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dirmngr: Support rsaPSS also in the general validate module.
* dirmngr/validate.c (hash_algo_from_buffer): New. (uint_from_buffer): New. (check_cert_sig): Support rsaPSS. * sm/certcheck.c (gpgsm_check_cert_sig): Fix small memory leak on error. -- Yes, I know that there is a lot of code duplication. In fact some of the code is ugly and it would be better if we enhance Libgcrypt to guarantee that returned memory buffers via gcry_sexp_extract_param are allways Nul terminated and we should also enhance that function to directly extract into an unsigned int or char *. GnuPG-bug-id: 4538 Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
Werner Koch
parent
b45ab0ca08
commit
ba34f14153
@ -888,6 +888,53 @@ pk_algo_from_sexp (gcry_sexp_t pkey)
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}
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/* Return the hash algorithm's algo id from its name given in the
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* non-null termnated string in (buffer,buflen). Returns 0 on failure
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* or if the algo is not known. */
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static int
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hash_algo_from_buffer (const void *buffer, size_t buflen)
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{
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char *string;
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int algo;
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string = xtrymalloc (buflen + 1);
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if (!string)
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{
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log_error (_("out of core\n"));
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return 0;
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}
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memcpy (string, buffer, buflen);
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string[buflen] = 0;
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algo = gcry_md_map_name (string);
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if (!algo)
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log_error ("unknown digest algorithm '%s' used in certificate\n", string);
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xfree (string);
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return algo;
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}
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/* Return an unsigned integer from the non-null termnated string
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* (buffer,buflen). Returns 0 on failure. */
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static unsigned int
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uint_from_buffer (const void *buffer, size_t buflen)
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{
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char *string;
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unsigned int val;
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string = xtrymalloc (buflen + 1);
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if (!string)
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{
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log_error (_("out of core\n"));
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return 0;
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}
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memcpy (string, buffer, buflen);
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string[buflen] = 0;
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val = strtoul (string, NULL, 10);
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xfree (string);
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return val;
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}
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/* Check the signature on CERT using the ISSUER_CERT. This function
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* does only test the cryptographic signature and nothing else. It is
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* assumed that the ISSUER_CERT is valid. */
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@ -897,32 +944,85 @@ check_cert_sig (ksba_cert_t issuer_cert, ksba_cert_t cert)
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gpg_error_t err;
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const char *algoid;
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gcry_md_hd_t md;
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int i, algo;
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int algo;
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ksba_sexp_t p;
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size_t n;
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gcry_sexp_t s_sig, s_hash, s_pkey;
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const char *s;
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char algo_name[16+1]; /* hash algorithm name converted to lower case. */
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const char *algo_name; /* hash algorithm name converted to lower case. */
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int digestlen;
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unsigned char *digest;
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int use_pss = 0;
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unsigned int saltlen;
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/* Hash the target certificate using the algorithm from that certificate. */
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algoid = ksba_cert_get_digest_algo (cert);
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algo = gcry_md_map_name (algoid);
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if (!algo)
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if (!algo && algoid && !strcmp (algoid, "1.2.840.113549.1.1.10"))
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use_pss = 1;
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else if (!algo)
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{
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log_error (_("unknown hash algorithm '%s'\n"), algoid? algoid:"?");
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return gpg_error (GPG_ERR_GENERAL);
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}
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s = gcry_md_algo_name (algo);
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for (i=0; *s && i < sizeof algo_name - 1; s++, i++)
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algo_name[i] = tolower (*s);
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algo_name[i] = 0;
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/* Get the signature value out of the target certificate. */
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p = ksba_cert_get_sig_val (cert);
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n = gcry_sexp_canon_len (p, 0, NULL, NULL);
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if (!n)
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{
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log_error ("libksba did not return a proper S-Exp\n");
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ksba_free (p);
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return gpg_error (GPG_ERR_BUG);
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}
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err = gcry_sexp_sscan ( &s_sig, NULL, p, n);
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ksba_free (p);
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if (err)
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{
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log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (err));
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return err;
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}
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if (DBG_CRYPTO)
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gcry_log_debugsxp ("sigval", s_sig);
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if (use_pss)
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{
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/* Extract the hash algorithm and the salt length from the sigval. */
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gcry_buffer_t ioarray[2] = { {0}, {0} };
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err = gcry_sexp_extract_param (s_sig, "sig-val",
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"&'hash-algo''salt-length'",
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ioarray+0, ioarray+1, NULL);
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if (err)
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{
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gcry_sexp_release (s_sig);
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log_error ("extracting params from PSS failed: %s\n",
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gpg_strerror (err));
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return err;
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}
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algo = hash_algo_from_buffer (ioarray[0].data, ioarray[0].len);
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saltlen = uint_from_buffer (ioarray[1].data, ioarray[1].len);
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xfree (ioarray[0].data);
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xfree (ioarray[1].data);
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if (saltlen < 20)
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{
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log_error ("length of PSS salt too short\n");
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gcry_sexp_release (s_sig);
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return gpg_error (GPG_ERR_DIGEST_ALGO);
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}
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if (!algo)
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{
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gcry_sexp_release (s_sig);
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return gpg_error (GPG_ERR_DIGEST_ALGO);
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}
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/* log_debug ("PSS hash=%d saltlen=%u\n", algo, saltlen); */
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}
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algo_name = hash_algo_to_string (algo);
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err = gcry_md_open (&md, algo, 0);
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if (err)
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{
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log_error ("md_open failed: %s\n", gpg_strerror (err));
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gcry_sexp_release (s_sig);
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return err;
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}
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if (DBG_HASHING)
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@ -933,38 +1033,11 @@ check_cert_sig (ksba_cert_t issuer_cert, ksba_cert_t cert)
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{
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log_error ("ksba_cert_hash failed: %s\n", gpg_strerror (err));
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gcry_md_close (md);
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gcry_sexp_release (s_sig);
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return err;
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}
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gcry_md_final (md);
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/* Get the signature value out of the target certificate. */
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p = ksba_cert_get_sig_val (cert);
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n = gcry_sexp_canon_len (p, 0, NULL, NULL);
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if (!n)
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{
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log_error ("libksba did not return a proper S-Exp\n");
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gcry_md_close (md);
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ksba_free (p);
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return gpg_error (GPG_ERR_BUG);
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}
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if (DBG_CRYPTO)
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{
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int j;
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log_debug ("signature value:");
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for (j=0; j < n; j++)
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log_printf (" %02X", p[j]);
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log_printf ("\n");
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}
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err = gcry_sexp_sscan ( &s_sig, NULL, p, n);
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ksba_free (p);
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if (err)
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{
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log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (err));
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gcry_md_close (md);
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return err;
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}
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/* Get the public key from the issuer certificate. */
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p = ksba_cert_get_public_key (issuer_cert);
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n = gcry_sexp_canon_len (p, 0, NULL, NULL);
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@ -994,10 +1067,22 @@ check_cert_sig (ksba_cert_t issuer_cert, ksba_cert_t cert)
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* S_SIG - Signature value as given in the certificate.
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* MD - Finalized hash context with hash of the certificate.
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* ALGO_NAME - Lowercase hash algorithm name
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* SALTLEN - Salt length for rsaPSS.
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*/
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digestlen = gcry_md_get_algo_dlen (algo);
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digest = gcry_md_read (md, algo);
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if (pk_algo_from_sexp (s_pkey) == GCRY_PK_DSA)
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if (use_pss)
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{
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err = gcry_sexp_build (&s_hash, NULL,
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"(data (flags pss)"
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"(hash %s %b)"
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"(salt-length %u))",
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algo_name,
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(int)digestlen,
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digest,
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saltlen);
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}
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else if (pk_algo_from_sexp (s_pkey) == GCRY_PK_DSA)
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{
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/* NB.: We support only SHA-1 here because we had problems back
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* then to get test data for DSA-2. Meanwhile DSA has been
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@ -1010,18 +1095,16 @@ check_cert_sig (ksba_cert_t issuer_cert, ksba_cert_t cert)
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gcry_sexp_release (s_pkey);
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return gpg_error (GPG_ERR_INTERNAL);
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}
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if ( gcry_sexp_build (&s_hash, NULL, "(data(flags raw)(value %b))",
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(int)digestlen, digest) )
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BUG ();
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err = gcry_sexp_build (&s_hash, NULL, "(data(flags raw)(value %b))",
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(int)digestlen, digest);
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}
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else /* Not DSA - we assume RSA */
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{
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if ( gcry_sexp_build (&s_hash, NULL, "(data(flags pkcs1)(hash %s %b))",
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algo_name, (int)digestlen, digest) )
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BUG ();
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err = gcry_sexp_build (&s_hash, NULL, "(data(flags pkcs1)(hash %s %b))",
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algo_name, (int)digestlen, digest);
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}
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if (!err)
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err = gcry_pk_verify (s_sig, s_hash, s_pkey);
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if (DBG_X509)
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log_debug ("gcry_pk_verify: %s\n", gpg_strerror (err));
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@ -340,10 +340,14 @@ gpgsm_check_cert_sig (ksba_cert_t issuer_cert, ksba_cert_t cert)
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if (saltlen < 20)
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{
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log_error ("length of PSS salt too short\n");
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gcry_sexp_release (s_sig);
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return gpg_error (GPG_ERR_DIGEST_ALGO);
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}
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if (!algo)
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{
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gcry_sexp_release (s_sig);
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return gpg_error (GPG_ERR_DIGEST_ALGO);
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}
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/* log_debug ("PSS hash=%d saltlen=%u\n", algo, saltlen); */
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}
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