Commit 51a91f9d authored by Chong Yidong's avatar Chong Yidong

Fix permissions handling (CVE-2010-0825).

* movemail.c (main): Check return values of setuid.  Avoid
possibility of symlink attack when movemail is setgid mail
(CVE-2010-0825).
parent a9ae306f
2010-04-02 Dan Rosenberg <dan.j.rosenberg@gmail.com> (tiny change)
* movemail.c (main): Check return values of setuid. Avoid
possibility of symlink attack when movemail is setgid mail
(CVE-2010-0825).
2010-04-02 Dan Nicolaescu <dann@ics.uci.edu>
Remove extern errno declarations.
......
......@@ -194,6 +194,9 @@ main (argc, argv)
# define ARGSTR "p"
#endif /* MAIL_USE_POP */
uid_t real_gid = getgid();
uid_t priv_gid = getegid();
#ifdef WINDOWSNT
/* Ensure all file i/o is in binary mode. */
_fmode = _O_BINARY;
......@@ -244,25 +247,6 @@ main (argc, argv)
if (*outname == 0)
fatal ("Destination file name is empty", 0, 0);
/* Check access to output file. */
if (access (outname, F_OK) == 0 && access (outname, W_OK) != 0)
pfatal_with_name (outname);
/* Also check that outname's directory is writable to the real uid. */
{
char *buf = (char *) xmalloc (strlen (outname) + 1);
char *p;
strcpy (buf, outname);
p = buf + strlen (buf);
while (p > buf && !IS_DIRECTORY_SEP (p[-1]))
*--p = 0;
if (p == buf)
*p++ = '.';
if (access (buf, W_OK) != 0)
pfatal_with_name (buf);
free (buf);
}
#ifdef MAIL_USE_POP
if (!strncmp (inname, "po:", 3))
{
......@@ -274,15 +258,12 @@ main (argc, argv)
exit (status);
}
setuid (getuid ());
if (setuid (getuid ()) < 0)
fatal ("Failed to drop privileges", 0, 0);
#endif /* MAIL_USE_POP */
#ifndef DISABLE_DIRECT_ACCESS
/* Check access to input file. */
if (access (inname, R_OK | W_OK) != 0)
pfatal_with_name (inname);
#ifndef MAIL_USE_MMDF
#ifndef MAIL_USE_SYSTEM_LOCK
#ifdef MAIL_USE_MAILLOCK
......@@ -376,7 +357,8 @@ main (argc, argv)
time_t touched_lock, now;
#endif
setuid (getuid ());
if (setuid (getuid ()) < 0 || setegid (real_gid) < 0)
fatal ("Failed to drop privileges", 0, 0);
#ifndef MAIL_USE_MMDF
#ifdef MAIL_USE_SYSTEM_LOCK
......@@ -402,6 +384,9 @@ main (argc, argv)
if (outdesc < 0)
pfatal_with_name (outname);
if (setegid (priv_gid) < 0)
fatal ("Failed to regain privileges", 0, 0);
/* This label exists so we can retry locking
after a delay, if it got EAGAIN or EBUSY. */
retry_lock:
......@@ -495,6 +480,10 @@ main (argc, argv)
pfatal_and_delete (outname);
#endif
/* Prevent symlink attacks truncating other users' mailboxes */
if (setegid (real_gid) < 0)
fatal ("Failed to drop privileges", 0, 0);
/* Check to make sure no errors before we zap the inbox. */
if (close (outdesc) != 0)
pfatal_and_delete (outname);
......@@ -526,6 +515,10 @@ main (argc, argv)
}
#endif /* not MAIL_USE_SYSTEM_LOCK */
/* End of mailbox truncation */
if (setegid (priv_gid) < 0)
fatal ("Failed to regain privileges", 0, 0);
#ifdef MAIL_USE_MAILLOCK
/* This has to occur in the child, i.e., in the process that
acquired the lock! */
......
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