it
inside ber_read_id_len as an unsigned, so as to avoid undefined
behaviour on integer overflow, and toint() it before return.
Thanks to Hanno Böck for spotting this, with the aid of AFL.
(cherry picked from commit 5b7833cd474a24ec098654dcba8cb9509f3bf2c1)
Conflicts:
import.c
(cherry-picker's note: resolving the conflict involved removing an
entire section of the original commit which fixed ECDSA code not
present on this branch)
changeset: 4619:9c6c638d98d8
user: Simon Tatham <[email protected]>
date: Sun Jul 14 10:45:54 2013 +0000
files: import.c ssh.c sshdss.c sshpubk.c sshrsa.c
description:
Tighten up a lot of casts from unsigned to int which are read by one
of the GET_32BIT macros and then used as length fields. Missing bounds
checks against zero have been added, and also I've introduced a helper
function toint() which casts from unsigned to int in such a way as to
avoid C undefined behaviour, since I'm not sure I trust compilers any
more to do the obviously sensible thing.
[originally from svn r9918]
changeset: 4618:3957829f24d3
user: Simon Tatham <[email protected]>
date: Mon Jul 08 22:36:04 2013 +0000
files: import.c sshdss.c sshrsa.c
description:
Add an assortment of extra safety checks.
[originally from svn r9896]
changeset: 4617:2cddee0bce12
user: Jacob Nevins <[email protected]>
date: Wed Dec 07 00:24:45 2005 +0000
files: import.c
description:
Institutional failure to memset() things pointed at rather than pointers.
Things should now be zeroed and memory not leaked. Spotted by Brant Thomsen.
[originally from svn r6476]
changeset: 4616:24ac78a9c71d
user: Simon Tatham <[email protected]>
date: Wed Feb 11 13:58:27 2004 +0000
files: import.c
description:
Jacob's last-minute testing found a couple of trivial bugs in
import.c, and my attempts to reproduce them in cmdgen found another
one there :-)
[originally from svn r3847]
changeset: 4615:088d39a73db0
user: Simon Tatham <[email protected]>
date: Thu Jan 22 18:52:49 2004 +0000
files: import.c
description:
Placate some gcc warnings.
[originally from svn r3761]
changeset: 4614:e4288bad4d93
parent: 1758:108b8924593d
user: Simon Tatham <[email protected]>
date: Fri Oct 03 21:21:23 2003 +0000
files: import.c
description:
My ASN.1 decoder returned wrong IDs for anything above 0x1E! Good
job it's never had to yet. Ahem.
[originally from svn r3479]
author | Matt Johnston <matt@ucc.asn.au> |
---|---|
date | Tue, 12 Jul 2016 23:00:01 +0800 |
parents | 3a383aaeb487 |
children | 750ec4ec4cbe |
line wrap: on
line source
/* * Dropbear - a SSH2 server * * Copyright (c) 2002,2003 Matt Johnston * All rights reserved. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. */ #include "includes.h" #ifndef DISABLE_X11FWD #include "x11fwd.h" #include "session.h" #include "ssh.h" #include "dbutil.h" #include "chansession.h" #include "channel.h" #include "packet.h" #include "buffer.h" #include "auth.h" #define X11BASEPORT 6000 #define X11BINDBASE 6010 static void x11accept(struct Listener* listener, int sock); static int bindport(int fd); static int send_msg_channel_open_x11(int fd, struct sockaddr_in* addr); /* Check untrusted xauth strings for metacharacters */ /* Returns DROPBEAR_SUCCESS/DROPBEAR_FAILURE */ static int xauth_valid_string(const char *s) { size_t i; for (i = 0; s[i] != '\0'; i++) { if (!isalnum(s[i]) && s[i] != '.' && s[i] != ':' && s[i] != '/' && s[i] != '-' && s[i] != '_') { return DROPBEAR_FAILURE; } } return DROPBEAR_SUCCESS; } /* called as a request for a session channel, sets up listening X11 */ /* returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */ int x11req(struct ChanSess * chansess) { int fd = -1; if (!svr_pubkey_allows_x11fwd()) { return DROPBEAR_FAILURE; } /* we already have an x11 connection */ if (chansess->x11listener != NULL) { return DROPBEAR_FAILURE; } chansess->x11singleconn = buf_getbool(ses.payload); chansess->x11authprot = buf_getstring(ses.payload, NULL); chansess->x11authcookie = buf_getstring(ses.payload, NULL); chansess->x11screennum = buf_getint(ses.payload); if (xauth_valid_string(chansess->x11authprot) == DROPBEAR_FAILURE || xauth_valid_string(chansess->x11authcookie) == DROPBEAR_FAILURE) { dropbear_log(LOG_WARNING, "Bad xauth request"); goto fail; } /* create listening socket */ fd = socket(PF_INET, SOCK_STREAM, 0); if (fd < 0) { goto fail; } /* allocate port and bind */ chansess->x11port = bindport(fd); if (chansess->x11port < 0) { goto fail; } /* listen */ if (listen(fd, 20) < 0) { goto fail; } /* set non-blocking */ setnonblocking(fd); /* listener code will handle the socket now. * No cleanup handler needed, since listener_remove only happens * from our cleanup anyway */ chansess->x11listener = new_listener( &fd, 1, 0, chansess, x11accept, NULL); if (chansess->x11listener == NULL) { goto fail; } return DROPBEAR_SUCCESS; fail: /* cleanup */ m_free(chansess->x11authprot); m_free(chansess->x11authcookie); m_close(fd); return DROPBEAR_FAILURE; } /* accepts a new X11 socket */ /* returns DROPBEAR_FAILURE or DROPBEAR_SUCCESS */ static void x11accept(struct Listener* listener, int sock) { int fd; struct sockaddr_in addr; socklen_t len; int ret; struct ChanSess * chansess = (struct ChanSess *)(listener->typedata); len = sizeof(addr); fd = accept(sock, (struct sockaddr*)&addr, &len); if (fd < 0) { return; } /* if single-connection we close it up */ if (chansess->x11singleconn) { x11cleanup(chansess); } ret = send_msg_channel_open_x11(fd, &addr); if (ret == DROPBEAR_FAILURE) { close(fd); } } /* This is called after switching to the user, and sets up the xauth * and environment variables. */ void x11setauth(struct ChanSess *chansess) { char display[20]; /* space for "localhost:12345.123" */ FILE * authprog = NULL; int val; if (chansess->x11listener == NULL) { return; } /* create the DISPLAY string */ val = snprintf(display, sizeof(display), "localhost:%d.%u", chansess->x11port - X11BASEPORT, chansess->x11screennum); if (val < 0 || val >= (int)sizeof(display)) { /* string was truncated */ return; } addnewvar("DISPLAY", display); /* create the xauth string */ val = snprintf(display, sizeof(display), "unix:%d.%u", chansess->x11port - X11BASEPORT, chansess->x11screennum); if (val < 0 || val >= (int)sizeof(display)) { /* string was truncated */ return; } /* code is strongly based on OpenSSH's */ authprog = popen(XAUTH_COMMAND, "w"); if (authprog) { fprintf(authprog, "add %s %s %s\n", display, chansess->x11authprot, chansess->x11authcookie); pclose(authprog); } else { fprintf(stderr, "Failed to run %s\n", XAUTH_COMMAND); } } void x11cleanup(struct ChanSess *chansess) { m_free(chansess->x11authprot); m_free(chansess->x11authcookie); TRACE(("chansess %p", (void*)chansess)) if (chansess->x11listener != NULL) { remove_listener(chansess->x11listener); chansess->x11listener = NULL; } } static int x11_inithandler(struct Channel *channel) { channel->prio = DROPBEAR_CHANNEL_PRIO_INTERACTIVE; return 0; } static const struct ChanType chan_x11 = { 0, /* sepfds */ "x11", x11_inithandler, /* inithandler */ NULL, /* checkclose */ NULL, /* reqhandler */ NULL /* closehandler */ }; static int send_msg_channel_open_x11(int fd, struct sockaddr_in* addr) { char* ipstring = NULL; if (send_msg_channel_open_init(fd, &chan_x11) == DROPBEAR_SUCCESS) { ipstring = inet_ntoa(addr->sin_addr); buf_putstring(ses.writepayload, ipstring, strlen(ipstring)); buf_putint(ses.writepayload, addr->sin_port); encrypt_packet(); return DROPBEAR_SUCCESS; } else { return DROPBEAR_FAILURE; } } /* returns the port bound to, or -1 on failure. * Will attempt to bind to a port X11BINDBASE (6010 usually) or upwards */ static int bindport(int fd) { struct sockaddr_in addr; uint16_t port; memset((void*)&addr, 0x0, sizeof(addr)); addr.sin_family = AF_INET; addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK); /* if we can't find one in 2000 ports free, something's wrong */ for (port = X11BINDBASE; port < X11BINDBASE + 2000; port++) { addr.sin_port = htons(port); if (bind(fd, (struct sockaddr*)&addr, sizeof(struct sockaddr_in)) == 0) { /* success */ return port; } if (errno == EADDRINUSE) { /* try the next port */ continue; } /* otherwise it was an error we don't know about */ dropbear_log(LOG_DEBUG, "Failed to bind x11 socket"); break; } return -1; } #endif /* DROPBEAR_X11FWD */