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Diffstat (limited to '')
| -rw-r--r-- | src/auths/dovecot.c | 521 |
1 files changed, 521 insertions, 0 deletions
diff --git a/src/auths/dovecot.c b/src/auths/dovecot.c new file mode 100644 index 0000000..3331cb8 --- /dev/null +++ b/src/auths/dovecot.c @@ -0,0 +1,521 @@ +/* + * Copyright (c) 2004 Andrey Panin <pazke@donpac.ru> + * Copyright (c) 2006-2020 The Exim Maintainers + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published + * by the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + */ + +/* A number of modifications have been made to the original code. Originally I +commented them specially, but now they are getting quite extensive, so I have +ceased doing that. The biggest change is to use unbuffered I/O on the socket +because using C buffered I/O gives problems on some operating systems. PH */ + +/* Protocol specifications: + * Dovecot 1, protocol version 1.1 + * http://wiki.dovecot.org/Authentication%20Protocol + * + * Dovecot 2, protocol version 1.1 + * http://wiki2.dovecot.org/Design/AuthProtocol + */ + +#include "../exim.h" +#include "dovecot.h" + +#define VERSION_MAJOR 1 +#define VERSION_MINOR 0 + +/* http://wiki.dovecot.org/Authentication%20Protocol +"The maximum line length isn't defined, + but it's currently expected to fit into 8192 bytes" +*/ +#define DOVECOT_AUTH_MAXLINELEN 8192 + +/* This was hard-coded as 8. +AUTH req C->S sends {"AUTH", id, mechanism, service } + params, 5 defined for +Dovecot 1; Dovecot 2 (same protocol version) defines 9. + +Master->Server sends {"USER", id, userid} + params, 6 defined. +Server->Client only gives {"OK", id} + params, unspecified, only 1 guaranteed. + +We only define here to accept S->C; max seen is 3+<unspecified>, plus the two +for the command and id, where unspecified might include _at least_ user=... + +So: allow for more fields than we ever expect to see, while aware that count +can go up without changing protocol version. +The cost is the length of an array of pointers on the stack. +*/ +#define DOVECOT_AUTH_MAXFIELDCOUNT 16 + +/* Options specific to the authentication mechanism. */ +optionlist auth_dovecot_options[] = { + { "server_socket", opt_stringptr, OPT_OFF(auth_dovecot_options_block, server_socket) }, +/*{ "server_tls", opt_bool, OPT_OFF(auth_dovecot_options_block, server_tls) },*/ +}; + +/* Size of the options list. An extern variable has to be used so that its +address can appear in the tables drtables.c. */ + +int auth_dovecot_options_count = nelem(auth_dovecot_options); + +/* Default private options block for the authentication method. */ + +auth_dovecot_options_block auth_dovecot_option_defaults = { + .server_socket = NULL, +/* .server_tls = FALSE,*/ +}; + + + + +#ifdef MACRO_PREDEF + +/* Dummy values */ +void auth_dovecot_init(auth_instance *ablock) {} +int auth_dovecot_server(auth_instance *ablock, uschar *data) {return 0;} +int auth_dovecot_client(auth_instance *ablock, void * sx, + int timeout, uschar *buffer, int buffsize) {return 0;} + +#else /*!MACRO_PREDEF*/ + + +/* Static variables for reading from the socket */ + +static uschar sbuffer[256]; +static int socket_buffer_left; + + + +/************************************************* + * Initialization entry point * + *************************************************/ + +/* Called for each instance, after its options have been read, to +enable consistency checks to be done, or anything else that needs +to be set up. */ + +void auth_dovecot_init(auth_instance *ablock) +{ +auth_dovecot_options_block *ob = + (auth_dovecot_options_block *)(ablock->options_block); + +if (!ablock->public_name) ablock->public_name = ablock->name; +if (ob->server_socket) ablock->server = TRUE; +ablock->client = FALSE; +} + +/************************************************* + * "strcut" to split apart server lines * + *************************************************/ + +/* Dovecot auth protocol uses TAB \t as delimiter; a line consists +of a command-name, TAB, and then any parameters, each separated by a TAB. +A parameter can be param=value or a bool, just param. + +This function modifies the original str in-place, inserting NUL characters. +It initialises ptrs entries, setting all to NULL and only setting +non-NULL N entries, where N is the return value, the number of fields seen +(one more than the number of tabs). + +Note that the return value will always be at least 1, is the count of +actual fields (so last valid offset into ptrs is one less). +*/ + +static int +strcut(uschar *str, uschar **ptrs, int nptrs) +{ +uschar *last_sub_start = str; +int n; + +for (n = 0; n < nptrs; n++) + ptrs[n] = NULL; +n = 1; + +while (*str) + if (*str++ == '\t') + if (n++ <= nptrs) + { + *ptrs++ = last_sub_start; + last_sub_start = str; + str[-1] = '\0'; + } + +/* It's acceptable for the string to end with a tab character. We see +this in AUTH PLAIN without an initial response from the client, which +causing us to send "334 " and get the data from the client. */ +if (n <= nptrs) + *ptrs = last_sub_start; +else + { + HDEBUG(D_auth) + debug_printf("dovecot: warning: too many results from tab-splitting;" + " saw %d fields, room for %d\n", n, nptrs); + n = nptrs; + } + +return n <= nptrs ? n : nptrs; +} + +static void debug_strcut(uschar **ptrs, int nlen, int alen) ARG_UNUSED; +static void +debug_strcut(uschar **ptrs, int nlen, int alen) +{ +int i; +debug_printf("%d read but unreturned bytes; strcut() gave %d results: ", + socket_buffer_left, nlen); +for (i = 0; i < nlen; i++) + debug_printf(" {%s}", ptrs[i]); +if (nlen < alen) + debug_printf(" last is %s\n", ptrs[i] ? ptrs[i] : US"<null>"); +else + debug_printf(" (max for capacity)\n"); +} + +#define CHECK_COMMAND(str, arg_min, arg_max) do { \ + if (strcmpic(US(str), args[0]) != 0) \ + goto out; \ + if (nargs - 1 < (arg_min)) \ + goto out; \ + if ( (arg_max != -1) && (nargs - 1 > (arg_max)) ) \ + goto out; \ +} while (0) + +#define OUT(msg) do { \ + auth_defer_msg = (US msg); \ + goto out; \ +} while(0) + + + +/************************************************* +* "fgets" to read directly from socket * +*************************************************/ + +/* Added by PH after a suggestion by Steve Usher because the previous use of +C-style buffered I/O gave trouble. */ + +static uschar * +dc_gets(uschar *s, int n, client_conn_ctx * cctx) +{ +int p = 0; +int count = 0; + +for (;;) + { + if (socket_buffer_left == 0) + { + if ((socket_buffer_left = +#ifndef DISABLE_TLS + cctx->tls_ctx ? tls_read(cctx->tls_ctx, sbuffer, sizeof(sbuffer)) : +#endif + read(cctx->sock, sbuffer, sizeof(sbuffer))) <= 0) + if (count == 0) + return NULL; + else + break; + p = 0; + } + + while (p < socket_buffer_left) + { + if (count >= n - 1) break; + s[count++] = sbuffer[p]; + if (sbuffer[p++] == '\n') break; + } + + memmove(sbuffer, sbuffer + p, socket_buffer_left - p); + socket_buffer_left -= p; + + if (s[count-1] == '\n' || count >= n - 1) break; + } + +s[count] = '\0'; +return s; +} + + + + +/************************************************* +* Server entry point * +*************************************************/ + +int +auth_dovecot_server(auth_instance * ablock, uschar * data) +{ +auth_dovecot_options_block *ob = + (auth_dovecot_options_block *) ablock->options_block; +uschar buffer[DOVECOT_AUTH_MAXLINELEN]; +uschar *args[DOVECOT_AUTH_MAXFIELDCOUNT]; +uschar *auth_command; +uschar *auth_extra_data = US""; +uschar *p; +int nargs, tmp; +int crequid = 1, ret = DEFER; +host_item host; +client_conn_ctx cctx = {.sock = -1, .tls_ctx = NULL}; +BOOL found = FALSE, have_mech_line = FALSE; + +HDEBUG(D_auth) debug_printf("dovecot authentication\n"); + +if (!data) + { + ret = FAIL; + goto out; + } + +/*XXX timeout? */ +cctx.sock = ip_streamsocket(ob->server_socket, &auth_defer_msg, 5, &host); +if (cctx.sock < 0) + goto out; + +#ifdef notdef +# ifndef DISABLE_TLS +if (ob->server_tls) + { + uschar * s; + smtp_connect_args conn_args = { .host = &host }; + tls_support tls_dummy = {.sni=NULL}; + uschar * errstr; + + if (!tls_client_start(&cctx, &conn_args, NULL, &tls_dummy, &errstr)) + { + auth_defer_msg = string_sprintf("TLS connect failed: %s", errstr); + goto out; + } + } +# endif +#endif + +auth_defer_msg = US"authentication socket protocol error"; + +socket_buffer_left = 0; /* Global, used to read more than a line but return by line */ +for (;;) + { +debug_printf("%s %d\n", __FUNCTION__, __LINE__); + if (!dc_gets(buffer, sizeof(buffer), &cctx)) + OUT("authentication socket read error or premature eof"); +debug_printf("%s %d\n", __FUNCTION__, __LINE__); + p = buffer + Ustrlen(buffer) - 1; + if (*p != '\n') + OUT("authentication socket protocol line too long"); + + *p = '\0'; + HDEBUG(D_auth) debug_printf("received: '%s'\n", buffer); + + nargs = strcut(buffer, args, nelem(args)); + + HDEBUG(D_auth) debug_strcut(args, nargs, nelem(args)); + + /* Code below rewritten by Kirill Miazine (km@krot.org). Only check commands that + Exim will need. Original code also failed if Dovecot server sent unknown + command. E.g. COOKIE in version 1.1 of the protocol would cause troubles. */ + /* pdp: note that CUID is a per-connection identifier sent by the server, + which increments at server discretion. + By contrast, the "id" field of the protocol is a connection-specific request + identifier, which needs to be unique per request from the client and is not + connected to the CUID value, so we ignore CUID from server. It's purely for + diagnostics. */ + + if (Ustrcmp(args[0], US"VERSION") == 0) + { + CHECK_COMMAND("VERSION", 2, 2); + if (Uatoi(args[1]) != VERSION_MAJOR) + OUT("authentication socket protocol version mismatch"); + } + else if (Ustrcmp(args[0], US"MECH") == 0) + { + CHECK_COMMAND("MECH", 1, INT_MAX); + have_mech_line = TRUE; + if (strcmpic(US args[1], ablock->public_name) == 0) + found = TRUE; + } + else if (Ustrcmp(args[0], US"SPID") == 0) + { + /* Unfortunately the auth protocol handshake wasn't designed well + to differentiate between auth-client/userdb/master. auth-userdb + and auth-master send VERSION + SPID lines only and nothing + afterwards, while auth-client sends VERSION + MECH + SPID + + CUID + more. The simplest way that we can determine if we've + connected to the correct socket is to see if MECH line exists or + not (alternatively we'd have to have a small timeout after SPID + to see if CUID is sent or not). */ + + if (!have_mech_line) + OUT("authentication socket type mismatch" + " (connected to auth-master instead of auth-client)"); + } + else if (Ustrcmp(args[0], US"DONE") == 0) + { + CHECK_COMMAND("DONE", 0, 0); + break; + } + } + +if (!found) + { + auth_defer_msg = string_sprintf( + "Dovecot did not advertise mechanism \"%s\" to us", ablock->public_name); + goto out; + } + +/* Added by PH: data must not contain tab (as it is +b64 it shouldn't, but check for safety). */ + +if (Ustrchr(data, '\t') != NULL) + { + ret = FAIL; + goto out; + } + +/* Added by PH: extra fields when TLS is in use or if the TCP/IP +connection is local. */ + +if (tls_in.cipher) + auth_extra_data = string_sprintf("secured\t%s%s", + tls_in.certificate_verified ? "valid-client-cert" : "", + tls_in.certificate_verified ? "\t" : ""); + +else if ( interface_address + && Ustrcmp(sender_host_address, interface_address) == 0) + auth_extra_data = US"secured\t"; + + +/**************************************************************************** +The code below was the original code here. It didn't work. A reading of the +file auth-protocol.txt.gz that came with Dovecot 1.0_beta8 indicated that +this was not right. Maybe something changed. I changed it to move the +service indication into the AUTH command, and it seems to be better. PH + +fprintf(f, "VERSION\t%d\t%d\r\nSERVICE\tSMTP\r\nCPID\t%d\r\n" + "AUTH\t%d\t%s\trip=%s\tlip=%s\tresp=%s\r\n", + VERSION_MAJOR, VERSION_MINOR, getpid(), cuid, + ablock->public_name, sender_host_address, interface_address, + data ? CS data : ""); + +Subsequently, the command was modified to add "secured" and "valid-client- +cert" when relevant. +****************************************************************************/ + +auth_command = string_sprintf("VERSION\t%d\t%d\nCPID\t%d\n" + "AUTH\t%d\t%s\tservice=smtp\t%srip=%s\tlip=%s\tnologin\tresp=%s\n", + VERSION_MAJOR, VERSION_MINOR, getpid(), crequid, + ablock->public_name, auth_extra_data, sender_host_address, + interface_address, data); + +if (( +#ifndef DISABLE_TLS + cctx.tls_ctx ? tls_write(cctx.tls_ctx, auth_command, Ustrlen(auth_command), FALSE) : +#endif + write(cctx.sock, auth_command, Ustrlen(auth_command))) < 0) + HDEBUG(D_auth) debug_printf("error sending auth_command: %s\n", + strerror(errno)); + +HDEBUG(D_auth) debug_printf("sent: '%s'\n", auth_command); + +while (1) + { + uschar *temp; + uschar *auth_id_pre = NULL; + + if (!dc_gets(buffer, sizeof(buffer), &cctx)) + { + auth_defer_msg = US"authentication socket read error or premature eof"; + goto out; + } + + buffer[Ustrlen(buffer) - 1] = 0; + HDEBUG(D_auth) debug_printf("received: '%s'\n", buffer); + nargs = strcut(buffer, args, nelem(args)); + HDEBUG(D_auth) debug_strcut(args, nargs, nelem(args)); + + if (Uatoi(args[1]) != crequid) + OUT("authentication socket connection id mismatch"); + + switch (toupper(*args[0])) + { + case 'C': + CHECK_COMMAND("CONT", 1, 2); + + if ((tmp = auth_get_no64_data(&data, US args[2])) != OK) + { + ret = tmp; + goto out; + } + + /* Added by PH: data must not contain tab (as it is + b64 it shouldn't, but check for safety). */ + + if (Ustrchr(data, '\t') != NULL) + { + ret = FAIL; + goto out; + } + + temp = string_sprintf("CONT\t%d\t%s\n", crequid, data); + if (( +#ifndef DISABLE_TLS + cctx.tls_ctx ? tls_write(cctx.tls_ctx, temp, Ustrlen(temp), FALSE) : +#endif + write(cctx.sock, temp, Ustrlen(temp))) < 0) + OUT("authentication socket write error"); + break; + + case 'F': + CHECK_COMMAND("FAIL", 1, -1); + + for (int i = 2; i < nargs && !auth_id_pre; i++) + if (Ustrncmp(args[i], US"user=", 5) == 0) + { + auth_id_pre = args[i] + 5; + expand_nstring[1] = auth_vars[0] = string_copy(auth_id_pre); /* PH */ + expand_nlength[1] = Ustrlen(auth_id_pre); + expand_nmax = 1; + } + ret = FAIL; + goto out; + + case 'O': + CHECK_COMMAND("OK", 2, -1); + + /* Search for the "user=$USER" string in the args array + and return the proper value. */ + + for (int i = 2; i < nargs && !auth_id_pre; i++) + if (Ustrncmp(args[i], US"user=", 5) == 0) + { + auth_id_pre = args[i] + 5; + expand_nstring[1] = auth_vars[0] = string_copy(auth_id_pre); /* PH */ + expand_nlength[1] = Ustrlen(auth_id_pre); + expand_nmax = 1; + } + + if (!auth_id_pre) + OUT("authentication socket protocol error, username missing"); + + auth_defer_msg = NULL; + ret = OK; + /* fallthrough */ + + default: + goto out; + } + } + +out: +/* close the socket used by dovecot */ +#ifndef DISABLE_TLS +if (cctx.tls_ctx) + tls_close(cctx.tls_ctx, TRUE); +#endif +if (cctx.sock >= 0) + close(cctx.sock); + +/* Expand server_condition as an authorization check */ +return ret == OK ? auth_check_serv_cond(ablock) : ret; +} + + +#endif /*!MACRO_PREDEF*/ |