From 999ae6be3243c7b4a815247199447b53c39a3d65 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Mon, 6 May 2024 03:26:58 +0200 Subject: Adding upstream version 1:7.9p1. Signed-off-by: Daniel Baumann --- authfd.c | 580 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 580 insertions(+) create mode 100644 authfd.c (limited to 'authfd.c') diff --git a/authfd.c b/authfd.c new file mode 100644 index 0000000..ecdd869 --- /dev/null +++ b/authfd.c @@ -0,0 +1,580 @@ +/* $OpenBSD: authfd.c,v 1.111 2018/07/09 21:59:10 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 "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); + POKE_U32(buf, len); + + /* Send the length and then the packet to the agent. */ + if (atomicio(vwrite, sock, buf, 4) != 4 || + atomicio(vwrite, sock, sshbuf_mutable_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 = PEEK_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; +} + + +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, struct ssh_identitylist **idlp) +{ + u_char type; + u_int32_t num, i; + struct sshbuf *msg; + struct ssh_identitylist *idl = NULL; + int r; + + /* + * 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, SSH2_AGENTC_REQUEST_IDENTITIES)) != 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 != SSH2_AGENT_IDENTITIES_ANSWER) { + 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;) { + 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; + } + 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. + */ + + +/* encode signature algorithm in flag bits, so we can keep the msg format */ +static u_int +agent_encode_alg(const 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, const 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 *sig = NULL, type = 0; + size_t 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 ((msg = sshbuf_new()) == NULL) + return SSH_ERR_ALLOC_FAIL; + flags |= agent_encode_alg(key, alg); + if ((r = sshbuf_put_u8(msg, SSH2_AGENTC_SIGN_REQUEST)) != 0 || + (r = sshkey_puts(key, msg)) != 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, &sig, &len)) != 0) + goto out; + /* Check what we actually got back from the agent. */ + if ((r = sshkey_check_sigtype(sig, len, alg)) != 0) + goto out; + /* success */ + *sigp = sig; + *lenp = len; + sig = NULL; + len = 0; + r = 0; + out: + freezero(sig, len); + sshbuf_free(msg); + return r; +} + +/* Encode key for a message to the agent. */ + + +static int +encode_constraints(struct sshbuf *m, u_int life, u_int confirm, u_int maxsign) +{ + 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; + } + if (maxsign != 0) { + if ((r = sshbuf_put_u8(m, SSH_AGENT_CONSTRAIN_MAXSIGN)) != 0 || + (r = sshbuf_put_u32(m, maxsign)) != 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, const struct sshkey *key, + const char *comment, u_int life, u_int confirm, u_int maxsign) +{ + struct sshbuf *msg; + int r, constrained = (life || confirm || maxsign); + u_char type; + + if ((msg = sshbuf_new()) == NULL) + return SSH_ERR_ALLOC_FAIL; + + switch (key->type) { +#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: + case KEY_XMSS: + case KEY_XMSS_CERT: + type = constrained ? + SSH2_AGENTC_ADD_ID_CONSTRAINED : + SSH2_AGENTC_ADD_IDENTITY; + if ((r = sshbuf_put_u8(msg, type)) != 0 || + (r = sshkey_private_serialize_maxsign(key, msg, maxsign, + NULL)) != 0 || + (r = sshbuf_put_cstring(msg, comment)) != 0) + goto out; + break; + default: + r = SSH_ERR_INVALID_ARGUMENT; + goto out; + } + if (constrained && + (r = encode_constraints(msg, life, confirm, maxsign)) != 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; + + 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)) != 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. + * + * This supports the SSH protocol 1 message to because, when clearing all + * keys from an agent, we generally want to clear both protocol v1 and v2 + * keys. + */ +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; +} -- cgit v1.2.3