From 78fbed8c3eda1d7f3e0ffa41b54cd3c6ae31a0fe Mon Sep 17 00:00:00 2001 From: Matt Johnston Date: Wed, 3 Apr 2013 00:32:55 +0800 Subject: Don't usually need to recalculate dh_e for the repeated kexdh_init packet --HG-- branch : kexguess --- cli-kex.c | 17 +++++++++++++---- cli-session.c | 10 +++++++--- common-algo.c | 2 +- session.h | 1 + sysoptions.h | 5 +++-- 5 files changed, 25 insertions(+), 10 deletions(-) diff --git a/cli-kex.c b/cli-kex.c index 833529a..1158aa6 100644 --- a/cli-kex.c +++ b/cli-kex.c @@ -43,11 +43,19 @@ static void checkhostkey(unsigned char* keyblob, unsigned int keybloblen); void send_msg_kexdh_init() { TRACE(("send_msg_kexdh_init()")) - cli_ses.dh_e = (mp_int*)m_malloc(sizeof(mp_int)); - cli_ses.dh_x = (mp_int*)m_malloc(sizeof(mp_int)); - m_mp_init_multi(cli_ses.dh_e, cli_ses.dh_x, NULL); + if ((cli_ses.dh_e && cli_ses.dh_x + && cli_ses.dh_val_algo == ses.newkeys->algo_kex)) { + TRACE(("reusing existing dh_e from first_kex_packet_follows")) + } else { + if (!cli_ses.dh_e || !cli_ses.dh_e) { + cli_ses.dh_e = (mp_int*)m_malloc(sizeof(mp_int)); + cli_ses.dh_x = (mp_int*)m_malloc(sizeof(mp_int)); + m_mp_init_multi(cli_ses.dh_e, cli_ses.dh_x, NULL); + } - gen_kexdh_vals(cli_ses.dh_e, cli_ses.dh_x); + gen_kexdh_vals(cli_ses.dh_e, cli_ses.dh_x); + cli_ses.dh_val_algo = ses.newkeys->algo_kex; + } CHECKCLEARTOWRITE(); buf_putbyte(ses.writepayload, SSH_MSG_KEXDH_INIT); @@ -99,6 +107,7 @@ void recv_msg_kexdh_reply() { mp_clear_multi(cli_ses.dh_e, cli_ses.dh_x, NULL); m_free(cli_ses.dh_e); m_free(cli_ses.dh_x); + cli_ses.dh_val_algo = DROPBEAR_KEX_NONE; if (buf_verify(ses.payload, hostkey, ses.hash, SHA1_HASH_SIZE) != DROPBEAR_SUCCESS) { diff --git a/cli-session.c b/cli-session.c index 600827f..9e64281 100644 --- a/cli-session.c +++ b/cli-session.c @@ -182,6 +182,11 @@ static void cli_sessionloop() { TRACE2(("enter cli_sessionloop")) + if (ses.lastpacket == 0) { + TRACE2(("exit cli_sessionloop: no real packets yet")) + return; + } + if (ses.lastpacket == SSH_MSG_KEXINIT && cli_ses.kex_state == KEX_NOTHING) { /* We initiate the KEXDH. If DH wasn't the correct type, the KEXINIT * negotiation would have failed. */ @@ -206,10 +211,9 @@ static void cli_sessionloop() { return; } - /* We should exit if we haven't donefirstkex: we shouldn't reach here - * in normal operation */ if (ses.kexstate.donefirstkex == 0) { - TRACE(("XXX XXX might be bad! leave cli_sessionloop: haven't donefirstkex")) + /* We might reach here if we have partial packet reads or have + * received SSG_MSG_IGNORE etc. Just skip it */ return; } diff --git a/common-algo.c b/common-algo.c index 8267852..b698611 100644 --- a/common-algo.c +++ b/common-algo.c @@ -214,8 +214,8 @@ algo_type sshhostkey[] = { }; algo_type sshkex[] = { - {"diffie-hellman-group1-sha1", DROPBEAR_KEX_DH_GROUP1, NULL, 1, NULL}, {"diffie-hellman-group14-sha1", DROPBEAR_KEX_DH_GROUP14, NULL, 1, NULL}, + {"diffie-hellman-group1-sha1", DROPBEAR_KEX_DH_GROUP1, NULL, 1, NULL}, {KEXGUESS2_ALGO_NAME, KEXGUESS2_ALGO_ID, NULL, 1, NULL}, {NULL, 0, NULL, 0, NULL} }; diff --git a/session.h b/session.h index 33c1539..9bbeac4 100644 --- a/session.h +++ b/session.h @@ -241,6 +241,7 @@ typedef enum { struct clientsession { mp_int *dh_e, *dh_x; /* Used during KEX */ + int dh_val_algo; /* KEX algorithm corresponding to current dh_e and dh_x */ cli_kex_state kex_state; /* Used for progressing KEX */ cli_state state; /* Used to progress auth/channelsession etc */ unsigned donefirstkex : 1; /* Set when we set sentnewkeys, never reset */ diff --git a/sysoptions.h b/sysoptions.h index 6e60294..4d648c1 100644 --- a/sysoptions.h +++ b/sysoptions.h @@ -61,8 +61,9 @@ #define DROPBEAR_FAILURE -1 /* various algorithm identifiers */ -#define DROPBEAR_KEX_DH_GROUP1 0 -#define DROPBEAR_KEX_DH_GROUP14 1 +#define DROPBEAR_KEX_NONE 0 +#define DROPBEAR_KEX_DH_GROUP1 1 +#define DROPBEAR_KEX_DH_GROUP14 2 #define DROPBEAR_SIGNKEY_ANY 0 #define DROPBEAR_SIGNKEY_RSA 1 -- cgit v1.2.3