Auth-tokens can expire. For by reconnecting when the server uses auth-gen-toke.
Behaviour of OpenVPN client is to never fallback to the previous authentication method and continue using the auth-token. Depending on auth-retry it either quit or tried endlessly with an expired token. Since auth-gen-token tokens expire on reconnect, a client will not survive a reconnect. This patches changes the behaviour on failed auth when using an auth-token as a soft error (USR1) and clean the auth-token falling back to the original auth method. Patch V2: properly formatted commit message, fix openvpn3 detection Patch V3: remove all server changes, include only minimal non intrusive client changes that only improve error recovery but don't change overall behaviour. Patch V4: forget add push.c to git index, now also included --- doc/openvpn.8 | 8 +++++++- src/openvpn/misc.c | 16 ++++++++++------ src/openvpn/misc.h | 3 +-- src/openvpn/push.c | 16 ++++++++++++++-- src/openvpn/ssl.c | 36 ++++++++++++++++++++++-------------- src/openvpn/ssl.h | 2 ++ 6 files changed, 56 insertions(+), 25 deletions(-) diff --git a/doc/openvpn.8 b/doc/openvpn.8 index 6ced4e4b..dc210890 100644 --- a/doc/openvpn.8 +++ b/doc/openvpn.8 @@ -5362,7 +5362,13 @@ push "auth\-token UNIQUE_TOKEN_VALUE" into the file/buffer for dynamic configuration data. This will then make the OpenVPN server to push this value to the client, which replaces the local password with the -UNIQUE_TOKEN_VALUE. +UNIQUE_TOKEN_VALUE. + +Newer clients (2.4.6+) will fall back to the original password method +after a failed auth. Older clients will keep using +the token value and react acording to +.B \-\-auth-retry +. .\"********************************************************* .TP .B \-\-tls\-verify cmd diff --git a/src/openvpn/misc.c b/src/openvpn/misc.c index fc68027f..f2449eed 100644 --- a/src/openvpn/misc.c +++ b/src/openvpn/misc.c @@ -882,7 +882,7 @@ purge_user_pass(struct user_pass *up, const bool force) * don't show warning if the pass has been replaced by a token: this is an * artificial "auth-nocache" */ - else if (!warn_shown && (!up->tokenized)) + else if (!warn_shown) { msg(M_WARN, "WARNING: this configuration may cache passwords in memory -- use the auth-nocache option to prevent this"); warn_shown = true; @@ -890,14 +890,18 @@ purge_user_pass(struct user_pass *up, const bool force) } void -set_auth_token(struct user_pass *up, const char *token) +set_auth_token(struct user_pass *up, struct user_pass *tk, const char *token) { - if (token && strlen(token) && up && up->defined && !up->nocache) + + if (token && strlen(token) && up && up->defined) { - CLEAR(up->password); - strncpynt(up->password, token, USER_PASS_LEN); - up->tokenized = true; + strncpynt(tk->password, token, USER_PASS_LEN); + strncpynt(tk->username, up->username, USER_PASS_LEN); + tk->defined = true; } + + /* Cleans user/pass for nocache */ + purge_user_pass(up, false); } /* diff --git a/src/openvpn/misc.h b/src/openvpn/misc.h index 5680c274..29a6b89a 100644 --- a/src/openvpn/misc.h +++ b/src/openvpn/misc.h @@ -102,7 +102,6 @@ struct user_pass { bool defined; bool nocache; - bool tokenized; /* true if password has been substituted by a token */ bool wait_for_push; /* true if this object is waiting for a push-reply */ /* max length of username/password */ @@ -184,7 +183,7 @@ void fail_user_pass(const char *prefix, void purge_user_pass(struct user_pass *up, const bool force); -void set_auth_token(struct user_pass *up, const char *token); +void set_auth_token(struct user_pass *up, struct user_pass *tk, const char *token); /* * Process string received by untrusted peer before diff --git a/src/openvpn/push.c b/src/openvpn/push.c index 6a30e479..43df91ba 100644 --- a/src/openvpn/push.c +++ b/src/openvpn/push.c @@ -55,8 +55,19 @@ receive_auth_failed(struct context *c, const struct buffer *buffer) if (c->options.pull) { - switch (auth_retry_get()) + /* Before checking how to react on AUTH_FAILED, first check if the failed authed might be + * the result of an expired auth-token. + * Note that a server restart will trigger a generic AUTH_FAILED instead an AUTH_FAILED,SESSION so + * handle all AUTH_FAILED message identical for this scenario */ + if (ssl_clean_auth_token()) { + c->sig->signal_received = SIGUSR1; /* SOFT-SIGUSR1 -- Auth failure error */ + c->sig->signal_text = "auth-failure (auth-token)"; + } + else + { + switch (auth_retry_get()) + { case AR_NONE: c->sig->signal_received = SIGTERM; /* SOFT-SIGTERM -- Auth failure error */ break; @@ -70,8 +81,9 @@ receive_auth_failed(struct context *c, const struct buffer *buffer) default: ASSERT(0); + } + c->sig->signal_text = "auth-failure"; } - c->sig->signal_text = "auth-failure"; #ifdef ENABLE_MANAGEMENT if (management) { diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c index 669f941b..1c1ba305 100644 --- a/src/openvpn/ssl.c +++ b/src/openvpn/ssl.c @@ -398,6 +398,7 @@ pem_password_callback(char *buf, int size, int rwflag, void *u) static bool auth_user_pass_enabled; /* GLOBAL */ static struct user_pass auth_user_pass; /* GLOBAL */ +static struct user_pass auth_token; /* GLOBAL */ #ifdef ENABLE_CLIENT_CR static char *auth_challenge; /* GLOBAL */ @@ -407,7 +408,7 @@ void auth_user_pass_setup(const char *auth_file, const struct static_challenge_info *sci) { auth_user_pass_enabled = true; - if (!auth_user_pass.defined) + if (!auth_user_pass.defined && !auth_token.defined) { #if AUTO_USERID get_user_pass_auto_userid(&auth_user_pass, auth_file); @@ -449,7 +450,7 @@ ssl_set_auth_nocache(void) { passbuf.nocache = true; auth_user_pass.nocache = true; - /* wait for push-reply, because auth-token may invert nocache */ + /* wait for push-reply, because auth-token may still need the username */ auth_user_pass.wait_for_push = true; } @@ -459,15 +460,18 @@ ssl_set_auth_nocache(void) void ssl_set_auth_token(const char *token) { - if (auth_user_pass.nocache) - { - msg(M_INFO, - "auth-token received, disabling auth-nocache for the " - "authentication token"); - auth_user_pass.nocache = false; - } + set_auth_token(&auth_user_pass, &auth_token, token); +} - set_auth_token(&auth_user_pass, token); +/* + * Cleans an auth token and checks if it was active + */ +bool +ssl_clean_auth_token (void) +{ + bool wasdefined = auth_token.defined; + purge_user_pass(&auth_token, true); + return wasdefined; } /* @@ -2377,19 +2381,23 @@ key_method_2_write(struct buffer *buf, struct tls_session *session) #else auth_user_pass_setup(session->opt->auth_user_pass_file, NULL); #endif - if (!write_string(buf, auth_user_pass.username, -1)) + struct user_pass* up = &auth_user_pass; + + /* If we have a valid auth-token, send that instead of real username/password */ + if (auth_token.defined) + up = &auth_token; + + if (!write_string(buf, up->username, -1)) { goto error; } - if (!write_string(buf, auth_user_pass.password, -1)) + else if (!write_string(buf, up->password, -1)) { goto error; } /* if auth-nocache was specified, the auth_user_pass object reaches * a "complete" state only after having received the push-reply * message. - * This is the case because auth-token statement in a push-reply would - * invert its nocache. * * For this reason, skip the purge operation here if no push-reply * message has been received yet. diff --git a/src/openvpn/ssl.h b/src/openvpn/ssl.h index a2501c9b..116e76a1 100644 --- a/src/openvpn/ssl.h +++ b/src/openvpn/ssl.h @@ -428,6 +428,8 @@ void ssl_purge_auth(const bool auth_user_pass_only); void ssl_set_auth_token(const char *token); +bool ssl_clean_auth_token(void); + #ifdef ENABLE_CLIENT_CR /* * ssl_get_auth_challenge will parse the server-pushed auth-failed -- 2.16.2 ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Openvpn-devel mailing list Openvpn-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/openvpn-devel