Date: Mon, 26 Feb 2024 18:14:34 +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: <2zwthawswhf5surxumjhhmvqpg6bauwl7ucog5kv3d33bej4ai@tpqxvtitsnt4> In-Reply-To: <202402261735.41QHZvL1027958@gitrepo.freebsd.org> References: <202402261735.41QHZvL1027958@gitrepo.freebsd.org>
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--b5b3qdh2angfxah3 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable 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=3D6e69612d5df1c1d5bd86990ea4= d9a170c030b292 >=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 variabl= es. > For now the only usage is to have a XDG_RUNTIME_DIR environment setup= at > user login. > All other environment variable have a default fallback so no need to = export > them in this module. > The directory is created according to the XDG Base directory specific= ation. > =20 > The default base directory is /var/run/xdg/<username> but can be conf= igured > using the runtime_dir=3D<dir> module option. > =20 > According to the spec the directory *must* not survive a reboot so ad= ding > 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(+) [snip] > diff --git a/lib/libpam/modules/pam_xdg/pam_xdg.c b/lib/libpam/modules/pa= m_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 distributio= n. > + * > + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 PU= RPOSE > + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIAB= LE > + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUE= NTIAL > + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOO= DS > + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) > + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, S= TRICT > + * 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/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_pr= efix : 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_d= ir); > + 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, r= v); > + 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, us= er, 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_PREFIX,= 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, user= ); > + rv =3D PAM_SESSION_ERR; > + goto out; > + } > + } > + > + /* Setup the environment variable */ > + asprintf(&runtime_dir, "XDG_RUNTIME_DIR=3D%s/%s", RUNTIME_DIR_PREFIX, u= ser); > + 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); If asprintf fails, xdg_session_file will be NULL. > + printf("Trying to open %s\n", xdg_session_file); > + session_file =3D openat(rt_dir_prefix, xdg_session_file, O_CREAT | O_E= XCL, RUNTIME_DIR_MODE); If xdg_session_file is NULL, there is a NULL pointer dereference vulnerability in the above call to openat(2). > + free(xdg_session_file); > + if (session_file >=3D 0) > + break; 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 --b5b3qdh2angfxah3 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEA6TL67gupaZ9nzhT/y5nonf44foFAmXc1P0ACgkQ/y5nonf4 4fpsJA//dsUTrurhgPoofonbjZfhXiv1lXpdSToscxMogUEG1TAsGrMn+cvJPNne 0RUDc9FSuKz7mn/VCDxO9N1dEND9kbyZy2XEc0FJ64GFbM0Lr2eqKfO9Ez3lWI/l P7bSfiD3NONgtlmHQDtYE4PmRi0q8kHq596OvQlOAuADHK2xT5BuOyqsLCZp1aPM Db2zQxqt1+G6J46oOjGMWRaZH1l+ZCH4Q52cl9JDyZ0y7TlHyHCAsqm30e0C/7k+ u1UGBbwSeQYq4btlUBtjS7Yiivse+a65Dmdlz5GvKgf6fWgu144Py8GcV1ilACPQ u0h20GJVsOKqiDdxVHZzZVCsnTyyMMo6ifW31WU9Ob0H14O2p3ftywYIdd8UOirV EC1cuqmgtLcNwmGvn+wuRvmHteqzX+aoMnS/iRceuBK2Pt69AbMMgY1rLv0tQOwK /9k/K8IRVDMU2c3bOZRd6TSpv1579O8uVZhn9agBlJ78nqnsOf9BbCb6yh9wG4Fj cM0tk5KfHqrXWZdxHclg+LwA7aEsjuxsViI5KKPisIrhBIC5ZKu84f7Ki8qsvbt/ 9fyKTPEctzO4cKNJoO/7XGnsWmw56a1ElLjVP0UTkuLBCc/T0C+CZNqLB7LjhFtf 4AjmqJRinqSLJxPQs1E/NMAERZVtu5X01TcDe3tV5mNGlR2Zto8= =jG4B -----END PGP SIGNATURE----- --b5b3qdh2angfxah3--
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