Refactor crypto.[ch] into smaller xof+digest module.

Add two new files (crypto_digest.c, crypto_digest.h) as new module of
crypto.[ch].  This new module includes all functions and dependencies related
to digest and xof operations. Those have been removed from crypto.[ch].

Follows #24658.

Signed-off-by: Fernando Fernandez Mancera <ffmancera@riseup.net>

1 files changed, 610 insertions, 0 deletions

diff --git a/src/common/crypto_digest.c b/src/common/crypto_digest.c
new file mode 100644
index 0000000000..d316300e8c
--- /dev/null
+++ b/src/common/crypto_digest.c
@@ -0,0 +1,610 @@
+/* Copyright (c) 2001, Matej Pfajfar.
+ * Copyright (c) 2001-2004, Roger Dingledine.
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2017, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file crypto_digest.c
+ * \brief Block of functions related with digest and xof utilities and
+ * operations.
+ **/
+
+#include "crypto_digest.h"
+
+#include "crypto.h" /* common functions */
+#include "crypto_rsa.h"
+
+DISABLE_GCC_WARNING(redundant-decls)
+
+#include <openssl/hmac.h>
+
+ENABLE_GCC_WARNING(redundant-decls)
+
+#include "container.h"
+
+/* public key crypto digest functions */
+
+/** Check a siglen-byte long signature at <b>sig</b> against
+ * <b>datalen</b> bytes of data at <b>data</b>, using the public key
+ * in <b>env</b>. Return 0 if <b>sig</b> is a correct signature for
+ * SHA1(data).  Else return -1.
+ */
+MOCK_IMPL(int,
+crypto_pk_public_checksig_digest,(crypto_pk_t *env, const char *data,
+                                  size_t datalen, const char *sig,
+                                  size_t siglen))
+{
+  char digest[DIGEST_LEN];
+  char *buf;
+  size_t buflen;
+  int r;
+
+  tor_assert(env);
+  tor_assert(data);
+  tor_assert(sig);
+  tor_assert(datalen < SIZE_T_CEILING);
+  tor_assert(siglen < SIZE_T_CEILING);
+
+  if (crypto_digest(digest,data,datalen)<0) {
+    log_warn(LD_BUG, "couldn't compute digest");
+    return -1;
+  }
+  buflen = crypto_pk_keysize(env);
+  buf = tor_malloc(buflen);
+  r = crypto_pk_public_checksig(env,buf,buflen,sig,siglen);
+  if (r != DIGEST_LEN) {
+    log_warn(LD_CRYPTO, "Invalid signature");
+    tor_free(buf);
+    return -1;
+  }
+  if (tor_memneq(buf, digest, DIGEST_LEN)) {
+    log_warn(LD_CRYPTO, "Signature mismatched with digest.");
+    tor_free(buf);
+    return -1;
+  }
+  tor_free(buf);
+
+  return 0;
+}
+
+/** Compute a SHA1 digest of <b>fromlen</b> bytes of data stored at
+ * <b>from</b>; sign the data with the private key in <b>env</b>, and
+ * store it in <b>to</b>.  Return the number of bytes written on
+ * success, and -1 on failure.
+ *
+ * <b>tolen</b> is the number of writable bytes in <b>to</b>, and must be
+ * at least the length of the modulus of <b>env</b>.
+ */
+int
+crypto_pk_private_sign_digest(crypto_pk_t *env, char *to, size_t tolen,
+                              const char *from, size_t fromlen)
+{
+  int r;
+  char digest[DIGEST_LEN];
+  if (crypto_digest(digest,from,fromlen)<0)
+    return -1;
+  r = crypto_pk_private_sign(env,to,tolen,digest,DIGEST_LEN);
+  memwipe(digest, 0, sizeof(digest));
+  return r;
+}
+
+/** Given a private or public key <b>pk</b>, put a SHA1 hash of the
+ * public key into <b>digest_out</b> (must have DIGEST_LEN bytes of space).
+ * Return 0 on success, -1 on failure.
+ */
+int
+crypto_pk_get_digest(const crypto_pk_t *pk, char *digest_out)
+{
+  char *buf;
+  size_t buflen;
+  int len;
+  int rv = -1;
+
+  buflen = crypto_pk_keysize(pk)*2;
+  buf = tor_malloc(buflen);
+  len = crypto_pk_asn1_encode(pk, buf, buflen);
+  if (len < 0)
+    goto done;
+
+  if (crypto_digest(digest_out, buf, len) < 0)
+    goto done;
+
+  rv = 0;
+  done:
+  tor_free(buf);
+  return rv;
+}
+
+/** Compute all digests of the DER encoding of <b>pk</b>, and store them
+ * in <b>digests_out</b>.  Return 0 on success, -1 on failure. */
+int
+crypto_pk_get_common_digests(crypto_pk_t *pk, common_digests_t *digests_out)
+{
+  char *buf;
+  size_t buflen;
+  int len;
+  int rv = -1;
+
+  buflen = crypto_pk_keysize(pk)*2;
+  buf = tor_malloc(buflen);
+  len = crypto_pk_asn1_encode(pk, buf, buflen);
+  if (len < 0)
+    goto done;
+
+  if (crypto_common_digests(digests_out, (char*)buf, len) < 0)
+    goto done;
+
+  rv = 0;
+ done:
+  tor_free(buf);
+  return rv;
+}
+
+/* Crypto digest functions */
+
+/** Compute the SHA1 digest of the <b>len</b> bytes on data stored in
+ * <b>m</b>.  Write the DIGEST_LEN byte result into <b>digest</b>.
+ * Return 0 on success, -1 on failure.
+ */
+int
+crypto_digest(char *digest, const char *m, size_t len)
+{
+  tor_assert(m);
+  tor_assert(digest);
+  if (SHA1((const unsigned char*)m,len,(unsigned char*)digest) == NULL)
+    return -1;
+  return 0;
+}
+
+/** Compute a 256-bit digest of <b>len</b> bytes in data stored in <b>m</b>,
+ * using the algorithm <b>algorithm</b>.  Write the DIGEST_LEN256-byte result
+ * into <b>digest</b>.  Return 0 on success, -1 on failure. */
+int
+crypto_digest256(char *digest, const char *m, size_t len,
+                 digest_algorithm_t algorithm)
+{
+  tor_assert(m);
+  tor_assert(digest);
+  tor_assert(algorithm == DIGEST_SHA256 || algorithm == DIGEST_SHA3_256);
+
+  int ret = 0;
+  if (algorithm == DIGEST_SHA256)
+    ret = (SHA256((const uint8_t*)m,len,(uint8_t*)digest) != NULL);
+  else
+    ret = (sha3_256((uint8_t *)digest, DIGEST256_LEN,(const uint8_t *)m, len)
+           > -1);
+
+  if (!ret)
+    return -1;
+  return 0;
+}
+
+/** Compute a 512-bit digest of <b>len</b> bytes in data stored in <b>m</b>,
+ * using the algorithm <b>algorithm</b>.  Write the DIGEST_LEN512-byte result
+ * into <b>digest</b>.  Return 0 on success, -1 on failure. */
+int
+crypto_digest512(char *digest, const char *m, size_t len,
+                 digest_algorithm_t algorithm)
+{
+  tor_assert(m);
+  tor_assert(digest);
+  tor_assert(algorithm == DIGEST_SHA512 || algorithm == DIGEST_SHA3_512);
+
+  int ret = 0;
+  if (algorithm == DIGEST_SHA512)
+    ret = (SHA512((const unsigned char*)m,len,(unsigned char*)digest)
+           != NULL);
+  else
+    ret = (sha3_512((uint8_t*)digest, DIGEST512_LEN, (const uint8_t*)m, len)
+           > -1);
+
+  if (!ret)
+    return -1;
+  return 0;
+}
+
+/** Set the common_digests_t in <b>ds_out</b> to contain every digest on the
+ * <b>len</b> bytes in <b>m</b> that we know how to compute.  Return 0 on
+ * success, -1 on failure. */
+int
+crypto_common_digests(common_digests_t *ds_out, const char *m, size_t len)
+{
+  tor_assert(ds_out);
+  memset(ds_out, 0, sizeof(*ds_out));
+  if (crypto_digest(ds_out->d[DIGEST_SHA1], m, len) < 0)
+    return -1;
+  if (crypto_digest256(ds_out->d[DIGEST_SHA256], m, len, DIGEST_SHA256) < 0)
+    return -1;
+
+  return 0;
+}
+
+/** Return the name of an algorithm, as used in directory documents. */
+const char *
+crypto_digest_algorithm_get_name(digest_algorithm_t alg)
+{
+  switch (alg) {
+    case DIGEST_SHA1:
+      return "sha1";
+    case DIGEST_SHA256:
+      return "sha256";
+    case DIGEST_SHA512:
+      return "sha512";
+    case DIGEST_SHA3_256:
+      return "sha3-256";
+    case DIGEST_SHA3_512:
+      return "sha3-512";
+      // LCOV_EXCL_START
+    default:
+      tor_fragile_assert();
+      return "??unknown_digest??";
+      // LCOV_EXCL_STOP
+  }
+}
+
+/** Given the name of a digest algorithm, return its integer value, or -1 if
+ * the name is not recognized. */
+int
+crypto_digest_algorithm_parse_name(const char *name)
+{
+  if (!strcmp(name, "sha1"))
+    return DIGEST_SHA1;
+  else if (!strcmp(name, "sha256"))
+    return DIGEST_SHA256;
+  else if (!strcmp(name, "sha512"))
+    return DIGEST_SHA512;
+  else if (!strcmp(name, "sha3-256"))
+    return DIGEST_SHA3_256;
+  else if (!strcmp(name, "sha3-512"))
+    return DIGEST_SHA3_512;
+  else
+    return -1;
+}
+
+/** Given an algorithm, return the digest length in bytes. */
+size_t
+crypto_digest_algorithm_get_length(digest_algorithm_t alg)
+{
+  switch (alg) {
+    case DIGEST_SHA1:
+      return DIGEST_LEN;
+    case DIGEST_SHA256:
+      return DIGEST256_LEN;
+    case DIGEST_SHA512:
+      return DIGEST512_LEN;
+    case DIGEST_SHA3_256:
+      return DIGEST256_LEN;
+    case DIGEST_SHA3_512:
+      return DIGEST512_LEN;
+    default:
+      tor_assert(0);              // LCOV_EXCL_LINE
+      return 0; /* Unreachable */ // LCOV_EXCL_LINE
+  }
+}
+
+/** Intermediate information about the digest of a stream of data. */
+struct crypto_digest_t {
+  digest_algorithm_t algorithm; /**< Which algorithm is in use? */
+   /** State for the digest we're using.  Only one member of the
+    * union is usable, depending on the value of <b>algorithm</b>. Note also
+    * that space for other members might not even be allocated!
+    */
+  union {
+    SHA_CTX sha1; /**< state for SHA1 */
+    SHA256_CTX sha2; /**< state for SHA256 */
+    SHA512_CTX sha512; /**< state for SHA512 */
+    keccak_state sha3; /**< state for SHA3-[256,512] */
+  } d;
+};
+
+#ifdef TOR_UNIT_TESTS
+
+digest_algorithm_t
+crypto_digest_get_algorithm(crypto_digest_t *digest)
+{
+  tor_assert(digest);
+
+  return digest->algorithm;
+}
+
+#endif /* defined(TOR_UNIT_TESTS) */
+
+/**
+ * Return the number of bytes we need to malloc in order to get a
+ * crypto_digest_t for <b>alg</b>, or the number of bytes we need to wipe
+ * when we free one.
+ */
+static size_t
+crypto_digest_alloc_bytes(digest_algorithm_t alg)
+{
+  /* Helper: returns the number of bytes in the 'f' field of 'st' */
+#define STRUCT_FIELD_SIZE(st, f) (sizeof( ((st*)0)->f ))
+  /* Gives the length of crypto_digest_t through the end of the field 'd' */
+#define END_OF_FIELD(f) (offsetof(crypto_digest_t, f) + \
+                         STRUCT_FIELD_SIZE(crypto_digest_t, f))
+  switch (alg) {
+    case DIGEST_SHA1:
+      return END_OF_FIELD(d.sha1);
+    case DIGEST_SHA256:
+      return END_OF_FIELD(d.sha2);
+    case DIGEST_SHA512:
+      return END_OF_FIELD(d.sha512);
+    case DIGEST_SHA3_256:
+    case DIGEST_SHA3_512:
+      return END_OF_FIELD(d.sha3);
+    default:
+      tor_assert(0); // LCOV_EXCL_LINE
+      return 0;      // LCOV_EXCL_LINE
+  }
+#undef END_OF_FIELD
+#undef STRUCT_FIELD_SIZE
+}
+
+/**
+ * Internal function: create and return a new digest object for 'algorithm'.
+ * Does not typecheck the algorithm.
+ */
+static crypto_digest_t *
+crypto_digest_new_internal(digest_algorithm_t algorithm)
+{
+  crypto_digest_t *r = tor_malloc(crypto_digest_alloc_bytes(algorithm));
+  r->algorithm = algorithm;
+
+  switch (algorithm)
+    {
+    case DIGEST_SHA1:
+      SHA1_Init(&r->d.sha1);
+      break;
+    case DIGEST_SHA256:
+      SHA256_Init(&r->d.sha2);
+      break;
+    case DIGEST_SHA512:
+      SHA512_Init(&r->d.sha512);
+      break;
+    case DIGEST_SHA3_256:
+      keccak_digest_init(&r->d.sha3, 256);
+      break;
+    case DIGEST_SHA3_512:
+      keccak_digest_init(&r->d.sha3, 512);
+      break;
+    default:
+      tor_assert_unreached();
+    }
+
+  return r;
+}
+
+/** Allocate and return a new digest object to compute SHA1 digests.
+ */
+crypto_digest_t *
+crypto_digest_new(void)
+{
+  return crypto_digest_new_internal(DIGEST_SHA1);
+}
+
+/** Allocate and return a new digest object to compute 256-bit digests
+ * using <b>algorithm</b>. */
+crypto_digest_t *
+crypto_digest256_new(digest_algorithm_t algorithm)
+{
+  tor_assert(algorithm == DIGEST_SHA256 || algorithm == DIGEST_SHA3_256);
+  return crypto_digest_new_internal(algorithm);
+}
+
+/** Allocate and return a new digest object to compute 512-bit digests
+ * using <b>algorithm</b>. */
+crypto_digest_t *
+crypto_digest512_new(digest_algorithm_t algorithm)
+{
+  tor_assert(algorithm == DIGEST_SHA512 || algorithm == DIGEST_SHA3_512);
+  return crypto_digest_new_internal(algorithm);
+}
+
+/** Deallocate a digest object.
+ */
+void
+crypto_digest_free_(crypto_digest_t *digest)
+{
+  if (!digest)
+    return;
+  size_t bytes = crypto_digest_alloc_bytes(digest->algorithm);
+  memwipe(digest, 0, bytes);
+  tor_free(digest);
+}
+
+/** Add <b>len</b> bytes from <b>data</b> to the digest object.
+ */
+void
+crypto_digest_add_bytes(crypto_digest_t *digest, const char *data,
+                        size_t len)
+{
+  tor_assert(digest);
+  tor_assert(data);
+  /* Using the SHA*_*() calls directly means we don't support doing
+   * SHA in hardware. But so far the delay of getting the question
+   * to the hardware, and hearing the answer, is likely higher than
+   * just doing it ourselves. Hashes are fast.
+   */
+  switch (digest->algorithm) {
+    case DIGEST_SHA1:
+      SHA1_Update(&digest->d.sha1, (void*)data, len);
+      break;
+    case DIGEST_SHA256:
+      SHA256_Update(&digest->d.sha2, (void*)data, len);
+      break;
+    case DIGEST_SHA512:
+      SHA512_Update(&digest->d.sha512, (void*)data, len);
+      break;
+    case DIGEST_SHA3_256: /* FALLSTHROUGH */
+    case DIGEST_SHA3_512:
+      keccak_digest_update(&digest->d.sha3, (const uint8_t *)data, len);
+      break;
+    default:
+      /* LCOV_EXCL_START */
+      tor_fragile_assert();
+      break;
+      /* LCOV_EXCL_STOP */
+  }
+}
+
+/** Compute the hash of the data that has been passed to the digest
+ * object; write the first out_len bytes of the result to <b>out</b>.
+ * <b>out_len</b> must be \<= DIGEST512_LEN.
+ */
+void
+crypto_digest_get_digest(crypto_digest_t *digest,
+                         char *out, size_t out_len)
+{
+  unsigned char r[DIGEST512_LEN];
+  crypto_digest_t tmpenv;
+  tor_assert(digest);
+  tor_assert(out);
+  tor_assert(out_len <= crypto_digest_algorithm_get_length(digest->algorithm));
+
+  /* The SHA-3 code handles copying into a temporary ctx, and also can handle
+   * short output buffers by truncating appropriately. */
+  if (digest->algorithm == DIGEST_SHA3_256 ||
+      digest->algorithm == DIGEST_SHA3_512) {
+    keccak_digest_sum(&digest->d.sha3, (uint8_t *)out, out_len);
+    return;
+  }
+
+  const size_t alloc_bytes = crypto_digest_alloc_bytes(digest->algorithm);
+  /* memcpy into a temporary ctx, since SHA*_Final clears the context */
+  memcpy(&tmpenv, digest, alloc_bytes);
+  switch (digest->algorithm) {
+    case DIGEST_SHA1:
+      SHA1_Final(r, &tmpenv.d.sha1);
+      break;
+    case DIGEST_SHA256:
+      SHA256_Final(r, &tmpenv.d.sha2);
+      break;
+    case DIGEST_SHA512:
+      SHA512_Final(r, &tmpenv.d.sha512);
+      break;
+//LCOV_EXCL_START
+    case DIGEST_SHA3_256: /* FALLSTHROUGH */
+    case DIGEST_SHA3_512:
+    default:
+      log_warn(LD_BUG, "Handling unexpected algorithm %d", digest->algorithm);
+      /* This is fatal, because it should never happen. */
+      tor_assert_unreached();
+      break;
+//LCOV_EXCL_STOP
+  }
+  memcpy(out, r, out_len);
+  memwipe(r, 0, sizeof(r));
+}
+
+/** Allocate and return a new digest object with the same state as
+ * <b>digest</b>
+ */
+crypto_digest_t *
+crypto_digest_dup(const crypto_digest_t *digest)
+{
+  tor_assert(digest);
+  const size_t alloc_bytes = crypto_digest_alloc_bytes(digest->algorithm);
+  return tor_memdup(digest, alloc_bytes);
+}
+
+/** Replace the state of the digest object <b>into</b> with the state
+ * of the digest object <b>from</b>.  Requires that 'into' and 'from'
+ * have the same digest type.
+ */
+void
+crypto_digest_assign(crypto_digest_t *into,
+                     const crypto_digest_t *from)
+{
+  tor_assert(into);
+  tor_assert(from);
+  tor_assert(into->algorithm == from->algorithm);
+  const size_t alloc_bytes = crypto_digest_alloc_bytes(from->algorithm);
+  memcpy(into,from,alloc_bytes);
+}
+
+/** Given a list of strings in <b>lst</b>, set the <b>len_out</b>-byte digest
+ * at <b>digest_out</b> to the hash of the concatenation of those strings,
+ * plus the optional string <b>append</b>, computed with the algorithm
+ * <b>alg</b>.
+ * <b>out_len</b> must be \<= DIGEST512_LEN. */
+void
+crypto_digest_smartlist(char *digest_out, size_t len_out,
+                        const smartlist_t *lst,
+                        const char *append,
+                        digest_algorithm_t alg)
+{
+  crypto_digest_smartlist_prefix(digest_out, len_out, NULL, lst, append, alg);
+}
+
+/** Given a list of strings in <b>lst</b>, set the <b>len_out</b>-byte digest
+ * at <b>digest_out</b> to the hash of the concatenation of: the
+ * optional string <b>prepend</b>, those strings,
+ * and the optional string <b>append</b>, computed with the algorithm
+ * <b>alg</b>.
+ * <b>len_out</b> must be \<= DIGEST512_LEN. */
+void
+crypto_digest_smartlist_prefix(char *digest_out, size_t len_out,
+                        const char *prepend,
+                        const smartlist_t *lst,
+                        const char *append,
+                        digest_algorithm_t alg)
+{
+  crypto_digest_t *d = crypto_digest_new_internal(alg);
+  if (prepend)
+    crypto_digest_add_bytes(d, prepend, strlen(prepend));
+  SMARTLIST_FOREACH(lst, const char *, cp,
+                    crypto_digest_add_bytes(d, cp, strlen(cp)));
+  if (append)
+    crypto_digest_add_bytes(d, append, strlen(append));
+  crypto_digest_get_digest(d, digest_out, len_out);
+  crypto_digest_free(d);
+}
+
+/** Compute the HMAC-SHA-256 of the <b>msg_len</b> bytes in <b>msg</b>, using
+ * the <b>key</b> of length <b>key_len</b>.  Store the DIGEST256_LEN-byte
+ * result in <b>hmac_out</b>. Asserts on failure.
+ */
+void
+crypto_hmac_sha256(char *hmac_out,
+                   const char *key, size_t key_len,
+                   const char *msg, size_t msg_len)
+{
+  unsigned char *rv = NULL;
+  /* If we've got OpenSSL >=0.9.8 we can use its hmac implementation. */
+  tor_assert(key_len < INT_MAX);
+  tor_assert(msg_len < INT_MAX);
+  tor_assert(hmac_out);
+  rv = HMAC(EVP_sha256(), key, (int)key_len, (unsigned char*)msg, (int)msg_len,
+            (unsigned char*)hmac_out, NULL);
+  tor_assert(rv);
+}
+
+/** Compute a MAC using SHA3-256 of <b>msg_len</b> bytes in <b>msg</b> using a
+ * <b>key</b> of length <b>key_len</b> and a <b>salt</b> of length
+ * <b>salt_len</b>. Store the result of <b>len_out</b> bytes in in
+ * <b>mac_out</b>. This function can't fail. */
+void
+crypto_mac_sha3_256(uint8_t *mac_out, size_t len_out,
+                    const uint8_t *key, size_t key_len,
+                    const uint8_t *msg, size_t msg_len)
+{
+  crypto_digest_t *digest;
+
+  const uint64_t key_len_netorder = tor_htonll(key_len);
+
+  tor_assert(mac_out);
+  tor_assert(key);
+  tor_assert(msg);
+
+  digest = crypto_digest256_new(DIGEST_SHA3_256);
+
+  /* Order matters here that is any subsystem using this function should
+   * expect this very precise ordering in the MAC construction. */
+  crypto_digest_add_bytes(digest, (const char *) &key_len_netorder,
+                          sizeof(key_len_netorder));
+  crypto_digest_add_bytes(digest, (const char *) key, key_len);
+  crypto_digest_add_bytes(digest, (const char *) msg, msg_len);
+  crypto_digest_get_digest(digest, (char *) mac_out, len_out);
+  crypto_digest_free(digest);
+}