X-Git-Url: https://git.exim.org/users/jgh/exim.git/blobdiff_plain/10385c155b0e1266c02535b76ab73b32fa83d73f..1ba28e2b955b005ce4825fec792df17f75a8de1e:/src/src/exim.c diff --git a/src/src/exim.c b/src/src/exim.c index a68a06227..f086a00e8 100644 --- a/src/src/exim.c +++ b/src/src/exim.c @@ -1,4 +1,4 @@ -/* $Cambridge: exim/src/src/exim.c,v 1.69 2010/06/06 02:46:13 pdp Exp $ */ +/* $Cambridge: exim/src/src/exim.c,v 1.71 2010/06/07 00:12:42 pdp Exp $ */ /************************************************* * Exim - an Internet mail transport agent * @@ -14,6 +14,8 @@ Also a few functions that don't naturally fit elsewhere. */ #include "exim.h" +extern void init_lookup_list(void); + /************************************************* @@ -358,7 +360,7 @@ Returns: nothing */ void -set_process_info(char *format, ...) +set_process_info(const char *format, ...) { int len; va_list ap; @@ -395,7 +397,7 @@ Returns: the fopened FILE or NULL */ FILE * -modefopen(uschar *filename, char *options, mode_t mode) +modefopen(const uschar *filename, const char *options, mode_t mode) { mode_t saved_umask = umask(0777); FILE *f = Ufopen(filename, options); @@ -568,17 +570,20 @@ if (euid == root_uid || euid != uid || egid != gid || igflag) DEBUG(D_uid) { - int group_count; + int group_count, save_errno; gid_t group_list[NGROUPS_MAX]; debug_printf("changed uid/gid: %s\n uid=%ld gid=%ld pid=%ld\n", msg, (long int)geteuid(), (long int)getegid(), (long int)getpid()); group_count = getgroups(NGROUPS_MAX, group_list); + save_errno = errno; debug_printf(" auxiliary group list:"); if (group_count > 0) { int i; for (i = 0; i < group_count; i++) debug_printf(" %d", (int)group_list[i]); } + else if (group_count < 0) + debug_printf(" ", strerror(save_errno)); else debug_printf(" "); debug_printf("\n"); } @@ -776,53 +781,53 @@ fprintf(f, "Support for:"); #endif fprintf(f, "\n"); -fprintf(f, "Lookups:"); -#ifdef LOOKUP_LSEARCH +fprintf(f, "Lookups (built-in):"); +#if defined(LOOKUP_LSEARCH) && LOOKUP_LSEARCH!=2 fprintf(f, " lsearch wildlsearch nwildlsearch iplsearch"); #endif -#ifdef LOOKUP_CDB +#if defined(LOOKUP_CDB) && LOOKUP_CDB!=2 fprintf(f, " cdb"); #endif -#ifdef LOOKUP_DBM +#if defined(LOOKUP_DBM) && LOOKUP_DBM!=2 fprintf(f, " dbm dbmnz"); #endif -#ifdef LOOKUP_DNSDB +#if defined(LOOKUP_DNSDB) && LOOKUP_DNSDB!=2 fprintf(f, " dnsdb"); #endif -#ifdef LOOKUP_DSEARCH +#if defined(LOOKUP_DSEARCH) && LOOKUP_DSEARCH!=2 fprintf(f, " dsearch"); #endif -#ifdef LOOKUP_IBASE +#if defined(LOOKUP_IBASE) && LOOKUP_IBASE!=2 fprintf(f, " ibase"); #endif -#ifdef LOOKUP_LDAP +#if defined(LOOKUP_LDAP) && LOOKUP_LDAP!=2 fprintf(f, " ldap ldapdn ldapm"); #endif -#ifdef LOOKUP_MYSQL +#if defined(LOOKUP_MYSQL) && LOOKUP_MYSQL!=2 fprintf(f, " mysql"); #endif -#ifdef LOOKUP_NIS +#if defined(LOOKUP_NIS) && LOOKUP_NIS!=2 fprintf(f, " nis nis0"); #endif -#ifdef LOOKUP_NISPLUS +#if defined(LOOKUP_NISPLUS) && LOOKUP_NISPLUS!=2 fprintf(f, " nisplus"); #endif -#ifdef LOOKUP_ORACLE +#if defined(LOOKUP_ORACLE) && LOOKUP_ORACLE!=2 fprintf(f, " oracle"); #endif -#ifdef LOOKUP_PASSWD +#if defined(LOOKUP_PASSWD) && LOOKUP_PASSWD!=2 fprintf(f, " passwd"); #endif -#ifdef LOOKUP_PGSQL +#if defined(LOOKUP_PGSQL) && LOOKUP_PGSQL!=2 fprintf(f, " pgsql"); #endif -#ifdef LOOKUP_SQLITE +#if defined(LOOKUP_SQLITE) && LOOKUP_SQLITE!=2 fprintf(f, " sqlite"); #endif -#ifdef LOOKUP_TESTDB +#if defined(LOOKUP_TESTDB) && LOOKUP_TESTDB!=2 fprintf(f, " testdb"); #endif -#ifdef LOOKUP_WHOSON +#if defined(LOOKUP_WHOSON) && LOOKUP_WHOSON!=2 fprintf(f, " whoson"); #endif fprintf(f, "\n"); @@ -905,7 +910,7 @@ if (fixed_never_users[0] > 0) fprintf(f, "%d\n", (unsigned int)fixed_never_users[i]); } -fprintf(f, "Size of off_t: %d\n", sizeof(off_t)); +fprintf(f, "Size of off_t: " SIZE_T_FMT "\n", sizeof(off_t)); /* This runtime check is to help diagnose library linkage mismatches which result in segfaults and the like; as such, it's left until the end, @@ -914,6 +919,49 @@ come. */ #ifdef SUPPORT_TLS tls_version_report(f); #endif + +/* Everything else is details which are only worth reporting when debugging. +Perhaps the tls_version_report should move into this too. */ +DEBUG(D_any) do { + + int i; + +#ifdef AUTH_CYRUS_SASL + auth_cyrus_sasl_version_report(f); +#endif + + fprintf(f, "Library version: PCRE: Compile: %d.%d%s\n" + " Runtime: %s\n", + PCRE_MAJOR, PCRE_MINOR, + /* PRE_PRERELEASE is either defined and empty or a string. + * unless its an ancient version of PCRE in which case it + * is not defined */ +#ifdef PCRE_PRERELEASE + PCRE_PRERELEASE "", +#else + "", +#endif + pcre_version()); + + init_lookup_list(); + for (i = 0; i < lookup_list_count; i++) + { + if (lookup_list[i]->version_report) + lookup_list[i]->version_report(f); + } + +#ifdef WHITELIST_D_MACROS + fprintf(f, "WHITELIST_D_MACROS: \"%s\"\n", WHITELIST_D_MACROS); +#else + fprintf(f, "WHITELIST_D_MACROS unset\n"); +#endif +#ifdef TRUSTED_CONFIG_LIST + fprintf(f, "TRUSTED_CONFIG_LIST: \"%s\"\n", TRUSTED_CONFIG_LIST); +#else + fprintf(f, "TRUSTED_CONFIG_LIST unset\n"); +#endif + +} while (0); } @@ -990,8 +1038,8 @@ Returns: the dlopen handle or NULL on failure */ static void * -set_readline(char * (**fn_readline_ptr)(char *), - char * (**fn_addhist_ptr)(char *)) +set_readline(char * (**fn_readline_ptr)(const char *), + void (**fn_addhist_ptr)(const char *)) { void *dlhandle; void *dlhandle_curses = dlopen("libcurses.so", RTLD_GLOBAL|RTLD_LAZY); @@ -1001,8 +1049,12 @@ if (dlhandle_curses != NULL) dlclose(dlhandle_curses); if (dlhandle != NULL) { - *fn_readline_ptr = (char *(*)(char*))dlsym(dlhandle, "readline"); - *fn_addhist_ptr = (char *(*)(char*))dlsym(dlhandle, "add_history"); + /* Checked manual pages; at least in GNU Readline 6.1, the prototypes are: + * char * readline (const char *prompt); + * void add_history (const char *string); + */ + *fn_readline_ptr = (char *(*)(const char*))dlsym(dlhandle, "readline"); + *fn_addhist_ptr = (void(*)(const char*))dlsym(dlhandle, "add_history"); } else { @@ -1032,7 +1084,7 @@ Returns: pointer to dynamic memory, or NULL at end of file */ static uschar * -get_stdinput(char *(*fn_readline)(char *), char *(*fn_addhist)(char *)) +get_stdinput(char *(*fn_readline)(const char *), void(*fn_addhist)(const char *)) { int i; int size = 0; @@ -1131,6 +1183,117 @@ exit(EXIT_FAILURE); +/************************************************* +* Validate that the macros given are okay * +*************************************************/ + +/* Typically, Exim will drop privileges if macros are supplied. In some +cases, we want to not do so. + +Arguments: none (macros is a global) +Returns: true if trusted, false otherwise +*/ + +static BOOL +macros_trusted(void) +{ +#ifdef WHITELIST_D_MACROS +macro_item *m; +uschar *whitelisted, *end, *p, **whites, **w; +int white_count, i, n; +size_t len; +BOOL prev_char_item, found; +#endif + +if (macros == NULL) + return TRUE; +#ifndef WHITELIST_D_MACROS +return FALSE; +#else + +/* We only trust -D overrides for some invoking users: +root, the exim run-time user, the optional config owner user. +I don't know why config-owner would be needed, but since they can own the +config files anyway, there's no security risk to letting them override -D. */ +if ( ! ((real_uid == root_uid) + || (real_uid == exim_uid) +#ifdef CONFIGURE_OWNER + || (real_uid == config_uid) +#endif + )) + { + debug_printf("macros_trusted rejecting macros for uid %d\n", (int) real_uid); + return FALSE; + } + +/* Get a list of macros which are whitelisted */ +whitelisted = string_copy_malloc(US WHITELIST_D_MACROS); +prev_char_item = FALSE; +white_count = 0; +for (p = whitelisted; *p != '\0'; ++p) + { + if (*p == ':' || isspace(*p)) + { + *p = '\0'; + if (prev_char_item) + ++white_count; + prev_char_item = FALSE; + continue; + } + if (!prev_char_item) + prev_char_item = TRUE; + } +end = p; +if (prev_char_item) + ++white_count; +if (!white_count) + return FALSE; +whites = store_malloc(sizeof(uschar *) * (white_count+1)); +for (p = whitelisted, i = 0; (p != end) && (i < white_count); ++p) + { + if (*p != '\0') + { + whites[i++] = p; + if (i == white_count) + break; + while (*p != '\0' && p < end) + ++p; + } + } +whites[i] = NULL; + +/* The list of macros should be very short. Accept the N*M complexity. */ +for (m = macros; m != NULL; m = m->next) + { + found = FALSE; + for (w = whites; *w; ++w) + if (Ustrcmp(*w, m->name) == 0) + { + found = TRUE; + break; + } + if (!found) + return FALSE; + if (m->replacement == NULL) + continue; + len = Ustrlen(m->replacement); + if (len == 0) + continue; + n = pcre_exec(regex_whitelisted_macro, NULL, CS m->replacement, len, + 0, PCRE_EOPT, NULL, 0); + if (n < 0) + { + if (n != PCRE_ERROR_NOMATCH) + debug_printf("macros_trusted checking %s returned %d\n", m->name, n); + return FALSE; + } + } +DEBUG(D_any) debug_printf("macros_trusted overriden to true by whitelisting\n"); +return TRUE; +#endif +} + + /************************************************* * Entry point and high-level code * *************************************************/ @@ -1160,7 +1323,7 @@ int arg_error_handling = error_handling; int filter_sfd = -1; int filter_ufd = -1; int group_count; -int i; +int i, rv; int list_queue_option = 0; int msg_action = 0; int msg_action_arg = -1; @@ -1268,6 +1431,10 @@ if (!route_finduser(US CONFIGURE_OWNERNAME, NULL, &config_uid)) } #endif +/* We default the system_filter_user to be the Exim run-time user, as a +sane non-root value. */ +system_filter_uid = exim_uid; + #ifdef CONFIGURE_GROUPNAME if (!route_findgroup(US CONFIGURE_GROUPNAME, &config_gid)) { @@ -1413,6 +1580,15 @@ regex_smtp_code = regex_must_compile(US"^\\d\\d\\d\\s(?:\\d\\.\\d\\d?\\d?\\.\\d\\d?\\d?\\s)?", FALSE, TRUE); +#ifdef WHITELIST_D_MACROS +/* Precompile the regular expression used to filter the content of macros +given to -D for permissibility. */ + +regex_whitelisted_macro = + regex_must_compile(US"^[A-Za-z0-9_/.-]*$", FALSE, TRUE); +#endif + + /* If the program is called as "mailq" treat it as equivalent to "exim -bp"; this seems to be a generally accepted convention, since one finds symbolic links called "mailq" in standard OS configurations. */ @@ -1486,8 +1662,20 @@ real_gid = getgid(); if (real_uid == root_uid) { - setgid(real_gid); - setuid(real_uid); + rv = setgid(real_gid); + if (rv) + { + fprintf(stderr, "exim: setgid(%ld) failed: %s\n", + (long int)real_gid, strerror(errno)); + exit(EXIT_FAILURE); + } + rv = setuid(real_uid); + if (rv) + { + fprintf(stderr, "exim: setuid(%ld) failed: %s\n", + (long int)real_uid, strerror(errno)); + exit(EXIT_FAILURE); + } } /* If neither the original real uid nor the original euid was root, Exim is @@ -1570,7 +1758,7 @@ for (i = 1; i < argc; i++) else if (Ustrcmp(argrest, "version") == 0) { switchchar = 'b'; - argrest = "V"; + argrest = US"V"; } } @@ -1845,6 +2033,103 @@ for (i = 1; i < argc; i++) } } #endif + if (real_uid != root_uid) + { + #ifdef TRUSTED_CONFIG_LIST + + if (real_uid != exim_uid + #ifdef CONFIGURE_OWNER + && real_uid != config_uid + #endif + ) + trusted_config = FALSE; + else + { + FILE *trust_list = Ufopen(TRUSTED_CONFIG_LIST, "rb"); + if (trust_list) + { + struct stat statbuf; + + if (fstat(fileno(trust_list), &statbuf) != 0 || + (statbuf.st_uid != root_uid /* owner not root */ + #ifdef CONFIGURE_OWNER + && statbuf.st_uid != config_uid /* owner not the special one */ + #endif + ) || /* or */ + (statbuf.st_gid != root_gid /* group not root */ + #ifdef CONFIGURE_GROUP + && statbuf.st_gid != config_gid /* group not the special one */ + #endif + && (statbuf.st_mode & 020) != 0 /* group writeable */ + ) || /* or */ + (statbuf.st_mode & 2) != 0) /* world writeable */ + { + trusted_config = FALSE; + fclose(trust_list); + } + else + { + /* Well, the trust list at least is up to scratch... */ + void *reset_point = store_get(0); + uschar *trusted_configs[32]; + int nr_configs = 0; + int i = 0; + + while (Ufgets(big_buffer, big_buffer_size, trust_list)) + { + uschar *start = big_buffer, *nl; + while (*start && isspace(*start)) + start++; + if (*start != '/') + continue; + nl = Ustrchr(start, '\n'); + if (nl) + *nl = 0; + trusted_configs[nr_configs++] = string_copy(start); + if (nr_configs == 32) + break; + } + fclose(trust_list); + + if (nr_configs) + { + int sep = 0; + uschar *list = argrest; + uschar *filename; + while (trusted_config && (filename = string_nextinlist(&list, + &sep, big_buffer, big_buffer_size)) != NULL) + { + for (i=0; i < nr_configs; i++) + { + if (Ustrcmp(filename, trusted_configs[i]) == 0) + break; + } + if (i == nr_configs) + { + trusted_config = FALSE; + break; + } + } + store_reset(reset_point); + } + else + { + /* No valid prefixes found in trust_list file. */ + trusted_config = FALSE; + } + } + } + else + { + /* Could not open trust_list file. */ + trusted_config = FALSE; + } + } + #else + /* Not root; don't trust config */ + trusted_config = FALSE; + #endif + } config_main_filelist = argrest; config_changed = TRUE; @@ -2922,7 +3207,8 @@ if (debug_selector != 0) debug_printf("Exim version %s uid=%ld gid=%ld pid=%d D=%x\n", version_string, (long int)real_uid, (long int)real_gid, (int)getpid(), debug_selector); - show_whats_supported(stderr); + if (!version_printed) + show_whats_supported(stderr); } } @@ -3002,6 +3288,11 @@ till after reading the config, which might specify the exim gid. Therefore, save the group list here first. */ group_count = getgroups(NGROUPS_MAX, group_list); +if (group_count < 0) + { + fprintf(stderr, "exim: getgroups() failed: %s\n", strerror(errno)); + exit(EXIT_FAILURE); + } /* There is a fundamental difference in some BSD systems in the matter of groups. FreeBSD and BSDI are known to be different; NetBSD and OpenBSD are @@ -3030,11 +3321,11 @@ if (setgroups(0, NULL) != 0) /* If the configuration file name has been altered by an argument on the command line (either a new file name or a macro definition) and the caller is -not root or the exim user, or if this is a filter testing run, remove any -setuid privilege the program has, and run as the underlying user. +not root, or if this is a filter testing run, remove any setuid privilege the +program has and run as the underlying user. -If ALT_CONFIG_ROOT_ONLY is defined, the exim user is locked out of this, which -severely restricts the use of -C for some purposes. +The exim user is locked out of this, which severely restricts the use of -C +for some purposes. Otherwise, set the real ids to the effective values (should be root unless run from inetd, which it can either be root or the exim uid, if one is configured). @@ -3046,11 +3337,9 @@ values (such as the path name). If running in the test harness, pretend that configuration file changes and macro definitions haven't happened. */ if (( /* EITHER */ - (config_changed || macros != NULL) && /* Config changed, and */ + (!trusted_config || /* Config changed, or */ + !macros_trusted()) && /* impermissible macros and */ real_uid != root_uid && /* Not root, and */ - #ifndef ALT_CONFIG_ROOT_ONLY /* (when not locked out) */ - real_uid != exim_uid && /* Not exim, and */ - #endif !running_in_test_harness /* Not fudged */ ) || /* OR */ expansion_test /* expansion testing */ @@ -3066,9 +3355,13 @@ if (( /* EITHER */ and should be used for any logging information because attempts to write to the log will usually fail. To arrange this, we unset really_exim. However, if no stderr is available there is no point - we might as well have a go - at the log (if it fails, syslog will be written). */ + at the log (if it fails, syslog will be written). - if (log_stderr != NULL) really_exim = FALSE; + Note that if the invoker is Exim, the logs remain available. Messing with + this causes unlogged successful deliveries. */ + + if ((log_stderr != NULL) && (real_uid != exim_uid)) + really_exim = FALSE; } /* Privilege is to be retained for the moment. It may be dropped later, @@ -3238,15 +3531,12 @@ else } /* Handle the case when we have removed the setuid privilege because of -C or --D. This means that the caller of Exim was not root, and, provided that -ALT_CONFIG_ROOT_ONLY is not defined, was not the Exim user that is built into -the binary. +-D. This means that the caller of Exim was not root. -If ALT_CONFIG_ROOT_ONLY is not defined, there is a problem if it turns out we -were running as the exim user defined in the configuration file (different to -the one in the binary). The sysadmin may expect this case to retain privilege -because "the binary was called by the Exim user", but it hasn't, because of the -order in which it handles this stuff. There are two possibilities: +There is a problem if we were running as the Exim user. The sysadmin may +expect this case to retain privilege because "the binary was called by the +Exim user", but it hasn't, because either the -D option set macros, or the +-C option set a non-trusted configuration file. There are two possibilities: (1) If deliver_drop_privilege is set, Exim is not going to re-exec in order to do message deliveries. Thus, the fact that it is running as a @@ -3258,27 +3548,18 @@ order in which it handles this stuff. There are two possibilities: (2) If deliver_drop_privilege is not set, the configuration won't work as apparently intended, and so we log a panic message. In order to retain - root for -C or -D, the caller must either be root or the Exim user - defined in the binary (when deliver_drop_ privilege is false). - -If ALT_CONFIG_ROOT_ONLY is defined, we don't know whether we were called by the -built-in exim user or one defined in the configuration. In either event, -re-enable log processing, assuming the sysadmin knows what they are doing. */ + root for -C or -D, the caller must either be root or be invoking a + trusted configuration file (when deliver_drop_privilege is false). */ -if (removed_privilege && (config_changed || macros != NULL) && +if (removed_privilege && (!trusted_config || macros != NULL) && real_uid == exim_uid) { - #ifdef ALT_CONFIG_ROOT_ONLY - really_exim = TRUE; /* let logging work normally */ - #else - if (deliver_drop_privilege) really_exim = TRUE; /* let logging work normally */ else log_write(0, LOG_MAIN|LOG_PANIC, - "exim user (uid=%d) is defined only at runtime; privilege lost for %s", - (int)exim_uid, config_changed? "-C" : "-D"); - #endif + "exim user lost privilege for using %s option", + trusted_config? "-D" : "-C"); } /* Start up Perl interpreter if Perl support is configured and there is a @@ -3303,6 +3584,13 @@ if (opt_perl_at_start && opt_perl_startup != NULL) } #endif /* EXIM_PERL */ +/* Initialise lookup_list +If debugging, already called above via version reporting. +This does mean that debugging causes the list to be initialised while root. +This *should* be harmless -- all modules are loaded from a fixed dir and +it's code that would, if not a module, be part of Exim already. */ +init_lookup_list(); + /* Log the arguments of the call if the configuration file said so. This is a debugging feature for finding out what arguments certain MUAs actually use. Don't attempt it if logging is disabled, or if listing variables or if @@ -3618,11 +3906,33 @@ if (!unprivileged && /* originally had root AND */ /* When we are retaining a privileged uid, we still change to the exim gid. */ -else setgid(exim_gid); +else + { + int rv; + rv = setgid(exim_gid); + /* Impact of failure is that some stuff might end up with an incorrect group. + We track this for failures from root, since any attempt to change privilege + by root should succeed and failures should be examined. For non-root, + there's no security risk. For me, it's { exim -bV } on a just-built binary, + no need to complain then. */ + if (rv == -1) + { + if (!(unprivileged || removed_privilege)) + { + fprintf(stderr, + "exim: changing group failed: %s\n", strerror(errno)); + exit(EXIT_FAILURE); + } + else + DEBUG(D_any) debug_printf("changing group to %ld failed: %s\n", + (long int)exim_gid, strerror(errno)); + } + } /* Handle a request to scan a file for malware */ if (malware_test_file) { +#ifdef WITH_CONTENT_SCAN int result; set_process_info("scanning file for malware"); result = malware_in_file(malware_test_file); @@ -3640,6 +3950,9 @@ if (malware_test_file) printf("Malware found: %s\n", malware_name); else printf("Malware scan detected malware of unknown name.\n"); +#else + printf("Malware scanning not enabled at compile time.\n"); +#endif exit(EXIT_FAILURE); } @@ -4246,8 +4559,8 @@ if (expansion_test) else { - char *(*fn_readline)(char *) = NULL; - char *(*fn_addhist)(char *) = NULL; + char *(*fn_readline)(const char *) = NULL; + void (*fn_addhist)(const char *) = NULL; #ifdef USE_READLINE void *dlhandle = set_readline(&fn_readline, &fn_addhist);