/* command.c - gpg-agent command handler * Copyright (C) 2001, 2002, 2003 Free Software Foundation, Inc. * * This file is part of GnuPG. * * GnuPG is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * GnuPG is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA */ /* FIXME: we should not use the default assuan buffering but setup some buffering in secure mempory to protect session keys etc. */ #include #include #include #include #include #include #include #include #include "agent.h" /* maximum allowed size of the inquired ciphertext */ #define MAXLEN_CIPHERTEXT 4096 /* maximum allowed size of the key parameters */ #define MAXLEN_KEYPARAM 1024 #define set_error(e,t) assuan_set_error (ctx, ASSUAN_ ## e, (t)) #if MAX_DIGEST_LEN < 20 #error MAX_DIGEST_LEN shorter than keygrip #endif /* Data used to associate an Assuan context with local server data */ struct server_local_s { ASSUAN_CONTEXT assuan_ctx; int message_fd; int use_cache_for_signing; }; static void reset_notify (ASSUAN_CONTEXT ctx) { CTRL ctrl = assuan_get_pointer (ctx); memset (ctrl->keygrip, 0, 20); ctrl->have_keygrip = 0; ctrl->digest.valuelen = 0; } /* Check whether the option NAME appears in LINE */ static int has_option (const char *line, const char *name) { const char *s; int n = strlen (name); s = strstr (line, name); return (s && (s == line || spacep (s-1)) && (!s[n] || spacep (s+n))); } /* Parse a hex string. Return an Assuan error code or 0 on success and the length of the parsed string in LEN. */ static int parse_hexstring (ASSUAN_CONTEXT ctx, const char *string, size_t *len) { const char *p; size_t n; /* parse the hash value */ for (p=string, n=0; hexdigitp (p); p++, n++) ; if (*p) return set_error (Parameter_Error, "invalid hexstring"); if ((n&1)) return set_error (Parameter_Error, "odd number of digits"); *len = n; return 0; } /* Parse the keygrip in STRING into the provided buffer BUF. BUF must provide space for 20 bytes. BUF is not changed if the fucntions returns an error. */ static int parse_keygrip (ASSUAN_CONTEXT ctx, const char *string, unsigned char *buf) { int rc; size_t n; const unsigned char *p; rc = parse_hexstring (ctx, string, &n); if (rc) return rc; n /= 2; if (n != 20) return set_error (Parameter_Error, "invalid length of keygrip"); for (p=string, n=0; n < 20; p += 2, n++) buf[n] = xtoi_2 (p); return 0; } /* ISTRUSTED Return OK when we have an entry with this fingerprint in our trustlist */ static int cmd_istrusted (ASSUAN_CONTEXT ctx, char *line) { int rc, n, i; char *p; char fpr[41]; /* parse the fingerprint value */ for (p=line,n=0; hexdigitp (p); p++, n++) ; if (*p || !(n == 40 || n == 32)) return set_error (Parameter_Error, "invalid fingerprint"); i = 0; if (n==32) { strcpy (fpr, "00000000"); i += 8; } for (p=line; i < 40; p++, i++) fpr[i] = *p >= 'a'? (*p & 0xdf): *p; fpr[i] = 0; rc = agent_istrusted (fpr); if (!rc) return 0; else if (rc == -1) return ASSUAN_Not_Trusted; else { log_error ("command is_trusted failed: %s\n", gpg_strerror (rc)); return map_to_assuan_status (rc); } } /* LISTTRUSTED List all entries from the trustlist */ static int cmd_listtrusted (ASSUAN_CONTEXT ctx, char *line) { int rc = agent_listtrusted (ctx); if (rc) log_error ("command listtrusted failed: %s\n", gpg_strerror (rc)); return map_to_assuan_status (rc); } /* MARKTRUSTED Store a new key in into the trustlist*/ static int cmd_marktrusted (ASSUAN_CONTEXT ctx, char *line) { CTRL ctrl = assuan_get_pointer (ctx); int rc, n, i; char *p; char fpr[41]; int flag; /* parse the fingerprint value */ for (p=line,n=0; hexdigitp (p); p++, n++) ; if (!spacep (p) || !(n == 40 || n == 32)) return set_error (Parameter_Error, "invalid fingerprint"); i = 0; if (n==32) { strcpy (fpr, "00000000"); i += 8; } for (p=line; i < 40; p++, i++) fpr[i] = *p >= 'a'? (*p & 0xdf): *p; fpr[i] = 0; while (spacep (p)) p++; flag = *p++; if ( (flag != 'S' && flag != 'P') || !spacep (p) ) return set_error (Parameter_Error, "invalid flag - must be P or S"); while (spacep (p)) p++; rc = agent_marktrusted (ctrl, p, fpr, flag); if (rc) log_error ("command marktrusted failed: %s\n", gpg_strerror (rc)); return map_to_assuan_status (rc); } /* HAVEKEY Return success when the secret key is available */ static int cmd_havekey (ASSUAN_CONTEXT ctx, char *line) { int rc; unsigned char buf[20]; rc = parse_keygrip (ctx, line, buf); if (rc) return rc; if (agent_key_available (buf)) return ASSUAN_No_Secret_Key; return 0; } /* SIGKEY SETKEY Set the key used for a sign or decrypt operation */ static int cmd_sigkey (ASSUAN_CONTEXT ctx, char *line) { int rc; CTRL ctrl = assuan_get_pointer (ctx); rc = parse_keygrip (ctx, line, ctrl->keygrip); if (rc) return rc; ctrl->have_keygrip = 1; return 0; } /* SETHASH The client can use this command to tell the server about the data (which usually is a hash) to be signed. */ static int cmd_sethash (ASSUAN_CONTEXT ctx, char *line) { int rc; size_t n; char *p; CTRL ctrl = assuan_get_pointer (ctx); unsigned char *buf; char *endp; int algo; /* parse the algo number and check it */ algo = (int)strtoul (line, &endp, 10); for (line = endp; *line == ' ' || *line == '\t'; line++) ; if (!algo || gcry_md_test_algo (algo)) return set_error (Unsupported_Algorithm, NULL); ctrl->digest.algo = algo; /* parse the hash value */ rc = parse_hexstring (ctx, line, &n); if (rc) return rc; n /= 2; if (n != 16 && n != 20 && n != 24 && n != 32) return set_error (Parameter_Error, "unsupported length of hash"); if (n > MAX_DIGEST_LEN) return set_error (Parameter_Error, "hash value to long"); buf = ctrl->digest.value; ctrl->digest.valuelen = n; for (p=line, n=0; n < ctrl->digest.valuelen; p += 2, n++) buf[n] = xtoi_2 (p); for (; n < ctrl->digest.valuelen; n++) buf[n] = 0; return 0; } /* PKSIGN Perform the actual sign operation. Neither input nor output are sensitive to eavesdropping */ static int cmd_pksign (ASSUAN_CONTEXT ctx, char *line) { int rc; int ignore_cache = 0; CTRL ctrl = assuan_get_pointer (ctx); if (opt.ignore_cache_for_signing) ignore_cache = 1; else if (!ctrl->server_local->use_cache_for_signing) ignore_cache = 1; rc = agent_pksign (ctrl, assuan_get_data_fp (ctx), ignore_cache); if (rc) log_error ("command pksign failed: %s\n", gpg_strerror (rc)); return map_to_assuan_status (rc); } /* PKDECRYPT Perform the actual decrypt operation. Input is not sensitive to eavesdropping */ static int cmd_pkdecrypt (ASSUAN_CONTEXT ctx, char *line) { int rc; CTRL ctrl = assuan_get_pointer (ctx); char *value; size_t valuelen; /* First inquire the data to decrypt */ rc = assuan_inquire (ctx, "CIPHERTEXT", &value, &valuelen, MAXLEN_CIPHERTEXT); if (rc) return rc; rc = agent_pkdecrypt (ctrl, value, valuelen, assuan_get_data_fp (ctx)); xfree (value); if (rc) log_error ("command pkdecrypt failed: %s\n", gpg_strerror (rc)); return map_to_assuan_status (rc); } /* GENKEY Generate a new key, store the secret part and return the public part. Here is an example transaction: C: GENKEY S: INQUIRE KEYPARM C: D (genkey (rsa (nbits 1024))) C: END S: D (public-key S: D (rsa (n 326487324683264) (e 10001))) S OK key created */ static int cmd_genkey (ASSUAN_CONTEXT ctx, char *line) { CTRL ctrl = assuan_get_pointer (ctx); int rc; char *value; size_t valuelen; /* First inquire the parameters */ rc = assuan_inquire (ctx, "KEYPARAM", &value, &valuelen, MAXLEN_KEYPARAM); if (rc) return rc; rc = agent_genkey (ctrl, value, valuelen, assuan_get_data_fp (ctx)); xfree (value); if (rc) log_error ("command genkey failed: %s\n", gpg_strerror (rc)); return map_to_assuan_status (rc); } static void plus_to_blank (char *s) { for (; *s; s++) { if (*s == '+') *s = ' '; } } /* GET_PASSPHRASE [ ] This function is usually used to ask for a passphrase to be used for conventional encryption, but may also be used by programs which need specal handling of passphrases. This command uses a syntax which helps clients to use the agent with minimum effort. The agent either returns with an error or with a OK followed by the hex encoded passphrase. Note that the length of the strings is implicitly limited by the maximum length of a command. */ static int cmd_get_passphrase (ASSUAN_CONTEXT ctx, char *line) { CTRL ctrl = assuan_get_pointer (ctx); int rc; const char *pw; char *response; char *cacheid = NULL, *desc = NULL, *prompt = NULL, *errtext = NULL; char *p; void *cache_marker; /* parse the stuff */ for (p=line; *p == ' '; p++) ; cacheid = p; p = strchr (cacheid, ' '); if (p) { *p++ = 0; while (*p == ' ') p++; errtext = p; p = strchr (errtext, ' '); if (p) { *p++ = 0; while (*p == ' ') p++; prompt = p; p = strchr (prompt, ' '); if (p) { *p++ = 0; while (*p == ' ') p++; desc = p; p = strchr (desc, ' '); if (p) *p = 0; /* ignore garbage */ } } } if (!cacheid || !*cacheid || strlen (cacheid) > 50) return set_error (Parameter_Error, "invalid length of cacheID"); if (!desc) return set_error (Parameter_Error, "no description given"); if (!strcmp (cacheid, "X")) cacheid = NULL; if (!strcmp (errtext, "X")) errtext = NULL; if (!strcmp (prompt, "X")) prompt = NULL; if (!strcmp (desc, "X")) desc = NULL; /* Note: we store the hexified versions in the cache. */ pw = cacheid ? agent_get_cache (cacheid, &cache_marker) : NULL; if (pw) { assuan_begin_confidential (ctx); rc = assuan_set_okay_line (ctx, pw); agent_unlock_cache_entry (&cache_marker); } else { /* Note, that we only need to replace the + characters and should leave the other escaping in place because the escaped string is send verbatim to the pinentry which does the unescaping (but not the + replacing) */ if (errtext) plus_to_blank (errtext); if (prompt) plus_to_blank (prompt); if (desc) plus_to_blank (desc); rc = agent_get_passphrase (ctrl, &response, desc, prompt, errtext); if (!rc) { if (cacheid) agent_put_cache (cacheid, response, 0); assuan_begin_confidential (ctx); rc = assuan_set_okay_line (ctx, response); xfree (response); } } if (rc) log_error ("command get_passphrase failed: %s\n", gpg_strerror (rc)); return map_to_assuan_status (rc); } /* CLEAR_PASSPHRASE may be used to invalidate the cache entry for a passphrase. The function returns with OK even when there is no cached passphrase. */ static int cmd_clear_passphrase (ASSUAN_CONTEXT ctx, char *line) { char *cacheid = NULL; char *p; /* parse the stuff */ for (p=line; *p == ' '; p++) ; cacheid = p; p = strchr (cacheid, ' '); if (p) *p = 0; /* ignore garbage */ if (!cacheid || !*cacheid || strlen (cacheid) > 50) return set_error (Parameter_Error, "invalid length of cacheID"); agent_put_cache (cacheid, NULL, 0); return 0; } /* LEARN [--send] Learn something about the currently inserted smartcard. With --send the new certificates are send back. */ static int cmd_learn (ASSUAN_CONTEXT ctx, char *line) { int rc; rc = agent_handle_learn (has_option (line, "--send")? ctx : NULL); if (rc) log_error ("command learn failed: %s\n", gpg_strerror (rc)); return map_to_assuan_status (rc); } /* PASSWD Change the passphrase/PID for the key identified by keygrip in LINE. */ static int cmd_passwd (ASSUAN_CONTEXT ctx, char *line) { CTRL ctrl = assuan_get_pointer (ctx); int rc; unsigned char grip[20]; GCRY_SEXP s_skey = NULL; unsigned char *shadow_info = NULL; rc = parse_keygrip (ctx, line, grip); if (rc) return rc; /* we can't jump to leave because this is already an Assuan error code. */ s_skey = agent_key_from_file (ctrl, grip, &shadow_info, 1); if (!s_skey && !shadow_info) rc = gpg_error (GPG_ERR_NO_SECKEY); else if (!s_skey) { log_error ("changing a smartcard PIN is not yet supported\n"); rc = gpg_error (GPG_ERR_NOT_IMPLEMENTED); } else rc = agent_protect_and_store (ctrl, s_skey); gcry_sexp_release (s_skey); xfree (shadow_info); if (rc) log_error ("command passwd failed: %s\n", gpg_strerror (rc)); return map_to_assuan_status (rc); } static int option_handler (ASSUAN_CONTEXT ctx, const char *key, const char *value) { CTRL ctrl = assuan_get_pointer (ctx); if (!strcmp (key, "display")) { if (ctrl->display) free (ctrl->display); ctrl->display = strdup (value); if (!ctrl->display) return ASSUAN_Out_Of_Core; } else if (!strcmp (key, "ttyname")) { if (!opt.keep_tty) { if (ctrl->ttyname) free (ctrl->ttyname); ctrl->ttyname = strdup (value); if (!ctrl->ttyname) return ASSUAN_Out_Of_Core; } } else if (!strcmp (key, "ttytype")) { if (!opt.keep_tty) { if (ctrl->ttytype) free (ctrl->ttytype); ctrl->ttytype = strdup (value); if (!ctrl->ttytype) return ASSUAN_Out_Of_Core; } } else if (!strcmp (key, "lc-ctype")) { if (ctrl->lc_ctype) free (ctrl->lc_ctype); ctrl->lc_ctype = strdup (value); if (!ctrl->lc_ctype) return ASSUAN_Out_Of_Core; } else if (!strcmp (key, "lc-messages")) { if (ctrl->lc_messages) free (ctrl->lc_messages); ctrl->lc_messages = strdup (value); if (!ctrl->lc_messages) return ASSUAN_Out_Of_Core; } else if (!strcmp (key, "use-cache-for-signing")) ctrl->server_local->use_cache_for_signing = *value? atoi (value) : 0; else return ASSUAN_Invalid_Option; return 0; } /* Tell the assuan library about our commands */ static int register_commands (ASSUAN_CONTEXT ctx) { static struct { const char *name; int (*handler)(ASSUAN_CONTEXT, char *line); } table[] = { { "ISTRUSTED", cmd_istrusted }, { "HAVEKEY", cmd_havekey }, { "SIGKEY", cmd_sigkey }, { "SETKEY", cmd_sigkey }, { "SETHASH", cmd_sethash }, { "PKSIGN", cmd_pksign }, { "PKDECRYPT", cmd_pkdecrypt }, { "GENKEY", cmd_genkey }, { "GET_PASSPHRASE", cmd_get_passphrase }, { "CLEAR_PASSPHRASE", cmd_clear_passphrase }, { "LISTTRUSTED", cmd_listtrusted }, { "MARKTRUSTED", cmd_marktrusted }, { "LEARN", cmd_learn }, { "PASSWD", cmd_passwd }, { "INPUT", NULL }, { "OUTPUT", NULL }, { NULL } }; int i, rc; for (i=0; table[i].name; i++) { rc = assuan_register_command (ctx, table[i].name, table[i].handler); if (rc) return rc; } assuan_register_reset_notify (ctx, reset_notify); assuan_register_option_handler (ctx, option_handler); return 0; } /* Startup the server. If LISTEN_FD and FD is given as -1, this is a simple piper server, otherwise it is a regular server */ void start_command_handler (int listen_fd, int fd) { int rc; ASSUAN_CONTEXT ctx; struct server_control_s ctrl; memset (&ctrl, 0, sizeof ctrl); agent_init_default_ctrl (&ctrl); if (listen_fd == -1 && fd == -1) { int filedes[2]; filedes[0] = 0; filedes[1] = 1; rc = assuan_init_pipe_server (&ctx, filedes); } else if (listen_fd != -1) { rc = assuan_init_socket_server (&ctx, listen_fd); } else { rc = assuan_init_connected_socket_server (&ctx, fd); } if (rc) { log_error ("failed to initialize the server: %s\n", assuan_strerror(rc)); agent_exit (2); } rc = register_commands (ctx); if (rc) { log_error ("failed to register commands with Assuan: %s\n", assuan_strerror(rc)); agent_exit (2); } assuan_set_pointer (ctx, &ctrl); ctrl.server_local = xcalloc (1, sizeof *ctrl.server_local); ctrl.server_local->assuan_ctx = ctx; ctrl.server_local->message_fd = -1; ctrl.server_local->use_cache_for_signing = 1; if (DBG_ASSUAN) assuan_set_log_stream (ctx, log_get_stream ()); for (;;) { rc = assuan_accept (ctx); if (rc == -1) { break; } else if (rc) { log_info ("Assuan accept problem: %s\n", assuan_strerror (rc)); break; } rc = assuan_process (ctx); if (rc) { log_info ("Assuan processing failed: %s\n", assuan_strerror (rc)); continue; } } assuan_deinit_server (ctx); if (ctrl.display) free (ctrl.display); if (ctrl.ttyname) free (ctrl.ttyname); if (ctrl.ttytype) free (ctrl.ttytype); if (ctrl.lc_ctype) free (ctrl.lc_ctype); if (ctrl.lc_messages) free (ctrl.lc_messages); }