X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/1dd353b59d3feeaef262801cde4a023eed3c983e..346ad9c0594a6040c28e8dbe1aba8aea2a2d8663:/ssh.c diff --git a/ssh.c b/ssh.c index 339b98ea..d998d08f 100644 --- a/ssh.c +++ b/ssh.c @@ -182,6 +182,7 @@ static const char *const ssh2_disconnect_reasons[] = { #define BUG_NEEDS_SSH1_PLAIN_PASSWORD 4 #define BUG_CHOKES_ON_RSA 8 #define BUG_SSH2_RSA_PADDING 16 +#define BUG_SSH2_DERIVEKEY 32 static int ssh_pkt_ctx = 0; @@ -515,8 +516,6 @@ static const struct ssh_compress *sccomp = NULL; static const struct ssh_kex *kex = NULL; static const struct ssh_signkey *hostkey = NULL; static unsigned char ssh2_session_id[20]; -int (*ssh_get_line) (const char *prompt, char *str, int maxlen, - int is_pw) = NULL; static char *savedhost; static int savedport; @@ -805,11 +804,11 @@ static int ssh1_rdpkt(unsigned char **data, int *datalen) if (pktin.type == SSH1_MSG_DEBUG) { /* log debug message */ - char buf[80]; + char buf[512]; int stringlen = GET_32BIT(pktin.body); - strcpy(buf, "Remote: "); - if (stringlen > 70) - stringlen = 70; + strcpy(buf, "Remote debug message: "); + if (stringlen > 480) + stringlen = 480; memcpy(buf + 8, pktin.body + 4, stringlen); buf[8 + stringlen] = '\0'; logevent(buf); @@ -887,6 +886,15 @@ static int ssh2_rdpkt(unsigned char **data, int *datalen) st->pad = pktin.data[4]; /* + * _Completely_ silly lengths should be stomped on before they + * do us any more damage. + */ + if (st->len < 0 || st->pad < 0 || st->len + st->pad < 0) { + bombout(("Incoming packet was garbled on decryption")); + crReturn(0); + } + + /* * This enables us to deduce the payload length. */ st->payload = st->len - st->pad - 1; @@ -1541,6 +1549,7 @@ static int ssh2_pkt_getbool(void) static void ssh2_pkt_getstring(char **p, int *length) { *p = NULL; + *length = 0; if (pktin.length - pktin.savedpos < 4) return; *length = GET_32BIT(pktin.data + pktin.savedpos); @@ -1693,6 +1702,16 @@ static void ssh_detect_bugs(char *vstring) logevent("We believe remote version has SSH2 HMAC bug"); } + if (!strncmp(imp, "2.0.", 4)) { + /* + * These versions have the key-derivation bug (failing to + * include the literal shared secret in the hashes that + * generate the keys). + */ + ssh_remote_bugs |= BUG_SSH2_DERIVEKEY; + logevent("We believe remote version has SSH2 key-derivation bug"); + } + if ((!strncmp(imp, "OpenSSH_2.", 10) && imp[10]>='5' && imp[10]<='9') || (!strncmp(imp, "OpenSSH_3.", 10) && imp[10]>='0' && imp[10]<='2')) { /* @@ -1711,6 +1730,7 @@ static int do_ssh_init(unsigned char c) static int vstrsize; static char *vlog; static int i; + static int proto1, proto2; crBegin; @@ -1767,12 +1787,26 @@ static int do_ssh_init(unsigned char c) sfree(vlog); /* - * Server version "1.99" means we can choose whether we use v1 - * or v2 protocol. Choice is based on cfg.sshprot. + * Decide which SSH protocol version to support. */ - if (ssh_versioncmp(version, cfg.sshprot == 1 ? "2.0" : "1.99") >= 0) { + + /* Anything strictly below "2.0" means protocol 1 is supported. */ + proto1 = ssh_versioncmp(version, "2.0") < 0; + /* Anything greater or equal to "1.99" means protocol 2 is supported. */ + proto2 = ssh_versioncmp(version, "1.99") >= 0; + + if (cfg.sshprot == 0 && !proto1) { + bombout(("SSH protocol version 1 required by user but not provided by server")); + crReturn(0); + } + if (cfg.sshprot == 3 && !proto2) { + bombout(("SSH protocol version 2 required by user but not provided by server")); + crReturn(0); + } + + if (proto2 && (cfg.sshprot >= 2 || !proto1)) { /* - * This is a v2 server. Begin v2 protocol. + * Use v2 protocol. */ char verstring[80], vlog[100]; sprintf(verstring, "SSH-2.0-%s", sshver); @@ -1792,7 +1826,7 @@ static int do_ssh_init(unsigned char c) s_rdpkt = ssh2_rdpkt; } else { /* - * This is a v1 server. Begin v1 protocol. + * Use v1 protocol. */ char verstring[80], vlog[100]; sprintf(verstring, "SSH-%s-%s", @@ -1801,11 +1835,6 @@ static int do_ssh_init(unsigned char c) sprintf(vlog, "We claim version: %s", verstring); logevent(vlog); strcat(verstring, "\n"); - - if (cfg.sshprot == 3) { - bombout(("SSH protocol version 2 required by user but not provided by server")); - crReturn(0); - } logevent("Using SSH protocol version 1"); sk_write(s, verstring, strlen(verstring)); @@ -2040,6 +2069,76 @@ static void ssh_throttle_all(int enable, int bufsize) } /* + * Username and password input, abstracted off into reusable + * routines (hopefully even reusable between SSH1 and SSH2!). + */ +static char *ssh_userpass_input_buffer; +static int ssh_userpass_input_buflen; +static int ssh_userpass_input_bufpos; +static int ssh_userpass_input_echo; + +/* Set up a username or password input loop on a given buffer. */ +void setup_userpass_input(char *buffer, int buflen, int echo) +{ + ssh_userpass_input_buffer = buffer; + ssh_userpass_input_buflen = buflen; + ssh_userpass_input_bufpos = 0; + ssh_userpass_input_echo = echo; +} + +/* + * Process some terminal data in the course of username/password + * input. Returns >0 for success (line of input returned in + * buffer), <0 for failure (user hit ^C/^D, bomb out and exit), 0 + * for inconclusive (keep waiting for more input please). + */ +int process_userpass_input(unsigned char *in, int inlen) +{ + char c; + + while (inlen--) { + switch (c = *in++) { + case 10: + case 13: + ssh_userpass_input_buffer[ssh_userpass_input_bufpos] = 0; + ssh_userpass_input_buffer[ssh_userpass_input_buflen-1] = 0; + return +1; + break; + case 8: + case 127: + if (ssh_userpass_input_bufpos > 0) { + if (ssh_userpass_input_echo) + c_write_str("\b \b"); + ssh_userpass_input_bufpos--; + } + break; + case 21: + case 27: + while (ssh_userpass_input_bufpos > 0) { + if (ssh_userpass_input_echo) + c_write_str("\b \b"); + ssh_userpass_input_bufpos--; + } + break; + case 3: + case 4: + return -1; + break; + default: + if (((c >= ' ' && c <= '~') || + ((unsigned char) c >= 160)) + && ssh_userpass_input_bufpos < ssh_userpass_input_buflen-1) { + ssh_userpass_input_buffer[ssh_userpass_input_bufpos++] = c; + if (ssh_userpass_input_echo) + c_write(&c, 1); + } + break; + } + } + return 0; +} + +/* * Handle the key exchange and user authentication phases. */ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) @@ -2224,10 +2323,8 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) fflush(stdout); { - static int pos = 0; - static char c; if ((flags & FLAG_INTERACTIVE) && !*cfg.username) { - if (ssh_get_line) { + if (ssh_get_line && !ssh_getline_pw_only) { if (!ssh_get_line("login as: ", username, sizeof(username), FALSE)) { /* @@ -2239,47 +2336,18 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) crReturn(1); } } else { + static int ret; c_write_str("login as: "); ssh_send_ok = 1; - while (pos >= 0) { + + setup_userpass_input(username, sizeof(username), 1); + do { crWaitUntil(!ispkt); - while (inlen--) - switch (c = *in++) { - case 10: - case 13: - username[pos] = 0; - pos = -1; - break; - case 8: - case 127: - if (pos > 0) { - c_write_str("\b \b"); - pos--; - } - break; - case 21: - case 27: - while (pos > 0) { - c_write_str("\b \b"); - pos--; - } - break; - case 3: - case 4: - cleanup_exit(0); - break; - default: - if (((c >= ' ' && c <= '~') || - ((unsigned char) c >= 160)) - && pos < sizeof(username)-1) { - username[pos++] = c; - c_write(&c, 1); - } - break; - } - } + ret = process_userpass_input(in, inlen); + } while (ret == 0); + if (ret < 0) + cleanup_exit(0); c_write_str("\r\n"); - username[strcspn(username, "\n\r")] = '\0'; } } else { strncpy(username, cfg.username, 99); @@ -2563,37 +2631,17 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt) } else { /* Prompt may have come from server. We've munged it a bit, so * we know it to be zero-terminated at least once. */ + static int ret; c_write_untrusted(prompt, strlen(prompt)); pos = 0; - ssh_send_ok = 1; - while (pos >= 0) { + + setup_userpass_input(password, sizeof(password), 0); + do { crWaitUntil(!ispkt); - while (inlen--) - switch (c = *in++) { - case 10: - case 13: - password[pos] = 0; - pos = -1; - break; - case 8: - case 127: - if (pos > 0) - pos--; - break; - case 21: - case 27: - pos = 0; - break; - case 3: - case 4: - cleanup_exit(0); - break; - default: - if (pos < sizeof(password)-1) - password[pos++] = c; - break; - } - } + ret = process_userpass_input(in, inlen); + } while (ret == 0); + if (ret < 0) + cleanup_exit(0); c_write_str("\r\n"); } @@ -3460,14 +3508,16 @@ static void ssh2_mkkey(Bignum K, char *H, char *sessid, char chr, SHA_State s; /* First 20 bytes. */ SHA_Init(&s); - sha_mpint(&s, K); + if (!(ssh_remote_bugs & BUG_SSH2_DERIVEKEY)) + sha_mpint(&s, K); SHA_Bytes(&s, H, 20); SHA_Bytes(&s, &chr, 1); SHA_Bytes(&s, sessid, 20); SHA_Final(&s, keyspace); /* Next 20 bytes. */ SHA_Init(&s); - sha_mpint(&s, K); + if (!(ssh_remote_bugs & BUG_SSH2_DERIVEKEY)) + sha_mpint(&s, K); SHA_Bytes(&s, H, 20); SHA_Bytes(&s, keyspace, 20); SHA_Final(&s, keyspace + 20); @@ -4034,7 +4084,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) static int tried_pubkey_config, tried_agent, tried_keyb_inter; static int kbd_inter_running; static int we_are_in; - static int num_prompts, echo; + static int num_prompts, curr_prompt, echo; static char username[100]; static int got_username; static char pwprompt[200]; @@ -4083,13 +4133,9 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) username[0] = '\0'; got_username = FALSE; do { - static int pos; - static char c; - /* * Get a username. */ - pos = 0; if (got_username && !cfg.change_username) { /* * We got a username last time round this loop, and @@ -4097,7 +4143,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) * it again. */ } else if ((flags & FLAG_INTERACTIVE) && !*cfg.username) { - if (ssh_get_line) { + if (ssh_get_line && !ssh_getline_pw_only) { if (!ssh_get_line("login as: ", username, sizeof(username), FALSE)) { /* @@ -4109,45 +4155,16 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) crReturnV; } } else { + static int ret; c_write_str("login as: "); ssh_send_ok = 1; - while (pos >= 0) { + setup_userpass_input(username, sizeof(username), 1); + do { crWaitUntilV(!ispkt); - while (inlen--) - switch (c = *in++) { - case 10: - case 13: - username[pos] = 0; - pos = -1; - break; - case 8: - case 127: - if (pos > 0) { - c_write_str("\b \b"); - pos--; - } - break; - case 21: - case 27: - while (pos > 0) { - c_write_str("\b \b"); - pos--; - } - break; - case 3: - case 4: - cleanup_exit(0); - break; - default: - if (((c >= ' ' && c <= '~') || - ((unsigned char) c >= 160)) - && pos < sizeof(username)-1) { - username[pos++] = c; - c_write(&c, 1); - } - break; - } - } + ret = process_userpass_input(in, inlen); + } while (ret == 0); + if (ret < 0) + cleanup_exit(0); } c_write_str("\r\n"); username[strcspn(username, "\n\r")] = '\0'; @@ -4235,9 +4252,14 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) if (kbd_inter_running && pktin.type == SSH2_MSG_USERAUTH_INFO_REQUEST) { /* - * This is a further prompt in keyboard-interactive - * authentication. Do nothing. + * This is either a further set-of-prompts packet + * in keyboard-interactive authentication, or it's + * the same one and we came back here with `gotit' + * set. In the former case, we must reset the + * curr_prompt variable. */ + if (!gotit) + curr_prompt = 0; } else if (pktin.type != SSH2_MSG_USERAUTH_FAILURE) { bombout(("Strange packet received during authentication: type %d", pktin.type)); @@ -4311,6 +4333,14 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) method = 0; ssh_pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK; + /* + * Most password/passphrase prompts will be + * non-echoing, so we set this to 0 by default. + * Exception is that some keyboard-interactive prompts + * can be echoing, in which case we'll set this to 1. + */ + echo = 0; + if (!method && can_pubkey && agent_exists() && !tried_agent) { /* * Attempt public-key authentication using Pageant. @@ -4321,6 +4351,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) static int authed = FALSE; void *r; + ssh_pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK; ssh_pkt_ctx |= SSH2_PKTCTX_PUBLICKEY; tried_agent = TRUE; @@ -4463,6 +4494,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) tried_pubkey_config = TRUE; + ssh_pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK; ssh_pkt_ctx |= SSH2_PKTCTX_PUBLICKEY; /* @@ -4517,6 +4549,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) type = AUTH_TYPE_KEYBOARD_INTERACTIVE; tried_keyb_inter = TRUE; + ssh_pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK; ssh_pkt_ctx |= SSH2_PKTCTX_KBDINTER; ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST); @@ -4537,6 +4570,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) } kbd_inter_running = TRUE; + curr_prompt = 0; } if (kbd_inter_running) { @@ -4544,34 +4578,58 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) type = AUTH_TYPE_KEYBOARD_INTERACTIVE; tried_keyb_inter = TRUE; + ssh_pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK; ssh_pkt_ctx |= SSH2_PKTCTX_KBDINTER; - /* We've got packet with that "interactive" info - dump banners, and set its prompt as ours */ - { - char *name, *inst, *lang, *prompt; - int name_len, inst_len, lang_len, prompt_len; + if (curr_prompt == 0) { + /* + * We've got a fresh USERAUTH_INFO_REQUEST. + * Display header data, and start going through + * the prompts. + */ + char *name, *inst, *lang; + int name_len, inst_len, lang_len; + ssh2_pkt_getstring(&name, &name_len); ssh2_pkt_getstring(&inst, &inst_len); ssh2_pkt_getstring(&lang, &lang_len); - if (name_len > 0) + if (name_len > 0) { c_write_untrusted(name, name_len); - if (inst_len > 0) + c_write_str("\r\n"); + } + if (inst_len > 0) { c_write_untrusted(inst, inst_len); + c_write_str("\r\n"); + } num_prompts = ssh2_pkt_getuint32(); + } - ssh2_pkt_getstring(&prompt, &prompt_len); - strncpy(pwprompt, prompt, sizeof(pwprompt)); - pwprompt[prompt_len < sizeof(pwprompt) ? - prompt_len : sizeof(pwprompt)-1] = '\0'; - need_pw = TRUE; + /* + * If there are prompts remaining in the packet, + * display one and get a response. + */ + if (curr_prompt < num_prompts) { + char *prompt; + int prompt_len; + ssh2_pkt_getstring(&prompt, &prompt_len); + if (prompt_len > 0) { + strncpy(pwprompt, prompt, sizeof(pwprompt)); + pwprompt[prompt_len < sizeof(pwprompt) ? + prompt_len : sizeof(pwprompt)-1] = '\0'; + } else { + strcpy(pwprompt, + ": "); + } echo = ssh2_pkt_getbool(); - } + need_pw = TRUE; + } else + need_pw = FALSE; } if (!method && can_passwd) { method = AUTH_PASSWORD; + ssh_pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK; ssh_pkt_ctx |= SSH2_PKTCTX_PASSWORD; sprintf(pwprompt, "%.90s@%.90s's password: ", username, savedhost); @@ -4600,41 +4658,17 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) crReturnV; } } else { - static int pos = 0; - static char c; - + static int ret; c_write_untrusted(pwprompt, strlen(pwprompt)); ssh_send_ok = 1; - pos = 0; - while (pos >= 0) { + setup_userpass_input(password, sizeof(password), echo); + do { crWaitUntilV(!ispkt); - while (inlen--) - switch (c = *in++) { - case 10: - case 13: - password[pos] = 0; - pos = -1; - break; - case 8: - case 127: - if (pos > 0) - pos--; - break; - case 21: - case 27: - pos = 0; - break; - case 3: - case 4: - cleanup_exit(0); - break; - default: - if (pos < sizeof(password)-1) - password[pos++] = c; - break; - } - } + ret = process_userpass_input(in, inlen); + } while (ret == 0); + if (ret < 0) + cleanup_exit(0); c_write_str("\r\n"); } } @@ -4763,11 +4797,28 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) logevent("Sent password"); type = AUTH_TYPE_PASSWORD; } else if (method == AUTH_KEYBOARD_INTERACTIVE) { - ssh2_pkt_init(SSH2_MSG_USERAUTH_INFO_RESPONSE); - ssh2_pkt_adduint32(num_prompts); - ssh2_pkt_addstring(password); - memset(password, 0, sizeof(password)); - ssh2_pkt_send(); + if (curr_prompt == 0) { + ssh2_pkt_init(SSH2_MSG_USERAUTH_INFO_RESPONSE); + ssh2_pkt_adduint32(num_prompts); + } + if (need_pw) { /* only add pw if we just got one! */ + ssh2_pkt_addstring(password); + memset(password, 0, sizeof(password)); + curr_prompt++; + } + if (curr_prompt >= num_prompts) { + ssh2_pkt_send(); + } else { + /* + * If there are prompts remaining, we set + * `gotit' so that we won't attempt to get + * another packet. Then we go back round the + * loop and will end up retrieving another + * prompt out of the existing packet. Funky or + * what? + */ + gotit = TRUE; + } type = AUTH_TYPE_KEYBOARD_INTERACTIVE; } else { c_write_str @@ -5357,7 +5408,6 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt) c->type = CHAN_SOCKDATA; c->v.v2.remwindow = ssh2_pkt_getuint32(); c->v.v2.remmaxpkt = ssh2_pkt_getuint32(); - bufchain_init(&c->v.v2.outbuffer); if (c->u.pfd.s) pfd_confirm(c->u.pfd.s); if (c->closes) { @@ -5759,6 +5809,7 @@ void *new_sock_channel(Socket s) c->closes = 0; c->type = CHAN_SOCKDATA_DORMANT;/* identify channel type */ c->u.pfd.s = s; + bufchain_init(&c->v.v2.outbuffer); add234(ssh_channels, c); } return c;