[tor-commits] [tor/master] Remove DynamicDHGroups as obsoleted by PluggableTransports or P256.
nickm at torproject.org
nickm at torproject.org
Wed Apr 1 17:47:05 UTC 2015
commit 511ca9b91cec03f4ef6f23adccd5cdd47a245e5f
Author: Nick Mathewson <nickm at torproject.org>
Date: Sat Mar 14 12:40:55 2015 -0400
Remove DynamicDHGroups as obsoleted by PluggableTransports or P256.
Closes ticket 13736.
---
changes/bug13736 | 5 +
src/common/crypto.c | 251 +--------------------------------------------
src/common/crypto.h | 4 +-
src/or/config.c | 25 +----
src/or/or.h | 2 -
src/test/testing_common.c | 2 +-
6 files changed, 14 insertions(+), 275 deletions(-)
diff --git a/changes/bug13736 b/changes/bug13736
new file mode 100644
index 0000000..686d2f1
--- /dev/null
+++ b/changes/bug13736
@@ -0,0 +1,5 @@
+ o Removed features:
+ - Remove the (seldom-used) DynamicDHGroups feature. For
+ anti-fingerprinting we now recommend pluggable transports; for
+ forward-secrecy in TLS, we now use the P-256 group.
+ Closes ticket 13736.
diff --git a/src/common/crypto.c b/src/common/crypto.c
index 218c7be..55f816a 100644
--- a/src/common/crypto.c
+++ b/src/common/crypto.c
@@ -1768,235 +1768,12 @@ static BIGNUM *dh_param_p_tls = NULL;
/** Shared G parameter for our DH key exchanges. */
static BIGNUM *dh_param_g = NULL;
-/** Generate and return a reasonable and safe DH parameter p. */
-static BIGNUM *
-crypto_generate_dynamic_dh_modulus(void)
-{
- BIGNUM *dynamic_dh_modulus;
- DH *dh_parameters;
- int r, dh_codes;
- char *s;
-
- dynamic_dh_modulus = BN_new();
- tor_assert(dynamic_dh_modulus);
-
- dh_parameters = DH_new();
- tor_assert(dh_parameters);
-
- r = DH_generate_parameters_ex(dh_parameters,
- DH_BYTES*8, DH_GENERATOR, NULL);
- tor_assert(r == 0);
-
- r = DH_check(dh_parameters, &dh_codes);
- tor_assert(r && !dh_codes);
-
- BN_copy(dynamic_dh_modulus, dh_parameters->p);
- tor_assert(dynamic_dh_modulus);
-
- DH_free(dh_parameters);
-
- { /* log the dynamic DH modulus: */
- s = BN_bn2hex(dynamic_dh_modulus);
- tor_assert(s);
- log_info(LD_OR, "Dynamic DH modulus generated: [%s]", s);
- OPENSSL_free(s);
- }
-
- return dynamic_dh_modulus;
-}
-
-/** Store our dynamic DH modulus (and its group parameters) to
- <b>fname</b> for future use. */
-static int
-crypto_store_dynamic_dh_modulus(const char *fname)
-{
- int len, new_len;
- DH *dh = NULL;
- unsigned char *dh_string_repr = NULL;
- char *base64_encoded_dh = NULL;
- char *file_string = NULL;
- int retval = -1;
- static const char file_header[] = "# This file contains stored Diffie-"
- "Hellman parameters for future use.\n# You *do not* need to edit this "
- "file.\n\n";
-
- tor_assert(fname);
-
- if (!dh_param_p_tls) {
- log_info(LD_CRYPTO, "Tried to store a DH modulus that does not exist.");
- goto done;
- }
-
- if (!(dh = DH_new()))
- goto done;
- if (!(dh->p = BN_dup(dh_param_p_tls)))
- goto done;
- if (!(dh->g = BN_new()))
- goto done;
- if (!BN_set_word(dh->g, DH_GENERATOR))
- goto done;
-
- len = i2d_DHparams(dh, &dh_string_repr);
- if ((len < 0) || (dh_string_repr == NULL)) {
- log_warn(LD_CRYPTO, "Error occured while DER encoding DH modulus (2).");
- goto done;
- }
-
- base64_encoded_dh = tor_calloc(len, 2); /* should be enough */
- new_len = base64_encode(base64_encoded_dh, len * 2,
- (char *)dh_string_repr, len);
- if (new_len < 0) {
- log_warn(LD_CRYPTO, "Error occured while base64-encoding DH modulus.");
- goto done;
- }
-
- /* concatenate file header and the dh parameters blob */
- new_len = tor_asprintf(&file_string, "%s%s", file_header, base64_encoded_dh);
-
- /* write to file */
- if (write_bytes_to_new_file(fname, file_string, new_len, 0) < 0) {
- log_info(LD_CRYPTO, "'%s' was already occupied.", fname);
- goto done;
- }
-
- retval = 0;
-
- done:
- if (dh)
- DH_free(dh);
- if (dh_string_repr)
- OPENSSL_free(dh_string_repr);
- tor_free(base64_encoded_dh);
- tor_free(file_string);
-
- return retval;
-}
-
-/** Return the dynamic DH modulus stored in <b>fname</b>. If there is no
- dynamic DH modulus stored in <b>fname</b>, return NULL. */
-static BIGNUM *
-crypto_get_stored_dynamic_dh_modulus(const char *fname)
-{
- int retval;
- char *contents = NULL;
- const char *contents_tmp = NULL;
- int dh_codes;
- DH *stored_dh = NULL;
- BIGNUM *dynamic_dh_modulus = NULL;
- int length = 0;
- unsigned char *base64_decoded_dh = NULL;
- const unsigned char *cp = NULL;
-
- tor_assert(fname);
-
- contents = read_file_to_str(fname, RFTS_IGNORE_MISSING, NULL);
- if (!contents) {
- log_info(LD_CRYPTO, "Could not open file '%s'", fname);
- goto done; /*usually means that ENOENT. don't try to move file to broken.*/
- }
-
- /* skip the file header */
- contents_tmp = eat_whitespace(contents);
- if (!*contents_tmp) {
- log_warn(LD_CRYPTO, "Stored dynamic DH modulus file "
- "seems corrupted (eat_whitespace).");
- goto err;
- }
-
- /* 'fname' contains the DH parameters stored in base64-ed DER
- * format. We are only interested in the DH modulus.
- * NOTE: We allocate more storage here than we need. Since we're already
- * doing that, we can also add 1 byte extra to appease Coverity's
- * scanner. */
-
- cp = base64_decoded_dh = tor_malloc_zero(strlen(contents_tmp) + 1);
- length = base64_decode((char *)base64_decoded_dh, strlen(contents_tmp),
- contents_tmp, strlen(contents_tmp));
- if (length < 0) {
- log_warn(LD_CRYPTO, "Stored dynamic DH modulus seems corrupted (base64).");
- goto err;
- }
-
- stored_dh = d2i_DHparams(NULL, &cp, length);
- if ((!stored_dh) || (cp - base64_decoded_dh != length)) {
- log_warn(LD_CRYPTO, "Stored dynamic DH modulus seems corrupted (d2i).");
- goto err;
- }
-
- { /* check the cryptographic qualities of the stored dynamic DH modulus: */
- retval = DH_check(stored_dh, &dh_codes);
- if (!retval || dh_codes) {
- log_warn(LD_CRYPTO, "Stored dynamic DH modulus is not a safe prime.");
- goto err;
- }
-
- retval = DH_size(stored_dh);
- if (retval < DH_BYTES) {
- log_warn(LD_CRYPTO, "Stored dynamic DH modulus is smaller "
- "than '%d' bits.", DH_BYTES*8);
- goto err;
- }
-
- if (!BN_is_word(stored_dh->g, 2)) {
- log_warn(LD_CRYPTO, "Stored dynamic DH parameters do not use '2' "
- "as the group generator.");
- goto err;
- }
- }
-
- { /* log the dynamic DH modulus: */
- char *s = BN_bn2hex(stored_dh->p);
- tor_assert(s);
- log_info(LD_OR, "Found stored dynamic DH modulus: [%s]", s);
- OPENSSL_free(s);
- }
-
- goto done;
-
- err:
-
- {
- /* move broken prime to $filename.broken */
- char *fname_new=NULL;
- tor_asprintf(&fname_new, "%s.broken", fname);
-
- log_warn(LD_CRYPTO, "Moving broken dynamic DH prime to '%s'.", fname_new);
-
- if (replace_file(fname, fname_new))
- log_notice(LD_CRYPTO, "Error while moving '%s' to '%s'.",
- fname, fname_new);
-
- tor_free(fname_new);
- }
-
- if (stored_dh) {
- DH_free(stored_dh);
- stored_dh = NULL;
- }
-
- done:
- tor_free(contents);
- tor_free(base64_decoded_dh);
-
- if (stored_dh) {
- dynamic_dh_modulus = BN_dup(stored_dh->p);
- DH_free(stored_dh);
- }
-
- return dynamic_dh_modulus;
-}
-
-/** Set the global TLS Diffie-Hellman modulus.
- * If <b>dynamic_dh_modulus_fname</b> is set, try to read a dynamic DH modulus
- * off it and use it as the DH modulus. If that's not possible,
- * generate a new dynamic DH modulus.
- * If <b>dynamic_dh_modulus_fname</b> is NULL, use the Apache mod_ssl DH
+/** Set the global TLS Diffie-Hellman modulus. Use the Apache mod_ssl DH
* modulus. */
void
-crypto_set_tls_dh_prime(const char *dynamic_dh_modulus_fname)
+crypto_set_tls_dh_prime(void)
{
BIGNUM *tls_prime = NULL;
- int store_dh_prime_afterwards = 0;
int r;
/* If the space is occupied, free the previous TLS DH prime */
@@ -2005,18 +1782,7 @@ crypto_set_tls_dh_prime(const char *dynamic_dh_modulus_fname)
dh_param_p_tls = NULL;
}
- if (dynamic_dh_modulus_fname) { /* use dynamic DH modulus: */
- log_info(LD_OR, "Using stored dynamic DH modulus.");
- tls_prime = crypto_get_stored_dynamic_dh_modulus(dynamic_dh_modulus_fname);
-
- if (!tls_prime) {
- log_notice(LD_OR, "Generating fresh dynamic DH modulus. "
- "This might take a while...");
- tls_prime = crypto_generate_dynamic_dh_modulus();
-
- store_dh_prime_afterwards++;
- }
- } else { /* use the static DH prime modulus used by Apache in mod_ssl: */
+ if (1) {
tls_prime = BN_new();
tor_assert(tls_prime);
@@ -2036,13 +1802,6 @@ crypto_set_tls_dh_prime(const char *dynamic_dh_modulus_fname)
tor_assert(tls_prime);
dh_param_p_tls = tls_prime;
-
- if (store_dh_prime_afterwards)
- /* save the new dynamic DH modulus to disk. */
- if (crypto_store_dynamic_dh_modulus(dynamic_dh_modulus_fname)) {
- log_notice(LD_CRYPTO, "Failed while storing dynamic DH modulus. "
- "Make sure your data directory is sane.");
- }
}
/** Initialize dh_param_p and dh_param_g if they are not already
@@ -2079,10 +1838,8 @@ init_dh_param(void)
dh_param_p = circuit_dh_prime;
dh_param_g = generator;
- /* Ensure that we have TLS DH parameters set up, too, even if we're
- going to change them soon. */
if (!dh_param_p_tls) {
- crypto_set_tls_dh_prime(NULL);
+ crypto_set_tls_dh_prime();
}
}
diff --git a/src/common/crypto.h b/src/common/crypto.h
index d305bc1..440ff23 100644
--- a/src/common/crypto.h
+++ b/src/common/crypto.h
@@ -122,8 +122,7 @@ int crypto_global_cleanup(void);
crypto_pk_t *crypto_pk_new(void);
void crypto_pk_free(crypto_pk_t *env);
-void crypto_set_tls_dh_prime(const char *dynamic_dh_modulus_fname);
-
+void crypto_set_tls_dh_prime(void);
crypto_cipher_t *crypto_cipher_new(const char *key);
crypto_cipher_t *crypto_cipher_new_with_iv(const char *key, const char *iv);
void crypto_cipher_free(crypto_cipher_t *env);
@@ -297,4 +296,3 @@ struct dh_st *crypto_dh_get_dh_(crypto_dh_t *dh);
void crypto_add_spaces_to_fp(char *out, size_t outlen, const char *in);
#endif
-
diff --git a/src/or/config.c b/src/or/config.c
index fca350c..a29cbce 100644
--- a/src/or/config.c
+++ b/src/or/config.c
@@ -225,7 +225,7 @@ static config_var_t option_vars_[] = {
V(DisableDebuggerAttachment, BOOL, "1"),
V(DisableIOCP, BOOL, "1"),
OBSOLETE("DisableV2DirectoryInfo_"),
- V(DynamicDHGroups, BOOL, "0"),
+ OBSOLETE("DynamicDHGroups"),
VPORT(DNSPort, LINELIST, NULL),
V(DNSListenAddress, LINELIST, NULL),
V(DownloadExtraInfo, BOOL, "0"),
@@ -1318,10 +1318,6 @@ options_transition_requires_fresh_tls_context(const or_options_t *old_options,
if (!old_options)
return 0;
- if ((old_options->DynamicDHGroups != new_options->DynamicDHGroups)) {
- return 1;
- }
-
if (!opt_streq(old_options->TLSECGroup, new_options->TLSECGroup))
return 1;
@@ -1503,23 +1499,8 @@ options_act(const or_options_t *old_options)
finish_daemon(options->DataDirectory);
}
- /* If needed, generate a new TLS DH prime according to the current torrc. */
- if (server_mode(options) && options->DynamicDHGroups) {
- char *keydir = get_datadir_fname("keys");
- if (check_private_dir(keydir, CPD_CREATE, options->User)) {
- tor_free(keydir);
- return -1;
- }
- tor_free(keydir);
-
- if (!old_options || !old_options->DynamicDHGroups) {
- char *fname = get_datadir_fname2("keys", "dynamic_dh_params");
- crypto_set_tls_dh_prime(fname);
- tor_free(fname);
- }
- } else { /* clients don't need a dynamic DH prime. */
- crypto_set_tls_dh_prime(NULL);
- }
+ /* Probably not needed any longer XXXX */
+ crypto_set_tls_dh_prime();
/* We want to reinit keys as needed before we do much of anything else:
keys are important, and other things can depend on them. */
diff --git a/src/or/or.h b/src/or/or.h
index 6723f93..612743e 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -3384,8 +3384,6 @@ typedef struct {
char *Address; /**< OR only: configured address for this onion router. */
char *PidFile; /**< Where to store PID of Tor process. */
- int DynamicDHGroups; /**< Dynamic generation of prime moduli for use in DH.*/
-
routerset_t *ExitNodes; /**< Structure containing nicknames, digests,
* country codes and IP address patterns of ORs to
* consider as exits. */
diff --git a/src/test/testing_common.c b/src/test/testing_common.c
index 403c83b..60be460 100644
--- a/src/test/testing_common.c
+++ b/src/test/testing_common.c
@@ -269,7 +269,7 @@ main(int c, const char **v)
printf("Can't initialize crypto subsystem; exiting.\n");
return 1;
}
- crypto_set_tls_dh_prime(NULL);
+ crypto_set_tls_dh_prime();
crypto_seed_rng(1);
rep_hist_init();
network_init();
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