/* $OpenBSD: authfd.c,v 1.100 2015/12/04 16:41:28 markus Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland * All rights reserved * Functions for connecting the local authentication agent. * * 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". * * SSH2 implementation, * Copyright (c) 2000 Markus Friedl. 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. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 #include #include #include #include #include #include #include #include #include #include "xmalloc.h" #include "ssh.h" #include "rsa.h" #include "sshbuf.h" #include "sshkey.h" #include "authfd.h" #include "cipher.h" #include "compat.h" #include "log.h" #include "atomicio.h" #include "misc.h" #include "ssherr.h" #define MAX_AGENT_IDENTITIES 2048 /* Max keys in agent reply */ #define MAX_AGENT_REPLY_LEN (256 * 1024) /* Max bytes in agent reply */ /* macro to check for "agent failure" message */ #define agent_failed(x) \ ((x == SSH_AGENT_FAILURE) || \ (x == SSH_COM_AGENT2_FAILURE) || \ (x == SSH2_AGENT_FAILURE)) /* Convert success/failure response from agent to a err.h status */ static int decode_reply(u_char type) { if (agent_failed(type)) return SSH_ERR_AGENT_FAILURE; else if (type == SSH_AGENT_SUCCESS) return 0; else return SSH_ERR_INVALID_FORMAT; } /* Returns the number of the authentication fd, or -1 if there is none. */ int ssh_get_authentication_socket(int *fdp) { const char *authsocket; int sock, oerrno; struct sockaddr_un sunaddr; if (fdp != NULL) *fdp = -1; authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME); if (!authsocket) return SSH_ERR_AGENT_NOT_PRESENT; memset(&sunaddr, 0, sizeof(sunaddr)); sunaddr.sun_family = AF_UNIX; strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path)); if ((sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) return SSH_ERR_SYSTEM_ERROR; /* close on exec */ if (fcntl(sock, F_SETFD, FD_CLOEXEC) == -1 || connect(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) { oerrno = errno; close(sock); errno = oerrno; return SSH_ERR_SYSTEM_ERROR; } if (fdp != NULL) *fdp = sock; else close(sock); return 0; } /* Communicate with agent: send request and read reply */ static int ssh_request_reply(int sock, struct sshbuf *request, struct sshbuf *reply) { int r; size_t l, len; char buf[1024]; /* Get the length of the message, and format it in the buffer. */ len = sshbuf_len(request); put_u32(buf, len); /* Send the length and then the packet to the agent. */ if (atomicio(vwrite, sock, buf, 4) != 4 || atomicio(vwrite, sock, (u_char *)sshbuf_ptr(request), sshbuf_len(request)) != sshbuf_len(request)) return SSH_ERR_AGENT_COMMUNICATION; /* * Wait for response from the agent. First read the length of the * response packet. */ if (atomicio(read, sock, buf, 4) != 4) return SSH_ERR_AGENT_COMMUNICATION; /* Extract the length, and check it for sanity. */ len = get_u32(buf); if (len > MAX_AGENT_REPLY_LEN) return SSH_ERR_INVALID_FORMAT; /* Read the rest of the response in to the buffer. */ sshbuf_reset(reply); while (len > 0) { l = len; if (l > sizeof(buf)) l = sizeof(buf); if (atomicio(read, sock, buf, l) != l) return SSH_ERR_AGENT_COMMUNICATION; if ((r = sshbuf_put(reply, buf, l)) != 0) return r; len -= l; } return 0; } /* * Closes the agent socket if it should be closed (depends on how it was * obtained). The argument must have been returned by * ssh_get_authentication_socket(). */ void ssh_close_authentication_socket(int sock) { if (getenv(SSH_AUTHSOCKET_ENV_NAME)) close(sock); } /* Lock/unlock agent */ int ssh_lock_agent(int sock, int lock, const char *password) { int r; u_char type = lock ? SSH_AGENTC_LOCK : SSH_AGENTC_UNLOCK; struct sshbuf *msg; if ((msg = sshbuf_new()) == NULL) return SSH_ERR_ALLOC_FAIL; if ((r = sshbuf_put_u8(msg, type)) != 0 || (r = sshbuf_put_cstring(msg, password)) != 0) goto out; if ((r = ssh_request_reply(sock, msg, msg)) != 0) goto out; if ((r = sshbuf_get_u8(msg, &type)) != 0) goto out; r = decode_reply(type); out: sshbuf_free(msg); return r; } #ifdef WITH_SSH1 static int deserialise_identity1(struct sshbuf *ids, struct sshkey **keyp, char **commentp) { struct sshkey *key; int r, keybits; u_int32_t bits; char *comment = NULL; if ((key = sshkey_new(KEY_RSA1)) == NULL) return SSH_ERR_ALLOC_FAIL; if ((r = sshbuf_get_u32(ids, &bits)) != 0 || (r = sshbuf_get_bignum1(ids, key->rsa->e)) != 0 || (r = sshbuf_get_bignum1(ids, key->rsa->n)) != 0 || (r = sshbuf_get_cstring(ids, &comment, NULL)) != 0) goto out; keybits = BN_num_bits(key->rsa->n); /* XXX previously we just warned here. I think we should be strict */ if (keybits < 0 || bits != (u_int)keybits) { r = SSH_ERR_KEY_BITS_MISMATCH; goto out; } if (keyp != NULL) { *keyp = key; key = NULL; } if (commentp != NULL) { *commentp = comment; comment = NULL; } r = 0; out: sshkey_free(key); free(comment); return r; } #endif static int deserialise_identity2(struct sshbuf *ids, struct sshkey **keyp, char **commentp) { int r; char *comment = NULL; const u_char *blob; size_t blen; if ((r = sshbuf_get_string_direct(ids, &blob, &blen)) != 0 || (r = sshbuf_get_cstring(ids, &comment, NULL)) != 0) goto out; if ((r = sshkey_from_blob(blob, blen, keyp)) != 0) goto out; if (commentp != NULL) { *commentp = comment; comment = NULL; } r = 0; out: free(comment); return r; } /* * Fetch list of identities held by the agent. */ int ssh_fetch_identitylist(int sock, int version, struct ssh_identitylist **idlp) { u_char type, code1 = 0, code2 = 0; u_int32_t num, i; struct sshbuf *msg; struct ssh_identitylist *idl = NULL; int r; /* Determine request and expected response types */ switch (version) { case 1: code1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES; code2 = SSH_AGENT_RSA_IDENTITIES_ANSWER; break; case 2: code1 = SSH2_AGENTC_REQUEST_IDENTITIES; code2 = SSH2_AGENT_IDENTITIES_ANSWER; break; default: return SSH_ERR_INVALID_ARGUMENT; } /* * Send a message to the agent requesting for a list of the * identities it can represent. */ if ((msg = sshbuf_new()) == NULL) return SSH_ERR_ALLOC_FAIL; if ((r = sshbuf_put_u8(msg, code1)) != 0) goto out; if ((r = ssh_request_reply(sock, msg, msg)) != 0) goto out; /* Get message type, and verify that we got a proper answer. */ if ((r = sshbuf_get_u8(msg, &type)) != 0) goto out; if (agent_failed(type)) { r = SSH_ERR_AGENT_FAILURE; goto out; } else if (type != code2) { r = SSH_ERR_INVALID_FORMAT; goto out; } /* Get the number of entries in the response and check it for sanity. */ if ((r = sshbuf_get_u32(msg, &num)) != 0) goto out; if (num > MAX_AGENT_IDENTITIES) { r = SSH_ERR_INVALID_FORMAT; goto out; } if (num == 0) { r = SSH_ERR_AGENT_NO_IDENTITIES; goto out; } /* Deserialise the response into a list of keys/comments */ if ((idl = calloc(1, sizeof(*idl))) == NULL || (idl->keys = calloc(num, sizeof(*idl->keys))) == NULL || (idl->comments = calloc(num, sizeof(*idl->comments))) == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } for (i = 0; i < num;) { switch (version) { case 1: #ifdef WITH_SSH1 if ((r = deserialise_identity1(msg, &(idl->keys[i]), &(idl->comments[i]))) != 0) goto out; #endif break; case 2: if ((r = deserialise_identity2(msg, &(idl->keys[i]), &(idl->comments[i]))) != 0) { if (r == SSH_ERR_KEY_TYPE_UNKNOWN) { /* Gracefully skip unknown key types */ num--; continue; } else goto out; } break; } i++; } idl->nkeys = num; *idlp = idl; idl = NULL; r = 0; out: sshbuf_free(msg); if (idl != NULL) ssh_free_identitylist(idl); return r; } void ssh_free_identitylist(struct ssh_identitylist *idl) { size_t i; if (idl == NULL) return; for (i = 0; i < idl->nkeys; i++) { if (idl->keys != NULL) sshkey_free(idl->keys[i]); if (idl->comments != NULL) free(idl->comments[i]); } free(idl); } /* * Sends a challenge (typically from a server via ssh(1)) to the agent, * and waits for a response from the agent. * Returns true (non-zero) if the agent gave the correct answer, zero * otherwise. */ #ifdef WITH_SSH1 int ssh_decrypt_challenge(int sock, struct sshkey* key, BIGNUM *challenge, u_char session_id[16], u_char response[16]) { struct sshbuf *msg; int r; u_char type; if (key->type != KEY_RSA1) return SSH_ERR_INVALID_ARGUMENT; if ((msg = sshbuf_new()) == NULL) return SSH_ERR_ALLOC_FAIL; if ((r = sshbuf_put_u8(msg, SSH_AGENTC_RSA_CHALLENGE)) != 0 || (r = sshbuf_put_u32(msg, BN_num_bits(key->rsa->n))) != 0 || (r = sshbuf_put_bignum1(msg, key->rsa->e)) != 0 || (r = sshbuf_put_bignum1(msg, key->rsa->n)) != 0 || (r = sshbuf_put_bignum1(msg, challenge)) != 0 || (r = sshbuf_put(msg, session_id, 16)) != 0 || (r = sshbuf_put_u32(msg, 1)) != 0) /* Response type for proto 1.1 */ goto out; if ((r = ssh_request_reply(sock, msg, msg)) != 0) goto out; if ((r = sshbuf_get_u8(msg, &type)) != 0) goto out; if (agent_failed(type)) { r = SSH_ERR_AGENT_FAILURE; goto out; } else if (type != SSH_AGENT_RSA_RESPONSE) { r = SSH_ERR_INVALID_FORMAT; goto out; } if ((r = sshbuf_get(msg, response, 16)) != 0) goto out; r = 0; out: sshbuf_free(msg); return r; } #endif /* encode signature algoritm in flag bits, so we can keep the msg format */ static u_int agent_encode_alg(struct sshkey *key, const char *alg) { if (alg != NULL && key->type == KEY_RSA) { if (strcmp(alg, "rsa-sha2-256") == 0) return SSH_AGENT_RSA_SHA2_256; else if (strcmp(alg, "rsa-sha2-512") == 0) return SSH_AGENT_RSA_SHA2_512; } return 0; } /* ask agent to sign data, returns err.h code on error, 0 on success */ int ssh_agent_sign(int sock, struct sshkey *key, u_char **sigp, size_t *lenp, const u_char *data, size_t datalen, const char *alg, u_int compat) { struct sshbuf *msg; u_char *blob = NULL, type; size_t blen = 0, len = 0; u_int flags = 0; int r = SSH_ERR_INTERNAL_ERROR; *sigp = NULL; *lenp = 0; if (datalen > SSH_KEY_MAX_SIGN_DATA_SIZE) return SSH_ERR_INVALID_ARGUMENT; if (compat & SSH_BUG_SIGBLOB) flags |= SSH_AGENT_OLD_SIGNATURE; if ((msg = sshbuf_new()) == NULL) return SSH_ERR_ALLOC_FAIL; if ((r = sshkey_to_blob(key, &blob, &blen)) != 0) goto out; flags |= agent_encode_alg(key, alg); if ((r = sshbuf_put_u8(msg, SSH2_AGENTC_SIGN_REQUEST)) != 0 || (r = sshbuf_put_string(msg, blob, blen)) != 0 || (r = sshbuf_put_string(msg, data, datalen)) != 0 || (r = sshbuf_put_u32(msg, flags)) != 0) goto out; if ((r = ssh_request_reply(sock, msg, msg)) != 0) goto out; if ((r = sshbuf_get_u8(msg, &type)) != 0) goto out; if (agent_failed(type)) { r = SSH_ERR_AGENT_FAILURE; goto out; } else if (type != SSH2_AGENT_SIGN_RESPONSE) { r = SSH_ERR_INVALID_FORMAT; goto out; } if ((r = sshbuf_get_string(msg, sigp, &len)) != 0) goto out; *lenp = len; r = 0; out: if (blob != NULL) { explicit_bzero(blob, blen); free(blob); } sshbuf_free(msg); return r; } /* Encode key for a message to the agent. */ #ifdef WITH_SSH1 static int ssh_encode_identity_rsa1(struct sshbuf *b, RSA *key, const char *comment) { int r; /* To keep within the protocol: p < q for ssh. in SSL p > q */ if ((r = sshbuf_put_u32(b, BN_num_bits(key->n))) != 0 || (r = sshbuf_put_bignum1(b, key->n)) != 0 || (r = sshbuf_put_bignum1(b, key->e)) != 0 || (r = sshbuf_put_bignum1(b, key->d)) != 0 || (r = sshbuf_put_bignum1(b, key->iqmp)) != 0 || (r = sshbuf_put_bignum1(b, key->q)) != 0 || (r = sshbuf_put_bignum1(b, key->p)) != 0 || (r = sshbuf_put_cstring(b, comment)) != 0) return r; return 0; } #endif static int ssh_encode_identity_ssh2(struct sshbuf *b, struct sshkey *key, const char *comment) { int r; if ((r = sshkey_private_serialize(key, b)) != 0 || (r = sshbuf_put_cstring(b, comment)) != 0) return r; return 0; } static int encode_constraints(struct sshbuf *m, u_int life, u_int confirm) { int r; if (life != 0) { if ((r = sshbuf_put_u8(m, SSH_AGENT_CONSTRAIN_LIFETIME)) != 0 || (r = sshbuf_put_u32(m, life)) != 0) goto out; } if (confirm != 0) { if ((r = sshbuf_put_u8(m, SSH_AGENT_CONSTRAIN_CONFIRM)) != 0) goto out; } r = 0; out: return r; } /* * Adds an identity to the authentication server. * This call is intended only for use by ssh-add(1) and like applications. */ int ssh_add_identity_constrained(int sock, struct sshkey *key, const char *comment, u_int life, u_int confirm) { struct sshbuf *msg; int r, constrained = (life || confirm); u_char type; if ((msg = sshbuf_new()) == NULL) return SSH_ERR_ALLOC_FAIL; switch (key->type) { #ifdef WITH_SSH1 case KEY_RSA1: type = constrained ? SSH_AGENTC_ADD_RSA_ID_CONSTRAINED : SSH_AGENTC_ADD_RSA_IDENTITY; if ((r = sshbuf_put_u8(msg, type)) != 0 || (r = ssh_encode_identity_rsa1(msg, key->rsa, comment)) != 0) goto out; break; #endif #ifdef WITH_OPENSSL case KEY_RSA: case KEY_RSA_CERT: case KEY_DSA: case KEY_DSA_CERT: case KEY_ECDSA: case KEY_ECDSA_CERT: #endif case KEY_ED25519: case KEY_ED25519_CERT: type = constrained ? SSH2_AGENTC_ADD_ID_CONSTRAINED : SSH2_AGENTC_ADD_IDENTITY; if ((r = sshbuf_put_u8(msg, type)) != 0 || (r = ssh_encode_identity_ssh2(msg, key, comment)) != 0) goto out; break; default: r = SSH_ERR_INVALID_ARGUMENT; goto out; } if (constrained && (r = encode_constraints(msg, life, confirm)) != 0) goto out; if ((r = ssh_request_reply(sock, msg, msg)) != 0) goto out; if ((r = sshbuf_get_u8(msg, &type)) != 0) goto out; r = decode_reply(type); out: sshbuf_free(msg); return r; } /* * Removes an identity from the authentication server. * This call is intended only for use by ssh-add(1) and like applications. */ int ssh_remove_identity(int sock, struct sshkey *key) { struct sshbuf *msg; int r; u_char type, *blob = NULL; size_t blen; if ((msg = sshbuf_new()) == NULL) return SSH_ERR_ALLOC_FAIL; #ifdef WITH_SSH1 if (key->type == KEY_RSA1) { if ((r = sshbuf_put_u8(msg, SSH_AGENTC_REMOVE_RSA_IDENTITY)) != 0 || (r = sshbuf_put_u32(msg, BN_num_bits(key->rsa->n))) != 0 || (r = sshbuf_put_bignum1(msg, key->rsa->e)) != 0 || (r = sshbuf_put_bignum1(msg, key->rsa->n)) != 0) goto out; } else #endif if (key->type != KEY_UNSPEC) { if ((r = sshkey_to_blob(key, &blob, &blen)) != 0) goto out; if ((r = sshbuf_put_u8(msg, SSH2_AGENTC_REMOVE_IDENTITY)) != 0 || (r = sshbuf_put_string(msg, blob, blen)) != 0) goto out; } else { r = SSH_ERR_INVALID_ARGUMENT; goto out; } if ((r = ssh_request_reply(sock, msg, msg)) != 0) goto out; if ((r = sshbuf_get_u8(msg, &type)) != 0) goto out; r = decode_reply(type); out: if (blob != NULL) { explicit_bzero(blob, blen); free(blob); } sshbuf_free(msg); return r; } /* * Add/remove an token-based identity from the authentication server. * This call is intended only for use by ssh-add(1) and like applications. */ int ssh_update_card(int sock, int add, const char *reader_id, const char *pin, u_int life, u_int confirm) { struct sshbuf *msg; int r, constrained = (life || confirm); u_char type; if (add) { type = constrained ? SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED : SSH_AGENTC_ADD_SMARTCARD_KEY; } else type = SSH_AGENTC_REMOVE_SMARTCARD_KEY; if ((msg = sshbuf_new()) == NULL) return SSH_ERR_ALLOC_FAIL; if ((r = sshbuf_put_u8(msg, type)) != 0 || (r = sshbuf_put_cstring(msg, reader_id)) != 0 || (r = sshbuf_put_cstring(msg, pin)) != 0) goto out; if (constrained && (r = encode_constraints(msg, life, confirm)) != 0) goto out; if ((r = ssh_request_reply(sock, msg, msg)) != 0) goto out; if ((r = sshbuf_get_u8(msg, &type)) != 0) goto out; r = decode_reply(type); out: sshbuf_free(msg); return r; } /* * Removes all identities from the agent. * This call is intended only for use by ssh-add(1) and like applications. */ int ssh_remove_all_identities(int sock, int version) { struct sshbuf *msg; u_char type = (version == 1) ? SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES : SSH2_AGENTC_REMOVE_ALL_IDENTITIES; int r; if ((msg = sshbuf_new()) == NULL) return SSH_ERR_ALLOC_FAIL; if ((r = sshbuf_put_u8(msg, type)) != 0) goto out; if ((r = ssh_request_reply(sock, msg, msg)) != 0) goto out; if ((r = sshbuf_get_u8(msg, &type)) != 0) goto out; r = decode_reply(type); out: sshbuf_free(msg); return r; }