path: root/src/local/mailbox.c

/*++
/* NAME
/*	mailbox 3
/* SUMMARY
/*	mailbox delivery
/* SYNOPSIS
/*	#include "local.h"
/*
/*	int	deliver_mailbox(state, usr_attr, statusp)
/*	LOCAL_STATE state;
/*	USER_ATTR usr_attr;
/*	int	*statusp;
/* DESCRIPTION
/*	deliver_mailbox() delivers to mailbox, with duplicate
/*	suppression. The default is direct mailbox delivery to
/*	/var/[spool/]mail/\fIuser\fR; when a \fIhome_mailbox\fR
/*	has been configured, mail is delivered to ~/$\fIhome_mailbox\fR;
/*	and when a \fImailbox_command\fR has been configured, the message
/*	is piped into the command instead.
/*
/*	A zero result means that the named user was not found.
/*
/*	Arguments:
/* .IP state
/*	The attributes that specify the message, recipient and more.
/*	Attributes describing alias, include or forward expansion.
/*	A table with the results from expanding aliases or lists.
/* .IP usr_attr
/*	Attributes describing user rights and environment.
/* .IP statusp
/*	Delivery status: see below.
/* DIAGNOSTICS
/*	The message delivery status is non-zero when delivery should be tried
/*	again.
/* LICENSE
/* .ad
/* .fi
/*	The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*	Wietse Venema
/*	IBM T.J. Watson Research
/*	P.O. Box 704
/*	Yorktown Heights, NY 10598, USA
/*
/*	Wietse Venema
/*	Google, Inc.
/*	111 8th Avenue
/*	New York, NY 10011, USA
/*--*/

/* System library. */

#include <sys_defs.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>

/* Utility library. */

#include <msg.h>
#include <htable.h>
#include <vstring.h>
#include <vstream.h>
#include <mymalloc.h>
#include <stringops.h>
#include <set_eugid.h>
#include <warn_stat.h>

/* Global library. */

#include <mail_copy.h>
#include <defer.h>
#include <sent.h>
#include <mypwd.h>
#include <been_here.h>
#include <mail_params.h>
#include <deliver_pass.h>
#include <mbox_open.h>
#include <maps.h>
#include <dsn_util.h>

/* Application-specific. */

#include "local.h"
#include "biff_notify.h"

#define YES	1
#define NO	0

/* deliver_mailbox_file - deliver to recipient mailbox */

static int deliver_mailbox_file(LOCAL_STATE state, USER_ATTR usr_attr)
{
    const char *myname = "deliver_mailbox_file";
    char   *spool_dir;
    char   *mailbox;
    DSN_BUF *why = state.msg_attr.why;
    MBOX   *mp;
    int     mail_copy_status;
    int     deliver_status;
    int     copy_flags;
    VSTRING *biff;
    off_t   end;
    struct stat st;
    uid_t   spool_uid;
    gid_t   spool_gid;
    uid_t   chown_uid;
    gid_t   chown_gid;

    /*
     * Make verbose logging easier to understand.
     */
    state.level++;
    if (msg_verbose)
	MSG_LOG_STATE(myname, state);

    /*
     * Don't deliver trace-only requests.
     */
    if (DEL_REQ_TRACE_ONLY(state.request->flags)) {
	dsb_simple(why, "2.0.0", "delivers to mailbox");
	return (sent(BOUNCE_FLAGS(state.request), SENT_ATTR(state.msg_attr)));
    }

    /*
     * Initialize. Assume the operation will fail. Set the delivered
     * attribute to reflect the final recipient.
     */
    if (vstream_fseek(state.msg_attr.fp, state.msg_attr.offset, SEEK_SET) < 0)
	msg_fatal("seek message file %s: %m", VSTREAM_PATH(state.msg_attr.fp));
    if (var_frozen_delivered == 0)
	state.msg_attr.delivered = state.msg_attr.rcpt.address;
    mail_copy_status = MAIL_COPY_STAT_WRITE;
    if (*var_home_mailbox) {
	spool_dir = 0;
	mailbox = concatenate(usr_attr.home, "/", var_home_mailbox, (char *) 0);
    } else {
	spool_dir = var_mail_spool_dir;
	mailbox = concatenate(spool_dir, "/", state.msg_attr.user, (char *) 0);
    }

    /*
     * Mailbox delivery with least privilege. As long as we do not use root
     * privileges this code may also work over NFS.
     * 
     * If delivering to the recipient's home directory, perform all operations
     * (including file locking) as that user (Mike Muuss, Army Research
     * Laboratory, USA).
     * 
     * If delivering to the mail spool directory, and the spool directory is
     * world-writable, deliver as the recipient; if the spool directory is
     * group-writable, use the recipient user id and the mail spool group id.
     * 
     * Otherwise, use root privileges and chown the mailbox if we create it.
     */
    if (spool_dir == 0
	|| stat(spool_dir, &st) < 0
	|| (st.st_mode & S_IWOTH) != 0) {
	spool_uid = usr_attr.uid;
	spool_gid = usr_attr.gid;
    } else if ((st.st_mode & S_IWGRP) != 0) {
	spool_uid = usr_attr.uid;
	spool_gid = st.st_gid;
    } else {
	spool_uid = 0;
	spool_gid = 0;
    }
    if (spool_uid == usr_attr.uid) {
	chown_uid = -1;
	chown_gid = -1;
    } else {
	chown_uid = usr_attr.uid;
	chown_gid = usr_attr.gid;
    }
    if (msg_verbose)
	msg_info("spool_uid/gid %ld/%ld chown_uid/gid %ld/%ld",
		 (long) spool_uid, (long) spool_gid,
		 (long) chown_uid, (long) chown_gid);

    /*
     * Lock the mailbox and open/create the mailbox file. Depending on the
     * type of locking used, we lock first or we open first.
     * 
     * Write the file as the recipient, so that file quota work.
     */
    copy_flags = MAIL_COPY_MBOX;
    if ((local_deliver_hdr_mask & DELIVER_HDR_FILE) == 0)
	copy_flags &= ~MAIL_COPY_DELIVERED;

    set_eugid(spool_uid, spool_gid);
    mp = mbox_open(mailbox, O_APPEND | O_WRONLY | O_CREAT,
		   S_IRUSR | S_IWUSR, &st, chown_uid, chown_gid,
		   local_mbox_lock_mask, "5.2.0", why);
    if (mp != 0) {
	if (spool_uid != usr_attr.uid || spool_gid != usr_attr.gid)
	    set_eugid(usr_attr.uid, usr_attr.gid);
	if (S_ISREG(st.st_mode) == 0) {
	    vstream_fclose(mp->fp);
	    dsb_simple(why, "5.2.0",
		       "destination %s is not a regular file", mailbox);
	} else if (var_strict_mbox_owner && st.st_uid != usr_attr.uid) {
	    vstream_fclose(mp->fp);
	    dsb_simple(why, "4.2.0",
		       "destination %s is not owned by recipient", mailbox);
	    msg_warn("specify \"%s = no\" to ignore mailbox ownership mismatch",
		     VAR_STRICT_MBOX_OWNER);
	} else {
	    if ((end = vstream_fseek(mp->fp, (off_t) 0, SEEK_END)) < 0)
		msg_fatal("seek mailbox file %s: %m", mailbox);
	    mail_copy_status = mail_copy(COPY_ATTR(state.msg_attr), mp->fp,
					 copy_flags, "\n", why);
	}
	if (spool_uid != usr_attr.uid || spool_gid != usr_attr.gid)
	    set_eugid(spool_uid, spool_gid);
	mbox_release(mp);
    }
    set_eugid(var_owner_uid, var_owner_gid);

    /*
     * As the mail system, bounce, defer delivery, or report success.
     */
    if (mail_copy_status & MAIL_COPY_STAT_CORRUPT) {
	deliver_status = DEL_STAT_DEFER;
    } else if (mail_copy_status != 0) {
	vstring_sprintf_prepend(why->reason,
				"cannot update mailbox %s for user %s. ",
				mailbox, state.msg_attr.user);
	deliver_status =
	    (STR(why->status)[0] == '4' ?
	     defer_append : bounce_append)
	    (BOUNCE_FLAGS(state.request), BOUNCE_ATTR(state.msg_attr));
    } else {
	dsb_simple(why, "2.0.0", "delivered to mailbox");
	deliver_status = sent(BOUNCE_FLAGS(state.request),
			      SENT_ATTR(state.msg_attr));
	if (var_biff) {
	    biff = vstring_alloc(100);
	    vstring_sprintf(biff, "%s@%ld", usr_attr.logname, (long) end);
	    biff_notify(STR(biff), VSTRING_LEN(biff) + 1);
	    vstring_free(biff);
	}
    }

    /*
     * Clean up.
     */
    myfree(mailbox);
    return (deliver_status);
}

/* deliver_mailbox - deliver to recipient mailbox */

int     deliver_mailbox(LOCAL_STATE state, USER_ATTR usr_attr, int *statusp)
{
    const char *myname = "deliver_mailbox";
    int     status;
    struct mypasswd *mbox_pwd;
    char   *path;
    static MAPS *transp_maps;
    const char *map_transport;
    static MAPS *cmd_maps;
    const char *map_command;

    /*
     * Make verbose logging easier to understand.
     */
    state.level++;
    if (msg_verbose)
	MSG_LOG_STATE(myname, state);

    /*
     * DUPLICATE ELIMINATION
     * 
     * Don't come here more than once, whether or not the recipient exists.
     */
    if (been_here(state.dup_filter, "mailbox %s", state.msg_attr.local))
	return (YES);

    /*
     * Delegate mailbox delivery to another message transport.
     */
    if (*var_mbox_transp_maps && transp_maps == 0)
	transp_maps = maps_create(VAR_MBOX_TRANSP_MAPS, var_mbox_transp_maps,
				  DICT_FLAG_LOCK | DICT_FLAG_NO_REGSUB
				  | DICT_FLAG_UTF8_REQUEST);
    /* The -1 is a hint for the down-stream deliver_completed() function. */
    if (transp_maps
	&& (map_transport = maps_find(transp_maps, state.msg_attr.user,
				      DICT_FLAG_NONE)) != 0) {
	state.msg_attr.rcpt.offset = -1L;
	*statusp = deliver_pass(MAIL_CLASS_PRIVATE, map_transport,
				state.request, &state.msg_attr.rcpt);
	return (YES);
    } else if (transp_maps && transp_maps->error != 0) {
	/* Details in the logfile. */
	dsb_simple(state.msg_attr.why, "4.3.0", "table lookup failure");
	*statusp = defer_append(BOUNCE_FLAGS(state.request),
				BOUNCE_ATTR(state.msg_attr));
	return (YES);
    }
    if (*var_mailbox_transport) {
	state.msg_attr.rcpt.offset = -1L;
	*statusp = deliver_pass(MAIL_CLASS_PRIVATE, var_mailbox_transport,
				state.request, &state.msg_attr.rcpt);
	return (YES);
    }

    /*
     * Skip delivery when this recipient does not exist.
     */
    if ((errno = mypwnam_err(state.msg_attr.user, &mbox_pwd)) != 0) {
	msg_warn("error looking up passwd info for %s: %m",
		 state.msg_attr.user);
	dsb_simple(state.msg_attr.why, "4.0.0", "user lookup error");
	*statusp = defer_append(BOUNCE_FLAGS(state.request),
				BOUNCE_ATTR(state.msg_attr));
	return (YES);
    }
    if (mbox_pwd == 0)
	return (NO);

    /*
     * No early returns or we have a memory leak.
     */

    /*
     * DELIVERY RIGHTS
     * 
     * Use the rights of the recipient user.
     */
    SET_USER_ATTR(usr_attr, mbox_pwd, state.level);

    /*
     * Deliver to mailbox, maildir or to external command.
     */
#define LAST_CHAR(s) (s[strlen(s) - 1])

    if (*var_mailbox_cmd_maps && cmd_maps == 0)
	cmd_maps = maps_create(VAR_MAILBOX_CMD_MAPS, var_mailbox_cmd_maps,
			       DICT_FLAG_LOCK | DICT_FLAG_PARANOID
			       | DICT_FLAG_UTF8_REQUEST);

    if (cmd_maps && (map_command = maps_find(cmd_maps, state.msg_attr.user,
					     DICT_FLAG_NONE)) != 0) {
	status = deliver_command(state, usr_attr, map_command);
    } else if (cmd_maps && cmd_maps->error != 0) {
	/* Details in the logfile. */
	dsb_simple(state.msg_attr.why, "4.3.0", "table lookup failure");
	status = defer_append(BOUNCE_FLAGS(state.request),
			      BOUNCE_ATTR(state.msg_attr));
    } else if (*var_mailbox_command) {
	status = deliver_command(state, usr_attr, var_mailbox_command);
    } else if (*var_home_mailbox && LAST_CHAR(var_home_mailbox) == '/') {
	path = concatenate(usr_attr.home, "/", var_home_mailbox, (char *) 0);
	status = deliver_maildir(state, usr_attr, path);
	myfree(path);
    } else if (*var_mail_spool_dir && LAST_CHAR(var_mail_spool_dir) == '/') {
	path = concatenate(var_mail_spool_dir, state.msg_attr.user,
			   "/", (char *) 0);
	status = deliver_maildir(state, usr_attr, path);
	myfree(path);
    } else
	status = deliver_mailbox_file(state, usr_attr);

    /*
     * Cleanup.
     */
    mypwfree(mbox_pwd);
    *statusp = status;
    return (YES);
}