X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/0b242b12f247fc000b6667df700d8a4523fc60fe..1e5e896ca0af10d05ff7b5248c07f03a026181dc:/auth-rsa.c diff --git a/auth-rsa.c b/auth-rsa.c index d7deabf2..f7ae03cf 100644 --- a/auth-rsa.c +++ b/auth-rsa.c @@ -1,48 +1,46 @@ /* - * - * auth-rsa.c - * * Author: Tatu Ylonen - * * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland * All rights reserved - * - * Created: Mon Mar 27 01:46:52 1995 ylo - * * RSA-based authentication. This code determines whether to admit a login * based on RSA authentication. This file also contains functions to check * validity of the host key. * + * As far as I am concerned, the code I have written for this software + * can be used freely for any purpose. Any derived versions of this + * software must be clearly marked as such, and if the derived work is + * incompatible with the protocol description in the RFC file, it must be + * called by a name other than "ssh" or "Secure Shell". */ #include "includes.h" -RCSID("$Id$"); +RCSID("$OpenBSD: auth-rsa.c,v 1.50 2001/12/28 14:50:54 markus Exp $"); + +#include +#include #include "rsa.h" #include "packet.h" #include "xmalloc.h" -#include "ssh.h" +#include "ssh1.h" #include "mpaux.h" #include "uidswap.h" #include "match.h" +#include "auth-options.h" +#include "pathnames.h" +#include "log.h" #include "servconf.h" +#include "auth.h" +#include "hostfile.h" -#include -#include - -/* Flags that may be set in authorized_keys options. */ -extern int no_port_forwarding_flag; -extern int no_agent_forwarding_flag; -extern int no_x11_forwarding_flag; -extern int no_pty_flag; -extern char *forced_command; -extern struct envstring *custom_environment; +/* import */ +extern ServerOptions options; /* * Session identifier that is used to bind key exchange and authentication * responses to a particular session. */ -extern unsigned char session_id[16]; +extern u_char session_id[16]; /* * The .ssh/authorized_keys file contains public keys, one per line, in the @@ -65,17 +63,20 @@ auth_rsa_challenge_dialog(RSA *pk) { BIGNUM *challenge, *encrypted_challenge; BN_CTX *ctx; - unsigned char buf[32], mdbuf[16], response[16]; + u_char buf[32], mdbuf[16], response[16]; MD5_CTX md; - unsigned int i; - int plen, len; + u_int i; + int len; - encrypted_challenge = BN_new(); - challenge = BN_new(); + if ((encrypted_challenge = BN_new()) == NULL) + fatal("auth_rsa_challenge_dialog: BN_new() failed"); + if ((challenge = BN_new()) == NULL) + fatal("auth_rsa_challenge_dialog: BN_new() failed"); /* Generate a random challenge. */ BN_rand(challenge, 256, 0, 0); - ctx = BN_CTX_new(); + if ((ctx = BN_CTX_new()) == NULL) + fatal("auth_rsa_challenge_dialog: BN_CTX_new() failed"); BN_mod(challenge, challenge, pk->n, ctx); BN_CTX_free(ctx); @@ -90,10 +91,10 @@ auth_rsa_challenge_dialog(RSA *pk) packet_write_wait(); /* Wait for a response. */ - packet_read_expect(&plen, SSH_CMSG_AUTH_RSA_RESPONSE); - packet_integrity_check(plen, 16, SSH_CMSG_AUTH_RSA_RESPONSE); + packet_read_expect(SSH_CMSG_AUTH_RSA_RESPONSE); for (i = 0; i < 16; i++) response[i] = packet_get_char(); + packet_check_eom(); /* The response is MD5 of decrypted challenge plus session id. */ len = BN_num_bytes(challenge); @@ -125,26 +126,31 @@ auth_rsa_challenge_dialog(RSA *pk) int auth_rsa(struct passwd *pw, BIGNUM *client_n) { - extern ServerOptions options; - char line[8192], file[1024]; + char line[8192], *file; int authenticated; - unsigned int bits; + u_int bits; FILE *f; - unsigned long linenum = 0; + u_long linenum = 0; struct stat st; - RSA *pk; + Key *key; + char *fp; + + /* no user given */ + if (pw == NULL) + return 0; /* Temporarily use the user's uid. */ - temporarily_use_uid(pw->pw_uid); + temporarily_use_uid(pw); /* The authorized keys. */ - snprintf(file, sizeof file, "%.500s/%.100s", pw->pw_dir, - SSH_USER_PERMITTED_KEYS); + file = authorized_keys_file(pw); + debug("trying public RSA key file %s", file); /* Fail quietly if file does not exist */ if (stat(file, &st) < 0) { /* Restore the privileged uid. */ restore_uid(); + xfree(file); return 0; } /* Open the file containing the authorized keys. */ @@ -154,50 +160,22 @@ auth_rsa(struct passwd *pw, BIGNUM *client_n) restore_uid(); packet_send_debug("Could not open %.900s for reading.", file); packet_send_debug("If your home is on an NFS volume, it may need to be world-readable."); + xfree(file); return 0; } - if (options.strict_modes) { - int fail = 0; - char buf[1024]; - /* Check open file in order to avoid open/stat races */ - if (fstat(fileno(f), &st) < 0 || - (st.st_uid != 0 && st.st_uid != pw->pw_uid) || - (st.st_mode & 022) != 0) { - snprintf(buf, sizeof buf, "RSA authentication refused for %.100s: " - "bad ownership or modes for '%s'.", pw->pw_name, file); - fail = 1; - } else { - /* Check path to SSH_USER_PERMITTED_KEYS */ - int i; - static const char *check[] = { - "", SSH_USER_DIR, NULL - }; - for (i = 0; check[i]; i++) { - snprintf(line, sizeof line, "%.500s/%.100s", pw->pw_dir, check[i]); - if (stat(line, &st) < 0 || - (st.st_uid != 0 && st.st_uid != pw->pw_uid) || - (st.st_mode & 022) != 0) { - snprintf(buf, sizeof buf, "RSA authentication refused for %.100s: " - "bad ownership or modes for '%s'.", pw->pw_name, line); - fail = 1; - break; - } - } - } - if (fail) { - fclose(f); - log(buf); - packet_send_debug(buf); - restore_uid(); - return 0; - } + if (options.strict_modes && + secure_filename(f, file, pw, line, sizeof(line)) != 0) { + xfree(file); + fclose(f); + log("Authentication refused: %s", line); + packet_send_debug("Authentication refused: %s", line); + restore_uid(); + return 0; } /* Flag indicating whether authentication has succeeded. */ authenticated = 0; - pk = RSA_new(); - pk->e = BN_new(); - pk->n = BN_new(); + key = key_new(KEY_RSA1); /* * Go though the accepted keys, looking for the current key. If @@ -235,235 +213,73 @@ auth_rsa(struct passwd *pw, BIGNUM *client_n) options = NULL; /* Parse the key from the line. */ - if (!auth_rsa_read_key(&cp, &bits, pk->e, pk->n)) { - debug("%.100s, line %lu: bad key syntax", - SSH_USER_PERMITTED_KEYS, linenum); - packet_send_debug("%.100s, line %lu: bad key syntax", - SSH_USER_PERMITTED_KEYS, linenum); + if (hostfile_read_key(&cp, &bits, key) == 0) { + debug("%.100s, line %lu: non ssh1 key syntax", + file, linenum); continue; } /* cp now points to the comment part. */ /* Check if the we have found the desired key (identified by its modulus). */ - if (BN_cmp(pk->n, client_n) != 0) + if (BN_cmp(key->rsa->n, client_n) != 0) continue; /* check the real bits */ - if (bits != BN_num_bits(pk->n)) - log("Warning: %s, line %ld: keysize mismatch: " + if (bits != BN_num_bits(key->rsa->n)) + log("Warning: %s, line %lu: keysize mismatch: " "actual %d vs. announced %d.", - file, linenum, BN_num_bits(pk->n), bits); + file, linenum, BN_num_bits(key->rsa->n), bits); /* We have found the desired key. */ + /* + * If our options do not allow this key to be used, + * do not send challenge. + */ + if (!auth_parse_options(pw, options, file, linenum)) + continue; /* Perform the challenge-response dialog for this key. */ - if (!auth_rsa_challenge_dialog(pk)) { + if (!auth_rsa_challenge_dialog(key->rsa)) { /* Wrong response. */ verbose("Wrong response to RSA authentication challenge."); packet_send_debug("Wrong response to RSA authentication challenge."); - continue; + /* + * Break out of the loop. Otherwise we might send + * another challenge and break the protocol. + */ + break; } /* * Correct response. The client has been successfully * authenticated. Note that we have not yet processed the * options; this will be reset if the options cause the * authentication to be rejected. - */ - authenticated = 1; - - /* RSA part of authentication was accepted. Now process the options. */ - if (options) { - while (*options && *options != ' ' && *options != '\t') { - cp = "no-port-forwarding"; - if (strncmp(options, cp, strlen(cp)) == 0) { - packet_send_debug("Port forwarding disabled."); - no_port_forwarding_flag = 1; - options += strlen(cp); - goto next_option; - } - cp = "no-agent-forwarding"; - if (strncmp(options, cp, strlen(cp)) == 0) { - packet_send_debug("Agent forwarding disabled."); - no_agent_forwarding_flag = 1; - options += strlen(cp); - goto next_option; - } - cp = "no-X11-forwarding"; - if (strncmp(options, cp, strlen(cp)) == 0) { - packet_send_debug("X11 forwarding disabled."); - no_x11_forwarding_flag = 1; - options += strlen(cp); - goto next_option; - } - cp = "no-pty"; - if (strncmp(options, cp, strlen(cp)) == 0) { - packet_send_debug("Pty allocation disabled."); - no_pty_flag = 1; - options += strlen(cp); - goto next_option; - } - cp = "command=\""; - if (strncmp(options, cp, strlen(cp)) == 0) { - int i; - options += strlen(cp); - forced_command = xmalloc(strlen(options) + 1); - i = 0; - while (*options) { - if (*options == '"') - break; - if (*options == '\\' && options[1] == '"') { - options += 2; - forced_command[i++] = '"'; - continue; - } - forced_command[i++] = *options++; - } - if (!*options) { - debug("%.100s, line %lu: missing end quote", - SSH_USER_PERMITTED_KEYS, linenum); - packet_send_debug("%.100s, line %lu: missing end quote", - SSH_USER_PERMITTED_KEYS, linenum); - continue; - } - forced_command[i] = 0; - packet_send_debug("Forced command: %.900s", forced_command); - options++; - goto next_option; - } - cp = "environment=\""; - if (strncmp(options, cp, strlen(cp)) == 0) { - int i; - char *s; - struct envstring *new_envstring; - options += strlen(cp); - s = xmalloc(strlen(options) + 1); - i = 0; - while (*options) { - if (*options == '"') - break; - if (*options == '\\' && options[1] == '"') { - options += 2; - s[i++] = '"'; - continue; - } - s[i++] = *options++; - } - if (!*options) { - debug("%.100s, line %lu: missing end quote", - SSH_USER_PERMITTED_KEYS, linenum); - packet_send_debug("%.100s, line %lu: missing end quote", - SSH_USER_PERMITTED_KEYS, linenum); - continue; - } - s[i] = 0; - packet_send_debug("Adding to environment: %.900s", s); - debug("Adding to environment: %.900s", s); - options++; - new_envstring = xmalloc(sizeof(struct envstring)); - new_envstring->s = s; - new_envstring->next = custom_environment; - custom_environment = new_envstring; - goto next_option; - } - cp = "from=\""; - if (strncmp(options, cp, strlen(cp)) == 0) { - char *patterns = xmalloc(strlen(options) + 1); - int i; - options += strlen(cp); - i = 0; - while (*options) { - if (*options == '"') - break; - if (*options == '\\' && options[1] == '"') { - options += 2; - patterns[i++] = '"'; - continue; - } - patterns[i++] = *options++; - } - if (!*options) { - debug("%.100s, line %lu: missing end quote", - SSH_USER_PERMITTED_KEYS, linenum); - packet_send_debug("%.100s, line %lu: missing end quote", - SSH_USER_PERMITTED_KEYS, linenum); - continue; - } - patterns[i] = 0; - options++; - if (!match_hostname(get_canonical_hostname(), patterns, - strlen(patterns)) && - !match_hostname(get_remote_ipaddr(), patterns, - strlen(patterns))) { - log("RSA authentication tried for %.100s with correct key but not from a permitted host (host=%.200s, ip=%.200s).", - pw->pw_name, get_canonical_hostname(), - get_remote_ipaddr()); - packet_send_debug("Your host '%.200s' is not permitted to use this key for login.", - get_canonical_hostname()); - xfree(patterns); - /* key invalid for this host, reset flags */ - authenticated = 0; - no_agent_forwarding_flag = 0; - no_port_forwarding_flag = 0; - no_pty_flag = 0; - no_x11_forwarding_flag = 0; - while (custom_environment) { - struct envstring *ce = custom_environment; - custom_environment = ce->next; - xfree(ce->s); - xfree(ce); - } - if (forced_command) { - xfree(forced_command); - forced_command = NULL; - } - break; - } - xfree(patterns); - /* Host name matches. */ - goto next_option; - } - bad_option: - log("Bad options in %.100s file, line %lu: %.50s", - SSH_USER_PERMITTED_KEYS, linenum, options); - packet_send_debug("Bad options in %.100s file, line %lu: %.50s", - SSH_USER_PERMITTED_KEYS, linenum, options); - authenticated = 0; - break; - - next_option: - /* - * Skip the comma, and move to the next option - * (or break out if there are no more). - */ - if (!*options) - fatal("Bugs in auth-rsa.c option processing."); - if (*options == ' ' || *options == '\t') - break; /* End of options. */ - if (*options != ',') - goto bad_option; - options++; - /* Process the next option. */ - continue; - } - } - /* * Break out of the loop if authentication was successful; * otherwise continue searching. */ - if (authenticated) - break; + authenticated = 1; + + fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); + verbose("Found matching %s key: %s", + key_type(key), fp); + xfree(fp); + + break; } /* Restore the privileged uid. */ restore_uid(); /* Close the file. */ + xfree(file); fclose(f); - RSA_free(pk); + key_free(key); if (authenticated) packet_send_debug("RSA authentication accepted."); + else + auth_clear_options(); /* Return authentication result. */ return authenticated;