first version of LOCAL pam backend

2 files changed, 422 insertions, 0 deletions

diff --git a/server/util/nss_sha512crypt.c b/server/util/nss_sha512crypt.c
new file mode 100644
index 000000000..84cb61c27
--- /dev/null
+++ b/server/util/nss_sha512crypt.c
@@ -0,0 +1,419 @@
+/* This file is based on the work of Ulrich Drepper
+ * (http://people.redhat.com/drepper/SHA-crypt.txt). I have replaced the
+ * included SHA512 implementation by calls to NSS
+ * (http://www.mozilla.org/projects/security/pki/nss/).
+ *
+ *  Sumit Bose <sbose@redhat.com>
+ */
+/* SHA512-based Unix crypt implementation.
+   Released into the Public Domain by Ulrich Drepper <drepper@redhat.com>.  */
+
+#define _GNU_SOURCE
+#include <endian.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/param.h>
+#include <sys/types.h>
+
+#include <prinit.h>
+#include <nss.h>
+#include <sechash.h>
+#include <pk11func.h>
+
+
+static int nspr_nss_init_done = 0;
+
+/* according to
+ * http://www.mozilla.org/projects/security/pki/nss/ref/ssl/sslfnc.html#1234224
+ * PR_Init must be called, but at least for the HASH_* calls it seems to work
+ * quite well without. */
+static int nspr_nss_init(void)
+{
+  int ret;
+  PR_Init(PR_USER_THREAD, PR_PRIORITY_NORMAL, 0);
+  ret = NSS_NoDB_Init(NULL);
+  if (ret != SECSuccess) {
+    return ret;
+  }
+  nspr_nss_init_done = 1;
+  return 0;
+}
+
+/* added for completness, so far not used */
+static int nspr_nss_cleanup(void)
+{
+  int ret;
+  ret=NSS_Shutdown();
+  if (ret != SECSuccess ) {
+    return ret;
+  }
+  PR_Cleanup();
+  nspr_nss_init_done = 0;
+  return 0;
+}
+
+/* Define our magic string to mark salt for SHA512 "encryption"
+   replacement.  */
+static const char sha512_salt_prefix[] = "$6$";
+
+/* Prefix for optional rounds specification.  */
+static const char sha512_rounds_prefix[] = "rounds=";
+
+/* Maximum salt string length.  */
+#define SALT_LEN_MAX 16
+/* Default number of rounds if not explicitly specified.  */
+#define ROUNDS_DEFAULT 5000
+/* Minimum number of rounds.  */
+#define ROUNDS_MIN 1000
+/* Maximum number of rounds.  */
+#define ROUNDS_MAX 999999999
+
+/* Table with characters for base64 transformation.  */
+static const char b64t[64] =
+"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+
+
+static char *
+sha512_crypt_r (const char *key, const char *salt, char *buffer, int buflen)
+{
+  unsigned char alt_result[64]
+    __attribute__ ((__aligned__ (__alignof__ (uint64_t))));
+  unsigned char temp_result[64]
+    __attribute__ ((__aligned__ (__alignof__ (uint64_t))));
+  HASHContext *ctx;
+  HASHContext *alt_ctx;
+  size_t salt_len;
+  size_t key_len;
+  size_t cnt;
+  char *cp;
+  char *copied_key = NULL;
+  char *copied_salt = NULL;
+  char *p_bytes;
+  char *s_bytes;
+  /* Default number of rounds.  */
+  size_t rounds = ROUNDS_DEFAULT;
+  bool rounds_custom = false;
+
+  int ret;
+  unsigned int part;
+
+  /* Find beginning of salt string.  The prefix should normally always
+     be present.  Just in case it is not.  */
+  if (strncmp (sha512_salt_prefix, salt, sizeof (sha512_salt_prefix) - 1) == 0)
+    /* Skip salt prefix.  */
+    salt += sizeof (sha512_salt_prefix) - 1;
+
+  if (strncmp (salt, sha512_rounds_prefix, sizeof (sha512_rounds_prefix) - 1)
+      == 0)
+    {
+      const char *num = salt + sizeof (sha512_rounds_prefix) - 1;
+      char *endp;
+      unsigned long int srounds = strtoul (num, &endp, 10);
+      if (*endp == '$')
+    {
+      salt = endp + 1;
+      rounds = MAX (ROUNDS_MIN, MIN (srounds, ROUNDS_MAX));
+      rounds_custom = true;
+    }
+    }
+
+  salt_len = MIN (strcspn (salt, "$"), SALT_LEN_MAX);
+  key_len = strlen (key);
+
+  if ((key - (char *) 0) % __alignof__ (uint64_t) != 0)
+    {
+      char *tmp = (char *) alloca (key_len + __alignof__ (uint64_t));
+      key = copied_key =
+    memcpy (tmp + __alignof__ (uint64_t)
+        - (tmp - (char *) 0) % __alignof__ (uint64_t),
+        key, key_len);
+    }
+
+  if ((salt - (char *) 0) % __alignof__ (uint64_t) != 0)
+    {
+      char *tmp = (char *) alloca (salt_len + __alignof__ (uint64_t));
+      salt = copied_salt =
+    memcpy (tmp + __alignof__ (uint64_t)
+        - (tmp - (char *) 0) % __alignof__ (uint64_t),
+        salt, salt_len);
+    }
+
+
+  if (!nspr_nss_init_done) {
+    ret = nspr_nss_init();
+    if (ret != SECSuccess) return NULL;
+  }
+
+  ctx = HASH_Create(HASH_AlgSHA512);
+  if ( ctx == NULL ) {
+    return NULL;
+  }
+
+  alt_ctx = HASH_Create(HASH_AlgSHA512);
+  if ( alt_ctx == NULL ) {
+    return NULL;
+  }
+
+
+  /* Prepare for the real work.  */
+  HASH_Begin(ctx);
+
+  /* Add the key string.  */
+  HASH_Update(ctx, key, key_len);
+
+  /* The last part is the salt string.  This must be at most 16
+     characters and it ends at the first `$' character (for
+     compatibility with existing implementations).  */
+  HASH_Update(ctx, salt, salt_len);
+
+
+  /* Compute alternate SHA512 sum with input KEY, SALT, and KEY.  The
+     final result will be added to the first context.  */
+  HASH_Begin(alt_ctx);
+
+  /* Add key.  */
+  HASH_Update(alt_ctx, key, key_len);
+
+  /* Add salt.  */
+  HASH_Update(alt_ctx, salt, salt_len);
+
+  /* Add key again.  */
+  HASH_Update(alt_ctx, key, key_len);
+
+  /* Now get result of this (64 bytes) and add it to the other
+     context.  */
+  HASH_End(alt_ctx, alt_result, &part, HASH_ResultLenContext(alt_ctx));
+
+  /* Add for any character in the key one byte of the alternate sum.  */
+  for (cnt = key_len; cnt > 64; cnt -= 64) {
+    HASH_Update(ctx, alt_result, 64);
+  }
+  HASH_Update(ctx, alt_result, cnt);
+
+  /* Take the binary representation of the length of the key and for every
+     1 add the alternate sum, for every 0 the key.  */
+  for (cnt = key_len; cnt > 0; cnt >>= 1)
+    if ((cnt & 1) != 0) {
+      HASH_Update(ctx, alt_result, 64);
+    } else {
+      HASH_Update(ctx, key, key_len);
+    }
+
+  /* Create intermediate result.  */
+  HASH_End(ctx, alt_result, &part, HASH_ResultLenContext(ctx));
+
+  /* Start computation of P byte sequence.  */
+  HASH_Begin(alt_ctx);
+
+  /* For every character in the password add the entire password.  */
+  for (cnt = 0; cnt < key_len; ++cnt) {
+    HASH_Update(alt_ctx, key, key_len);
+  }
+
+  /* Finish the digest.  */
+  HASH_End(alt_ctx, temp_result, &part, HASH_ResultLenContext(alt_ctx));
+
+  /* Create byte sequence P.  */
+  cp = p_bytes = alloca (key_len);
+  for (cnt = key_len; cnt >= 64; cnt -= 64)
+    cp = mempcpy (cp, temp_result, 64);
+  memcpy (cp, temp_result, cnt);
+
+  /* Start computation of S byte sequence.  */
+  HASH_Begin(alt_ctx);
+
+  /* For every character in the password add the entire password.  */
+  for (cnt = 0; cnt < 16 + alt_result[0]; ++cnt) {
+    HASH_Update(alt_ctx, salt, salt_len);
+  }
+
+  /* Finish the digest.  */
+  HASH_End(alt_ctx, temp_result, &part, HASH_ResultLenContext(alt_ctx));
+
+  /* Create byte sequence S.  */
+  cp = s_bytes = alloca (salt_len);
+  for (cnt = salt_len; cnt >= 64; cnt -= 64)
+    cp = mempcpy (cp, temp_result, 64);
+  memcpy (cp, temp_result, cnt);
+
+  /* Repeatedly run the collected hash value through SHA512 to burn
+     CPU cycles.  */
+  for (cnt = 0; cnt < rounds; ++cnt)
+    {
+      /* New context.  */
+      HASH_Begin(ctx);
+
+      /* Add key or last result.  */
+      if ((cnt & 1) != 0) {
+        HASH_Update(ctx, p_bytes, key_len);
+      } else {
+        HASH_Update(ctx, alt_result, 64);
+      }
+
+      /* Add salt for numbers not divisible by 3.  */
+      if (cnt % 3 != 0) {
+        HASH_Update(ctx, s_bytes, salt_len);
+      }
+
+      /* Add key for numbers not divisible by 7.  */
+      if (cnt % 7 != 0) {
+        HASH_Update(ctx, p_bytes, key_len);
+      }
+
+      /* Add key or last result.  */
+      if ((cnt & 1) != 0) {
+        HASH_Update(ctx, alt_result, 64);
+      } else {
+        HASH_Update(ctx, p_bytes, key_len);
+      }
+
+      /* Create intermediate result.  */
+      HASH_End(ctx, alt_result, &part, HASH_ResultLenContext(ctx));
+    }
+
+  /* Now we can construct the result string.  It consists of three
+     parts.  */
+  cp = __stpncpy (buffer, sha512_salt_prefix, MAX (0, buflen));
+  buflen -= sizeof (sha512_salt_prefix) - 1;
+
+  if (rounds_custom)
+    {
+      int n = snprintf (cp, MAX (0, buflen), "%s%zu$",
+            sha512_rounds_prefix, rounds);
+      cp += n;
+      buflen -= n;
+    }
+
+  cp = __stpncpy (cp, salt, MIN ((size_t) MAX (0, buflen), salt_len));
+  buflen -= MIN ((size_t) MAX (0, buflen), salt_len);
+
+  if (buflen > 0)
+    {
+      *cp++ = '$';
+      --buflen;
+    }
+
+#define b64_from_24bit(B2, B1, B0, N)                         \
+  do {                                        \
+    unsigned int w = ((B2) << 16) | ((B1) << 8) | (B0);               \
+    int n = (N);                                  \
+    while (n-- > 0 && buflen > 0)                         \
+      {                                       \
+    *cp++ = b64t[w & 0x3f];                           \
+    --buflen;                                 \
+    w >>= 6;                                  \
+      }                                       \
+  } while (0)
+
+  b64_from_24bit (alt_result[0], alt_result[21], alt_result[42], 4);
+  b64_from_24bit (alt_result[22], alt_result[43], alt_result[1], 4);
+  b64_from_24bit (alt_result[44], alt_result[2], alt_result[23], 4);
+  b64_from_24bit (alt_result[3], alt_result[24], alt_result[45], 4);
+  b64_from_24bit (alt_result[25], alt_result[46], alt_result[4], 4);
+  b64_from_24bit (alt_result[47], alt_result[5], alt_result[26], 4);
+  b64_from_24bit (alt_result[6], alt_result[27], alt_result[48], 4);
+  b64_from_24bit (alt_result[28], alt_result[49], alt_result[7], 4);
+  b64_from_24bit (alt_result[50], alt_result[8], alt_result[29], 4);
+  b64_from_24bit (alt_result[9], alt_result[30], alt_result[51], 4);
+  b64_from_24bit (alt_result[31], alt_result[52], alt_result[10], 4);
+  b64_from_24bit (alt_result[53], alt_result[11], alt_result[32], 4);
+  b64_from_24bit (alt_result[12], alt_result[33], alt_result[54], 4);
+  b64_from_24bit (alt_result[34], alt_result[55], alt_result[13], 4);
+  b64_from_24bit (alt_result[56], alt_result[14], alt_result[35], 4);
+  b64_from_24bit (alt_result[15], alt_result[36], alt_result[57], 4);
+  b64_from_24bit (alt_result[37], alt_result[58], alt_result[16], 4);
+  b64_from_24bit (alt_result[59], alt_result[17], alt_result[38], 4);
+  b64_from_24bit (alt_result[18], alt_result[39], alt_result[60], 4);
+  b64_from_24bit (alt_result[40], alt_result[61], alt_result[19], 4);
+  b64_from_24bit (alt_result[62], alt_result[20], alt_result[41], 4);
+  b64_from_24bit (0, 0, alt_result[63], 2);
+
+  if (buflen <= 0)
+    {
+      errno = ERANGE;
+      buffer = NULL;
+    }
+  else
+    *cp = '\0';     /* Terminate the string.  */
+
+  /* Clear the buffer for the intermediate result so that people
+     attaching to processes or reading core dumps cannot get any
+     information.  We do it in this way to clear correct_words[]
+     inside the SHA512 implementation as well.  */
+  HASH_Destroy(ctx);
+  HASH_Destroy(alt_ctx);
+
+  memset (temp_result, '\0', sizeof (temp_result));
+  memset (p_bytes, '\0', key_len);
+  memset (s_bytes, '\0', salt_len);
+  memset (&ctx, '\0', sizeof (ctx));
+  memset (&alt_ctx, '\0', sizeof (alt_ctx));
+  if (copied_key != NULL)
+    memset (copied_key, '\0', key_len);
+  if (copied_salt != NULL)
+    memset (copied_salt, '\0', salt_len);
+
+  return buffer;
+}
+
+
+/* This entry point is equivalent to the `crypt' function in Unix
+   libcs.  */
+char *
+nss_sha512_crypt (const char *key, const char *salt)
+{
+  /* We don't want to have an arbitrary limit in the size of the
+     password.  We can compute an upper bound for the size of the
+     result in advance and so we can prepare the buffer we pass to
+     `sha512_crypt_r'.  */
+  static char *buffer;
+  static int buflen;
+  int needed = (sizeof (sha512_salt_prefix) - 1
+        + sizeof (sha512_rounds_prefix) + 9 + 1
+        + strlen (salt) + 1 + 86 + 1);
+
+  if (buflen < needed)
+    {
+      char *new_buffer = (char *) realloc (buffer, needed);
+      if (new_buffer == NULL)
+    return NULL;
+
+      buffer = new_buffer;
+      buflen = needed;
+    }
+
+  return sha512_crypt_r (key, salt, buffer, buflen);
+}
+
+char *gen_salt(void)
+{
+  int ret;
+  unsigned char bin_rand[12];
+  static char b64_rand[17];
+  char *cp;
+  int buflen;
+
+  if (!nspr_nss_init_done) {
+    ret = nspr_nss_init();
+    if (ret != SECSuccess) return NULL;
+  }
+
+  ret = PK11_GenerateRandom(bin_rand, sizeof(bin_rand)-1);
+  cp = b64_rand;
+  buflen = 16;
+  b64_from_24bit (bin_rand[0], bin_rand[1], bin_rand[2], 4);
+  b64_from_24bit (bin_rand[3], bin_rand[4], bin_rand[5], 4);
+  b64_from_24bit (bin_rand[6], bin_rand[7], bin_rand[8], 4);
+  b64_from_24bit (bin_rand[9], bin_rand[10], bin_rand[11], 4);
+
+  *cp++ = '\0';
+
+  return b64_rand;
+
+}
+
diff --git a/server/util/nss_sha512crypt.h b/server/util/nss_sha512crypt.h
new file mode 100644
index 000000000..0d0632177
--- /dev/null
+++ b/server/util/nss_sha512crypt.h
@@ -0,0 +1,3 @@
+
+char * nss_sha512_crypt (const char *key, const char *salt);
+char *gen_salt(void);