X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/tripe/blobdiff_plain/9cda68ab3974b1f2c08a5896929890bf4a973e9a..15e8239f47dbd30b4da82dfedf983e07bc2f4122:/server/keyset.c

diff --git a/server/keyset.c b/server/keyset.c
index f21a59a9..94fcae02 100644
--- a/server/keyset.c
+++ b/server/keyset.c
@@ -32,8 +32,6 @@
 
 #define KEYOK(ks, now) ((ks)->sz_exp > 0 && (ks)->t_exp > now)
 
-#define SEQSZ 4				/* Size of sequence number packet */
-
 /*----- Low-level packet encryption and decryption ------------------------*/
 
 /* --- Encrypted data format --- *
@@ -77,73 +75,37 @@
 
 static int doencrypt(keyset *ks, unsigned ty, buf *b, buf *bb)
 {
-  ghash *h;
-  gcipher *c = ks->cout;
-  const octet *p = BCUR(b);
+  int rc;
   size_t sz = BLEFT(b);
-  octet *qmac, *qseq, *qiv, *qpk;
-  uint32 oseq;
-  size_t ivsz = GC_CLASS(c)->blksz;
-  size_t tagsz = ks->tagsz;
   size_t osz, nsz;
-  octet t[4];
-  int rc = 0;
-
-  /* --- Allocate the required buffer space --- */
 
-  if (buf_ensure(bb, tagsz + SEQSZ + ivsz + sz))
-    return (0); /* Caution! */
-  qmac = BCUR(bb); qseq = qmac + tagsz; qiv = qseq + SEQSZ; qpk = qiv + ivsz;
-  BSTEP(bb, tagsz + SEQSZ + ivsz + sz);
-  STORE32(t, ty);
+  /* --- Initial tracing --- */
 
-  oseq = ks->oseq++; STORE32(qseq, oseq);
   IF_TRACING(T_KEYSET, {
-    trace(T_KEYSET, "keyset: encrypting packet %lu using keyset %u",
-	  (unsigned long)oseq, ks->seq);
-    trace_block(T_CRYPTO, "crypto: plaintext packet", p, sz);
+    trace(T_KEYSET,
+	  "keyset: encrypting packet %lu (type %u) using keyset %u",
+	  (unsigned long)ks->oseq, ty, ks->seq);
+    trace_block(T_CRYPTO, "crypto: plaintext packet", BCUR(b), sz);
   })
 
-  /* --- Encrypt the packet --- */
-
-  if (ivsz) {
-    rand_get(RAND_GLOBAL, qiv, ivsz);
-    GC_SETIV(c, qiv);
-    IF_TRACING(T_KEYSET, {
-      trace_block(T_CRYPTO, "crypto: initialization vector", qiv, ivsz);
-    })
-  }
-  GC_ENCRYPT(c, p, qpk, sz);
-  IF_TRACING(T_KEYSET, {
-    trace_block(T_CRYPTO, "crypto: encrypted packet", qpk, sz);
-  })
+  /* --- Apply the bulk-crypto transformation --- */
 
-  /* --- Now compute the MAC --- */
-
-  if (tagsz) {
-    h = GM_INIT(ks->mout);
-    GH_HASH(h, t, sizeof(t));
-    GH_HASH(h, qseq, SEQSZ + ivsz + sz);
-    memcpy(qmac, GH_DONE(h, 0), tagsz);
-    GH_DESTROY(h);
-    IF_TRACING(T_KEYSET, {
-      trace_block(T_CRYPTO, "crypto: computed MAC", qmac, tagsz);
-    })
-  }
+  rc = ks->bulk->encrypt(ks, ty, b, bb);
+  if (rc || !BOK(bb)) return (rc);
 
-  /* --- Deduct the packet size from the key's data life --- */
+  /* --- Do the necessary accounting for data volume --- */
 
   osz = ks->sz_exp;
-  if (osz > sz)
-    nsz = osz - sz;
-  else
-    nsz = 0;
+  nsz = osz > sz ? osz - sz : 0;
   if (osz >= ks->sz_regen && ks->sz_regen > nsz) {
     T( trace(T_KEYSET, "keyset: keyset %u data regen limit exceeded -- "
 	     "forcing exchange", ks->seq); )
     rc = KSERR_REGEN;
   }
   ks->sz_exp = nsz;
+
+  /* --- We're done --- */
+
   return (rc);
 }
 
@@ -167,71 +129,24 @@ static int doencrypt(keyset *ks, unsigned ty, buf *b, buf *bb)
 
 static int dodecrypt(keyset *ks, unsigned ty, buf *b, buf *bb, uint32 *seq)
 {
-  const octet *pmac, *piv, *pseq, *ppk;
-  size_t psz = BLEFT(b);
-  size_t sz;
-  octet *q = BCUR(bb);
-  ghash *h;
-  gcipher *c = ks->cin;
-  size_t ivsz = GC_CLASS(c)->blksz;
-  size_t tagsz = ks->tagsz;
-  octet *mac;
-  int eq;
-  octet t[4];
-
-  /* --- Break up the packet into its components --- */
-
-  if (psz < ivsz + SEQSZ + tagsz) {
-    T( trace(T_KEYSET, "keyset: block too small for keyset %u", ks->seq); )
-    return (KSERR_MALFORMED);
-  }
-  sz = psz - ivsz - SEQSZ - tagsz;
-  pmac = BCUR(b); pseq = pmac + tagsz; piv = pseq + SEQSZ; ppk = piv + ivsz;
-  STORE32(t, ty);
+  const octet *q = BCUR(bb);
+  int rc;
 
   IF_TRACING(T_KEYSET, {
-    trace(T_KEYSET, "keyset: decrypting using keyset %u", ks->seq);
-    trace_block(T_CRYPTO, "crypto: ciphertext packet", ppk, sz);
+    trace(T_KEYSET,
+	  "keyset: try decrypting packet (type %u) using keyset %u",
+	  ty, ks->seq);
+    trace_block(T_CRYPTO, "crypto: ciphertext packet", BCUR(b), BLEFT(b));
   })
 
-  /* --- Verify the MAC on the packet --- */
-
-  if (tagsz) {
-    h = GM_INIT(ks->min);
-    GH_HASH(h, t, sizeof(t));
-    GH_HASH(h, pseq, SEQSZ + ivsz + sz);
-    mac = GH_DONE(h, 0);
-    eq = !memcmp(mac, pmac, tagsz);
-    IF_TRACING(T_KEYSET, {
-      trace_block(T_CRYPTO, "crypto: computed MAC", mac, tagsz);
-    })
-    GH_DESTROY(h);
-    if (!eq) {
-      IF_TRACING(T_KEYSET, {
-	trace(T_KEYSET, "keyset: incorrect MAC: decryption failed");
-	trace_block(T_CRYPTO, "crypto: expected MAC", pmac, tagsz);
-      })
-      return (KSERR_DECRYPT);
-    }
-  }
-
-  /* --- Decrypt the packet --- */
+  rc = ks->bulk->decrypt(ks, ty, b, bb, seq);
+  if (rc) return (rc);
 
-  if (ivsz) {
-    GC_SETIV(c, piv);
-    IF_TRACING(T_KEYSET, {
-      trace_block(T_CRYPTO, "crypto: initialization vector", piv, ivsz);
-    })
-  }
-  GC_DECRYPT(c, ppk, q, sz);
-  if (seq)
-    *seq = LOAD32(pseq);
   IF_TRACING(T_KEYSET, {
     trace(T_KEYSET, "keyset: decrypted OK (sequence = %lu)",
-	  (unsigned long)LOAD32(pseq));
-    trace_block(T_CRYPTO, "crypto: decrypted packet", q, sz);
+	  (unsigned long)*seq);
+    trace_block(T_CRYPTO, "crypto: decrypted packet", q, BCUR(bb) - q);
   })
-  BSTEP(bb, sz);
   return (0);
 }
 
@@ -251,10 +166,19 @@ void ks_drop(keyset *ks)
 {
   if (--ks->ref)
     return;
-  GC_DESTROY(ks->cin);
-  GC_DESTROY(ks->cout);
-  GM_DESTROY(ks->min);
-  GM_DESTROY(ks->mout);
+
+#define DROP(dir, a, drop) do { if (ks->dir.a) drop(ks->dir.a); } while (0)
+#define DROP_DIR(dir) do {						\
+  DROP(dir, c, GC_DESTROY);						\
+  DROP(dir, m, GM_DESTROY);						\
+} while (0)
+
+  DROP_DIR(in);
+  DROP_DIR(out);
+
+#undef DROP
+#undef DROP_DIR
+
   DESTROY(ks);
 }
 
@@ -281,75 +205,67 @@ void ks_drop(keyset *ks)
  *		calling @ks_encrypt@ directly.
  */
 
+static void gen_dir(const algswitch *algs, struct ksdir *ksd,
+		    const char *whichdir,
+		    const octet *from, size_t fromsz,
+		    const octet *to, size_t tosz,
+		    const octet *both, size_t bothsz)
+{
+#define SETKEY(what, a, init) do {					\
+  ghash *_h;								\
+  octet *_hh;								\
+									\
+  if (!algs->a)								\
+    ksd->a = 0;								\
+  else {								\
+    _h = GH_INIT(algs->h);						\
+    HASH_STRING(_h, "tripe-" what);					\
+    GH_HASH(_h, from, fromsz);						\
+    GH_HASH(_h, to, tosz);						\
+    GH_HASH(_h, both, bothsz);						\
+    _hh = GH_DONE(_h, 0);						\
+    IF_TRACING(T_KEYSET, { IF_TRACING(T_CRYPTO, {			\
+      char _buf[32];							\
+      sprintf(_buf, "crypto: %s key " what, whichdir);			\
+      trace_block(T_CRYPTO, _buf, _hh, algs->a##ksz);			\
+    }) })								\
+    ksd->a = init(algs->a, _hh, algs->a##ksz);				\
+    GH_DESTROY(_h);							\
+  }									\
+} while (0)
+
+  SETKEY("encryption", c, GC_INIT);
+  SETKEY("integrity", m, GM_KEY);
+  SETKEY("blkc", b, GC_INIT);
+
+#undef SETKEY
+}
+
 keyset *ks_gen(const void *k, size_t x, size_t y, size_t z, peer *p)
 {
-  ghash *h;
-  const octet *hh;
   keyset *ks = CREATE(keyset);
   time_t now = time(0);
   const octet *pp = k;
+  const algswitch *algs = &p->kx.kpriv->algs;
   T( static unsigned seq = 0; )
 
   T( trace(T_KEYSET, "keyset: adding new keyset %u", seq); )
 
-  /* --- Construct the various keys --- *
-   *
-   * This is done with macros, because it's quite tedious.
-   */
-
-#define MINE GH_HASH(h, pp, x)
-#define YOURS GH_HASH(h, pp + x, y - x)
-#define OURS GH_HASH(h, pp + y, z - y)
-
-#define HASH_in MINE; YOURS; OURS
-#define HASH_out YOURS; MINE; OURS
-#define INIT_c(k) GC_INIT(algs.c, (k), algs.cksz)
-#define INIT_m(k) GM_KEY(algs.m, (k), algs.mksz)
-#define STR_c "encryption"
-#define STR_m "integrity"
-#define STR_in "incoming"
-#define STR_out "outgoing"
-
-#define SETKEY(a, dir) do {						\
-  h = GH_INIT(algs.h);							\
-  HASH_STRING(h, "tripe-" STR_##a);					\
-  HASH_##dir;								\
-  hh = GH_DONE(h, 0);							\
-  IF_TRACING(T_KEYSET, {						\
-    trace_block(T_CRYPTO, "crypto: " STR_##dir " key " STR_##a,		\
-		hh, algs.a##ksz);					\
-  })									\
-  ks->a##dir = INIT_##a(hh);						\
-  GH_DESTROY(h);							\
-} while (0)
-
-  SETKEY(c, in); SETKEY(c, out);
-  SETKEY(m, in); SETKEY(m, out);
-
-#undef MINE
-#undef YOURS
-#undef OURS
-#undef STR_c
-#undef STR_m
-#undef STR_in
-#undef STR_out
-#undef INIT_c
-#undef INIT_m
-#undef HASH_in
-#undef HASH_out
-#undef SETKEY
+  gen_dir(algs, &ks->in, "incoming", pp, x, pp + x, y - x, pp + y, z - y);
+  gen_dir(algs, &ks->out, "outgoing", pp + x, y - x, pp, x, pp + y, z - y);
 
   T( ks->seq = seq++; )
+  ks->bulk = algs->bulk;
   ks->ref = 1;
   ks->t_exp = now + T_EXP;
-  ks->sz_exp = algs.expsz;
-  ks->sz_regen = algs.expsz/2;
+  ks->sz_exp = algs->expsz;
+  ks->sz_regen = algs->expsz/2;
   ks->oseq = 0;
   seq_reset(&ks->iseq);
   ks->next = 0;
   ks->p = p;
   ks->f = KSF_LISTEN;
-  ks->tagsz = algs.tagsz;
+  ks->tagsz = algs->tagsz;
   return (ks);
 }
 
@@ -387,6 +303,11 @@ void ks_activate(keyset *ks)
  *		ought to be replaced' notification is only ever given once
  *		for each key.  Also note that this call forces a keyset to be
  *		used even if it's marked as not for data output.
+ *
+ *		The encryption transform is permitted to corrupt @buf_u@ for
+ *		its own purposes.  Neither the source nor destination should
+ *		be within @buf_u@; and callers mustn't expect anything stored
+ *		in @buf_u@ to still
  */
 
 int ks_encrypt(keyset *ks, unsigned ty, buf *b, buf *bb)
@@ -414,6 +335,11 @@ int ks_encrypt(keyset *ks, unsigned ty, buf *b, buf *bb)
  * Use:		Attempts to decrypt a message using a given key.  Note that
  *		requesting decryption with a key directly won't clear a
  *		marking that it's not for encryption.
+ *
+ *		The decryption transform is permitted to corrupt @buf_u@ for
+ *		its own purposes.  Neither the source nor destination should
+ *		be within @buf_u@; and callers mustn't expect anything stored
+ *		in @buf_u@ to still
  */
 
 int ks_decrypt(keyset *ks, unsigned ty, buf *b, buf *bb)