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dma-mbox-create: Restrict with Capsicum

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The restriction here is pretty late and pretty minimal. We need a lot
of authority to open password databases, and don't do much after that
point.

Feedback from:	lifanov at mail.lifanov.com (earlier version), emaste (earlier version)
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D7988
This commit is contained in:
Conrad Meyer 2016-12-16 01:48:55 +00:00
parent 941e22d17d
commit 9716e7d4e4
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=310140
1 changed files with 38 additions and 1 deletions
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39
contrib/dma/dma-mbox-create.c
View file

@ -38,9 +38,18 @@
* user-supplied information. Keep the root window as small as possible.
*/
#ifdef __FreeBSD__
#define USE_CAPSICUM 1
#endif
#include <sys/param.h>
#if USE_CAPSICUM
#include <sys/capsicum.h>
#endif
#include <sys/stat.h>
#include <capsicum_helpers.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
@ -84,6 +93,9 @@ logfail(int exitcode, const char *fmt, ...)
int
main(int argc, char **argv)
{
#if USE_CAPSICUM
cap_rights_t rights;
#endif
const char *user;
struct passwd *pw;
struct group *gr;
@ -91,7 +103,10 @@ main(int argc, char **argv)
gid_t mail_gid;
int f, maildirfd;
openlog("dma-mbox-create", 0, LOG_MAIL);
/*
* Open log fd now for capability sandbox.
*/
openlog("dma-mbox-create", LOG_NDELAY, LOG_MAIL);
errno = 0;
gr = getgrnam(DMA_GROUP);
@ -133,6 +148,28 @@ main(int argc, char **argv)
if (maildirfd < 0)
logfail(EX_NOINPUT, "cannot open maildir %s", _PATH_MAILDIR);
/*
* Cache NLS data, for strerror, for err(3), before entering capability
* mode.
*/
caph_cache_catpages();
/*
* Cache local time before entering Capsicum capability sandbox.
*/
caph_cache_tzdata();
#if USE_CAPSICUM
cap_rights_init(&rights, CAP_CREATE, CAP_FCHMOD, CAP_FCHOWN,
CAP_LOOKUP, CAP_READ);
if (cap_rights_limit(maildirfd, &rights) < 0 && errno != ENOSYS)
err(EX_OSERR, "can't limit maildirfd rights");
/* Enter Capsicum capability sandbox */
if (cap_enter() < 0 && errno != ENOSYS)
err(EX_OSERR, "cap_enter");
#endif
user_uid = pw->pw_uid;
f = openat(maildirfd, user, O_RDONLY|O_CREAT|O_NOFOLLOW, 0600);