X-Git-Url: https://vcs.fsf.org/?p=exim.git;a=blobdiff_plain;f=src%2Fsrc%2Fauths%2Fdovecot.c;h=3331cb85614626ee38b3a04f5b98b50c128866f6;hp=c11b2fe9b274b02c8bf47c823572bdf00d2c2ae9;hb=1e1ddfac79fbcd052f199500a6493c7f79cb8462;hpb=7befa435e5664f43d90bf5a2703fcf4f2a26139e diff --git a/src/src/auths/dovecot.c b/src/src/auths/dovecot.c index c11b2fe9b..3331cb856 100644 --- a/src/src/auths/dovecot.c +++ b/src/src/auths/dovecot.c @@ -1,7 +1,6 @@ -/* $Cambridge: exim/src/src/auths/dovecot.c,v 1.2 2006/10/16 13:43:22 ph10 Exp $ */ - /* * Copyright (c) 2004 Andrey Panin + * 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 @@ -9,31 +8,86 @@ * (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+, 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, - (void *)(offsetof(auth_dovecot_options_block, server_socket)) - }, + { "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 = - sizeof(auth_dovecot_options) / sizeof(optionlist); + +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 = { - NULL, /* server_socket */ + .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 * *************************************************/ @@ -41,51 +95,90 @@ auth_dovecot_options_block auth_dovecot_option_defaults = { /* 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 == NULL) - ablock->public_name = ablock->name; - if (ob->server_socket != NULL) - ablock->server = TRUE; - ablock->client = FALSE; +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 int strcut(char *str, char **ptrs, int nptrs) +static void debug_strcut(uschar **ptrs, int nlen, int alen) ARG_UNUSED; +static void +debug_strcut(uschar **ptrs, int nlen, int alen) { - char *tmp = str; - int n; - - for (n = 0; n < nptrs; n++) - ptrs[n] = NULL; - n = 1; - - while (*str) { - if (*str == '\t') { - if (n <= nptrs) { - *ptrs++ = tmp; - tmp = str + 1; - *str = 0; - } - n++; - } - str++; - } - - if (n < nptrs) - *ptrs = tmp; - - return n; +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""); +else + debug_printf(" (max for capacity)\n"); } #define CHECK_COMMAND(str, arg_min, arg_max) do { \ - if (strcasecmp((str), args[0]) != 0) \ + if (strcmpic(US(str), args[0]) != 0) \ goto out; \ if (nargs - 1 < (arg_min)) \ goto out; \ - if (nargs - 1 > (arg_max)) \ + if ( (arg_max != -1) && (nargs - 1 > (arg_max)) ) \ goto out; \ } while (0) @@ -97,217 +190,332 @@ static int strcut(char *str, char **ptrs, int nptrs) /************************************************* - * Server entry point * - *************************************************/ +* "fgets" to read directly from socket * +*************************************************/ -int auth_dovecot_server(auth_instance *ablock, uschar *data) +/* 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) { - auth_dovecot_options_block *ob = - (auth_dovecot_options_block *)(ablock->options_block); - struct sockaddr_un sa; - char buffer[4096]; - char *args[8]; - uschar *auth_command; - uschar *auth_extra_data = US""; - int nargs, tmp; - int cuid = 0, cont = 1, found = 0, fd, ret = DEFER; - FILE *f; - - HDEBUG(D_auth) debug_printf("dovecot authentication\n"); - - memset(&sa, 0, sizeof(sa)); - sa.sun_family = AF_UNIX; - - /* This was the original code here: it is nonsense because strncpy() - does not return an integer. I have converted this to use the function - that formats and checks length. PH */ - - /* - if (strncpy(sa.sun_path, ob->server_socket, sizeof(sa.sun_path)) < 0) { - */ - - if (!string_format(US sa.sun_path, sizeof(sa.sun_path), "%s", - ob->server_socket)) { - auth_defer_msg = US"authentication socket path too long"; - return DEFER; - } - - auth_defer_msg = US"authentication socket connection error"; - - fd = socket(PF_UNIX, SOCK_STREAM, 0); - if (fd < 0) - return DEFER; - - if (connect(fd, (struct sockaddr *) &sa, sizeof(sa)) < 0) - goto out; - - f = fdopen(fd, "a+"); - if (f == NULL) - goto out; - - auth_defer_msg = US"authentication socket protocol error"; - - while (cont) { - if (fgets(buffer, sizeof(buffer), f) == NULL) - OUT("authentication socket read error or premature eof"); - - buffer[strlen(buffer) - 1] = 0; - HDEBUG(D_auth) debug_printf("received: %s\n", buffer); - nargs = strcut(buffer, args, sizeof(args) / sizeof(args[0])); - - switch (toupper(*args[0])) { - case 'C': - CHECK_COMMAND("CUID", 1, 1); - cuid = atoi(args[1]); - break; - - case 'D': - CHECK_COMMAND("DONE", 0, 0); - cont = 0; - break; - - case 'M': - CHECK_COMMAND("MECH", 1, INT_MAX); - if (strcmpic(US args[1], ablock->public_name) == 0) - found = 1; - break; - - case 'S': - CHECK_COMMAND("SPID", 1, 1); - break; - - case 'V': - CHECK_COMMAND("VERSION", 2, 2); - if (atoi(args[1]) != VERSION_MAJOR) - OUT("authentication socket protocol version mismatch"); - break; - - default: - goto out; - } - } - - if (!found) - 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_cipher != NULL) - auth_extra_data = string_sprintf("secured\t%s%s", - tls_certificate_verified? "valid-client-cert" : "", - tls_certificate_verified? "\t" : ""); - else if (Ustrcmp(sender_host_address, interface_address) == 0) - auth_extra_data = US"secured\t"; +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 ? (char *) data : ""); - - Subsequently, the command was modified to add "secured" and "valid-client- - cert" when relevant. +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\tresp=%s\n", - VERSION_MAJOR, VERSION_MINOR, getpid(), cuid, - ablock->public_name, auth_extra_data, sender_host_address, - interface_address, data ? (char *) data : ""); - - fprintf(f, "%s", auth_command); - HDEBUG(D_auth) debug_printf("sent: %s", auth_command); - - while (1) { - if (fgets(buffer, sizeof(buffer), f) == NULL) { - auth_defer_msg = US"authentication socket read error or premature eof"; - goto out; - } - - buffer[strlen(buffer) - 1] = 0; - HDEBUG(D_auth) debug_printf("received: %s\n", buffer); - nargs = strcut(buffer, args, sizeof(args) / sizeof(args[0])); - - if (atoi(args[1]) != cuid) - OUT("authentication socket connection id mismatch"); - - switch (toupper(*args[0])) { - case 'C': - CHECK_COMMAND("CONT", 1, 2); - - tmp = auth_get_no64_data(&data, US args[2]); - if (tmp != 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; - } - - if (fprintf(f, "CONT\t%d\t%s\r\n", cuid, data) < 0) - OUT("authentication socket write error"); - - break; - - case 'F': - CHECK_COMMAND("FAIL", 1, 2); - - /* FIXME: add proper response handling */ - if (args[2]) { - uschar *p = US strchr(args[2], '='); - if (p) { - ++p; - expand_nstring[1] = auth_vars[0] = p; - expand_nlength[1] = Ustrlen(p); - expand_nmax = 1; - } - } - - ret = FAIL; - goto out; - - case 'O': - CHECK_COMMAND("OK", 2, 2); - { - /* FIXME: add proper response handling */ - uschar *p = US strchr(args[2], '='); - if (!p) - OUT("authentication socket protocol error, username missing"); - - p++; - expand_nstring[1] = auth_vars[0] = p; - expand_nlength[1] = Ustrlen(p); - expand_nmax = 1; - } - ret = OK; - /* fallthrough */ - - default: - goto out; - } - } - -out: close(fd); - return ret; +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*/