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mirror of https://git.FreeBSD.org/src.git synced 2024-12-15 10:17:20 +00:00
freebsd/contrib/dma/local.c
Baptiste Daroussin 2382c29e5f Import Dragonfly Mail Agent snapshort from 20160806 aka v0.11+
Most important change being:
dma - Fix security hole (#46)

Affecting DragonFly 4.6 and earlier, Matt Dillon fixed this in base after
finding out from BSDNow Episode 152. Comments following were from his commit
which explains better than I. Just taking his change and putting it here as well.

* dma makes an age-old mistake of not properly checking whether a file
owned by a user is a symlink or not, a bug which the original mail.local
also had.

* Add O_NOFOLLOW to disallow symlinks.

Thanks-to: BSDNow Episode 152, made me dive dma to check when they talked
about the mail.local bug.

MFC After:	2 days
2016-08-20 16:36:05 +00:00

255 lines
6.6 KiB
C

/*
* Copyright (c) 2008-2014, Simon Schubert <2@0x2c.org>.
* Copyright (c) 2008 The DragonFly Project. All rights reserved.
*
* This code is derived from software contributed to The DragonFly Project
* by Simon Schubert <2@0x2c.org>.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name of The DragonFly Project nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific, prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/types.h>
#include <sys/wait.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <paths.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <syslog.h>
#include <unistd.h>
#include "dma.h"
static int
create_mbox(const char *name)
{
struct sigaction sa, osa;
pid_t child, waitchild;
int status;
int i;
long maxfd;
int e;
int r = -1;
/*
* We need to enable SIGCHLD temporarily so that waitpid works.
*/
bzero(&sa, sizeof(sa));
sa.sa_handler = SIG_DFL;
sigaction(SIGCHLD, &sa, &osa);
do_timeout(100, 0);
child = fork();
switch (child) {
case 0:
/* child */
maxfd = sysconf(_SC_OPEN_MAX);
if (maxfd == -1)
maxfd = 1024; /* what can we do... */
for (i = 3; i <= maxfd; ++i)
close(i);
execl(LIBEXEC_PATH "/dma-mbox-create", "dma-mbox-create", name, NULL);
syslog(LOG_ERR, "cannot execute "LIBEXEC_PATH"/dma-mbox-create: %m");
exit(EX_SOFTWARE);
default:
/* parent */
waitchild = waitpid(child, &status, 0);
e = errno;
do_timeout(0, 0);
if (waitchild == -1 && e == EINTR) {
syslog(LOG_ERR, "hung child while creating mbox `%s': %m", name);
break;
}
if (waitchild == -1) {
syslog(LOG_ERR, "child disappeared while creating mbox `%s': %m", name);
break;
}
if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
syslog(LOG_ERR, "error creating mbox `%s'", name);
break;
}
/* success */
r = 0;
break;
case -1:
/* error */
syslog(LOG_ERR, "error creating mbox");
break;
}
sigaction(SIGCHLD, &osa, NULL);
return (r);
}
int
deliver_local(struct qitem *it)
{
char fn[PATH_MAX+1];
char line[1000];
const char *sender;
const char *newline = "\n";
size_t linelen;
int tries = 0;
int mbox;
int error;
int hadnl = 0;
off_t mboxlen;
time_t now = time(NULL);
error = snprintf(fn, sizeof(fn), "%s/%s", _PATH_MAILDIR, it->addr);
if (error < 0 || (size_t)error >= sizeof(fn)) {
syslog(LOG_NOTICE, "local delivery deferred: %m");
return (1);
}
retry:
/* wait for a maximum of 100s to get the lock to the file */
do_timeout(100, 0);
/* don't use O_CREAT here, because we might be running as the wrong user. */
mbox = open_locked(fn, O_WRONLY|O_APPEND);
if (mbox < 0) {
int e = errno;
do_timeout(0, 0);
switch (e) {
case EACCES:
case ENOENT:
/*
* The file does not exist or we can't access it.
* Call dma-mbox-create to create it and fix permissions.
*/
if (tries > 0 || create_mbox(it->addr) != 0) {
syslog(LOG_ERR, "local delivery deferred: can not create `%s'", fn);
return (1);
}
++tries;
goto retry;
case EINTR:
syslog(LOG_NOTICE, "local delivery deferred: can not lock `%s'", fn);
break;
default:
syslog(LOG_NOTICE, "local delivery deferred: can not open `%s': %m", fn);
break;
}
return (1);
}
do_timeout(0, 0);
mboxlen = lseek(mbox, 0, SEEK_END);
/* New mails start with \nFrom ...., unless we're at the beginning of the mbox */
if (mboxlen == 0)
newline = "";
/* If we're bouncing a message, claim it comes from MAILER-DAEMON */
sender = it->sender;
if (strcmp(sender, "") == 0)
sender = "MAILER-DAEMON";
if (fseek(it->mailf, 0, SEEK_SET) != 0) {
syslog(LOG_NOTICE, "local delivery deferred: can not seek: %m");
goto out;
}
error = snprintf(line, sizeof(line), "%sFrom %s %s", newline, sender, ctime(&now));
if (error < 0 || (size_t)error >= sizeof(line)) {
syslog(LOG_NOTICE, "local delivery deferred: can not write header: %m");
goto out;
}
if (write(mbox, line, error) != error)
goto wrerror;
while (!feof(it->mailf)) {
if (fgets(line, sizeof(line), it->mailf) == NULL)
break;
linelen = strlen(line);
if (linelen == 0 || line[linelen - 1] != '\n') {
syslog(LOG_CRIT, "local delivery failed: corrupted queue file");
snprintf(errmsg, sizeof(errmsg), "corrupted queue file");
error = -1;
goto chop;
}
/*
* mboxro processing:
* - escape lines that start with "From " with a > sign.
* - be reversable by escaping lines that contain an arbitrary
* number of > signs, followed by "From ", i.e. />*From / in regexp.
* - strict mbox processing only requires escaping after empty lines,
* yet most MUAs seem to relax this requirement and will treat any
* line starting with "From " as the beginning of a new mail.
*/
if ((!MBOX_STRICT || hadnl) &&
strncmp(&line[strspn(line, ">")], "From ", 5) == 0) {
const char *gt = ">";
if (write(mbox, gt, 1) != 1)
goto wrerror;
hadnl = 0;
} else if (strcmp(line, "\n") == 0) {
hadnl = 1;
} else {
hadnl = 0;
}
if ((size_t)write(mbox, line, linelen) != linelen)
goto wrerror;
}
close(mbox);
return (0);
wrerror:
syslog(LOG_ERR, "local delivery failed: write error: %m");
error = 1;
chop:
if (ftruncate(mbox, mboxlen) != 0)
syslog(LOG_WARNING, "error recovering mbox `%s': %m", fn);
out:
close(mbox);
return (error);
}