diff options
Diffstat (limited to 'cli-agentfwd.c')
| -rw-r--r-- | cli-agentfwd.c | 245 |
1 files changed, 245 insertions, 0 deletions
diff --git a/cli-agentfwd.c b/cli-agentfwd.c new file mode 100644 index 0000000..f0fe385 --- /dev/null +++ b/cli-agentfwd.c @@ -0,0 +1,245 @@ +/* + * Dropbear - a SSH2 server + * + * Copyright (c) 2005 Matt Johnston + * All rights reserved. + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. */ + +/* The basic protocol use to communicate with the agent is defined in + * draft-ylonen-ssh-protocol-00.txt, with the ssh2 extensions defined through + * openssh's implementation. */ + +#include "includes.h" + +#ifdef ENABLE_CLI_AGENTFWD + +#include "agentfwd.h" +#include "session.h" +#include "ssh.h" +#include "dbutil.h" +#include "chansession.h" +#include "channel.h" +#include "packet.h" +#include "buffer.h" +#include "random.h" +#include "listener.h" +#include "runopts.h" +#include "atomicio.h" +#include "signkey.h" +#include "auth.h" + +static int new_agent_chan(struct Channel * channel); + +const struct ChanType chan_cli_agent = { + 0, /* sepfds */ + "auth-agent@openssh.com", + new_agent_chan, + NULL, + NULL, + NULL +}; + +static int connect_agent() { + + int fd = -1; + char* agent_sock = NULL; + + agent_sock = getenv("SSH_AUTH_SOCK"); + if (agent_sock == NULL) + return -1; + + fd = connect_unix(agent_sock); + + return fd; +} + +// handle a request for a connection to the locally running ssh-agent +// or forward. +static int new_agent_chan(struct Channel * channel) { + + int fd = -1; + + if (!cli_opts.agent_fwd) + return SSH_OPEN_ADMINISTRATIVELY_PROHIBITED; + + fd = connect_agent(); + + setnonblocking(fd); + + ses.maxfd = MAX(ses.maxfd, fd); + + channel->infd = fd; + channel->outfd = fd; + + // success + return 0; +} + +/* Sends a request to the agent, returning a newly allocated buffer + * with the response */ +/* Packet format (from draft-ylonen) + 4 bytes Length, msb first. Does not include length itself. + 1 byte Packet type. The value 255 is reserved for future extensions. + data Any data, depending on packet type. Encoding as in the ssh packet + protocol. + + In this case, data is always empty +*/ +static buffer * agent_request(int fd, unsigned char type) { + + buffer * payload = NULL; + buffer * inbuf = NULL; + size_t readlen = 0; + ssize_t ret; + + payload = buf_new(4 + 1); + + buf_putint(payload, 1); + buf_putbyte(payload, type); + + ret = atomicio(write, fd, buf_getptr(payload, payload->len), payload->len); + if ((size_t)ret != payload->len) { + TRACE(("write failed for agent_request")) + goto out; + } + + buf_free(payload); + payload = NULL; + + /* Now we read the response */ + inbuf = buf_new(4); + ret = atomicio(read, fd, buf_getwriteptr(inbuf, 4), 4); + if (ret != 4) { + TRACE(("read of length failed for agent_request")) + goto out; + } + + readlen = buf_getint(inbuf); + if (readlen > MAX_AGENT_REPLY) { + TRACE(("agent reply is too big")); + goto out; + } + + buf_resize(inbuf, readlen); + ret = atomicio(read, fd, buf_getwriteptr(inbuf, readlen), readlen); + if ((size_t)ret != readlen) { + TRACE(("read of data failed for agent_request")) + goto out; + } + +out: + if (payload) + buf_free(payload); + + return inbuf; +} + +static SignKeyList * agent_get_key_list(int fd) +{ + buffer * inbuf = NULL; + unsigned int num = 0; + unsigned char packet_type; + unsigned int i; + struct SignKeyList *retkey = NULL, *key = NULL; + int ret; + + inbuf = agent_request(fd, SSH2_AGENTC_REQUEST_IDENTITIES); + if (!inbuf) { + goto out; + } + + /* The reply has a format of: + * byte packet_type + * int num_keys + * + * string keyblob1 + * string comment1 + * ... + * string keyblob(n) + * string comment(n) + */ + packet_type = buf_getbyte(inbuf); + if (packet_type != SSH2_AGENT_IDENTITIES_ANSWER) { + goto out; + } + + num = buf_getint(inbuf); + for (i = 0; i < num; i++) { + sign_key * pubkey = NULL; + char key_type = DROPBEAR_SIGNKEY_ANY; + struct SignKeyList *nextkey = NULL; + + nextkey = (struct SignKeyList*)m_malloc(sizeof(struct SignKeyList)); + if (key) + key->next = nextkey; + else + retkey = nextkey; + key = nextkey; + + pubkey = new_sign_key(); + ret = buf_get_pub_key(inbuf, pubkey, &key_type); + if (ret != DROPBEAR_SUCCESS) { + /* This is slack, properly would cleanup vars etc */ + dropbear_exit("Bad pubkey received from agent"); + } + + key->key = pubkey; + key->next = NULL; + key->type = key_type; + key->source = SIGNKEY_SOURCE_AGENT; + + /* We'll ignore the comment */ + buf_eatstring(inbuf); + } + +out: + if (inbuf) { + buf_free(inbuf); + inbuf = NULL; + } + + return retkey; +} + +/* return DROPBEAR_SUCCESS or DROPBEAR_FAILURE */ +SignKeyList * load_agent_keys() +{ + + SignKeyList * ret_list; + int fd; + fd = connect_agent(); + if (fd < 0) { + dropbear_log(LOG_INFO, "Failed to connect to agent"); + return NULL; + } + + ret_list = agent_get_key_list(fd); + close(fd); +} + +// general procedure: +// - get the list of keys from the agent +// - foreach, send a dummy userauth_pubkey message to the server and see +// if it lets us in +// - if it does, sign and auth +// - if not, repeat. +// + +#endif |