mirror of
https://github.com/clearml/dropbear
synced 2025-02-01 19:34:11 +00:00
Encrypt in-place, avoid an extra malloc
--HG-- extra : convert_revision : 981e3e4b44e6fdc8537775518e898a33e76a38db
This commit is contained in:
Matt Johnston
parent
4b37932ba1
commit
8e72bbaa9d
89
packet.c
89
packet.c
@ -36,7 +36,7 @@
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#include "channel.h"
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static void read_packet_init();
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static void writemac(buffer * outputbuffer, buffer * clearwritebuf);
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static void make_mac(buffer * clearwritebuf, unsigned char *output_mac);
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static int checkmac(buffer* hashbuf, buffer* readbuf);
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#define ZLIB_COMPRESS_INCR 20 /* this is 12 bytes + 0.1% of 8000 bytes */
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@ -449,11 +449,12 @@ void maybe_flush_reply_queue() {
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void encrypt_packet() {
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unsigned char padlen;
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unsigned char blocksize, macsize;
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buffer * writebuf; /* the packet which will go on the wire */
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buffer * clearwritebuf; /* unencrypted, possibly compressed */
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unsigned char blocksize, mac_size;
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buffer * writebuf; /* the packet which will go on the wire. This is
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encrypted in-place. */
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unsigned char type;
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unsigned int len;
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unsigned int len, encrypt_buf_size;
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unsigned char mac_bytes[MAX_MAC_LEN];
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type = ses.writepayload->data[0];
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TRACE(("enter encrypt_packet()"))
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@ -468,33 +469,35 @@ void encrypt_packet() {
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}
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blocksize = ses.keys->trans_algo_crypt->blocksize;
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macsize = ses.keys->trans_algo_mac->hashsize;
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mac_size = ses.keys->trans_algo_mac->hashsize;
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/* Encrypted packet len is payload+5, then worst case is if we are 3 away
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* from a blocksize multiple. In which case we need to pad to the
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* multiple, then add another blocksize (or MIN_PACKET_LEN) */
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len = (ses.writepayload->len+4+1) + MIN_PACKET_LEN + 3;
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encrypt_buf_size = (ses.writepayload->len+4+1) + MIN_PACKET_LEN + 3;
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/* add space for the MAC at the end */
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encrypt_buf_size += mac_size;
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#ifndef DISABLE_ZLIB
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len += ZLIB_COMPRESS_INCR; /* bit of a kludge, but we can't know len*/
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encrypt_buf_size += ZLIB_COMPRESS_INCR; /* bit of a kludge, but we can't know len*/
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#endif
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clearwritebuf = buf_new(len);
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buf_setlen(clearwritebuf, PACKET_PAYLOAD_OFF);
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buf_setpos(clearwritebuf, PACKET_PAYLOAD_OFF);
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writebuf = buf_new(encrypt_buf_size);
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buf_setlen(writebuf, PACKET_PAYLOAD_OFF);
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buf_setpos(writebuf, PACKET_PAYLOAD_OFF);
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buf_setpos(ses.writepayload, 0);
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#ifndef DISABLE_ZLIB
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/* compression */
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if (is_compress_trans()) {
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buf_compress(clearwritebuf, ses.writepayload, ses.writepayload->len);
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buf_compress(writebuf, ses.writepayload, ses.writepayload->len);
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} else
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#endif
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{
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memcpy(buf_getwriteptr(clearwritebuf, ses.writepayload->len),
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memcpy(buf_getwriteptr(writebuf, ses.writepayload->len),
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buf_getptr(ses.writepayload, ses.writepayload->len),
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ses.writepayload->len);
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buf_incrwritepos(clearwritebuf, ses.writepayload->len);
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buf_incrwritepos(writebuf, ses.writepayload->len);
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}
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/* finished with payload */
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@ -503,52 +506,45 @@ void encrypt_packet() {
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/* length of padding - packet length must be a multiple of blocksize,
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* with a minimum of 4 bytes of padding */
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padlen = blocksize - (clearwritebuf->len) % blocksize;
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padlen = blocksize - (writebuf->len) % blocksize;
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if (padlen < 4) {
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padlen += blocksize;
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}
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/* check for min packet length */
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if (clearwritebuf->len + padlen < MIN_PACKET_LEN) {
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if (writebuf->len + padlen < MIN_PACKET_LEN) {
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padlen += blocksize;
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}
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buf_setpos(clearwritebuf, 0);
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buf_setpos(writebuf, 0);
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/* packet length excluding the packetlength uint32 */
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buf_putint(clearwritebuf, clearwritebuf->len + padlen - 4);
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buf_putint(writebuf, writebuf->len + padlen - 4);
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/* padding len */
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buf_putbyte(clearwritebuf, padlen);
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buf_putbyte(writebuf, padlen);
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/* actual padding */
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buf_setpos(clearwritebuf, clearwritebuf->len);
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buf_incrlen(clearwritebuf, padlen);
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genrandom(buf_getptr(clearwritebuf, padlen), padlen);
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buf_setpos(writebuf, writebuf->len);
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buf_incrlen(writebuf, padlen);
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genrandom(buf_getptr(writebuf, padlen), padlen);
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/* do the actual encryption */
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buf_setpos(clearwritebuf, 0);
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/* create a new writebuffer, this is freed when it has been put on the
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* wire by writepacket() */
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writebuf = buf_new(clearwritebuf->len + macsize);
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make_mac(writebuf, mac_bytes);
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/* encrypt it */
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len = clearwritebuf->len;
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/* do the actual encryption, in-place */
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buf_setpos(writebuf, 0);
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/* encrypt it in-place*/
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len = writebuf->len;
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if (ses.keys->trans_crypt_mode->encrypt(
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buf_getptr(clearwritebuf, len),
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buf_getptr(writebuf, len),
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buf_getwriteptr(writebuf, len),
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len,
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&ses.keys->trans_cipher_state) != CRYPT_OK) {
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dropbear_exit("error encrypting");
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}
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buf_incrpos(clearwritebuf, len);
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buf_incrwritepos(writebuf, len);
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buf_incrpos(writebuf, len);
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/* now add a hmac and we're done */
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writemac(writebuf, clearwritebuf);
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/* stick the MAC on it */
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buf_putbytes(writebuf, mac_bytes, mac_size);
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/* clearwritebuf is finished with */
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buf_free(clearwritebuf);
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clearwritebuf = NULL;
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/* enqueue the packet for sending */
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/* enqueue the packet for sending. It will get freed after transmission. */
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buf_setpos(writebuf, 0);
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enqueue(&ses.writequeue, (void*)writebuf);
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@ -561,18 +557,15 @@ void encrypt_packet() {
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/* Create the packet mac, and append H(seqno|clearbuf) to the output */
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static void writemac(buffer * outputbuffer, buffer * clearwritebuf) {
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unsigned int macsize;
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/* output_mac must have ses.keys->trans_algo_mac->hashsize bytes. */
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static void make_mac(buffer * clearwritebuf, unsigned char *output_mac) {
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unsigned char seqbuf[4];
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unsigned char tempbuf[MAX_MAC_LEN];
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unsigned long bufsize;
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hmac_state hmac;
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TRACE(("enter writemac"))
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macsize = ses.keys->trans_algo_mac->hashsize;
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if (macsize > 0) {
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if (ses.keys->trans_algo_mac->hashsize > 0) {
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/* calculate the mac */
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if (hmac_init(&hmac,
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find_hash(ses.keys->trans_algo_mac->hashdesc->name),
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@ -596,12 +589,10 @@ static void writemac(buffer * outputbuffer, buffer * clearwritebuf) {
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dropbear_exit("HMAC error");
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}
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bufsize = sizeof(tempbuf);
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if (hmac_done(&hmac, tempbuf, &bufsize)
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!= CRYPT_OK) {
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bufsize = MAX_MAC_LEN;
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if (hmac_done(&hmac, output_mac, &bufsize) != CRYPT_OK) {
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dropbear_exit("HMAC error");
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}
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buf_putbytes(outputbuffer, tempbuf, macsize);
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}
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TRACE(("leave writemac"))
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}
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