src/lda/main.c

	main.c revision 0992011130e9d0a498ca860ddbe4028398a530c5
/* Copyright (c) 2005-2011 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "lib-signals.h"
#include "env-util.h"
#include "fd-set-nonblock.h"
#include "close-keep-errno.h"
#include "istream.h"
#include "istream-seekable.h"
#include "abspath.h"
#include "safe-mkstemp.h"
#include "eacces-error.h"
#include "ipwd.h"
#include "mkdir-parents.h"
#include "str.h"
#include "str-sanitize.h"
#include "strescape.h"
#include "unichar.h"
#include "rfc822-parser.h"
#include "message-address.h"
#include "imap-utf7.h"
#include "settings-parser.h"
#include "master-service.h"
#include "master-service-settings.h"
#include "mail-storage-service.h"
#include "mail-namespace.h"
#include "raw-storage.h"
#include "mail-deliver.h"
#include "mail-send.h"
#include "mbox-from.h"
#include "lda-settings.h"

#include <stdio.h>
#include <stdlib.h>
#include <sysexits.h>

#define DEFAULT_ENVELOPE_SENDER "MAILER-DAEMON"

/* After buffer grows larger than this, create a temporary file to /tmp
   where to read the mail. */
#define MAIL_MAX_MEMORY_BUFFER (1024*128)

static const char *wanted_headers[] = {
    "From", "To", "Message-ID", "Subject", "Return-Path",
    NULL
};

static const char *escape_local_part(const char *local_part)
{
    const char *p;

    /* if local_part isn't dot-atom-text, we need to return quoted-string
       dot-atom-text = 1*atext *("." 1*atext) */
    for (p = local_part; *p != '\0'; p++) {
        if (!IS_ATEXT(*p) && *p != '.')
            break;
    }
    if (*p != '\0' || *local_part == '.' ||
        (p != local_part && p[-1] == '.'))
        local_part = t_strdup_printf("\"%s\"", str_escape(local_part));
    return local_part;
}

static const char *address_sanitize(const char *address)
{
    struct message_address *addr;
    const char *ret, *mailbox;
    pool_t pool;

    pool = pool_alloconly_create("address sanitizer", 256);
    addr = message_address_parse(pool, (const unsigned char *)address,
                     strlen(address), 1, FALSE);

    if (addr == NULL || addr->mailbox == NULL || addr->domain == NULL ||
        *addr->mailbox == '\0')
        ret = DEFAULT_ENVELOPE_SENDER;
    else {
        mailbox = escape_local_part(addr->mailbox);
        if (*addr->domain == '\0')
            ret = t_strdup(mailbox);
        else
            ret = t_strdup_printf("%s@%s", mailbox, addr->domain);
    }
    pool_unref(&pool);
    return ret;
}

static int seekable_fd_callback(const char **path_r, void *context)
{
    struct mail_deliver_context *ctx = context;
    string_t *path;
    int fd;

    path = t_str_new(128);
    mail_user_set_get_temp_prefix(path, ctx->dest_user->set);
    fd = safe_mkstemp(path, 0600, (uid_t)-1, (gid_t)-1);
    if (fd == -1) {
        i_error("safe_mkstemp(%s) failed: %m", str_c(path));
        return -1;
    }

    /* we just want the fd, unlink it */
    if (unlink(str_c(path)) < 0) {
        /* shouldn't happen.. */
        i_error("unlink(%s) failed: %m", str_c(path));
        close_keep_errno(fd);
        return -1;
    }

    *path_r = str_c(path);
    return fd;
}

static struct istream *
create_raw_stream(struct mail_deliver_context *ctx,
          int fd, time_t *mtime_r)
{
    struct istream *input, *input2, *input_list[2];
    const unsigned char *data;
    char *sender = NULL;
    size_t i, size;
    int ret, tz;

    *mtime_r = (time_t)-1;
    fd_set_nonblock(fd, FALSE);

    input = i_stream_create_fd(fd, 4096, FALSE);
    input->blocking = TRUE;
    /* If input begins with a From-line, drop it */
    ret = i_stream_read_data(input, &data, &size, 5);
    if (ret > 0 && size >= 5 && memcmp(data, "From ", 5) == 0) {
        /* skip until the first LF */
        i_stream_skip(input, 5);
        while (i_stream_read_data(input, &data, &size, 0) > 0) {
            for (i = 0; i < size; i++) {
                if (data[i] == '\n')
                    break;
            }
            if (i != size) {
                (void)mbox_from_parse(data, i, mtime_r, &tz,
                              &sender);
                i_stream_skip(input, i + 1);
                break;
            }
            i_stream_skip(input, size);
        }
    }

    if (sender != NULL && ctx->src_envelope_sender == NULL) {
        /* use the envelope sender from From_-line, but only if it
           hasn't been specified with -f already. */
        ctx->src_envelope_sender = p_strdup(ctx->pool, sender);
    }
    i_free(sender);

    if (input->v_offset == 0) {
        input2 = input;
        i_stream_ref(input2);
    } else {
        input2 = i_stream_create_limit(input, (uoff_t)-1);
    }
    i_stream_unref(&input);

    input_list[0] = input2; input_list[1] = NULL;
    input = i_stream_create_seekable(input_list, MAIL_MAX_MEMORY_BUFFER,
                     seekable_fd_callback, ctx);
    i_stream_unref(&input2);
    return input;
}

static void failure_exit_callback(int *status)
{
    /* we want all our exit codes to be sysexits.h compatible.
       if we failed because of a logging related error, we most likely
       aren't writing to stderr, so try writing there to give some kind of
       a clue what's wrong. FATAL_LOGOPEN failure already wrote to
       stderr, so don't duplicate it. */
    switch (*status) {
    case FATAL_LOGWRITE:
        fputs("Failed to write to log file", stderr);
        break;
    case FATAL_LOGERROR:
        fputs("Internal logging error", stderr);
        break;
    case FATAL_LOGOPEN:
    case FATAL_OUTOFMEM:
    case FATAL_EXEC:
    case FATAL_DEFAULT:
        break;
    default:
        return;
    }
    *status = EX_TEMPFAIL;
}

static void print_help(void)
{
    printf(
"Usage: dovecot-lda [-c <config file>] [-a <address>] [-d <username>] [-p <path>]\n"
"                   [-f <envelope sender>] [-m <mailbox>] [-e] [-k]\n");
}

int main(int argc, char *argv[])
{
    const struct setting_parser_info *set_roots[] = {
        &lda_setting_parser_info,
        NULL
    };
    struct mail_deliver_context ctx;
    enum mail_storage_service_flags service_flags = 0;
    const char *user, *errstr, *path;
    struct mail_storage_service_ctx *storage_service;
    struct mail_storage_service_user *service_user;
    struct mail_storage_service_input service_input;
    struct mail_user *raw_mail_user;
    struct mail_namespace *raw_ns;
    struct mail_namespace_settings raw_ns_set;
    struct mail_storage *storage;
    struct mailbox *box;
    struct raw_mailbox *raw_box;
    struct istream *input;
    struct mailbox_transaction_context *t;
    struct mailbox_header_lookup_ctx *headers_ctx;
    const char *user_source = "";
    void **sets;
    uid_t process_euid;
    bool stderr_rejection = FALSE;
    time_t mtime;
    int ret, c;
    enum mail_error error;

    if (getuid() != geteuid() && geteuid() == 0) {
        /* running setuid - don't allow this if the binary is
           executable by anyone */
        struct stat st;

        if (stat(argv[0], &st) < 0) {
            fprintf(stderr, "stat(%s) failed: %s\n",
                argv[0], strerror(errno));
            return EX_TEMPFAIL;
        } else if ((st.st_mode & 1) != 0 && (st.st_mode & 04000) != 0) {
            fprintf(stderr, "%s must not be both world-executable "
                "and setuid-root. This allows root exploits. "
                "See http://wiki2.dovecot.org/LDA#multipleuids\n",
                argv[0]);
            return EX_TEMPFAIL;
        }
    }

    i_set_failure_exit_callback(failure_exit_callback);

    master_service = master_service_init("lda",
        MASTER_SERVICE_FLAG_STANDALONE |
        MASTER_SERVICE_FLAG_DONT_LOG_TO_STDERR,
        &argc, &argv, "a:d:ef:km:p:r:");

    memset(&ctx, 0, sizeof(ctx));
    ctx.session = mail_deliver_session_init();
    ctx.pool = ctx.session->pool;
    ctx.dest_mailbox_name = "INBOX";
    path = NULL;

    user = getenv("USER");
    while ((c = master_getopt(master_service)) > 0) {
        switch (c) {
        case 'a':
            /* original recipient address */
            ctx.dest_addr = optarg;
            break;
        case 'd':
            /* destination user */
            user = optarg;
            service_flags |= MAIL_STORAGE_SERVICE_FLAG_USERDB_LOOKUP;
            break;
        case 'e':
            stderr_rejection = TRUE;
            break;
        case 'f':
            /* envelope sender address */
            ctx.src_envelope_sender =
                p_strdup(ctx.pool, address_sanitize(optarg));
            break;
        case 'm':
            /* destination mailbox.
               Ignore -m "". This allows doing -m ${extension}
               in Postfix to handle user+mailbox */
            if (*optarg != '\0') T_BEGIN {
                if (!uni_utf8_str_is_valid(optarg)) {
                    i_fatal("Mailbox name not UTF-8: %s",
                        optarg);
                }
                ctx.dest_mailbox_name = optarg;
            } T_END;
            break;
        case 'p':
            /* input path */
            path = t_abspath(optarg);
            break;
        case 'r':
            /* final recipient address */
            ctx.final_dest_addr = optarg;
            break;
        default:
            print_help();
            return EX_USAGE;
        }
    }
    if (optind != argc) {
        print_help();
        i_fatal_status(EX_USAGE, "Unknown argument: %s", argv[optind]);
    }

    process_euid = geteuid();
    if ((service_flags & MAIL_STORAGE_SERVICE_FLAG_USERDB_LOOKUP) != 0)
        ;
    else if (process_euid != 0) {
        /* we're non-root. get our username and possibly our home. */
        struct passwd pw;
        const char *home;

        home = getenv("HOME");
        if (user != NULL && home != NULL) {
            /* no need for a pw lookup */
            user_source = "USER environment";
        } else if ((ret = i_getpwuid(process_euid, &pw)) > 0) {
            user = t_strdup(pw.pw_name);
            if (home == NULL)
                env_put(t_strconcat("HOME=", pw.pw_dir, NULL));
            user_source = "passwd lookup for process euid";
        } else if (ret < 0) {
            /* temporary failure */
            i_fatal("getpwuid() failed: %m");
        } else if (user == NULL) {
            i_fatal_status(EX_USAGE,
                       "Couldn't lookup our username (uid=%s)",
                       dec2str(process_euid));
        }
    } else {
        i_fatal_status(EX_USAGE,
            "destination user parameter (-d user) not given");
    }
    master_service_init_finish(master_service);

    memset(&service_input, 0, sizeof(service_input));
    service_input.module = "lda";
    service_input.service = "lda";
    service_input.username = user;

    service_flags |= MAIL_STORAGE_SERVICE_FLAG_DISALLOW_ROOT |
        MAIL_STORAGE_SERVICE_FLAG_USE_SYSEXITS;
    storage_service = mail_storage_service_init(master_service, set_roots,
                            service_flags);
    ret = mail_storage_service_lookup_next(storage_service, &service_input,
                           &service_user, &ctx.dest_user,
                           &errstr);
    if (ret <= 0) {
        if (ret < 0)
            i_fatal("%s", errstr);
        return EX_NOUSER;
    }

#ifdef SIGXFSZ
        lib_signals_ignore(SIGXFSZ, TRUE);
#endif
    ctx.set = mail_storage_service_user_get_set(service_user)[1];

    if (ctx.dest_user->mail_debug && *user_source != '\0') {
        i_debug("userdb lookup skipped, username taken from %s",
            user_source);
    }

    /* create a separate mail user for the internal namespace */
    sets = master_service_settings_get_others(master_service);
    raw_mail_user = mail_user_alloc(user, ctx.dest_user->set_info, sets[0]);
    mail_user_set_home(raw_mail_user, "/");
    if (mail_user_init(raw_mail_user, &errstr) < 0)
        i_fatal("Raw user initialization failed: %s", errstr);

    memset(&raw_ns_set, 0, sizeof(raw_ns_set));
    raw_ns_set.location = ":LAYOUT=none";

    raw_ns = mail_namespaces_init_empty(raw_mail_user);
    raw_ns->flags |= NAMESPACE_FLAG_NOQUOTA | NAMESPACE_FLAG_NOACL;
    raw_ns->set = &raw_ns_set;
    if (mail_storage_create(raw_ns, "raw", 0, &errstr) < 0)
        i_fatal("Couldn't create internal raw storage: %s", errstr);
    if (path == NULL) {
        input = create_raw_stream(&ctx, 0, &mtime);
        i_stream_set_name(input, "stdin");
        box = mailbox_alloc(raw_ns->list, "Dovecot Delivery Mail",
                    MAILBOX_FLAG_NO_INDEX_FILES);
        if (mailbox_open_stream(box, input) < 0) {
            i_fatal("Can't open delivery mail as raw: %s",
                mail_storage_get_last_error(box->storage, &error));
        }
        i_stream_unref(&input);
    } else {
        mtime = (time_t)-1;
        box = mailbox_alloc(raw_ns->list, path,
                    MAILBOX_FLAG_NO_INDEX_FILES);
        if (mailbox_open(box) < 0) {
            i_fatal("Can't open delivery mail as raw: %s",
                mail_storage_get_last_error(box->storage, &error));
        }
    }
    if (mailbox_sync(box, 0) < 0) {
        i_fatal("Can't sync delivery mail: %s",
            mail_storage_get_last_error(box->storage, &error));
    }
    raw_box = (struct raw_mailbox *)box;
    raw_box->envelope_sender = ctx.src_envelope_sender != NULL ?
        ctx.src_envelope_sender : DEFAULT_ENVELOPE_SENDER;
    raw_box->mtime = mtime;

    t = mailbox_transaction_begin(box, 0);
    headers_ctx = mailbox_header_lookup_init(box, wanted_headers);
    ctx.src_mail = mail_alloc(t, 0, headers_ctx);
    mailbox_header_lookup_unref(&headers_ctx);
    mail_set_seq(ctx.src_mail, 1);

    if (ctx.dest_addr == NULL &&
        *ctx.set->lda_original_recipient_header != '\0') {
        ctx.dest_addr = mail_deliver_get_address(ctx.src_mail,
                    ctx.set->lda_original_recipient_header);
    }
    if (ctx.dest_addr == NULL) {
        ctx.dest_addr = strchr(user, '@') != NULL ? user :
            t_strconcat(user, "@", ctx.set->hostname, NULL);
    }
    if (ctx.final_dest_addr == NULL)
        ctx.final_dest_addr = ctx.dest_addr;

    if (mail_deliver(&ctx, &storage) < 0) {
        if (storage == NULL) {
            /* This shouldn't happen */
            i_error("BUG: Saving failed to unknown storage");
            return EX_TEMPFAIL;
        }

        errstr = mail_storage_get_last_error(storage, &error);

        if (stderr_rejection) {
            /* write to stderr also for tempfails so that MTA
               can log the reason if it wants to. */
            fprintf(stderr, "%s\n", errstr);
        }

        if (error != MAIL_ERROR_NOSPACE ||
            ctx.set->quota_full_tempfail) {
            /* Saving to INBOX should always work unless
               we're over quota. If it didn't, it's probably a
               configuration problem. */
            return EX_TEMPFAIL;
        }

        /* we'll have to reply with permanent failure */
        mail_deliver_log(&ctx, "rejected: %s",
                 str_sanitize(errstr, 512));

        if (stderr_rejection)
            return EX_NOPERM;
        ret = mail_send_rejection(&ctx, user, errstr);
        if (ret != 0)
            return ret < 0 ? EX_TEMPFAIL : ret;
        /* ok, rejection sent */
    }

    mail_free(&ctx.src_mail);
    mailbox_transaction_rollback(&t);
    mailbox_free(&box);

    mail_user_unref(&ctx.dest_user);
    mail_user_unref(&raw_mail_user);
    mail_deliver_session_deinit(&ctx.session);

    mail_storage_service_user_free(&service_user);
    mail_storage_service_deinit(&storage_service);
    master_service_deinit(&master_service);
        return EX_OK;
}