X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=rsa.c;h=cda8d8924dfac0f4bd68a54d8648d8ec6fa670f6;hb=4b9f8efbb918eb573f8b4b0289aa0349a4e68f4c;hp=f7dd69db6f69115e03c94779a2529468b642619f;hpb=f15aefe4e0bb264fc1ceac17c7bbe1a534d190c9;p=secnet.git

diff --git a/rsa.c b/rsa.c
index f7dd69d..cda8d89 100644
--- a/rsa.c
+++ b/rsa.c
@@ -1,25 +1,55 @@
-/* This file is part of secnet, and is distributed under the terms of
-   the GNU General Public License version 2 or later.
+/*
+ * rsa.c: implementation of RSA with PKCS#1 padding
+ */
+/*
+ * This file is Free Software.  It was originally written for secnet.
+ *
+ * Copyright 1995-2003 Stephen Early
+ * Copyright 2002-2014 Ian Jackson
+ * Copyright 2001      Simon Tatham
+ * Copyright 2013      Mark Wooding
+ *
+ * You may redistribute secnet as a whole and/or modify it under the
+ * terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 3, or (at your option) any
+ * later version.
+ *
+ * You may redistribute this file and/or modify it under the terms of
+ * the GNU General Public License as published by the Free Software
+ * Foundation; either version 2, or (at your option) any later
+ * version.
+ *
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this software; if not, see
+ * https://www.gnu.org/licenses/gpl.html.
+ */
 
-   Copyright (C) 1995-2002 Stephen Early
-   Copyright (C) 2001 Simon Tatham
-   Copyright (C) 2002 Ian Jackson
-   */
 
 #include <stdio.h>
 #include <string.h>
 #include <gmp.h>
 #include "secnet.h"
 #include "util.h"
+#include "unaligned.h"
 
 #define AUTHFILE_ID_STRING "SSH PRIVATE KEY FILE FORMAT 1.1\n"
 
 #define mpp(s,n) do { char *p = mpz_get_str(NULL,16,n); printf("%s 0x%sL\n", s, p); free(p); } while (0)
 
+struct rsacommon {
+    uint8_t *hashbuf;
+};
+
 struct rsapriv {
     closure_t cl;
-    struct rsaprivkey_if ops;
+    struct sigprivkey_if ops;
     struct cloc loc;
+    struct rsacommon common;
     MP_INT n;
     MP_INT p, dp;
     MP_INT q, dq;
@@ -27,8 +57,9 @@ struct rsapriv {
 };
 struct rsapub {
     closure_t cl;
-    struct rsapubkey_if ops;
+    struct sigpubkey_if ops;
     struct cloc loc;
+    struct rsacommon common;
     MP_INT e;
     MP_INT n;
 };
@@ -42,6 +73,28 @@ struct rsapub {
 
 static const char *hexchars="0123456789abcdef";
 
+static void rsa_sethash(struct rsacommon *c, struct hash_if *hash,
+			const struct hash_if **in_ops)
+{
+    free(c->hashbuf);
+    c->hashbuf=safe_malloc(hash->hlen, "generate_msg");
+    *in_ops=hash;
+}
+static void rsa_pub_sethash(void *sst, struct hash_if *hash)
+{
+    struct rsapub *st=sst;
+    rsa_sethash(&st->common, hash, &st->ops.hash);
+}
+static void rsa_priv_sethash(void *sst, struct hash_if *hash)
+{
+    struct rsapriv *st=sst;
+    rsa_sethash(&st->common, hash, &st->ops.hash);
+}
+static void rsacommon_dispose(struct rsacommon *c)
+{
+    free(c->hashbuf);
+}
+
 static void emsa_pkcs1(MP_INT *n, MP_INT *m,
 		       const uint8_t *data, int32_t datalen)
 {
@@ -69,7 +122,7 @@ static void emsa_pkcs1(MP_INT *n, MP_INT *m,
     msize=mpz_sizeinbase(n, 16);
 
     if (datalen*2+6>=msize) {
-	fatal("rsa_sign: message too big");
+	fatal("rsa: message too big");
     }
 
     strcpy(buff,"0001");
@@ -90,17 +143,20 @@ static void emsa_pkcs1(MP_INT *n, MP_INT *m,
     mpz_set_str(m, buff, 16);
 }
 
-static string_t rsa_sign(void *sst, uint8_t *data, int32_t datalen)
+static bool_t rsa_sign(void *sst, uint8_t *data, int32_t datalen,
+		       struct buffer_if *msg)
 {
     struct rsapriv *st=sst;
     MP_INT a, b, u, v, tmp, tmp2;
-    string_t signature;
+    string_t signature = 0;
+    bool_t ok;
 
     mpz_init(&a);
     mpz_init(&b);
 
+    hash_hash(st->ops.hash,data,datalen,st->common.hashbuf);
     /* Construct the message representative. */
-    emsa_pkcs1(&st->n, &a, data, datalen);
+    emsa_pkcs1(&st->n, &a, st->common.hashbuf, st->ops.hash->hlen);
 
     /*
      * Produce an RSA signature (a^d mod n) using the Chinese
@@ -124,8 +180,8 @@ static string_t rsa_sign(void *sst, uint8_t *data, int32_t datalen)
     mpz_init(&u);
     mpz_init(&v);
 
-    mpz_powm(&u, &a, &st->dp, &st->p);
-    mpz_powm(&v, &a, &st->dq, &st->q);
+    mpz_powm_sec(&u, &a, &st->dp, &st->p);
+    mpz_powm_sec(&v, &a, &st->dq, &st->q);
     mpz_sub(&tmp, &u, &v);
     mpz_mul(&tmp2, &tmp, &st->w);
     mpz_add(&tmp, &tmp2, &v);
@@ -138,14 +194,45 @@ static string_t rsa_sign(void *sst, uint8_t *data, int32_t datalen)
 
     signature=write_mpstring(&b);
 
+    uint8_t *op = buf_append(msg,2);
+    if (!op) { ok=False; goto out; }
+    size_t l = strlen(signature);
+    assert(l < 65536);
+    put_uint16(op, l);
+    op = buf_append(msg,l);
+    if (!op) { ok=False; goto out; }
+    memcpy(op, signature, l);
+
+    ok = True;
+
+ out:
+    free(signature);
     mpz_clear(&b);
     mpz_clear(&a);
-    return signature;
+    return ok;
 }
 
-static rsa_checksig_fn rsa_sig_check;
+static bool_t rsa_sig_unpick(void *sst, struct buffer_if *msg,
+			     struct alg_msg_data *sig)
+{
+    uint8_t *lp = buf_unprepend(msg, 2);
+    if (!lp) return False;
+    sig->len = get_uint16(lp);
+    sig->start = buf_unprepend(msg, sig->len);
+    if (!sig->start) return False;
+
+    /* In `rsa_sig_check' below, we assume that we can write a nul
+     * terminator following the signature.  Make sure there's enough space.
+     */
+    if (msg->start >= msg->base + msg->alloclen)
+	return False;
+
+    return True;
+}
+
+static sig_checksig_fn rsa_sig_check;
 static bool_t rsa_sig_check(void *sst, uint8_t *data, int32_t datalen,
-			    cstring_t signature)
+			    const struct alg_msg_data *sig)
 {
     struct rsapub *st=sst;
     MP_INT a, b, c;
@@ -155,9 +242,14 @@ static bool_t rsa_sig_check(void *sst, uint8_t *data, int32_t datalen,
     mpz_init(&b);
     mpz_init(&c);
 
-    emsa_pkcs1(&st->n, &a, data, datalen);
+    hash_hash(st->ops.hash,data,datalen,st->common.hashbuf);
+    emsa_pkcs1(&st->n, &a, st->common.hashbuf, st->ops.hash->hlen);
 
-    mpz_set_str(&b, signature, 16);
+    /* Terminate signature with a '0' - already checked that this will fit */
+    int save = sig->start[sig->len];
+    sig->start[sig->len] = 0;
+    mpz_set_str(&b, sig->start, 16);
+    sig->start[sig->len] = save;
 
     mpz_powm(&c, &b, &st->e, &st->n);
 
@@ -170,6 +262,15 @@ static bool_t rsa_sig_check(void *sst, uint8_t *data, int32_t datalen,
     return ok;
 }
 
+static void rsapub_dispose(void *sst) {
+    struct rsapub *st=sst;
+
+    mpz_clear(&st->e);
+    mpz_clear(&st->n);
+    rsacommon_dispose(&st->common);
+    free(st);
+}
+
 static list_t *rsapub_apply(closure_t *self, struct cloc loc, dict_t *context,
 			    list_t *args)
 {
@@ -177,13 +278,18 @@ static list_t *rsapub_apply(closure_t *self, struct cloc loc, dict_t *context,
     item_t *i;
     string_t e,n;
 
-    st=safe_malloc(sizeof(*st),"rsapub_apply");
+    NEW(st);
     st->cl.description="rsapub";
-    st->cl.type=CL_RSAPUBKEY;
+    st->cl.type=CL_SIGPUBKEY;
     st->cl.apply=NULL;
     st->cl.interface=&st->ops;
     st->ops.st=st;
+    st->ops.sethash=rsa_pub_sethash;
+    st->common.hashbuf=NULL;
+    st->ops.unpick=rsa_sig_unpick;
     st->ops.check=rsa_sig_check;
+    st->ops.hash=0;
+    st->ops.dispose=rsapub_dispose;
     st->loc=loc;
 
     i=list_elem(args,0);
@@ -222,6 +328,23 @@ static list_t *rsapub_apply(closure_t *self, struct cloc loc, dict_t *context,
     return new_closure(&st->cl);
 }
 
+struct rsapriv_load_ctx {
+    void (*verror)(struct rsapriv_load_ctx *l,
+		   FILE *maybe_f, bool_t unsup,
+		   const char *message, va_list args);
+    union {
+	struct {
+	    struct cloc loc;
+	} apply;
+    } u;
+};
+
+#define LDFATAL(...)      ({ load_error(l,0,0,__VA_ARGS__); goto error_out; })
+#define LDUNSUP(...)      ({ load_error(l,0,1,__VA_ARGS__); goto error_out; })
+#define LDFATAL_FILE(...) ({ load_error(l,f,0,__VA_ARGS__); goto error_out; })
+#define LDUNSUP_FILE(...) ({ load_error(l,f,1,__VA_ARGS__); goto error_out; })
+#define FREE(b)                ({ free((b)); (b)=0; })
+
 static uint32_t keyfile_get_int(struct cloc loc, FILE *f)
 {
     uint32_t r;
@@ -242,103 +365,117 @@ static uint16_t keyfile_get_short(struct cloc loc, FILE *f)
     return r;
 }
 
-static list_t *rsapriv_apply(closure_t *self, struct cloc loc, dict_t *context,
-			     list_t *args)
+static void load_error(struct rsapriv_load_ctx *l, FILE *maybe_f,
+		       bool_t unsup, const char *fmt, ...)
 {
-    struct rsapriv *st;
-    FILE *f;
-    cstring_t filename;
-    item_t *i;
+    va_list al;
+    va_start(al,fmt);
+    l->verror(l,maybe_f,unsup,fmt,al);
+    va_end(al);
+}
+
+static void rsapriv_dispose(void *sst)
+{
+    struct rsapriv *st=sst;
+    mpz_clear(&st->n);
+    mpz_clear(&st->p); mpz_clear(&st->dp);
+    mpz_clear(&st->q); mpz_clear(&st->dq);
+    mpz_clear(&st->w);
+    rsacommon_dispose(&st->common);
+    free(st);
+}
+
+static struct rsapriv *rsa_loadpriv_core(struct rsapriv_load_ctx *l,
+					 FILE *f, struct cloc loc,
+					 bool_t do_validity_check,
+					 const char *filename)
+{
+    struct rsapriv *st=0;
     long length;
-    uint8_t *b, *c;
+    uint8_t *b=0, *c=0;
     int cipher_type;
     MP_INT e,d,iqmp,tmp,tmp2,tmp3;
     bool_t valid;
 
-    st=safe_malloc(sizeof(*st),"rsapriv_apply");
+    mpz_init(&e);
+    mpz_init(&d);
+    mpz_init(&iqmp);
+    mpz_init(&tmp);
+    mpz_init(&tmp2);
+    mpz_init(&tmp3);
+
+    NEW(st);
     st->cl.description="rsapriv";
-    st->cl.type=CL_RSAPRIVKEY;
+    st->cl.type=CL_SIGPRIVKEY;
     st->cl.apply=NULL;
     st->cl.interface=&st->ops;
     st->ops.st=st;
+    st->ops.sethash=rsa_priv_sethash;
+    st->common.hashbuf=NULL;
     st->ops.sign=rsa_sign;
+    st->ops.hash=0;
+    st->ops.dispose=rsapriv_dispose;
     st->loc=loc;
+    mpz_init(&st->n);
+    mpz_init(&st->q);
+    mpz_init(&st->p);
+    mpz_init(&st->dp);
+    mpz_init(&st->dq);
+    mpz_init(&st->w);
 
-    /* Argument is filename pointing to SSH1 private key file */
-    i=list_elem(args,0);
-    if (i) {
-	if (i->type!=t_string) {
-	    cfgfatal(i->loc,"rsa-public","first argument must be a string\n");
-	}
-	filename=i->data.string;
-    } else {
-	filename=NULL; /* Make compiler happy */
-	cfgfatal(loc,"rsa-private","you must provide a filename\n");
-    }
-
-    f=fopen(filename,"rb");
     if (!f) {
-	if (just_check_config) {
-	    Message(M_WARNING,"rsa-private (%s:%d): cannot open keyfile "
-		    "\"%s\"; assuming it's valid while we check the "
-		    "rest of the configuration\n",loc.file,loc.line,filename);
-	    goto assume_valid;
-	} else {
-	    fatal_perror("rsa-private (%s:%d): cannot open file \"%s\"",
-			 loc.file,loc.line,filename);
-	}
+	assert(just_check_config);
+	goto assume_valid;
     }
 
     /* Check that the ID string is correct */
     length=strlen(AUTHFILE_ID_STRING)+1;
     b=safe_malloc(length,"rsapriv_apply");
     if (fread(b,length,1,f)!=1 || memcmp(b,AUTHFILE_ID_STRING,length)!=0) {
-	cfgfatal_maybefile(f,loc,"rsa-private","failed to read magic ID"
+	LDUNSUP_FILE("failed to read magic ID"
 			   " string from SSH1 private keyfile \"%s\"\n",
 			   filename);
     }
-    free(b);
+    FREE(b);
 
     cipher_type=fgetc(f);
     keyfile_get_int(loc,f); /* "Reserved data" */
     if (cipher_type != 0) {
-	cfgfatal(loc,"rsa-private","we don't support encrypted keyfiles\n");
+	LDUNSUP("we don't support encrypted keyfiles\n");
     }
 
     /* Read the public key */
     keyfile_get_int(loc,f); /* Not sure what this is */
     length=(keyfile_get_short(loc,f)+7)/8;
     if (length>RSA_MAX_MODBYTES) {
-	cfgfatal(loc,"rsa-private","implausible length %ld for modulus\n",
+	LDFATAL("implausible length %ld for modulus\n",
 		 length);
     }
     b=safe_malloc(length,"rsapriv_apply");
     if (fread(b,length,1,f) != 1) {
-	cfgfatal_maybefile(f,loc,"rsa-private","error reading modulus\n");
+	LDFATAL_FILE("error reading modulus\n");
     }
-    mpz_init(&st->n);
     read_mpbin(&st->n,b,length);
-    free(b);
+    FREE(b);
     length=(keyfile_get_short(loc,f)+7)/8;
     if (length>RSA_MAX_MODBYTES) {
-	cfgfatal(loc,"rsa-private","implausible length %ld for e\n",length);
+	LDFATAL("implausible length %ld for e\n",length);
     }
     b=safe_malloc(length,"rsapriv_apply");
     if (fread(b,length,1,f)!=1) {
-	cfgfatal_maybefile(f,loc,"rsa-private","error reading e\n");
+	LDFATAL_FILE("error reading e\n");
     }
-    mpz_init(&e);
     read_mpbin(&e,b,length);
-    free(b);
+    FREE(b);
     
     length=keyfile_get_int(loc,f);
     if (length>1024) {
-	cfgfatal(loc,"rsa-private","implausibly long (%ld) key comment\n",
+	LDFATAL("implausibly long (%ld) key comment\n",
 		 length);
     }
     c=safe_malloc(length+1,"rsapriv_apply");
     if (fread(c,length,1,f)!=1) {
-	cfgfatal_maybefile(f,loc,"rsa-private","error reading key comment\n");
+	LDFATAL_FILE("error reading key comment\n");
     }
     c[length]=0;
 
@@ -346,68 +483,60 @@ static list_t *rsapriv_apply(closure_t *self, struct cloc loc, dict_t *context,
        keyfile is not encrypted, so they should be */
 
     if (keyfile_get_short(loc,f) != keyfile_get_short(loc,f)) {
-	cfgfatal(loc,"rsa-private","corrupt keyfile\n");
+	LDFATAL("corrupt keyfile\n");
     }
 
     /* Read d */
     length=(keyfile_get_short(loc,f)+7)/8;
     if (length>RSA_MAX_MODBYTES) {
-	cfgfatal(loc,"rsa-private","implausibly long (%ld) decryption key\n",
+	LDFATAL("implausibly long (%ld) decryption key\n",
 		 length);
     }
     b=safe_malloc(length,"rsapriv_apply");
     if (fread(b,length,1,f)!=1) {
-	cfgfatal_maybefile(f,loc,"rsa-private",
-			   "error reading decryption key\n");
+	LDFATAL_FILE("error reading decryption key\n");
     }
-    mpz_init(&d);
     read_mpbin(&d,b,length);
-    free(b);
+    FREE(b);
     /* Read iqmp (inverse of q mod p) */
     length=(keyfile_get_short(loc,f)+7)/8;
     if (length>RSA_MAX_MODBYTES) {
-	cfgfatal(loc,"rsa-private","implausibly long (%ld)"
+	LDFATAL("implausibly long (%ld)"
 		 " iqmp auxiliary value\n", length);
     }
     b=safe_malloc(length,"rsapriv_apply");
     if (fread(b,length,1,f)!=1) {
-	cfgfatal_maybefile(f,loc,"rsa-private",
-			   "error reading decryption key\n");
+	LDFATAL_FILE("error reading decryption key\n");
     }
-    mpz_init(&iqmp);
     read_mpbin(&iqmp,b,length);
-    free(b);
+    FREE(b);
     /* Read q (the smaller of the two primes) */
     length=(keyfile_get_short(loc,f)+7)/8;
     if (length>RSA_MAX_MODBYTES) {
-	cfgfatal(loc,"rsa-private","implausibly long (%ld) q value\n",
+	LDFATAL("implausibly long (%ld) q value\n",
 		 length);
     }
     b=safe_malloc(length,"rsapriv_apply");
     if (fread(b,length,1,f)!=1) {
-	cfgfatal_maybefile(f,loc,"rsa-private",
-			   "error reading q value\n");
+	LDFATAL_FILE("error reading q value\n");
     }
-    mpz_init(&st->q);
     read_mpbin(&st->q,b,length);
-    free(b);
+    FREE(b);
     /* Read p (the larger of the two primes) */
     length=(keyfile_get_short(loc,f)+7)/8;
     if (length>RSA_MAX_MODBYTES) {
-	cfgfatal(loc,"rsa-private","implausibly long (%ld) p value\n",
+	LDFATAL("implausibly long (%ld) p value\n",
 		 length);
     }
     b=safe_malloc(length,"rsapriv_apply");
     if (fread(b,length,1,f)!=1) {
-	cfgfatal_maybefile(f,loc,"rsa-private",
-			   "error reading p value\n");
+	LDFATAL_FILE("error reading p value\n");
     }
-    mpz_init(&st->p);
     read_mpbin(&st->p,b,length);
-    free(b);
+    FREE(b);
     
-    if (fclose(f)!=0) {
-	fatal_perror("rsa-private (%s:%d): fclose",loc.file,loc.line);
+    if (ferror(f)) {
+	fatal_perror("rsa-private (%s:%d): ferror",loc.file,loc.line);
     }
 
     /*
@@ -415,14 +544,7 @@ static list_t *rsapriv_apply(closure_t *self, struct cloc loc, dict_t *context,
      * values for fast CRT signing.
      */
     valid=False;
-    i=list_elem(args,1);
-    mpz_init(&tmp);
-    mpz_init(&tmp2);
-    mpz_init(&tmp3);
-    if (i && i->type==t_bool && i->data.bool==False) {
-	Message(M_INFO,"rsa-private (%s:%d): skipping RSA key validity "
-		"check\n",loc.file,loc.line);
-    } else {
+    if (do_validity_check) {
 	/* Verify that p*q is equal to n. */
 	mpz_mul(&tmp, &st->p, &st->q);
 	if (mpz_cmp(&tmp, &st->n) != 0)
@@ -462,9 +584,6 @@ static list_t *rsapriv_apply(closure_t *self, struct cloc loc, dict_t *context,
      *   dq == d mod (q-1)      similarly mod q
      *   w == iqmp * q          so that w == 0 mod q, and w == 1 mod p
      */
-    mpz_init(&st->dp);
-    mpz_init(&st->dq);
-    mpz_init(&st->w);
     mpz_sub_ui(&tmp, &st->p, 1);
     mpz_mod(&st->dp, &d, &tmp);
     mpz_sub_ui(&tmp, &st->q, 1);
@@ -473,19 +592,83 @@ static list_t *rsapriv_apply(closure_t *self, struct cloc loc, dict_t *context,
     
 done_checks:
     if (!valid) {
-	cfgfatal(loc,"rsa-private","file \"%s\" does not contain a "
+	LDFATAL("file \"%s\" does not contain a "
 		 "valid RSA key!\n",filename);
     }
+
+assume_valid:
+out:
     mpz_clear(&tmp);
     mpz_clear(&tmp2);
     mpz_clear(&tmp3);
 
-    free(c);
+    FREE(b);
+    FREE(c);
     mpz_clear(&e);
     mpz_clear(&d);
     mpz_clear(&iqmp);
 
-assume_valid:
+    return st;
+
+error_out:
+    if (st) rsapriv_dispose(st);
+    st=0;
+    goto out;
+}
+
+static void verror_cfgfatal(struct rsapriv_load_ctx *l,
+			    FILE *maybe_f, bool_t unsup,
+			    const char *message, va_list args)
+{
+    vcfgfatal_maybefile(maybe_f,l->u.apply.loc,"rsa-private",message,args);
+}
+
+static list_t *rsapriv_apply(closure_t *self, struct cloc loc, dict_t *context,
+			     list_t *args)
+{
+    struct rsapriv *st;
+    item_t *i;
+    cstring_t filename;
+    FILE *f;
+    struct rsapriv_load_ctx l[1];
+
+    l->verror=verror_cfgfatal;
+    l->u.apply.loc=loc;
+
+    /* Argument is filename pointing to SSH1 private key file */
+    i=list_elem(args,0);
+    if (i) {
+	if (i->type!=t_string) {
+	    cfgfatal(i->loc,"rsa-private","first argument must be a string\n");
+	}
+	filename=i->data.string;
+    } else {
+	filename=NULL; /* Make compiler happy */
+	cfgfatal(i->loc,"rsa-private","you must provide a filename\n");
+    }
+
+    f=fopen(filename,"rb");
+    if (!f) {
+	if (just_check_config) {
+	    Message(M_WARNING,"rsa-private (%s:%d): cannot open keyfile "
+		    "\"%s\"; assuming it's valid while we check the "
+		    "rest of the configuration\n",loc.file,loc.line,filename);
+	} else {
+	    fatal_perror("rsa-private (%s:%d): cannot open file \"%s\"",
+			 loc.file,loc.line,filename);
+	}
+    }
+
+    bool_t do_validity_check=True;
+    i=list_elem(args,1);
+    if (i && i->type==t_bool && i->data.bool==False) {
+	Message(M_INFO,"rsa-private (%s:%d): skipping RSA key validity "
+		"check\n",loc.file,loc.line);
+	do_validity_check=False;
+    }
+
+    st=rsa_loadpriv_core(l,f,loc,do_validity_check,filename);
+    fclose(f);
     return new_closure(&st->cl);
 }