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/*
* netsniff-ng - the packet sniffing beast
* Copyright 2011 - 2013 Daniel Borkmann.
* Subject to the GPL, version 2.
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <errno.h>
#include <fcntl.h>
#include <syslog.h>
#include <limits.h>
#include <string.h>
#include <pwd.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/stat.h>
#include "built_in.h"
#include "xmalloc.h"
#include "curve.h"
#include "ioops.h"
#include "rnd.h"
#include "die.h"
#include "str.h"
#include "curvetun.h"
#include "locking.h"
#include "crypto.h"
int curve25519_pubkey_hexparse_32(unsigned char *bin, size_t blen,
const char *ascii, size_t alen)
{
int ret = sscanf(ascii,
"%2hhx:%2hhx:%2hhx:%2hhx:%2hhx:%2hhx:%2hhx:%2hhx:"
"%2hhx:%2hhx:%2hhx:%2hhx:%2hhx:%2hhx:%2hhx:%2hhx:"
"%2hhx:%2hhx:%2hhx:%2hhx:%2hhx:%2hhx:%2hhx:%2hhx:"
"%2hhx:%2hhx:%2hhx:%2hhx:%2hhx:%2hhx:%2hhx:%2hhx",
&bin[0], &bin[1], &bin[2], &bin[3], &bin[4],
&bin[5], &bin[6], &bin[7], &bin[8], &bin[9],
&bin[10], &bin[11], &bin[12], &bin[13], &bin[14],
&bin[15], &bin[16], &bin[17], &bin[18], &bin[19],
&bin[20], &bin[21], &bin[22], &bin[23], &bin[24],
&bin[25], &bin[26], &bin[27], &bin[28], &bin[29],
&bin[30], &bin[31]);
return ret == 32;
}
void curve25519_alloc_or_maybe_die(struct curve25519_struct *curve)
{
curve->enc_size = curve->dec_size = TUNBUFF_SIZ;
curve->enc = xmalloc_aligned(curve->enc_size, 16);
curve->dec = xmalloc_aligned(curve->dec_size, 16);
spinlock_init(&curve->enc_lock);
spinlock_init(&curve->dec_lock);
}
void curve25519_free(void *curvep)
{
struct curve25519_struct *curve = curvep;
xzfree(curve->enc, curve->enc_size);
xzfree(curve->dec, curve->dec_size);
spinlock_destroy(&curve->enc_lock);
spinlock_destroy(&curve->dec_lock);
}
void curve25519_proto_init(struct curve25519_proto *proto,
unsigned char *pubkey_remote, size_t len)
{
int result;
char file[128];
struct passwd *pw = getpwuid(getuid());
unsigned char secretkey_own[crypto_box_sec_key_size];
unsigned char publickey_own[crypto_box_pub_key_size];
fmemset(secretkey_own, 0, sizeof(secretkey_own));
fmemset(publickey_own, 0, sizeof(publickey_own));
if (unlikely(!pubkey_remote || len != sizeof(publickey_own)))
panic("Invalid argument on curve25519_proto_init!\n");
slprintf(file, sizeof(file), "%s/%s", pw->pw_dir, FILE_PRIVKEY);
read_blob_or_die(file, secretkey_own, sizeof(secretkey_own));
crypto_scalarmult_curve25519_base(publickey_own, secretkey_own);
result = crypto_verify_32(publickey_own, pubkey_remote);
if (result == 0)
panic("Remote end has same public key as you have!\n");
crypto_box_beforenm(proto->key, pubkey_remote, secretkey_own);
fmemset(proto->enonce, 0, sizeof(proto->enonce));
fmemset(proto->dnonce, 0, sizeof(proto->dnonce));
xmemset(secretkey_own, 0, sizeof(secretkey_own));
xmemset(publickey_own, 0, sizeof(publickey_own));
}
ssize_t curve25519_encode(struct curve25519_struct *curve, struct curve25519_proto *proto,
unsigned char *plaintext, size_t size, unsigned char **chipertext)
{
int ret, i;
ssize_t done = size;
struct taia packet_taia;
spinlock_lock(&curve->enc_lock);
if (unlikely(size > curve->enc_size)) {
done = -ENOMEM;
goto out;
}
taia_now(&packet_taia);
taia_pack(proto->enonce + NONCE_OFFSET, &packet_taia);
memset(curve->enc, 0, curve->enc_size);
ret = crypto_box_afternm(curve->enc, plaintext, size, proto->enonce, proto->key);
if (unlikely(ret)) {
done = -EIO;
goto out;
}
fmemcpy(curve->enc + crypto_box_boxzerobytes - NONCE_LENGTH,
proto->enonce + NONCE_OFFSET, NONCE_LENGTH);
for (i = 0; i < crypto_box_boxzerobytes - NONCE_LENGTH; ++i)
curve->enc[i] = (uint8_t) secrand();
(*chipertext) = curve->enc;
out:
spinlock_unlock(&curve->enc_lock);
return done;
}
ssize_t curve25519_decode(struct curve25519_struct *curve, struct curve25519_proto *proto,
unsigned char *chipertext, size_t size, unsigned char **plaintext,
struct taia *arrival_taia)
{
int ret;
ssize_t done = size;
struct taia packet_taia, arrival_taia2;
spinlock_lock(&curve->dec_lock);
if (unlikely(size > curve->dec_size)) {
done = -ENOMEM;
goto out;
}
if (unlikely(size < crypto_box_boxzerobytes + NONCE_LENGTH)) {
done = 0;
goto out;
}
if (arrival_taia == NULL) {
taia_now(&arrival_taia2);
arrival_taia = &arrival_taia2;
}
taia_unpack(chipertext + crypto_box_boxzerobytes - NONCE_LENGTH, &packet_taia);
if (taia_looks_good(arrival_taia, &packet_taia) == 0) {
syslog(LOG_ERR, "Bad packet time! Dropping connection!\n");
done = 0;
goto out;
}
memcpy(proto->dnonce + NONCE_OFFSET, chipertext + crypto_box_boxzerobytes - NONCE_LENGTH, NONCE_LENGTH);
memset(curve->dec, 0, curve->dec_size);
ret = crypto_box_open_afternm(curve->dec, chipertext, size, proto->dnonce, proto->key);
if (unlikely(ret)) {
done = -EIO;
goto out;
}
(*plaintext) = curve->dec;
out:
spinlock_unlock(&curve->dec_lock);
return done;
}
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