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Diffstat (limited to 'common/ssh-utils.c')
| -rw-r--r-- | common/ssh-utils.c | 354 |
1 files changed, 354 insertions, 0 deletions
diff --git a/common/ssh-utils.c b/common/ssh-utils.c new file mode 100644 index 0000000..013b28e --- /dev/null +++ b/common/ssh-utils.c @@ -0,0 +1,354 @@ +/* ssh-utils.c - Secure Shell helper functions + * Copyright (C) 2011 Free Software Foundation, Inc. + * + * This file is part of GnuPG. + * + * This file is free software; you can redistribute it and/or modify + * it under the terms of either + * + * - the GNU Lesser General Public License as published by the Free + * Software Foundation; either version 3 of the License, or (at + * your option) any later version. + * + * or + * + * - 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. + * + * or both in parallel, as here. + * + * This file 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, see <https://www.gnu.org/licenses/>. + */ + +#include <config.h> +#include <stdlib.h> +#include <errno.h> +#include <ctype.h> +#include <assert.h> + +#include "util.h" +#include "ssh-utils.h" + + +/* Return true if KEYPARMS holds an EdDSA key. */ +static int +is_eddsa (gcry_sexp_t keyparms) +{ + int result = 0; + gcry_sexp_t list; + const char *s; + size_t n; + int i; + + list = gcry_sexp_find_token (keyparms, "flags", 0); + for (i = list ? gcry_sexp_length (list)-1 : 0; i > 0; i--) + { + s = gcry_sexp_nth_data (list, i, &n); + if (!s) + continue; /* Not a data element. */ + + if (n == 5 && !memcmp (s, "eddsa", 5)) + { + result = 1; + break; + } + } + gcry_sexp_release (list); + return result; +} + +/* Dummy functions for es_mopen. */ +static void *dummy_realloc (void *mem, size_t size) { (void) size; return mem; } +static void dummy_free (void *mem) { (void) mem; } + +/* Return the Secure Shell type fingerprint for KEY using digest ALGO. + The length of the fingerprint is returned at R_LEN and the + fingerprint itself at R_FPR. In case of a error code is returned + and NULL stored at R_FPR. */ +static gpg_error_t +get_fingerprint (gcry_sexp_t key, int algo, + void **r_fpr, size_t *r_len, int as_string) +{ + gpg_error_t err; + gcry_sexp_t list = NULL; + gcry_sexp_t l2 = NULL; + const char *s; + char *name = NULL; + int idx; + const char *elems; + gcry_md_hd_t md = NULL; + int blobmode = 0; + + *r_fpr = NULL; + *r_len = 0; + + /* Check that the first element is valid. */ + list = gcry_sexp_find_token (key, "public-key", 0); + if (!list) + list = gcry_sexp_find_token (key, "private-key", 0); + if (!list) + list = gcry_sexp_find_token (key, "protected-private-key", 0); + if (!list) + list = gcry_sexp_find_token (key, "shadowed-private-key", 0); + if (!list) + { + err = gpg_err_make (default_errsource, GPG_ERR_UNKNOWN_SEXP); + goto leave; + } + + l2 = gcry_sexp_cadr (list); + gcry_sexp_release (list); + list = l2; + l2 = NULL; + + name = gcry_sexp_nth_string (list, 0); + if (!name) + { + err = gpg_err_make (default_errsource, GPG_ERR_INV_SEXP); + goto leave; + } + + err = gcry_md_open (&md, algo, 0); + if (err) + goto leave; + + switch (gcry_pk_map_name (name)) + { + case GCRY_PK_RSA: + elems = "en"; + gcry_md_write (md, "\0\0\0\x07ssh-rsa", 11); + break; + + case GCRY_PK_DSA: + elems = "pqgy"; + gcry_md_write (md, "\0\0\0\x07ssh-dss", 11); + break; + + case GCRY_PK_ECC: + if (is_eddsa (list)) + { + elems = "q"; + blobmode = 1; + /* For now there is just one curve, thus no need to switch + on it. */ + gcry_md_write (md, "\0\0\0\x0b" "ssh-ed25519", 15); + } + else + { + /* We only support the 3 standard curves for now. It is + just a quick hack. */ + elems = "q"; + gcry_md_write (md, "\0\0\0\x13" "ecdsa-sha2-nistp", 20); + l2 = gcry_sexp_find_token (list, "curve", 0); + if (!l2) + elems = ""; + else + { + gcry_free (name); + name = gcry_sexp_nth_string (l2, 1); + gcry_sexp_release (l2); + l2 = NULL; + if (!name) + elems = ""; + else if (!strcmp (name, "NIST P-256")||!strcmp (name, "nistp256")) + gcry_md_write (md, "256\0\0\0\x08nistp256", 15); + else if (!strcmp (name, "NIST P-384")||!strcmp (name, "nistp384")) + gcry_md_write (md, "384\0\0\0\x08nistp384", 15); + else if (!strcmp (name, "NIST P-521")||!strcmp (name, "nistp521")) + gcry_md_write (md, "521\0\0\0\x08nistp521", 15); + else + elems = ""; + } + if (!*elems) + err = gpg_err_make (default_errsource, GPG_ERR_UNKNOWN_CURVE); + } + break; + + default: + elems = ""; + err = gpg_err_make (default_errsource, GPG_ERR_PUBKEY_ALGO); + break; + } + if (err) + goto leave; + + + for (idx = 0, s = elems; *s; s++, idx++) + { + l2 = gcry_sexp_find_token (list, s, 1); + if (!l2) + { + err = gpg_err_make (default_errsource, GPG_ERR_INV_SEXP); + goto leave; + } + if (blobmode) + { + const char *blob; + size_t bloblen; + unsigned char lenbuf[4]; + + blob = gcry_sexp_nth_data (l2, 1, &bloblen); + if (!blob) + { + err = gpg_err_make (default_errsource, GPG_ERR_INV_SEXP); + goto leave; + } + blob++; + bloblen--; + lenbuf[0] = bloblen >> 24; + lenbuf[1] = bloblen >> 16; + lenbuf[2] = bloblen >> 8; + lenbuf[3] = bloblen; + gcry_md_write (md, lenbuf, 4); + gcry_md_write (md, blob, bloblen); + } + else + { + gcry_mpi_t a; + unsigned char *buf; + size_t buflen; + + a = gcry_sexp_nth_mpi (l2, 1, GCRYMPI_FMT_USG); + gcry_sexp_release (l2); + l2 = NULL; + if (!a) + { + err = gpg_err_make (default_errsource, GPG_ERR_INV_SEXP); + goto leave; + } + + err = gcry_mpi_aprint (GCRYMPI_FMT_SSH, &buf, &buflen, a); + gcry_mpi_release (a); + if (err) + goto leave; + gcry_md_write (md, buf, buflen); + gcry_free (buf); + } + } + + if (as_string) + { + const char *algo_name; + char *fpr; + + /* Prefix string with the algorithm name and a colon. */ + algo_name = gcry_md_algo_name (algo); + *r_fpr = xtrymalloc (strlen (algo_name) + 1 + 3 * gcry_md_get_algo_dlen (algo) + 1); + if (*r_fpr == NULL) + { + err = gpg_err_make (default_errsource, gpg_err_code_from_syserror ()); + goto leave; + } + + memcpy (*r_fpr, algo_name, strlen (algo_name)); + fpr = (char *) *r_fpr + strlen (algo_name); + *fpr++ = ':'; + + if (algo == GCRY_MD_MD5) + { + bin2hexcolon (gcry_md_read (md, algo), gcry_md_get_algo_dlen (algo), fpr); + strlwr (fpr); + } + else + { + struct b64state b64s; + estream_t stream; + char *p; + long int len; + + /* Write the base64-encoded hash to fpr. */ + stream = es_mopen (fpr, 3 * gcry_md_get_algo_dlen (algo) + 1, 0, + 0, dummy_realloc, dummy_free, "w"); + if (stream == NULL) + { + err = gpg_err_make (default_errsource, gpg_err_code_from_syserror ()); + goto leave; + } + + err = b64enc_start_es (&b64s, stream, ""); + if (err) + { + es_fclose (stream); + goto leave; + } + + err = b64enc_write (&b64s, + gcry_md_read (md, algo), gcry_md_get_algo_dlen (algo)); + if (err) + { + es_fclose (stream); + goto leave; + } + + /* Finish, get the length, and close the stream. */ + err = b64enc_finish (&b64s); + len = es_ftell (stream); + es_fclose (stream); + if (err) + goto leave; + + /* Terminate. */ + fpr[len] = 0; + + /* Strip the trailing padding characters. */ + for (p = fpr + len - 1; p > fpr && *p == '='; p--) + *p = 0; + } + + *r_len = strlen (*r_fpr) + 1; + } + else + { + *r_len = gcry_md_get_algo_dlen (algo); + *r_fpr = xtrymalloc (*r_len); + if (!*r_fpr) + { + err = gpg_err_make (default_errsource, gpg_err_code_from_syserror ()); + goto leave; + } + memcpy (*r_fpr, gcry_md_read (md, algo), *r_len); + } + err = 0; + + leave: + gcry_free (name); + gcry_sexp_release (l2); + gcry_md_close (md); + gcry_sexp_release (list); + return err; +} + +/* Return the Secure Shell type fingerprint for KEY using digest ALGO. + The length of the fingerprint is returned at R_LEN and the + fingerprint itself at R_FPR. In case of an error an error code is + returned and NULL stored at R_FPR. */ +gpg_error_t +ssh_get_fingerprint (gcry_sexp_t key, int algo, + void **r_fpr, size_t *r_len) +{ + return get_fingerprint (key, algo, r_fpr, r_len, 0); +} + + +/* Return the Secure Shell type fingerprint for KEY using digest ALGO + as a string. The fingerprint is mallcoed and stored at R_FPRSTR. + In case of an error an error code is returned and NULL stored at + R_FPRSTR. */ +gpg_error_t +ssh_get_fingerprint_string (gcry_sexp_t key, int algo, char **r_fprstr) +{ + gpg_error_t err; + size_t dummy; + void *string; + + err = get_fingerprint (key, algo, &string, &dummy, 1); + *r_fprstr = string; + return err; +} |