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authorAris Adamantiadis <aris@0xbadc0de.be>2011-09-16 23:36:20 +0200
committerAris Adamantiadis <aris@0xbadc0de.be>2011-09-18 20:34:15 +0200
commit07abc3406df3b6b37471e10e495efb79003f5679 (patch)
tree73b635f912977b6d3cf5c8e3830d527eb3aef1ed
parent1b10b175fcd5c6f205168434cc5f6aca51b1d298 (diff)
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kex: split key selection and sending
-rw-r--r--include/libssh/ecdh.h3
-rw-r--r--include/libssh/kex.h7
-rw-r--r--include/libssh/priv.h11
-rw-r--r--include/libssh/session.h4
-rw-r--r--src/client.c7
-rw-r--r--src/ecdh.c8
-rw-r--r--src/kex.c81
-rw-r--r--src/server.c59
-rw-r--r--src/session.c2
-rw-r--r--src/wrapper.c14
10 files changed, 113 insertions, 83 deletions
diff --git a/include/libssh/ecdh.h b/include/libssh/ecdh.h
index 5cc208ce..e86bbe82 100644
--- a/include/libssh/ecdh.h
+++ b/include/libssh/ecdh.h
@@ -35,5 +35,8 @@
int ssh_client_ecdh_init(ssh_session session);
int ssh_client_ecdh_reply(ssh_session session, ssh_buffer packet);
+#ifdef WITH_SERVER
+int ssh_server_ecdh_init(ssh_session session, ssh_buffer packet);
+#endif /* WITH_SERVER */
#endif /* ECDH_H_ */
diff --git a/include/libssh/kex.h b/include/libssh/kex.h
index ce2a102b..dbf69ab9 100644
--- a/include/libssh/kex.h
+++ b/include/libssh/kex.h
@@ -25,6 +25,13 @@
#include "libssh/priv.h"
#include "libssh/callbacks.h"
+#define SSH_KEX_METHODS 10
+
+typedef struct ssh_kex_struct {
+ unsigned char cookie[16];
+ char *methods[SSH_KEX_METHODS];
+} KEX;
+
SSH_PACKET_CALLBACK(ssh_packet_kexinit);
#ifdef WITH_SSH1
SSH_PACKET_CALLBACK(ssh_packet_publickey1);
diff --git a/include/libssh/priv.h b/include/libssh/priv.h
index aa22d10f..80175ece 100644
--- a/include/libssh/priv.h
+++ b/include/libssh/priv.h
@@ -121,11 +121,6 @@ extern "C" {
#include <sys/time.h>
#endif
-typedef struct kex_struct {
- unsigned char cookie[16];
- char **methods;
-} KEX;
-
struct error_struct {
/* error handling */
int error_code;
@@ -137,6 +132,7 @@ struct error_struct {
struct ssh_message_struct;
struct ssh_common_struct;
+struct ssh_kex_struct;
/* server data */
@@ -197,8 +193,9 @@ void ssh_sock_set_blocking(socket_t sock);
/* in kex.c */
extern const char *ssh_kex_nums[];
int ssh_send_kex(ssh_session session, int server_kex);
-void ssh_list_kex(ssh_session session, KEX *kex);
-int set_kex(ssh_session session);
+void ssh_list_kex(ssh_session session, struct ssh_kex_struct *kex);
+int set_client_kex(ssh_session session);
+int ssh_kex_select_methods(ssh_session session);
int verify_existing_algo(int algo, const char *name);
char **space_tokenize(const char *chain);
int ssh_get_kex1(ssh_session session);
diff --git a/include/libssh/session.h b/include/libssh/session.h
index a1b2a798..ac2ca76e 100644
--- a/include/libssh/session.h
+++ b/include/libssh/session.h
@@ -27,6 +27,7 @@
#include "libssh/auth.h"
#include "libssh/channels.h"
#include "libssh/poll.h"
+#include "libssh/kex.h"
/* These are the different states a SSH session can be into its life */
enum ssh_session_state_e {
@@ -122,8 +123,11 @@ struct ssh_session_struct {
struct ssh_agent_state_struct *agent_state;
struct ssh_auth_auto_state_struct *auth_auto_state;
+ /* kex sent by server, client, and mutually elected methods */
KEX server_kex;
KEX client_kex;
+ char *kex_methods[SSH_KEX_METHODS];
+
ssh_buffer in_hashbuf;
ssh_buffer out_hashbuf;
struct ssh_crypto_struct *current_crypto;
diff --git a/src/client.c b/src/client.c
index c8500ba4..f3683079 100644
--- a/src/client.c
+++ b/src/client.c
@@ -546,9 +546,11 @@ static void ssh_client_connection_callback(ssh_session session){
case SSH_SESSION_STATE_KEXINIT_RECEIVED:
set_status(session,0.6f);
ssh_list_kex(session, &session->server_kex);
- if (set_kex(session) < 0) {
+ if (set_client_kex(session) < 0) {
goto error;
}
+ if (ssh_kex_select_methods(session) == SSH_ERROR)
+ goto error;
if (ssh_send_kex(session, 0) < 0) {
goto error;
}
@@ -819,8 +821,7 @@ error:
SAFE_FREE(session->server_kex.methods[i]);
}
}
- SAFE_FREE(session->client_kex.methods);
- SAFE_FREE(session->server_kex.methods);
+
if(session->ssh_message_list){
ssh_message msg;
while((msg=ssh_list_pop_head(ssh_message ,session->ssh_message_list))
diff --git a/src/ecdh.c b/src/ecdh.c
index 75620e44..3d411bbe 100644
--- a/src/ecdh.c
+++ b/src/ecdh.c
@@ -166,4 +166,12 @@ error:
return SSH_ERROR;
}
+#ifdef WITH_SERVER
+
+int ssh_server_ecdh_init(ssh_session session, ssh_buffer packet){
+ return SSH_OK;
+}
+
+#endif /* WITH_SERVER */
+
#endif /* HAVE_ECDH */
diff --git a/src/kex.c b/src/kex.c
index fdff206d..54ab0e95 100644
--- a/src/kex.c
+++ b/src/kex.c
@@ -303,22 +303,10 @@ SSH_PACKET_CALLBACK(ssh_packet_kexinit){
/* copy the server kex info into an array of strings */
if (server_kex) {
- session->client_kex.methods = malloc(10 * sizeof(char **));
- if (session->client_kex.methods == NULL) {
- ssh_set_error_oom(session);
- goto error;
- }
-
for (i = 0; i < 10; i++) {
session->client_kex.methods[i] = strings[i];
}
} else { /* client */
- session->server_kex.methods = malloc(10 * sizeof(char **));
- if (session->server_kex.methods == NULL) {
- ssh_set_error_oom(session);
- goto error;
- }
-
for (i = 0; i < 10; i++) {
session->server_kex.methods[i] = strings[i];
}
@@ -355,52 +343,61 @@ void ssh_list_kex(ssh_session session, KEX *kex) {
}
}
-/* set_kex basicaly look at the option structure of the session and set the output kex message */
-/* it must be aware of the server kex message */
-/* it can fail if option is null, not any user specified kex method matches the server one, if not any default kex matches */
-
-int set_kex(ssh_session session){
- KEX *server = &session->server_kex;
- KEX *client=&session->client_kex;
+/**
+ * @brief sets the key exchange parameters to be sent to the server,
+ * in function of the options and available methods.
+ */
+int set_client_kex(ssh_session session){
+ KEX *client= &session->client_kex;
int i;
const char *wanted;
enter_function();
ssh_get_random(client->cookie,16,0);
- client->methods=malloc(10 * sizeof(char **));
- if (client->methods == NULL) {
- ssh_set_error_oom(session);
- leave_function();
- return -1;
- }
memset(client->methods,0,10*sizeof(char **));
for (i=0;i<10;i++){
- if(!(wanted=session->wanted_methods[i]))
+ wanted=session->wanted_methods[i];
+ if(wanted == NULL)
wanted=default_methods[i];
- client->methods[i]=ssh_find_matching(server->methods[i],wanted);
- if(!client->methods[i] && i < SSH_LANG_C_S){
- ssh_set_error(session,SSH_FATAL,"kex error : did not find one of algos %s in list %s for %s",
- wanted,server->methods[i],ssh_kex_nums[i]);
- leave_function();
- return -1;
- } else {
- if ((i >= SSH_LANG_C_S) && (client->methods[i] == NULL)) {
+ client->methods[i]=strdup(wanted);
+ }
+ leave_function();
+ return SSH_OK;
+}
+
+/** @brief Select the different methods on basis of client's and
+ * server's kex messages, and watches out if a match is possible.
+ */
+int ssh_kex_select_methods (ssh_session session){
+ KEX *server = &session->server_kex;
+ KEX *client = &session->client_kex;
+ int rc = SSH_ERROR;
+ int i;
+
+ enter_function();
+
+ for (i=0;i<10;i++){
+ session->kex_methods[i]=ssh_find_matching(server->methods[i],client->methods[i]);
+ if(session->kex_methods[i] == NULL && i < SSH_LANG_C_S){
+ ssh_set_error(session,SSH_FATAL,"kex error : no match for method %s: server [%s], client [%s]",
+ ssh_kex_nums[i],server->methods[i],client->methods[i]);
+ goto error;
+ } else if ((i >= SSH_LANG_C_S) && (session->kex_methods[i] == NULL)) {
/* we can safely do that for languages */
- client->methods[i] = strdup("");
- if (client->methods[i] == NULL) {
- return -1;
- }
- }
+ session->kex_methods[i] = strdup("");
}
}
- if(strcmp(client->methods[SSH_KEX], "diffie-hellman-group1-sha1") == 0){
+ if(strcmp(session->kex_methods[SSH_KEX], "diffie-hellman-group1-sha1") == 0){
session->next_crypto->kex_type=SSH_KEX_DH_GROUP1_SHA1;
- } else if(strcmp(client->methods[SSH_KEX], "ecdh-sha2-nistp256") == 0){
+ } else if(strcmp(session->kex_methods[SSH_KEX], "ecdh-sha2-nistp256") == 0){
session->next_crypto->kex_type=SSH_KEX_ECDH_SHA2_NISTP256;
}
+ rc = SSH_OK;
+error:
leave_function();
- return 0;
+ return rc;
}
+
/* this function only sends the predefined set of kex methods */
int ssh_send_kex(ssh_session session, int server_kex) {
KEX *kex = (server_kex ? &session->server_kex : &session->client_kex);
diff --git a/src/server.c b/src/server.c
index 97eb40f3..baab4f57 100644
--- a/src/server.c
+++ b/src/server.c
@@ -104,11 +104,6 @@ static int server_set_kex(ssh_session session) {
}
}
- server->methods = malloc(10 * sizeof(char *));
- if (server->methods == NULL) {
- return -1;
- }
-
for (i = 0; i < 10; i++) {
if ((wanted = session->wanted_methods[i]) == NULL) {
wanted = supported_methods[i];
@@ -118,7 +113,6 @@ static int server_set_kex(ssh_session session) {
for (j = i - 1; j <= 0; j--) {
SAFE_FREE(server->methods[j]);
}
- SAFE_FREE(server->methods);
return -1;
}
}
@@ -126,29 +120,50 @@ static int server_set_kex(ssh_session session) {
return 0;
}
+/** @internal
+ * @brief parse an incoming SSH_MSG_KEXDH_INIT packet and complete
+ * key exchange
+ **/
+static int ssh_server_kexdh_init(ssh_session session, ssh_buffer packet){
+ ssh_string e;
+ e = buffer_get_ssh_string(packet);
+ if (e == NULL) {
+ ssh_set_error(session, SSH_FATAL, "No e number in client request");
+ return -1;
+ }
+ if (dh_import_e(session, e) < 0) {
+ ssh_set_error(session, SSH_FATAL, "Cannot import e number");
+ session->session_state=SSH_SESSION_STATE_ERROR;
+ } else {
+ session->dh_handshake_state=DH_STATE_INIT_SENT;
+ dh_handshake_server(session);
+ }
+ ssh_string_free(e);
+ return SSH_OK;
+}
+
SSH_PACKET_CALLBACK(ssh_packet_kexdh_init){
- ssh_string e;
+ int rc;
(void)type;
- (void)user;enter_function();
+ (void)user;
+ enter_function();
ssh_log(session,SSH_LOG_PACKET,"Received SSH_MSG_KEXDH_INIT");
if(session->dh_handshake_state != DH_STATE_INIT){
ssh_log(session,SSH_LOG_RARE,"Invalid state for SSH_MSG_KEXDH_INIT");
goto error;
}
- e = buffer_get_ssh_string(packet);
- if (e == NULL) {
- ssh_set_error(session, SSH_FATAL, "No e number in client request");
- return -1;
- }
- if (dh_import_e(session, e) < 0) {
- ssh_set_error(session, SSH_FATAL, "Cannot import e number");
- session->session_state=SSH_SESSION_STATE_ERROR;
- } else {
- session->dh_handshake_state=DH_STATE_INIT_SENT;
- dh_handshake_server(session);
+ switch(session->next_crypto->kex_type){
+ case SSH_KEX_DH_GROUP1_SHA1:
+ rc=ssh_server_kexdh_init(session, packet);
+ break;
+ #ifdef HAVE_ECDH
+ case SSH_KEX_ECDH_SHA2_NISTP256:
+ rc = ssh_server_ecdh_init(session, packet);
+ break;
+ #endif
+ default:
+ ssh_set_error(session,SSH_FATAL,"Wrong kex type in ssh_packet_kexdh_init");
}
- ssh_string_free(e);
-
error:
leave_function();
return SSH_PACKET_USED;
@@ -343,7 +358,7 @@ static void ssh_server_connection_callback(ssh_session session){
set_status(session,0.6f);
ssh_list_kex(session, &session->client_kex); // log client kex
crypt_set_algorithms_server(session);
- if (set_kex(session) < 0) {
+ if (ssh_kex_select_methods(session) < 0) {
goto error;
}
set_status(session,0.8f);
diff --git a/src/session.c b/src/session.c
index 55ff22a7..ba03a89b 100644
--- a/src/session.c
+++ b/src/session.c
@@ -208,8 +208,6 @@ void ssh_free(ssh_session session) {
SAFE_FREE(session->server_kex.methods[i]);
}
}
- SAFE_FREE(session->client_kex.methods);
- SAFE_FREE(session->server_kex.methods);
ssh_key_free(session->srv.dsa_key);
ssh_key_free(session->srv.rsa_key);
diff --git a/src/wrapper.c b/src/wrapper.c
index f1eebbc2..43648cb3 100644
--- a/src/wrapper.c
+++ b/src/wrapper.c
@@ -159,14 +159,14 @@ static int crypt_set_algorithms2(ssh_session session){
struct crypto_struct *ssh_ciphertab=ssh_get_ciphertab();
/* we must scan the kex entries to find crypto algorithms and set their appropriate structure */
/* out */
- wanted = session->client_kex.methods[SSH_CRYPT_C_S];
+ wanted = session->kex_methods[SSH_CRYPT_C_S];
while (ssh_ciphertab[i].name && strcmp(wanted, ssh_ciphertab[i].name)) {
i++;
}
if (ssh_ciphertab[i].name == NULL) {
ssh_set_error(session, SSH_FATAL,
- "Crypt_set_algorithms2: no crypto algorithm function found for %s",
+ "crypt_set_algorithms2: no crypto algorithm function found for %s",
wanted);
return SSH_ERROR;
}
@@ -180,7 +180,7 @@ static int crypt_set_algorithms2(ssh_session session){
i = 0;
/* in */
- wanted = session->client_kex.methods[SSH_CRYPT_S_C];
+ wanted = session->kex_methods[SSH_CRYPT_S_C];
while (ssh_ciphertab[i].name && strcmp(wanted, ssh_ciphertab[i].name)) {
i++;
}
@@ -200,16 +200,16 @@ static int crypt_set_algorithms2(ssh_session session){
}
/* compression */
- if (strcmp(session->client_kex.methods[SSH_COMP_C_S], "zlib") == 0) {
+ if (strcmp(session->kex_methods[SSH_COMP_C_S], "zlib") == 0) {
session->next_crypto->do_compress_out = 1;
}
- if (strcmp(session->client_kex.methods[SSH_COMP_S_C], "zlib") == 0) {
+ if (strcmp(session->kex_methods[SSH_COMP_S_C], "zlib") == 0) {
session->next_crypto->do_compress_in = 1;
}
- if (strcmp(session->client_kex.methods[SSH_COMP_C_S], "zlib@openssh.com") == 0) {
+ if (strcmp(session->kex_methods[SSH_COMP_C_S], "zlib@openssh.com") == 0) {
session->next_crypto->delayed_compress_out = 1;
}
- if (strcmp(session->client_kex.methods[SSH_COMP_S_C], "zlib@openssh.com") == 0) {
+ if (strcmp(session->kex_methods[SSH_COMP_S_C], "zlib@openssh.com") == 0) {
session->next_crypto->delayed_compress_in = 1;
}
return SSH_OK;