Date: Mon, 26 Feb 2024 20:08:35 +0000 From: Shawn Webb <shawn.webb@hardenedbsd.org> To: Emmanuel Vadot <manu@freebsd.org> Cc: src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: 6e69612d5df1 - main - pam: Add pam_xdg module Message-ID: <gkr5ivobwsddav6jtpsn4koh2mbaanfj2smpfsbh3acc4oc4le@u2rkbee4sjsf> In-Reply-To: <2zwthawswhf5surxumjhhmvqpg6bauwl7ucog5kv3d33bej4ai@tpqxvtitsnt4> References: <202402261735.41QHZvL1027958@gitrepo.freebsd.org> <2zwthawswhf5surxumjhhmvqpg6bauwl7ucog5kv3d33bej4ai@tpqxvtitsnt4>
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--plr4rvdeq7gdc5hf Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Feb 26, 2024 at 06:14:34PM +0000, Shawn Webb wrote: > On Mon, Feb 26, 2024 at 05:35:57PM +0000, Emmanuel Vadot wrote: > > The branch main has been updated by manu: > >=20 > > URL: https://cgit.FreeBSD.org/src/commit/?id=3D6e69612d5df1c1d5bd86990e= a4d9a170c030b292 > >=20 > > commit 6e69612d5df1c1d5bd86990ea4d9a170c030b292 > > Author: Emmanuel Vadot <manu@FreeBSD.org> > > AuthorDate: 2024-02-21 14:51:05 +0000 > > Commit: Emmanuel Vadot <manu@FreeBSD.org> > > CommitDate: 2024-02-26 17:34:52 +0000 > >=20 > > pam: Add pam_xdg module > > =20 > > This is a module to setup the XDG directories and environment varia= bles. > > For now the only usage is to have a XDG_RUNTIME_DIR environment set= up at > > user login. > > All other environment variable have a default fallback so no need t= o export > > them in this module. > > The directory is created according to the XDG Base directory specif= ication. > > =20 > > The default base directory is /var/run/xdg/<username> but can be co= nfigured > > using the runtime_dir=3D<dir> module option. > > =20 > > According to the spec the directory *must* not survive a reboot so = adding > > var_run_enable=3D"YES" to rc.conf is highly recommanded. > > =20 > > Reviewed by: des, pauamma (manpages) > > Differential Revision: https://reviews.freebsd.org/D44011 > > Sponsored by: Beckhoff Automation GmbH & Co. KG > > --- > > lib/libpam/modules/modules.inc | 1 + > > lib/libpam/modules/pam_xdg/Makefile | 6 + > > lib/libpam/modules/pam_xdg/pam_xdg.8 | 56 +++++++ > > lib/libpam/modules/pam_xdg/pam_xdg.c | 311 +++++++++++++++++++++++++++= ++++++++ > > 4 files changed, 374 insertions(+) >=20 > [snip] >=20 > > diff --git a/lib/libpam/modules/pam_xdg/pam_xdg.c b/lib/libpam/modules/= pam_xdg/pam_xdg.c > > new file mode 100644 > > index 000000000000..40012fe463e0 > > --- /dev/null > > +++ b/lib/libpam/modules/pam_xdg/pam_xdg.c > > @@ -0,0 +1,311 @@ > > +/*- > > + * SPDX-License-Identifier: BSD-2-Clause > > + * > > + * Copyright (c) 2024 Beckhoff Automation GmbH & Co. KG > > + * > > + * 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 distribut= ion. > > + * > > + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' = AND > > + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, T= HE > > + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR = PURPOSE > > + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LI= ABLE > > + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQ= UENTIAL > > + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE G= OODS > > + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTIO= N) > > + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,= STRICT > > + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN A= NY WAY > > + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY= OF > > + * SUCH DAMAGE. > > + */ > > + > > +#include <sys/stat.h> > > +#include <dirent.h> > > +#include <errno.h> > > +#include <fcntl.h> > > +#include <stdio.h> > > +#include <stdlib.h> > > +#include <string.h> > > +#include <unistd.h> > > +#include <pwd.h> > > + > > +#define PAM_SM_SESSION > > + > > +#include <security/pam_appl.h> > > +#include <security/pam_modules.h> > > +#include <security/pam_mod_misc.h> > > + > > +#define BASE_RUNTIME_DIR_PREFIX "/var/run/xdg" > > +#define RUNTIME_DIR_PREFIX runtime_dir_prefix !=3D NULL ? runtime_dir_= prefix : BASE_RUNTIME_DIR_PREFIX > > + > > +#define RUNTIME_DIR_PREFIX_MODE 0711 > > +#define RUNTIME_DIR_MODE 0700 /* XDG spec */ > > + > > +#define XDG_MAX_SESSION 100 /* Arbitrary limit because we need one */ > > + > > +static int > > +_pam_xdg_open(pam_handle_t *pamh, int flags __unused, > > + int argc __unused, const char *argv[] __unused) > > +{ > > + struct passwd *passwd; > > + const char *user; > > + const char *runtime_dir_prefix; > > + struct stat sb; > > + char *runtime_dir =3D NULL; > > + char *xdg_session_file; > > + int rv, rt_dir_prefix, rt_dir, session_file, i; > > + > > + session_file =3D -1; > > + rt_dir_prefix =3D -1; > > + runtime_dir_prefix =3D openpam_get_option(pamh, "runtime_dir_prefix"); > > + > > + /* Get user info */ > > + rv =3D pam_get_item(pamh, PAM_USER, (const void **)&user); > > + if (rv !=3D PAM_SUCCESS) { > > + PAM_VERBOSE_ERROR("Can't get user information"); > > + goto out; > > + } > > + if ((passwd =3D getpwnam(user)) =3D=3D NULL) { > > + PAM_VERBOSE_ERROR("Can't get user information"); > > + rv =3D PAM_SESSION_ERR; > > + goto out; > > + } > > + > > + /* Open or create the base xdg directory */ > > + rt_dir_prefix =3D open(RUNTIME_DIR_PREFIX, O_DIRECTORY | O_NOFOLLOW); > > + if (rt_dir_prefix < 0) { > > + rt_dir_prefix =3D mkdir(RUNTIME_DIR_PREFIX, RUNTIME_DIR_PREFIX_MODE); > > + if (rt_dir_prefix !=3D 0) { > > + PAM_VERBOSE_ERROR("Can't mkdir %s", RUNTIME_DIR_PREFIX); > > + rv =3D PAM_SESSION_ERR; > > + goto out; > > + } > > + rt_dir_prefix =3D open(RUNTIME_DIR_PREFIX, O_DIRECTORY | O_NOFOLLOW); > > + } > > + > > + /* Open or create the user xdg directory */ > > + rt_dir =3D openat(rt_dir_prefix, user, O_DIRECTORY | O_NOFOLLOW); > > + if (rt_dir < 0) { > > + rt_dir =3D mkdirat(rt_dir_prefix, user, RUNTIME_DIR_MODE); > > + if (rt_dir !=3D 0) { > > + PAM_VERBOSE_ERROR("mkdir: %s/%s (%d)", RUNTIME_DIR_PREFIX, user, rt= _dir); > > + rv =3D PAM_SESSION_ERR; > > + goto out; > > + } > > + rv =3D fchownat(rt_dir_prefix, user, passwd->pw_uid, passwd->pw_gid,= 0); > > + if (rv !=3D 0) { > > + PAM_VERBOSE_ERROR("fchownat: %s/%s (%d)", RUNTIME_DIR_PREFIX, user,= rv); > > + rv =3D unlinkat(rt_dir_prefix, user, AT_REMOVEDIR); > > + if (rv =3D=3D -1) > > + PAM_VERBOSE_ERROR("unlinkat: %s/%s (%d)", RUNTIME_DIR_PREFIX, user= , errno); > > + rv =3D PAM_SESSION_ERR; > > + goto out; > > + } > > + } else { > > + /* Check that the already create dir is correctly owned */ > > + rv =3D fstatat(rt_dir_prefix, user, &sb, 0); > > + if (rv =3D=3D -1) { > > + PAM_VERBOSE_ERROR("fstatat %s/%s failed (%d)", RUNTIME_DIR_PREFIX, = user, errno); > > + rv =3D PAM_SESSION_ERR; > > + goto out; > > + } > > + if (sb.st_uid !=3D passwd->pw_uid || > > + sb.st_gid !=3D passwd->pw_gid) { > > + PAM_VERBOSE_ERROR("%s/%s isn't owned by %d:%d\n", RUNTIME_DIR_PREFI= X, user, passwd->pw_uid, passwd->pw_gid); > > + rv =3D PAM_SESSION_ERR; > > + goto out; > > + } > > + /* Test directory mode */ > > + if ((sb.st_mode & 0x1FF) !=3D RUNTIME_DIR_MODE) { > > + PAM_VERBOSE_ERROR("%s/%s have wrong mode\n", RUNTIME_DIR_PREFIX, us= er); > > + rv =3D PAM_SESSION_ERR; > > + goto out; > > + } > > + } > > + > > + /* Setup the environment variable */ > > + asprintf(&runtime_dir, "XDG_RUNTIME_DIR=3D%s/%s", RUNTIME_DIR_PREFIX,= user); > > + rv =3D pam_putenv(pamh, runtime_dir); > > + if (rv !=3D PAM_SUCCESS) { > > + PAM_VERBOSE_ERROR("pam_putenv: failed (%d)", rv); > > + rv =3D PAM_SESSION_ERR; > > + goto out; > > + } > > + > > + /* Setup the session count file */ > > + for (i =3D 0; i < XDG_MAX_SESSION; i++) { > > + asprintf(&xdg_session_file, "%s/xdg_session.%d", user, i); >=20 > If asprintf fails, xdg_session_file will be NULL. >=20 > > + printf("Trying to open %s\n", xdg_session_file); > > + session_file =3D openat(rt_dir_prefix, xdg_session_file, O_CREAT | O= _EXCL, RUNTIME_DIR_MODE); >=20 > If xdg_session_file is NULL, there is a NULL pointer dereference > vulnerability in the above call to openat(2). >=20 > > + free(xdg_session_file); > > + if (session_file >=3D 0) > > + break; >=20 Fixed in HardenedBSD: https://git.hardenedbsd.org/hardenedbsd/HardenedBSD/-/commit/0b5bf32630b342= 9e0b5a321e6621a404dc93ecc5 But in that commit, I made a typo, which was subsequently fixed here: https://git.hardenedbsd.org/hardenedbsd/HardenedBSD/-/commit/865994a5cf2093= 7224bde0662bb1f96ba18e072f Thanks, --=20 Shawn Webb Cofounder / Security Engineer HardenedBSD Tor-ified Signal: +1 303-901-1600 https://git.hardenedbsd.org/hardenedbsd/pubkeys/-/raw/master/Shawn_Webb/03A= 4CBEBB82EA5A67D9F3853FF2E67A277F8E1FA.pub.asc --plr4rvdeq7gdc5hf Content-Type: application/pgp-signature; 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