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Be more strict about when to accept socks auth message

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In the code as it stood, we would accept any number of socks5
username/password authentication messages, regardless of whether we
had actually negotiated username/password authentication.  Instead,
we should only accept one, and only if we have really negotiated
username/password authentication.

This patch also makes some fields of socks_request_t into uint8_t,
for safety.
This commit is contained in:
Nick Mathewson 2011-06-29 12:00:00 -04:00
parent 9b3f48c074
commit aec396d9d0
2 changed files with 30 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
src/or/buffers.c
View File

@ -1636,18 +1636,12 @@ parse_socks(const char *data, size_t datalen, socks_request_t *req,
unsigned char usernamelen, passlen;
struct in_addr in;
socksver = *data;
switch (socksver) { /* which version of socks? */
case 1: /* socks5: username/password authentication request */
if (req->socks_version != 5) {
log_warn(LD_APP,
"socks5: Received authentication attempt before "
"authentication negotiated. Rejecting.");
return -1;
}
if (req->socks_version == 5 && !req->got_auth) {
/* See if we have received authentication. Strictly speaking, we should
also check whether we actually negotiated username/password
authentication. But some broken clients will send us authentication
even if we negotiated SOCKS_NO_AUTH. */
if (*data == 1) { /* username/pass version 1 */
/* Format is: authversion [1 byte] == 1
usernamelen [1 byte]
username [usernamelen bytes]
@ -1669,8 +1663,19 @@ parse_socks(const char *data, size_t datalen, socks_request_t *req,
log_debug(LD_APP,
"socks5: Accepted username/password without checking.");
*drain_out = 2u + usernamelen + 1u + passlen;
req->got_auth = 1;
return 0;
} else if (req->auth_type == SOCKS_USER_PASS) {
/* unknown version byte */
log_warn(LD_APP, "Socks5 username/password version %d not recognized; "
"rejecting.", (int)*data);
return -1;
}
}
socksver = *data;
switch (socksver) { /* which version of socks? */
case 5: /* socks5 */
if (req->socks_version != 5) { /* we need to negotiate a method */
@ -1691,7 +1696,8 @@ parse_socks(const char *data, size_t datalen, socks_request_t *req,
req->socks_version = 5; /* remember we've already negotiated auth */
log_debug(LD_APP,"socks5: accepted method 0 (no authentication)");
r=0;
} else if (memchr(data+2, SOCKS_USER_PASS,nummethods)) {
} else if (memchr(data+2, SOCKS_USER_PASS, nummethods)) {
req->auth_type = SOCKS_USER_PASS;
req->reply[1] = SOCKS_USER_PASS; /* tell client to use "user/pass"
auth method */
req->socks_version = 5; /* remember we've already negotiated auth */
@ -1911,7 +1917,7 @@ parse_socks(const char *data, size_t datalen, socks_request_t *req,
case 'H': /* head */
case 'P': /* put/post */
case 'C': /* connect */
strlcpy(req->reply,
strlcpy((char*)req->reply,
"HTTP/1.0 501 Tor is not an HTTP Proxy\r\n"
"Content-Type: text/html; charset=iso-8859-1\r\n\r\n"
"<html>\n"
@ -1937,7 +1943,7 @@ parse_socks(const char *data, size_t datalen, socks_request_t *req,
"</body>\n"
"</html>\n"
, MAX_SOCKS_REPLY_LEN);
req->replylen = strlen(req->reply)+1;
req->replylen = strlen((char*)req->reply)+1;
/* fall through */
default: /* version is not socks4 or socks5 */
log_warn(LD_APP,

12
src/or/or.h
View File

@ -3088,10 +3088,15 @@ struct socks_request_t {
/** Which version of SOCKS did the client use? One of "0, 4, 5" -- where
* 0 means that no socks handshake ever took place, and this is just a
* stub connection (e.g. see connection_ap_make_link()). */
char socks_version;
int command; /**< What is this stream's goal? One from the above list. */
uint8_t socks_version;
/** If using socks5 authentication, which authentication type did we
* negotiate? currently we support 0 (no authentication) and 2
* (username/password). */
uint8_t auth_type;
/** What is this stream's goal? One of the SOCKS_COMMAND_* values */
uint8_t command;
size_t replylen; /**< Length of <b>reply</b>. */
char reply[MAX_SOCKS_REPLY_LEN]; /**< Write an entry into this string if
uint8_t reply[MAX_SOCKS_REPLY_LEN]; /**< Write an entry into this string if
* we want to specify our own socks reply,
* rather than using the default socks4 or
* socks5 socks reply. We use this for the
@ -3103,6 +3108,7 @@ struct socks_request_t {
unsigned int has_finished : 1; /**< Has the SOCKS handshake finished? Used to
* make sure we send back a socks reply for
* every connection. */
unsigned int got_auth : 1; /**< Have we received any authentication data? */
};
/********************************* circuitbuild.c **********************/