diff options
Diffstat (limited to 'agent/findkey.c')
| -rw-r--r-- | agent/findkey.c | 359 |
1 files changed, 359 insertions, 0 deletions
diff --git a/agent/findkey.c b/agent/findkey.c new file mode 100644 index 000000000..db36cb1b9 --- /dev/null +++ b/agent/findkey.c @@ -0,0 +1,359 @@ +/* findkey.c - locate the secret key + * 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 + */ + +#include <config.h> +#include <errno.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <ctype.h> +#include <fcntl.h> +#include <assert.h> +#include <unistd.h> +#include <sys/stat.h> +#include <assert.h> + +#include "agent.h" + +/* Helper to pass data to the check callback of the unprotect function. */ +struct try_unprotect_arg_s { + const unsigned char *protected_key; + unsigned char *unprotected_key; +}; + + + +int +agent_write_private_key (const unsigned char *grip, + const void *buffer, size_t length, int force) +{ + int i; + char *fname; + FILE *fp; + char hexgrip[40+4+1]; + + for (i=0; i < 20; i++) + sprintf (hexgrip+2*i, "%02X", grip[i]); + strcpy (hexgrip+40, ".key"); + + fname = make_filename (opt.homedir, GNUPG_PRIVATE_KEYS_DIR, hexgrip, NULL); + if (force) + fp = fopen (fname, "wb"); + else + { + int fd; + + if (!access (fname, F_OK)) + { + log_error ("secret key file `%s' already exists\n", fname); + xfree (fname); + return gpg_error (GPG_ERR_GENERAL); + } + + /* We would like to create FNAME but only if it does not already + exist. We cannot make this guarantee just using POSIX (GNU + provides the "x" opentype for fopen, however, this is not + portable). Thus, we use the more flexible open function and + then use fdopen to obtain a stream. + + The mode parameter to open is what fopen uses. It will be + combined with the process' umask automatically. */ + fd = open (fname, O_CREAT | O_EXCL | O_RDWR, + S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH); + if (fd < 0) + fp = 0; + else + { + fp = fdopen (fd, "wb"); + if (!fp) + { + int save_e = errno; + close (fd); + errno = save_e; + } + } + } + + if (!fp) + { + gpg_error_t tmperr = gpg_error (gpg_err_code_from_errno (errno)); + log_error ("can't create `%s': %s\n", fname, strerror (errno)); + xfree (fname); + return tmperr; + } + + if (fwrite (buffer, length, 1, fp) != 1) + { + gpg_error_t tmperr = gpg_error (gpg_err_code_from_errno (errno)); + log_error ("error writing `%s': %s\n", fname, strerror (errno)); + fclose (fp); + remove (fname); + xfree (fname); + return tmperr; + } + if ( fclose (fp) ) + { + gpg_error_t tmperr = gpg_error (gpg_err_code_from_errno (errno)); + log_error ("error closing `%s': %s\n", fname, strerror (errno)); + remove (fname); + xfree (fname); + return tmperr; + } + + xfree (fname); + return 0; +} + + +/* Callback function to try the unprotection from the passpharse query + code. */ +static int +try_unprotect_cb (struct pin_entry_info_s *pi) +{ + struct try_unprotect_arg_s *arg = pi->check_cb_arg; + size_t dummy; + + assert (!arg->unprotected_key); + return agent_unprotect (arg->protected_key, pi->pin, + &arg->unprotected_key, &dummy); +} + + +/* Unprotect the canconical encoded S-expression key in KEYBUF. GRIP + should be the hex encoded keygrip of that key to be used with the + caching mechanism. */ +static int +unprotect (CTRL ctrl, + unsigned char **keybuf, const unsigned char *grip, int ignore_cache) +{ + struct pin_entry_info_s *pi; + struct try_unprotect_arg_s arg; + int rc, i; + unsigned char *result; + size_t resultlen; + char hexgrip[40+1]; + + for (i=0; i < 20; i++) + sprintf (hexgrip+2*i, "%02X", grip[i]); + hexgrip[40] = 0; + + /* first try to get it from the cache - if there is none or we can't + unprotect it, we fall back to ask the user */ + if (!ignore_cache) + { + void *cache_marker; + const char *pw = agent_get_cache (hexgrip, &cache_marker); + if (pw) + { + rc = agent_unprotect (*keybuf, pw, &result, &resultlen); + agent_unlock_cache_entry (&cache_marker); + if (!rc) + { + xfree (*keybuf); + *keybuf = result; + return 0; + } + rc = 0; + } + } + + pi = gcry_calloc_secure (1, sizeof (*pi) + 100); + pi->max_length = 100; + pi->min_digits = 0; /* we want a real passphrase */ + pi->max_digits = 8; + pi->max_tries = 3; + pi->check_cb = try_unprotect_cb; + arg.protected_key = *keybuf; + arg.unprotected_key = NULL; + pi->check_cb_arg = &arg; + + rc = agent_askpin (ctrl, NULL, pi); + if (!rc) + { + assert (arg.unprotected_key); + agent_put_cache (hexgrip, pi->pin, 0); + xfree (*keybuf); + *keybuf = arg.unprotected_key; + } + xfree (pi); + return rc; +} + + + +/* Return the secret key as an S-Exp after locating it using the grip. + Returns NULL if key is not available or the operation should be + diverted to a token. In the latter case shadow_info will point to + an allocated S-Expression with the shadow_info part from the file. + With IGNORE_CACHE passed as true the passphrase is not taken from + the cache.*/ +gcry_sexp_t +agent_key_from_file (CTRL ctrl, + const unsigned char *grip, unsigned char **shadow_info, + int ignore_cache) +{ + int i, rc; + char *fname; + FILE *fp; + struct stat st; + unsigned char *buf; + size_t len, buflen, erroff; + gcry_sexp_t s_skey; + char hexgrip[40+4+1]; + + if (shadow_info) + *shadow_info = NULL; + + for (i=0; i < 20; i++) + sprintf (hexgrip+2*i, "%02X", grip[i]); + strcpy (hexgrip+40, ".key"); + + fname = make_filename (opt.homedir, GNUPG_PRIVATE_KEYS_DIR, hexgrip, NULL); + fp = fopen (fname, "rb"); + if (!fp) + { + log_error ("can't open `%s': %s\n", fname, strerror (errno)); + xfree (fname); + return NULL; + } + + if (fstat (fileno(fp), &st)) + { + log_error ("can't stat `%s': %s\n", fname, strerror (errno)); + xfree (fname); + fclose (fp); + return NULL; + } + + buflen = st.st_size; + buf = xmalloc (buflen+1); + if (fread (buf, buflen, 1, fp) != 1) + { + log_error ("error reading `%s': %s\n", fname, strerror (errno)); + xfree (fname); + fclose (fp); + xfree (buf); + return NULL; + } + + rc = gcry_sexp_sscan (&s_skey, &erroff, buf, buflen); + xfree (fname); + fclose (fp); + xfree (buf); + if (rc) + { + log_error ("failed to build S-Exp (off=%u): %s\n", + (unsigned int)erroff, gpg_strerror (rc)); + return NULL; + } + len = gcry_sexp_sprint (s_skey, GCRYSEXP_FMT_CANON, NULL, 0); + assert (len); + buf = xtrymalloc (len); + if (!buf) + { + gcry_sexp_release (s_skey); + return NULL; + } + len = gcry_sexp_sprint (s_skey, GCRYSEXP_FMT_CANON, buf, len); + assert (len); + gcry_sexp_release (s_skey); + + switch (agent_private_key_type (buf)) + { + case PRIVATE_KEY_CLEAR: + break; /* no unprotection needed */ + case PRIVATE_KEY_PROTECTED: + rc = unprotect (ctrl, &buf, grip, ignore_cache); + if (rc) + log_error ("failed to unprotect the secret key: %s\n", + gpg_strerror (rc)); + break; + case PRIVATE_KEY_SHADOWED: + if (shadow_info) + { + const unsigned char *s; + size_t n; + + rc = agent_get_shadow_info (buf, &s); + if (!rc) + { + n = gcry_sexp_canon_len (s, 0, NULL,NULL); + assert (n); + *shadow_info = xtrymalloc (n); + if (!*shadow_info) + rc = out_of_core (); + else + { + memcpy (*shadow_info, s, n); + rc = 0; + } + } + if (rc) + log_error ("get_shadow_info failed: %s\n", gpg_strerror (rc)); + } + rc = -1; /* ugly interface: we return an error but keep a value + in shadow_info. */ + break; + default: + log_error ("invalid private key format\n"); + rc = gpg_error (GPG_ERR_BAD_SECKEY); + break; + } + if (rc) + { + xfree (buf); + return NULL; + } + + /* arggg FIXME: does scan support secure memory? */ + rc = gcry_sexp_sscan (&s_skey, &erroff, + buf, gcry_sexp_canon_len (buf, 0, NULL, NULL)); + xfree (buf); + if (rc) + { + log_error ("failed to build S-Exp (off=%u): %s\n", + (unsigned int)erroff, gpg_strerror (rc)); + return NULL; + } + + return s_skey; +} + +/* Return the secret key as an S-Exp after locating it using the grip. + Returns NULL if key is not available. 0 = key is available */ +int +agent_key_available (const unsigned char *grip) +{ + int i; + char *fname; + char hexgrip[40+4+1]; + + for (i=0; i < 20; i++) + sprintf (hexgrip+2*i, "%02X", grip[i]); + strcpy (hexgrip+40, ".key"); + + fname = make_filename (opt.homedir, GNUPG_PRIVATE_KEYS_DIR, hexgrip, NULL); + i = !access (fname, R_OK)? 0 : -1; + xfree (fname); + return i; +} + + + |