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-rw-r--r--common/ssh-utils.c354
1 files changed, 354 insertions, 0 deletions
diff --git a/common/ssh-utils.c b/common/ssh-utils.c
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+++ b/common/ssh-utils.c
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+/* 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;
+}