version 1.4, 2000/04/14 10:30:29 |
version 1.5, 2000/04/26 20:56:29 |
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#include "includes.h" |
#include "includes.h" |
RCSID("$OpenBSD$"); |
RCSID("$OpenBSD$"); |
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#include <openssl/dsa.h> |
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#include <openssl/rsa.h> |
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#include <openssl/evp.h> |
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#include "xmalloc.h" |
#include "xmalloc.h" |
#include "rsa.h" |
#include "rsa.h" |
#include "ssh.h" |
#include "ssh.h" |
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#include "compat.h" |
#include "compat.h" |
#include "channels.h" |
#include "channels.h" |
#include "match.h" |
#include "match.h" |
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#include "bufaux.h" |
#include "bufaux.h" |
#include "ssh2.h" |
#include "ssh2.h" |
#include "auth.h" |
#include "auth.h" |
#include "session.h" |
#include "session.h" |
#include "dispatch.h" |
#include "dispatch.h" |
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#include "key.h" |
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#include "kex.h" |
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#include "dsa.h" |
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#include "uidswap.h" |
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#include "channels.h" |
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/* import */ |
/* import */ |
extern ServerOptions options; |
extern ServerOptions options; |
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* If the user's shell is not executable, false will be returned. |
* If the user's shell is not executable, false will be returned. |
* Otherwise true is returned. |
* Otherwise true is returned. |
*/ |
*/ |
static int |
int |
allowed_user(struct passwd * pw) |
allowed_user(struct passwd * pw) |
{ |
{ |
struct stat st; |
struct stat st; |
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return 1; |
return 1; |
} |
} |
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/* import */ |
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extern ServerOptions options; |
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extern char *forced_command; |
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/* |
/* |
* convert ssh auth msg type into description |
* convert ssh auth msg type into description |
*/ |
*/ |
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do_authenticated(pw); |
do_authenticated(pw); |
} |
} |
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/* import */ |
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extern ServerOptions options; |
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extern unsigned char *session_id2; |
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extern int session_id2_len; |
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void input_service_request(int type, int plen); |
/* protocol */ |
void input_userauth_request(int type, int plen); |
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void ssh2_pty_cleanup(void); |
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void input_service_request(int type, int plen); |
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void input_userauth_request(int type, int plen); |
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void protocol_error(int type, int plen); |
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/* auth */ |
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int ssh2_auth_none(struct passwd *pw); |
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int ssh2_auth_password(struct passwd *pw); |
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int ssh2_auth_pubkey(struct passwd *pw, unsigned char *raw, unsigned int rlen); |
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/* helper */ |
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struct passwd* auth_set_user(char *u, char *s); |
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int user_dsa_key_allowed(struct passwd *pw, Key *key); |
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typedef struct Authctxt Authctxt; |
typedef struct Authctxt Authctxt; |
struct Authctxt { |
struct Authctxt { |
char *user; |
char *user; |
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static Authctxt *authctxt = NULL; |
static Authctxt *authctxt = NULL; |
static int userauth_success = 0; |
static int userauth_success = 0; |
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/* set and get current user */ |
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struct passwd* |
struct passwd* |
auth_get_user(void) |
auth_get_user(void) |
{ |
{ |
return (authctxt != NULL && authctxt->valid) ? &authctxt->pw : NULL; |
return (authctxt != NULL && authctxt->valid) ? &authctxt->pw : NULL; |
} |
} |
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struct passwd* |
struct passwd* |
auth_set_user(char *u, char *s) |
auth_set_user(char *u, char *s) |
{ |
{ |
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return auth_get_user(); |
return auth_get_user(); |
} |
} |
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static void |
/* |
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* loop until userauth_success == TRUE |
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*/ |
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void |
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do_authentication2() |
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{ |
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dispatch_init(&protocol_error); |
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dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); |
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dispatch_run(DISPATCH_BLOCK, &userauth_success); |
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do_authenticated2(); |
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} |
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void |
protocol_error(int type, int plen) |
protocol_error(int type, int plen) |
{ |
{ |
log("auth: protocol error: type %d plen %d", type, plen); |
log("auth: protocol error: type %d plen %d", type, plen); |
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packet_send(); |
packet_send(); |
packet_write_wait(); |
packet_write_wait(); |
} |
} |
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void |
void |
input_service_request(int type, int plen) |
input_service_request(int type, int plen) |
{ |
{ |
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} |
} |
xfree(service); |
xfree(service); |
} |
} |
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void |
void |
input_userauth_request(int type, int plen) |
input_userauth_request(int type, int plen) |
{ |
{ |
static int try = 0; |
static int try = 0; |
unsigned int len; |
unsigned int len, rlen; |
int c, authenticated = 0; |
int authenticated = 0; |
char *user, *service, *method; |
char *raw, *user, *service, *method; |
struct passwd *pw; |
struct passwd *pw; |
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if (++try == AUTH_FAIL_MAX) |
if (++try == AUTH_FAIL_MAX) |
packet_disconnect("too many failed userauth_requests"); |
packet_disconnect("too many failed userauth_requests"); |
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raw = packet_get_raw(&rlen); |
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if (plen != rlen) |
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fatal("plen != rlen"); |
user = packet_get_string(&len); |
user = packet_get_string(&len); |
service = packet_get_string(&len); |
service = packet_get_string(&len); |
method = packet_get_string(&len); |
method = packet_get_string(&len); |
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/* XXX we only allow the ssh-connection service */ |
/* XXX we only allow the ssh-connection service */ |
pw = auth_set_user(user, service); |
pw = auth_set_user(user, service); |
if (pw && strcmp(service, "ssh-connection")==0) { |
if (pw && strcmp(service, "ssh-connection")==0) { |
if (strcmp(method, "none") == 0 && try == 1) { |
if (strcmp(method, "none") == 0) { |
packet_done(); |
authenticated = ssh2_auth_none(pw); |
authenticated = auth_password(pw, ""); |
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} else if (strcmp(method, "password") == 0) { |
} else if (strcmp(method, "password") == 0) { |
char *password; |
authenticated = ssh2_auth_password(pw); |
c = packet_get_char(); |
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if (c) |
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debug("password change not supported"); |
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password = packet_get_string(&len); |
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packet_done(); |
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authenticated = auth_password(pw, password); |
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memset(password, 0, len); |
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xfree(password); |
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} else if (strcmp(method, "publickey") == 0) { |
} else if (strcmp(method, "publickey") == 0) { |
/* XXX TODO */ |
authenticated = ssh2_auth_pubkey(pw, raw, rlen); |
char *pkalg, *pkblob, *sig; |
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int have_sig = packet_get_char(); |
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pkalg = packet_get_string(&len); |
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pkblob = packet_get_string(&len); |
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if (have_sig) { |
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sig = packet_get_string(&len); |
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/* test for correct signature */ |
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packet_done(); |
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xfree(sig); |
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} else { |
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packet_done(); |
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/* test whether pkalg/pkblob are acceptable */ |
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} |
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xfree(pkalg); |
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xfree(pkblob); |
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} |
} |
} |
} |
/* XXX check if other auth methods are needed */ |
/* XXX check if other auth methods are needed */ |
if (authenticated) { |
if (authenticated == 1) { |
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log("userauth success for %s method %s", user, method); |
/* turn off userauth */ |
/* turn off userauth */ |
dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &protocol_error); |
dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &protocol_error); |
packet_start(SSH2_MSG_USERAUTH_SUCCESS); |
packet_start(SSH2_MSG_USERAUTH_SUCCESS); |
packet_send(); |
packet_send(); |
packet_write_wait(); |
packet_write_wait(); |
log("userauth success for %s", user); |
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/* now we can break out */ |
/* now we can break out */ |
userauth_success = 1; |
userauth_success = 1; |
} else { |
} else if (authenticated == 0) { |
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log("userauth failure for %s method %s", user, method); |
packet_start(SSH2_MSG_USERAUTH_FAILURE); |
packet_start(SSH2_MSG_USERAUTH_FAILURE); |
packet_put_cstring("password"); |
packet_put_cstring("publickey,password"); /* XXX dynamic */ |
packet_put_char(0); /* partial success */ |
packet_put_char(0); /* XXX partial success, unused */ |
packet_send(); |
packet_send(); |
packet_write_wait(); |
packet_write_wait(); |
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} else { |
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log("userauth postponed for %s method %s", user, method); |
} |
} |
xfree(service); |
xfree(service); |
xfree(user); |
xfree(user); |
xfree(method); |
xfree(method); |
} |
} |
void |
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do_authentication2() |
int |
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ssh2_auth_none(struct passwd *pw) |
{ |
{ |
dispatch_init(&protocol_error); |
packet_done(); |
dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); |
return auth_password(pw, ""); |
dispatch_run(DISPATCH_BLOCK, &userauth_success); |
} |
do_authenticated2(); |
int |
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ssh2_auth_password(struct passwd *pw) |
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{ |
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char *password; |
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int authenticated = 0; |
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int change; |
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unsigned int len; |
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change = packet_get_char(); |
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if (change) |
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log("password change not supported"); |
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password = packet_get_string(&len); |
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packet_done(); |
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if (auth_password(pw, password)) |
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authenticated = 1; |
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memset(password, 0, len); |
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xfree(password); |
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return authenticated; |
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} |
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int |
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ssh2_auth_pubkey(struct passwd *pw, unsigned char *raw, unsigned int rlen) |
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{ |
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Buffer b; |
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Key *key; |
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char *pkalg, *pkblob, *sig; |
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unsigned int alen, blen, slen; |
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int have_sig; |
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int authenticated = 0; |
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have_sig = packet_get_char(); |
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pkalg = packet_get_string(&alen); |
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if (strcmp(pkalg, KEX_DSS) != 0) { |
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xfree(pkalg); |
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log("bad pkalg %s", pkalg); /*XXX*/ |
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return 0; |
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} |
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pkblob = packet_get_string(&blen); |
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key = dsa_key_from_blob(pkblob, blen); |
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if (have_sig && key != NULL) { |
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sig = packet_get_string(&slen); |
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packet_done(); |
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buffer_init(&b); |
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buffer_append(&b, session_id2, session_id2_len); |
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buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); |
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if (slen + 4 > rlen) |
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fatal("bad rlen/slen"); |
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buffer_append(&b, raw, rlen - slen - 4); |
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#ifdef DEBUG_DSS |
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buffer_dump(&b); |
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#endif |
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/* test for correct signature */ |
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if (user_dsa_key_allowed(pw, key) && |
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dsa_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1) |
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authenticated = 1; |
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buffer_clear(&b); |
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xfree(sig); |
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} else if (!have_sig && key != NULL) { |
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packet_done(); |
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debug("test key..."); |
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/* test whether pkalg/pkblob are acceptable */ |
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/* XXX fake reply and always send PK_OK ? */ |
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if (user_dsa_key_allowed(pw, key)) { |
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packet_start(SSH2_MSG_USERAUTH_PK_OK); |
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packet_put_string(pkalg, alen); |
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packet_put_string(pkblob, blen); |
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packet_send(); |
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packet_write_wait(); |
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authenticated = -1; |
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} |
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} |
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xfree(pkalg); |
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xfree(pkblob); |
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return authenticated; |
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} |
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/* return 1 if user allows given key */ |
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int |
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user_dsa_key_allowed(struct passwd *pw, Key *key) |
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{ |
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char line[8192], file[1024]; |
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int found_key = 0; |
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unsigned int bits = -1; |
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FILE *f; |
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unsigned long linenum = 0; |
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struct stat st; |
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Key *found; |
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/* Temporarily use the user's uid. */ |
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temporarily_use_uid(pw->pw_uid); |
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/* The authorized keys. */ |
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snprintf(file, sizeof file, "%.500s/%.100s", pw->pw_dir, |
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SSH_USER_PERMITTED_KEYS2); |
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/* Fail quietly if file does not exist */ |
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if (stat(file, &st) < 0) { |
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/* Restore the privileged uid. */ |
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restore_uid(); |
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return 0; |
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} |
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/* Open the file containing the authorized keys. */ |
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f = fopen(file, "r"); |
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if (!f) { |
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/* Restore the privileged uid. */ |
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restore_uid(); |
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packet_send_debug("Could not open %.900s for reading.", file); |
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packet_send_debug("If your home is on an NFS volume, it may need to be world-readable."); |
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return 0; |
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} |
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if (options.strict_modes) { |
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int fail = 0; |
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char buf[1024]; |
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/* Check open file in order to avoid open/stat races */ |
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if (fstat(fileno(f), &st) < 0 || |
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(st.st_uid != 0 && st.st_uid != pw->pw_uid) || |
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(st.st_mode & 022) != 0) { |
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snprintf(buf, sizeof buf, "DSA authentication refused for %.100s: " |
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"bad ownership or modes for '%s'.", pw->pw_name, file); |
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fail = 1; |
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} else { |
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/* Check path to SSH_USER_PERMITTED_KEYS */ |
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int i; |
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static const char *check[] = { |
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"", SSH_USER_DIR, NULL |
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}; |
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for (i = 0; check[i]; i++) { |
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snprintf(line, sizeof line, "%.500s/%.100s", |
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pw->pw_dir, check[i]); |
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if (stat(line, &st) < 0 || |
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(st.st_uid != 0 && st.st_uid != pw->pw_uid) || |
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(st.st_mode & 022) != 0) { |
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snprintf(buf, sizeof buf, |
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"DSA authentication refused for %.100s: " |
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"bad ownership or modes for '%s'.", |
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pw->pw_name, line); |
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fail = 1; |
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break; |
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} |
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} |
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} |
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if (fail) { |
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log(buf); |
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fclose(f); |
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restore_uid(); |
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return 0; |
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} |
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} |
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found_key = 0; |
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found = key_new(KEY_DSA); |
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while (fgets(line, sizeof(line), f)) { |
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char *cp; |
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linenum++; |
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/* Skip leading whitespace, empty and comment lines. */ |
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for (cp = line; *cp == ' ' || *cp == '\t'; cp++) |
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; |
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if (!*cp || *cp == '\n' || *cp == '#') |
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continue; |
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bits = key_read(found, &cp); |
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if (bits == 0) |
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continue; |
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if (key_equal(found, key)) { |
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found_key = 1; |
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debug("matching key found: file %s, line %ld", |
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file, linenum); |
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break; |
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} |
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} |
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restore_uid(); |
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fclose(f); |
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key_free(found); |
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return found_key; |
} |
} |