blob: 3ead97909b68a6444bee552bd8cce637cbc6cba3 [file] [log] [blame]
/*
* 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.
*
* strlcat() is copyright as follows:
* Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
* 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.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED ``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 "dbutil.h"
#include "buffer.h"
#include "session.h"
#include "atomicio.h"
#define MAX_FMT 100
static void generic_dropbear_exit(int exitcode, const char* format,
va_list param);
static void generic_dropbear_log(int priority, const char* format,
va_list param);
void (*_dropbear_exit)(int exitcode, const char* format, va_list param)
= generic_dropbear_exit;
void (*_dropbear_log)(int priority, const char* format, va_list param)
= generic_dropbear_log;
#ifdef DEBUG_TRACE
int debug_trace = 0;
#endif
#ifndef DISABLE_SYSLOG
void startsyslog() {
openlog(PROGNAME, LOG_PID, LOG_AUTHPRIV);
}
#endif /* DISABLE_SYSLOG */
/* the "format" string must be <= 100 characters */
void dropbear_close(const char* format, ...) {
va_list param;
va_start(param, format);
_dropbear_exit(EXIT_SUCCESS, format, param);
va_end(param);
}
void dropbear_exit(const char* format, ...) {
va_list param;
va_start(param, format);
_dropbear_exit(EXIT_FAILURE, format, param);
va_end(param);
}
static void generic_dropbear_exit(int exitcode, const char* format,
va_list param) {
char fmtbuf[300];
snprintf(fmtbuf, sizeof(fmtbuf), "Exited: %s", format);
_dropbear_log(LOG_INFO, fmtbuf, param);
exit(exitcode);
}
static void generic_dropbear_log(int UNUSED(priority), const char* format,
va_list param) {
char printbuf[1024];
vsnprintf(printbuf, sizeof(printbuf), format, param);
fprintf(stderr, "%s\n", printbuf);
}
/* this is what can be called to write arbitrary log messages */
void dropbear_log(int priority, const char* format, ...) {
va_list param;
va_start(param, format);
_dropbear_log(priority, format, param);
va_end(param);
}
#ifdef DEBUG_TRACE
void dropbear_trace(const char* format, ...) {
va_list param;
if (!debug_trace) {
return;
}
va_start(param, format);
fprintf(stderr, "TRACE: ");
vfprintf(stderr, format, param);
fprintf(stderr, "\n");
va_end(param);
}
#endif /* DEBUG_TRACE */
/* Listen on address:port. Unless address is NULL, in which case listen on
* everything. If called with address == "", we'll listen on localhost/loopback.
* Returns the number of sockets bound on success, or -1 on failure. On
* failure, if errstring wasn't NULL, it'll be a newly malloced error
* string.*/
int dropbear_listen(const char* address, const char* port,
int *socks, unsigned int sockcount, char **errstring, int *maxfd) {
struct addrinfo hints, *res = NULL, *res0 = NULL;
int err;
unsigned int nsock;
struct linger linger;
int val;
int sock;
TRACE(("enter dropbear_listen"))
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_UNSPEC; /* TODO: let them flag v4 only etc */
hints.ai_socktype = SOCK_STREAM;
if (address && address[0] == '\0') {
TRACE(("dropbear_listen: local loopback"))
address = NULL;
} else {
TRACE(("dropbear_listen: not local loopback"))
hints.ai_flags = AI_PASSIVE;
}
err = getaddrinfo(address, port, &hints, &res0);
if (err) {
if (errstring != NULL && *errstring == NULL) {
int len;
len = 20 + strlen(gai_strerror(err));
*errstring = (char*)m_malloc(len);
snprintf(*errstring, len, "Error resolving: %s", gai_strerror(err));
}
TRACE(("leave dropbear_listen: failed resolving"))
return -1;
}
nsock = 0;
for (res = res0; res != NULL && nsock < sockcount;
res = res->ai_next) {
/* Get a socket */
socks[nsock] = socket(res->ai_family, res->ai_socktype,
res->ai_protocol);
sock = socks[nsock]; /* For clarity */
if (sock < 0) {
err = errno;
TRACE(("socket() failed"))
continue;
}
/* Various useful socket options */
val = 1;
/* set to reuse, quick timeout */
setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void*) &val, sizeof(val));
linger.l_onoff = 1;
linger.l_linger = 5;
setsockopt(sock, SOL_SOCKET, SO_LINGER, (void*)&linger, sizeof(linger));
/* disable nagle */
setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (void*)&val, sizeof(val));
if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
err = errno;
close(sock);
TRACE(("bind(%s) failed", port))
continue;
}
if (listen(sock, 20) < 0) {
err = errno;
close(sock);
TRACE(("listen() failed"))
continue;
}
*maxfd = MAX(*maxfd, sock);
nsock++;
}
if (nsock == 0) {
if (errstring != NULL && *errstring == NULL) {
int len;
len = 20 + strlen(strerror(err));
*errstring = (char*)m_malloc(len);
snprintf(*errstring, len, "Error listening: %s", strerror(err));
TRACE(("leave dropbear_listen: failure, %s", strerror(err)))
return -1;
}
}
TRACE(("leave dropbear_listen: success, %d socks bound", nsock))
return nsock;
}
/* Connect via TCP to a host. Connection will try ipv4 or ipv6, will
* return immediately if nonblocking is set. On failure, if errstring
* wasn't null, it will be a newly malloced error message */
/* TODO: maxfd */
int connect_remote(const char* remotehost, const char* remoteport,
int nonblocking, char ** errstring) {
struct addrinfo *res0 = NULL, *res = NULL, hints;
int sock;
int err;
TRACE(("enter connect_remote"))
if (errstring != NULL) {
*errstring = NULL;
}
memset(&hints, 0, sizeof(hints));
hints.ai_socktype = SOCK_STREAM;
hints.ai_family = PF_UNSPEC;
err = getaddrinfo(remotehost, remoteport, &hints, &res0);
if (err) {
if (errstring != NULL && *errstring == NULL) {
int len;
len = 20 + strlen(gai_strerror(err));
*errstring = (char*)m_malloc(len);
snprintf(*errstring, len, "Error resolving: %s", gai_strerror(err));
}
TRACE(("Error resolving: %s", gai_strerror(err)))
return -1;
}
sock = -1;
err = EADDRNOTAVAIL;
for (res = res0; res; res = res->ai_next) {
sock = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
if (sock < 0) {
err = errno;
continue;
}
if (nonblocking) {
if (fcntl(sock, F_SETFL, O_NONBLOCK) < 0) {
close(sock);
sock = -1;
if (errstring != NULL && *errstring == NULL) {
*errstring = m_strdup("Failed non-blocking");
}
TRACE(("Failed non-blocking: %s", strerror(errno)))
continue;
}
}
if (connect(sock, res->ai_addr, res->ai_addrlen) < 0) {
if (errno == EINPROGRESS && nonblocking) {
TRACE(("Connect in progress"))
break;
} else {
err = errno;
close(sock);
sock = -1;
continue;
}
}
break; /* Success */
}
if (sock < 0 && !(errno == EINPROGRESS && nonblocking)) {
/* Failed */
if (errstring != NULL && *errstring == NULL) {
int len;
len = 20 + strlen(strerror(err));
*errstring = (char*)m_malloc(len);
snprintf(*errstring, len, "Error connecting: %s", strerror(err));
}
TRACE(("Error connecting: %s", strerror(err)))
} else {
/* Success */
/* (err is used as a dummy var here) */
setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (void*)&err, sizeof(err));
}
freeaddrinfo(res0);
if (sock > 0 && errstring != NULL && *errstring != NULL) {
m_free(*errstring);
}
TRACE(("leave connect_remote: sock %d\n", sock))
return sock;
}
/* Return a string representation of the socket address passed. The return
* value is allocated with malloc() */
unsigned char * getaddrstring(struct sockaddr_storage* addr, int withport) {
char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
char *retstring = NULL;
int ret;
unsigned int len;
len = sizeof(struct sockaddr_storage);
/* Some platforms such as Solaris 8 require that len is the length
* of the specific structure. */
if (addr->ss_family == AF_INET) {
len = sizeof(struct sockaddr_in);
}
#ifdef AF_INET6
if (addr->ss_family == AF_INET6) {
len = sizeof(struct sockaddr_in6);
}
#endif
ret = getnameinfo((struct sockaddr*)addr, len, hbuf, sizeof(hbuf),
sbuf, sizeof(sbuf), NI_NUMERICSERV | NI_NUMERICHOST);
if (ret != 0) {
/* This is a fairly bad failure - it'll fallback to IP if it
* just can't resolve */
dropbear_exit("failed lookup (%d, %d)", ret, errno);
}
if (withport) {
len = strlen(hbuf) + 2 + strlen(sbuf);
retstring = (char*)m_malloc(len);
snprintf(retstring, len, "%s:%s", hbuf, sbuf);
} else {
retstring = m_strdup(hbuf);
}
return retstring;
}
/* Get the hostname corresponding to the address addr. On failure, the IP
* address is returned. The return value is allocated with strdup() */
char* getaddrhostname(struct sockaddr_storage * addr) {
char hbuf[NI_MAXHOST];
char sbuf[NI_MAXSERV];
int ret;
unsigned int len;
len = sizeof(struct sockaddr_storage);
/* Some platforms such as Solaris 8 require that len is the length
* of the specific structure. */
if (addr->ss_family == AF_INET) {
len = sizeof(struct sockaddr_in);
}
#ifdef AF_INET6
if (addr->ss_family == AF_INET6) {
len = sizeof(struct sockaddr_in6);
}
#endif
ret = getnameinfo((struct sockaddr*)addr, len, hbuf, sizeof(hbuf),
sbuf, sizeof(sbuf), NI_NUMERICSERV);
if (ret != 0) {
/* On some systems (Darwin does it) we get EINTR from getnameinfo
* somehow. Eew. So we'll just return the IP, since that doesn't seem
* to exhibit that behaviour. */
return getaddrstring(addr, 0);
}
return m_strdup(hbuf);
}
#ifdef DEBUG_TRACE
void printhex(unsigned char* buf, int len) {
int i;
for (i = 0; i < len; i++) {
fprintf(stderr, "%02x", buf[i]);
if (i % 16 == 15) {
fprintf(stderr, "\n");
}
else if (i % 2 == 1) {
fprintf(stderr, " ");
}
}
fprintf(stderr, "\n");
}
#endif
/* Strip all control characters from text (a null-terminated string), except
* for '\n', '\r' and '\t'.
* The result returned is a newly allocated string, this must be free()d after
* use */
char * stripcontrol(const char * text) {
char * ret;
int len, pos;
int i;
len = strlen(text);
ret = m_malloc(len+1);
pos = 0;
for (i = 0; i < len; i++) {
if ((text[i] <= '~' && text[i] >= ' ') /* normal printable range */
|| text[i] == '\n' || text[i] == '\r' || text[i] == '\t') {
ret[pos] = text[i];
pos++;
}
}
ret[pos] = 0x0;
return ret;
}
/* reads the contents of filename into the buffer buf, from the current
* position, either to the end of the file, or the buffer being full.
* Returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */
int buf_readfile(buffer* buf, const char* filename) {
int fd;
int len;
int maxlen;
fd = open(filename, O_RDONLY);
if (fd < 0) {
close(fd);
return DROPBEAR_FAILURE;
}
do {
maxlen = buf->size - buf->pos;
len = read(fd, buf_getwriteptr(buf, maxlen),
maxlen);
buf_incrwritepos(buf, len);
} while (len < maxlen && len > 0);
close(fd);
return DROPBEAR_SUCCESS;
}
/* get a line from the file into buffer in the style expected for an
* authkeys file.
* Will return DROPBEAR_SUCCESS if data is read, or DROPBEAR_FAILURE on EOF.*/
/* Only used for ~/.ssh/known_hosts and ~/.ssh/authorized_keys */
#if defined(DROPBEAR_CLIENT) || defined(ENABLE_SVR_PUBKEY_AUTH)
int buf_getline(buffer * line, FILE * authfile) {
int c = EOF;
TRACE(("enter buf_getline"))
buf_setpos(line, 0);
buf_setlen(line, 0);
while (line->pos < line->size) {
c = fgetc(authfile); /*getc() is weird with some uClibc systems*/
if (c == EOF || c == '\n' || c == '\r') {
goto out;
}
buf_putbyte(line, (unsigned char)c);
}
TRACE(("leave getauthline: line too long"))
/* We return success, but the line length will be zeroed - ie we just
* ignore that line */
buf_setlen(line, 0);
out:
/* if we didn't read anything before EOF or error, exit */
if (c == EOF && line->pos == 0) {
TRACE(("leave buf_getline: failure"))
return DROPBEAR_FAILURE;
} else {
TRACE(("leave buf_getline: success"))
buf_setpos(line, 0);
return DROPBEAR_SUCCESS;
}
}
#endif
/* loop until the socket is closed (in case of EINTR) or
* we get and error.
* Returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */
int m_close(int fd) {
int val;
do {
val = close(fd);
} while (val < 0 && errno == EINTR);
if (val == 0 || errno == EBADF) {
return DROPBEAR_SUCCESS;
} else {
return DROPBEAR_FAILURE;
}
}
void * m_malloc(size_t size) {
void* ret;
if (size == 0) {
dropbear_exit("m_malloc failed");
}
ret = calloc(1, size);
if (ret == NULL) {
dropbear_exit("m_malloc failed");
}
return ret;
}
void * m_strdup(const char * str) {
char* ret;
ret = strdup(str);
if (ret == NULL) {
dropbear_exit("m_strdup failed");
}
return ret;
}
void __m_free(void* ptr) {
if (ptr != NULL) {
free(ptr);
}
}
void * m_realloc(void* ptr, size_t size) {
void *ret;
if (size == 0) {
dropbear_exit("m_realloc failed");
}
ret = realloc(ptr, size);
if (ret == NULL) {
dropbear_exit("m_realloc failed");
}
return ret;
}
/* Clear the data, based on the method in David Wheeler's
* "Secure Programming for Linux and Unix HOWTO" */
/* Beware of calling this from within dbutil.c - things might get
* optimised away */
void m_burn(void *data, unsigned int len) {
volatile char *p = data;
if (data == NULL)
return;
while (len--) {
*p++ = 0x66;
}
}
void setnonblocking(int fd) {
TRACE(("setnonblocking: %d", fd))
if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0) {
dropbear_exit("Couldn't set nonblocking");
}
TRACE(("leave setnonblocking"))
}