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pam/pam-1.1.1-drop-privs.patch

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- fix insecure dropping of priviledges in pam_xauth, pam_env, and pam_mail - CVE-2010-3316 (#637898), CVE-2010-3435 (#641335) - fix insecure executing of scripts with user supplied environment variables in pam_namespace - CVE-2010-3853 (#643043)
2010-11-02 12:24:28 +00:00
diff -up Linux-PAM-1.1.1/libpam/include/security/_pam_dropprivs.h.drop-privs Linux-PAM-1.1.1/libpam/include/security/_pam_dropprivs.h
--- Linux-PAM-1.1.1/libpam/include/security/_pam_dropprivs.h.drop-privs 2010-10-20 15:33:27.000000000 +0200
+++ Linux-PAM-1.1.1/libpam/include/security/_pam_dropprivs.h 2010-10-20 15:33:27.000000000 +0200
@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2010 Dmitry V. Levin
+ *
+ * <security/_pam_dropprivs.h>
+ *
+ * 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, and the entire permission notice in its entirety,
+ * including the disclaimer of warranties.
+ * 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. The name of the author may not be used to endorse or promote
+ * products derived from this software without specific prior
+ * written permission.
+ *
+ * ALTERNATIVELY, this product may be distributed under the terms of
+ * the GNU Public License, in which case the provisions of the GPL are
+ * required INSTEAD OF the above restrictions. (This clause is
+ * necessary due to a potential bad interaction between the GPL and
+ * the restrictions contained in a BSD-style copyright.)
+ *
+ * THIS SOFTWARE IS PROVIDED ``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 AUTHOR 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.
+ */
+
+#ifndef _SECURITY__PAM_DROPPRIVS_H
+#define _SECURITY__PAM_DROPPRIVS_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <security/_pam_types.h>
+
+struct pam_modutil_privs {
+ gid_t *grplist;
+ int number_of_groups;
+ int allocated;
+ gid_t old_gid;
+ uid_t old_uid;
+ int is_dropped;
+};
+
+#define PAM_MODUTIL_NGROUPS 64
+#define PAM_MODUTIL_DEF_PRIVS(n) \
+ gid_t n##_grplist[PAM_MODUTIL_NGROUPS]; \
+ struct pam_modutil_privs n = { n##_grplist, PAM_MODUTIL_NGROUPS, 0, -1, -1, 0 }
+
+extern int PAM_NONNULL((1,2,3))
+pam_modutil_drop_priv(pam_handle_t *pamh,
+ struct pam_modutil_privs *p,
+ const struct passwd *pw);
+
+extern int PAM_NONNULL((1,2))
+pam_modutil_regain_priv(pam_handle_t *pamh,
+ struct pam_modutil_privs *p);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _SECURITY__PAM_DROPPRIVS_H */
diff -up Linux-PAM-1.1.1/libpam/Makefile.am.drop-privs Linux-PAM-1.1.1/libpam/Makefile.am
--- Linux-PAM-1.1.1/libpam/Makefile.am.drop-privs 2009-11-04 15:04:49.000000000 +0100
+++ Linux-PAM-1.1.1/libpam/Makefile.am 2010-10-20 15:46:14.000000000 +0200
@@ -18,11 +18,15 @@ include_HEADERS = include/security/_pam_
include/security/pam_ext.h include/security/pam_modutil.h
noinst_HEADERS = pam_prelude.h pam_private.h pam_tokens.h \
- pam_modutil_private.h pam_static_modules.h
+ pam_modutil_private.h pam_static_modules.h include/security/_pam_dropprivs.h
libpam_la_LDFLAGS = -no-undefined -version-info 82:2:82
libpam_la_LIBADD = @LIBAUDIT@ $(LIBPRELUDE_LIBS) @LIBDL@
+noinst_LIBRARIES = libdropprivs.a
+libdropprivs_a_SOURCES = pam_modutil_priv.c
+libdropprivs_a_CFLAGS = $(AM_CFLAGS) -fPIC
+
if STATIC_MODULES
libpam_la_LIBADD += $(shell ls ../modules/pam_*/*.lo) \
@LIBDB@ @LIBCRYPT@ @LIBNSL@ @LIBCRACK@ -lutil
@@ -41,4 +45,4 @@ libpam_la_SOURCES = pam_account.c pam_au
pam_vprompt.c pam_syslog.c pam_dynamic.c pam_audit.c \
pam_modutil_cleanup.c pam_modutil_getpwnam.c pam_modutil_ioloop.c \
pam_modutil_getgrgid.c pam_modutil_getpwuid.c pam_modutil_getgrnam.c \
- pam_modutil_getspnam.c pam_modutil_getlogin.c pam_modutil_ingroup.c
+ pam_modutil_getspnam.c pam_modutil_getlogin.c pam_modutil_ingroup.c
diff -up Linux-PAM-1.1.1/libpam/pam_modutil_priv.c.drop-privs Linux-PAM-1.1.1/libpam/pam_modutil_priv.c
--- Linux-PAM-1.1.1/libpam/pam_modutil_priv.c.drop-privs 2010-10-20 15:33:27.000000000 +0200
+++ Linux-PAM-1.1.1/libpam/pam_modutil_priv.c 2010-10-20 15:33:27.000000000 +0200
@@ -0,0 +1,171 @@
+/*
+ * $Id: pam_modutil_priv.c,v 1.1 2010/10/03 21:02:07 ldv Exp $
+ *
+ * This file provides two functions:
+ * pam_modutil_drop_priv:
+ * temporarily lower process fs privileges by switching to another uid/gid,
+ * pam_modutil_regain_priv:
+ * regain process fs privileges lowered by pam_modutil_drop_priv().
+ */
+
+#include "pam_modutil_private.h"
+#include <security/_pam_dropprivs.h>
+#include <security/pam_ext.h>
+#include <unistd.h>
+#include <syslog.h>
+#include <pwd.h>
+#include <grp.h>
+#include <sys/fsuid.h>
+
+/*
+ * Two setfsuid() calls in a row are necessary to check
+ * whether setfsuid() succeeded or not.
+ */
+static int change_uid(uid_t uid, uid_t *save)
+{
+ uid_t tmp = setfsuid(uid);
+ if (save)
+ *save = tmp;
+ return (uid_t) setfsuid(uid) == uid ? 0 : -1;
+}
+static int change_gid(gid_t gid, gid_t *save)
+{
+ gid_t tmp = setfsgid(gid);
+ if (save)
+ *save = tmp;
+ return (gid_t) setfsgid(gid) == gid ? 0 : -1;
+}
+
+static int cleanup(struct pam_modutil_privs *p)
+{
+ if (p->allocated) {
+ p->allocated = 0;
+ free(p->grplist);
+ }
+ p->grplist = NULL;
+ p->number_of_groups = 0;
+ return -1;
+}
+
+#define PRIV_MAGIC 0x1004000a
+#define PRIV_MAGIC_DONOTHING 0xdead000a
+
+int pam_modutil_drop_priv(pam_handle_t *pamh,
+ struct pam_modutil_privs *p,
+ const struct passwd *pw)
+{
+ int res;
+
+ if (p->is_dropped) {
+ pam_syslog(pamh, LOG_CRIT,
+ "pam_modutil_drop_priv: called with dropped privileges");
+ return -1;
+ }
+
+ /*
+ * If not root, we can do nothing.
+ * If switching to root, we have nothing to do.
+ * That is, in both cases, we do not care.
+ */
+ if (geteuid() != 0 || pw->pw_uid == 0) {
+ p->is_dropped = PRIV_MAGIC_DONOTHING;
+ return 0;
+ }
+
+ if (!p->grplist || p->number_of_groups <= 0) {
+ pam_syslog(pamh, LOG_CRIT,
+ "pam_modutil_drop_priv: called without room for supplementary groups");
+ return -1;
+ }
+ res = getgroups(0, NULL);
+ if (res < 0) {
+ pam_syslog(pamh, LOG_ERR,
+ "pam_modutil_drop_priv: getgroups failed: %m");
+ return -1;
+ }
+
+ p->allocated = 0;
+ if (res > p->number_of_groups) {
+ p->grplist = calloc(res, sizeof(gid_t));
+ if (!p->grplist) {
+ pam_syslog(pamh, LOG_ERR, "out of memory");
+ return cleanup(p);
+ }
+ p->allocated = 1;
+ p->number_of_groups = res;
+ }
+
+ res = getgroups(p->number_of_groups, p->grplist);
+ if (res < 0) {
+ pam_syslog(pamh, LOG_ERR,
+ "pam_modutil_drop_priv: getgroups failed: %m");
+ return cleanup(p);
+ }
+
+ p->number_of_groups = res;
+
+ /*
+ * We should care to leave process credentials in consistent state.
+ * That is, e.g. if change_gid() succeeded but change_uid() failed,
+ * we should try to restore old gid.
+ */
+ if (setgroups(0, NULL)) {
+ pam_syslog(pamh, LOG_ERR,
+ "pam_modutil_drop_priv: setgroups failed: %m");
+ return cleanup(p);
+ }
+ if (change_gid(pw->pw_gid, &p->old_gid)) {
+ pam_syslog(pamh, LOG_ERR,
+ "pam_modutil_drop_priv: change_gid failed: %m");
+ (void) setgroups(p->number_of_groups, p->grplist);
+ return cleanup(p);
+ }
+ if (change_uid(pw->pw_uid, &p->old_uid)) {
+ pam_syslog(pamh, LOG_ERR,
+ "pam_modutil_drop_priv: change_uid failed: %m");
+ (void) change_gid(p->old_gid, NULL);
+ (void) setgroups(p->number_of_groups, p->grplist);
+ return cleanup(p);
+ }
+
+ p->is_dropped = PRIV_MAGIC;
+ return 0;
+}
+
+int pam_modutil_regain_priv(pam_handle_t *pamh,
+ struct pam_modutil_privs *p)
+{
+ switch (p->is_dropped) {
+ case PRIV_MAGIC_DONOTHING:
+ p->is_dropped = 0;
+ return 0;
+
+ case PRIV_MAGIC:
+ break;
+
+ default:
+ pam_syslog(pamh, LOG_CRIT,
+ "pam_modutil_regain_priv: called with invalid state");
+ return -1;
+ }
+
+ if (change_uid(p->old_uid, NULL)) {
+ pam_syslog(pamh, LOG_ERR,
+ "pam_modutil_regain_priv: change_uid failed: %m");
+ return cleanup(p);
+ }
+ if (change_gid(p->old_gid, NULL)) {
+ pam_syslog(pamh, LOG_ERR,
+ "pam_modutil_regain_priv: change_gid failed: %m");
+ return cleanup(p);
+ }
+ if (setgroups(p->number_of_groups, p->grplist)) {
+ pam_syslog(pamh, LOG_ERR,
+ "pam_modutil_regain_priv: setgroups failed: %m");
+ return cleanup(p);
+ }
+
+ p->is_dropped = 0;
+ cleanup(p);
+ return 0;
+}
diff -up Linux-PAM-1.1.1/modules/pam_env/Makefile.am.drop-privs Linux-PAM-1.1.1/modules/pam_env/Makefile.am
--- Linux-PAM-1.1.1/modules/pam_env/Makefile.am.drop-privs 2009-06-29 09:24:27.000000000 +0200
+++ Linux-PAM-1.1.1/modules/pam_env/Makefile.am 2010-10-20 15:33:27.000000000 +0200
@@ -22,7 +22,7 @@ if HAVE_VERSIONING
endif
securelib_LTLIBRARIES = pam_env.la
-pam_env_la_LIBADD = -L$(top_builddir)/libpam -lpam
+pam_env_la_LIBADD = -L$(top_builddir)/libpam -ldropprivs -lpam
secureconf_DATA = pam_env.conf
sysconf_DATA = environment
diff -up Linux-PAM-1.1.1/modules/pam_env/pam_env.c.drop-privs Linux-PAM-1.1.1/modules/pam_env/pam_env.c
--- Linux-PAM-1.1.1/modules/pam_env/pam_env.c.drop-privs 2009-06-29 09:24:27.000000000 +0200
+++ Linux-PAM-1.1.1/modules/pam_env/pam_env.c 2010-10-20 15:33:27.000000000 +0200
@@ -10,7 +10,7 @@
#define DEFAULT_READ_ENVFILE 1
#define DEFAULT_USER_ENVFILE ".pam_environment"
-#define DEFAULT_USER_READ_ENVFILE 1
+#define DEFAULT_USER_READ_ENVFILE 0
#include "config.h"
@@ -42,6 +42,7 @@
#include <security/pam_modutil.h>
#include <security/_pam_macros.h>
#include <security/pam_ext.h>
+#include <security/_pam_dropprivs.h>
/* This little structure makes it easier to keep variables together */
@@ -772,13 +773,14 @@ handle_env (pam_handle_t *pamh, int argc
if(user_readenv && retval == PAM_SUCCESS) {
char *envpath = NULL;
- struct passwd *user_entry;
+ struct passwd *user_entry = NULL;
const char *username;
struct stat statbuf;
username = _pam_get_item_byname(pamh, "PAM_USER");
- user_entry = pam_modutil_getpwnam (pamh, username);
+ if (username)
+ user_entry = pam_modutil_getpwnam (pamh, username);
if (!user_entry) {
pam_syslog(pamh, LOG_ERR, "No such user!?");
}
@@ -789,7 +791,15 @@ handle_env (pam_handle_t *pamh, int argc
return PAM_BUF_ERR;
}
if (stat(envpath, &statbuf) == 0) {
- retval = _parse_config_file(pamh, envpath);
+ PAM_MODUTIL_DEF_PRIVS(privs);
+
+ if (pam_modutil_drop_priv(pamh, &privs, user_entry)) {
+ retval = PAM_SESSION_ERR;
+ } else {
+ retval = _parse_config_file(pamh, envpath);
+ if (pam_modutil_regain_priv(pamh, &privs))
+ retval = PAM_SESSION_ERR;
+ }
if (retval == PAM_IGNORE)
retval = PAM_SUCCESS;
}
diff -up Linux-PAM-1.1.1/modules/pam_env/pam_env.8.xml.drop-privs Linux-PAM-1.1.1/modules/pam_env/pam_env.8.xml
--- Linux-PAM-1.1.1/modules/pam_env/pam_env.8.xml.drop-privs 2009-06-16 09:35:09.000000000 +0200
+++ Linux-PAM-1.1.1/modules/pam_env/pam_env.8.xml 2010-10-20 15:33:27.000000000 +0200
@@ -143,7 +143,10 @@
<listitem>
<para>
Turns on or off the reading of the user specific environment
- file. 0 is off, 1 is on. By default this option is on.
+ file. 0 is off, 1 is on. By default this option is off as user
+ supplied environment variables in the PAM environment could affect
+ behavior of subsequent modules in the stack without the consent
+ of the system administrator.
</para>
</listitem>
</varlistentry>
diff -up Linux-PAM-1.1.1/modules/pam_mail/Makefile.am.drop-privs Linux-PAM-1.1.1/modules/pam_mail/Makefile.am
--- Linux-PAM-1.1.1/modules/pam_mail/Makefile.am.drop-privs 2009-06-29 09:24:27.000000000 +0200
+++ Linux-PAM-1.1.1/modules/pam_mail/Makefile.am 2010-10-20 15:33:27.000000000 +0200
@@ -22,7 +22,7 @@ if HAVE_VERSIONING
endif
securelib_LTLIBRARIES = pam_mail.la
-pam_mail_la_LIBADD = -L$(top_builddir)/libpam -lpam
+pam_mail_la_LIBADD = -L$(top_builddir)/libpam -ldropprivs -lpam
if ENABLE_REGENERATE_MAN
noinst_DATA = README
diff -up Linux-PAM-1.1.1/modules/pam_mail/pam_mail.c.drop-privs Linux-PAM-1.1.1/modules/pam_mail/pam_mail.c
--- Linux-PAM-1.1.1/modules/pam_mail/pam_mail.c.drop-privs 2008-09-25 13:53:03.000000000 +0200
+++ Linux-PAM-1.1.1/modules/pam_mail/pam_mail.c 2010-10-20 15:33:27.000000000 +0200
@@ -44,6 +44,7 @@
#include <security/_pam_macros.h>
#include <security/pam_modutil.h>
#include <security/pam_ext.h>
+#include <security/_pam_dropprivs.h>
/* argument parsing */
@@ -124,29 +125,16 @@ _pam_parse (const pam_handle_t *pamh, in
static int
get_folder(pam_handle_t *pamh, int ctrl,
- const char *path_mail, char **folder_p, size_t hashcount)
+ const char *path_mail, char **folder_p, size_t hashcount,
+ const struct passwd *pwd)
{
int retval;
- const char *user, *path;
+ const char *path;
char *folder = NULL;
- const struct passwd *pwd = NULL;
-
- retval = pam_get_user(pamh, &user, NULL);
- if (retval != PAM_SUCCESS || user == NULL) {
- pam_syslog(pamh, LOG_ERR, "cannot determine username");
- retval = PAM_USER_UNKNOWN;
- goto get_folder_cleanup;
- }
if (ctrl & PAM_NEW_MAIL_DIR) {
path = path_mail;
if (*path == '~') { /* support for $HOME delivery */
- pwd = pam_modutil_getpwnam(pamh, user);
- if (pwd == NULL) {
- pam_syslog(pamh, LOG_ERR, "user unknown");
- retval = PAM_USER_UNKNOWN;
- goto get_folder_cleanup;
- }
/*
* "~/xxx" and "~xxx" are treated as same
*/
@@ -168,18 +156,11 @@ get_folder(pam_handle_t *pamh, int ctrl,
/* put folder together */
- hashcount = hashcount < strlen(user) ? hashcount : strlen(user);
+ hashcount = hashcount < strlen(pwd->pw_name) ?
+ hashcount : strlen(pwd->pw_name);
retval = PAM_BUF_ERR;
if (ctrl & PAM_HOME_MAIL) {
- if (pwd == NULL) {
- pwd = pam_modutil_getpwnam(pamh, user);
- if (pwd == NULL) {
- pam_syslog(pamh, LOG_ERR, "user unknown");
- retval = PAM_USER_UNKNOWN;
- goto get_folder_cleanup;
- }
- }
if (asprintf(&folder, MAIL_FILE_FORMAT, pwd->pw_dir, "", path) < 0)
goto get_folder_cleanup;
} else {
@@ -192,11 +173,11 @@ get_folder(pam_handle_t *pamh, int ctrl,
for (i = 0; i < hashcount; i++) {
hash[2 * i] = '/';
- hash[2 * i + 1] = user[i];
+ hash[2 * i + 1] = pwd->pw_name[i];
}
hash[2 * i] = '\0';
- rc = asprintf(&folder, MAIL_FILE_FORMAT, path, hash, user);
+ rc = asprintf(&folder, MAIL_FILE_FORMAT, path, hash, pwd->pw_name);
_pam_overwrite(hash);
_pam_drop(hash);
if (rc < 0)
@@ -208,7 +189,6 @@ get_folder(pam_handle_t *pamh, int ctrl,
/* tidy up */
get_folder_cleanup:
- user = NULL;
path = NULL;
*folder_p = folder;
@@ -402,7 +382,9 @@ static int _do_mail(pam_handle_t *pamh,
int retval, ctrl, type;
size_t hashcount;
char *folder = NULL;
+ const char *user;
const char *path_mail = NULL;
+ const struct passwd *pwd = NULL;
/*
* this module (un)sets the MAIL environment variable, and checks if
@@ -411,9 +393,21 @@ static int _do_mail(pam_handle_t *pamh,
ctrl = _pam_parse(pamh, flags, argc, argv, &path_mail, &hashcount);
+ retval = pam_get_user(pamh, &user, NULL);
+ if (retval != PAM_SUCCESS || user == NULL) {
+ pam_syslog(pamh, LOG_ERR, "cannot determine username");
+ return PAM_USER_UNKNOWN;
+ }
+
+ pwd = pam_modutil_getpwnam (pamh, user);
+ if (pwd == NULL) {
+ pam_syslog(pamh, LOG_ERR, "user unknown");
+ return PAM_USER_UNKNOWN;
+ }
+
/* which folder? */
- retval = get_folder(pamh, ctrl, path_mail, &folder, hashcount);
+ retval = get_folder(pamh, ctrl, path_mail, &folder, hashcount, pwd);
if (retval != PAM_SUCCESS) {
D(("failed to find folder"));
return retval;
@@ -450,7 +444,19 @@ static int _do_mail(pam_handle_t *pamh,
if ((est && !(ctrl & PAM_NO_LOGIN))
|| (!est && (ctrl & PAM_LOGOUT_TOO))) {
- type = get_mail_status(pamh, ctrl, folder);
+ PAM_MODUTIL_DEF_PRIVS(privs);
+
+ if (pam_modutil_drop_priv(pamh, &privs, pwd)) {
+ retval = PAM_SESSION_ERR;
+ goto do_mail_cleanup;
+ } else {
+ type = get_mail_status(pamh, ctrl, folder);
+ if (pam_modutil_regain_priv(pamh, &privs)) {
+ retval = PAM_SESSION_ERR;
+ goto do_mail_cleanup;
+ }
+ }
+
if (type != 0) {
retval = report_mail(pamh, ctrl, type, folder);
type = 0;
diff -up Linux-PAM-1.1.1/modules/pam_xauth/Makefile.am.drop-privs Linux-PAM-1.1.1/modules/pam_xauth/Makefile.am
--- Linux-PAM-1.1.1/modules/pam_xauth/Makefile.am.drop-privs 2009-11-04 13:04:53.000000000 +0100
+++ Linux-PAM-1.1.1/modules/pam_xauth/Makefile.am 2010-10-20 15:33:27.000000000 +0200
@@ -17,7 +17,7 @@ secureconfdir = $(SCONFIGDIR)
AM_CFLAGS = -I$(top_srcdir)/libpam/include -I$(top_srcdir)/libpamc/include
AM_LDFLAGS = -no-undefined -avoid-version -module \
- -L$(top_builddir)/libpam -lpam @LIBSELINUX@
+ -L$(top_builddir)/libpam -ldropprivs -lpam @LIBSELINUX@
if HAVE_VERSIONING
AM_LDFLAGS += -Wl,--version-script=$(srcdir)/../modules.map
endif
diff -up Linux-PAM-1.1.1/modules/pam_xauth/pam_xauth.c.drop-privs Linux-PAM-1.1.1/modules/pam_xauth/pam_xauth.c
--- Linux-PAM-1.1.1/modules/pam_xauth/pam_xauth.c.drop-privs 2009-11-04 13:04:53.000000000 +0100
+++ Linux-PAM-1.1.1/modules/pam_xauth/pam_xauth.c 2010-10-20 15:33:27.000000000 +0200
@@ -35,8 +35,10 @@
#include "config.h"
#include <sys/types.h>
-#include <sys/fsuid.h>
#include <sys/wait.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
#include <errno.h>
#include <fnmatch.h>
#include <grp.h>
@@ -56,6 +58,7 @@
#include <security/_pam_macros.h>
#include <security/pam_modutil.h>
#include <security/pam_ext.h>
+#include <security/_pam_dropprivs.h>
#ifdef WITH_SELINUX
#include <selinux/selinux.h>
@@ -87,7 +90,7 @@ static const char * const xauthpaths[] =
/* Run a given command (with a NULL-terminated argument list), feeding it the
* given input on stdin, and storing any output it generates. */
static int
-run_coprocess(const char *input, char **output,
+run_coprocess(pam_handle_t *pamh, const char *input, char **output,
uid_t uid, gid_t gid, const char *command, ...)
{
int ipipe[2], opipe[2], i;
@@ -126,9 +129,26 @@ run_coprocess(const char *input, char **
const char *tmp;
int maxopened;
/* Drop privileges. */
- setgid(gid);
- setgroups(0, NULL);
- setuid(uid);
+ if (setgid(gid) == -1)
+ {
+ int err = errno;
+ pam_syslog (pamh, LOG_ERR, "setgid(%lu) failed: %m",
+ (unsigned long) getegid ());
+ _exit (err);
+ }
+ if (setgroups(0, NULL) == -1)
+ {
+ int err = errno;
+ pam_syslog (pamh, LOG_ERR, "setgroups() failed: %m");
+ _exit (err);
+ }
+ if (setuid(uid) == -1)
+ {
+ int err = errno;
+ pam_syslog (pamh, LOG_ERR, "setuid(%lu) failed: %m",
+ (unsigned long) geteuid ());
+ _exit (err);
+ }
/* Initialize the argument list. */
memset(args, 0, sizeof(args));
/* Set the pipe descriptors up as stdin and stdout, and close
@@ -215,9 +235,11 @@ check_acl(pam_handle_t *pamh,
{
char path[PATH_MAX];
struct passwd *pwd;
- FILE *fp;
- int i;
- uid_t euid;
+ FILE *fp = NULL;
+ int i, fd = -1, save_errno;
+ struct stat st;
+ PAM_MODUTIL_DEF_PRIVS(privs);
+
/* Check this user's <sense> file. */
pwd = pam_modutil_getpwnam(pamh, this_user);
if (pwd == NULL) {
@@ -233,11 +255,33 @@ check_acl(pam_handle_t *pamh,
"name of user's home directory is too long");
return PAM_SESSION_ERR;
}
- euid = geteuid();
- setfsuid(pwd->pw_uid);
- fp = fopen(path, "r");
- setfsuid(euid);
- if (fp != NULL) {
+ if (pam_modutil_drop_priv(pamh, &privs, pwd))
+ return PAM_SESSION_ERR;
+ if (!stat(path, &st)) {
+ if (!S_ISREG(st.st_mode))
+ errno = EINVAL;
+ else
+ fd = open(path, O_RDONLY | O_NOCTTY);
+ }
+ save_errno = errno;
+ if (pam_modutil_regain_priv(pamh, &privs)) {
+ if (fd >= 0)
+ close(fd);
+ return PAM_SESSION_ERR;
+ }
+ if (fd >= 0) {
+ if (!fstat(fd, &st)) {
+ if (!S_ISREG(st.st_mode))
+ errno = EINVAL;
+ else
+ fp = fdopen(fd, "r");
+ }
+ if (!fp) {
+ save_errno = errno;
+ close(fd);
+ }
+ }
+ if (fp) {
char buf[LINE_MAX], *tmp;
/* Scan the file for a list of specs of users to "trust". */
while (fgets(buf, sizeof(buf), fp) != NULL) {
@@ -268,6 +312,7 @@ check_acl(pam_handle_t *pamh,
return PAM_PERM_DENIED;
} else {
/* Default to okay if the file doesn't exist. */
+ errno = save_errno;
switch (errno) {
case ENOENT:
if (noent_code == PAM_SUCCESS) {
@@ -305,7 +350,7 @@ pam_sm_open_session (pam_handle_t *pamh,
struct passwd *tpwd, *rpwd;
int fd, i, debug = 0;
int retval = PAM_SUCCESS;
- uid_t systemuser = 499, targetuser = 0, euid;
+ uid_t systemuser = 499, targetuser = 0;
/* Parse arguments. We don't understand many, so no sense in breaking
* this into a separate function. */
@@ -463,14 +508,15 @@ pam_sm_open_session (pam_handle_t *pamh,
xauth, "-f", cookiefile, "nlist", display,
(unsigned long) getuid(), (unsigned long) getgid());
}
- if (run_coprocess(NULL, &cookie,
+ if (run_coprocess(pamh, NULL, &cookie,
getuid(), getgid(),
xauth, "-f", cookiefile, "nlist", display,
NULL) == 0) {
- int save_errno;
#ifdef WITH_SELINUX
security_context_t context = NULL;
#endif
+ PAM_MODUTIL_DEF_PRIVS(privs);
+
/* Check that we got a cookie. If not, we get creative. */
if (((cookie == NULL) || (strlen(cookie) == 0)) &&
((strncmp(display, "localhost:", 10) == 0) ||
@@ -521,7 +567,7 @@ pam_sm_open_session (pam_handle_t *pamh,
(unsigned long) getuid(),
(unsigned long) getgid());
}
- run_coprocess(NULL, &cookie,
+ run_coprocess(pamh, NULL, &cookie,
getuid(), getgid(),
xauth, "-f", cookiefile,
"nlist", t, NULL);
@@ -553,9 +599,10 @@ pam_sm_open_session (pam_handle_t *pamh,
}
/* Generate a new file to hold the data. */
- euid = geteuid();
- setfsuid(tpwd->pw_uid);
-
+ if (pam_modutil_drop_priv(pamh, &privs, tpwd)) {
+ retval = PAM_SESSION_ERR;
+ goto cleanup;
+ }
#ifdef WITH_SELINUX
if (is_selinux_enabled() > 0) {
struct selabel_handle *ctx = selabel_open(SELABEL_CTX_FILE, NULL, 0);
@@ -573,31 +620,24 @@ pam_sm_open_session (pam_handle_t *pamh,
}
}
}
+#endif /* WITH_SELINUX */
fd = mkstemp(xauthority + sizeof(XAUTHENV));
- save_errno = errno;
+ if (fd < 0)
+ pam_syslog(pamh, LOG_ERR,
+ "error creating temporary file `%s': %m",
+ xauthority + sizeof(XAUTHENV));
+#ifdef WITH_SELINUX
if (context != NULL) {
free(context);
setfscreatecon(NULL);
}
-#else
- fd = mkstemp(xauthority + sizeof(XAUTHENV));
- save_errno = errno;
-#endif
-
- setfsuid(euid);
- if (fd == -1) {
- errno = save_errno;
- pam_syslog(pamh, LOG_ERR,
- "error creating temporary file `%s': %m",
- xauthority + sizeof(XAUTHENV));
+#endif /* WITH_SELINUX */
+ if (fd >= 0)
+ close(fd);
+ if (pam_modutil_regain_priv(pamh, &privs) || fd < 0) {
retval = PAM_SESSION_ERR;
goto cleanup;
}
- /* Set permissions on the new file and dispose of the
- * descriptor. */
- if (fchown(fd, tpwd->pw_uid, tpwd->pw_gid) < 0)
- pam_syslog (pamh, LOG_ERR, "fchown: %m");
- close(fd);
/* Get a copy of the filename to save as a data item for
* removal at session-close time. */
@@ -669,7 +709,7 @@ pam_sm_open_session (pam_handle_t *pamh,
(unsigned long) tpwd->pw_uid,
(unsigned long) tpwd->pw_gid);
}
- run_coprocess(cookie, &tmp,
+ run_coprocess(pamh, cookie, &tmp,
tpwd->pw_uid, tpwd->pw_gid,
xauth, "-f", cookiefile, "nmerge", "-", NULL);
@@ -691,11 +731,21 @@ int
pam_sm_close_session (pam_handle_t *pamh, int flags UNUSED,
int argc, const char **argv)
{
- void *cookiefile;
int i, debug = 0;
+ const char *user;
+ const void *data;
+ const char *cookiefile;
+ struct passwd *tpwd;
+ PAM_MODUTIL_DEF_PRIVS(privs);
+
+ /* Try to retrieve the name of a file we created when
+ * the session was opened. */
+ if (pam_get_data(pamh, DATANAME, &data) != PAM_SUCCESS)
+ return PAM_SUCCESS;
+ cookiefile = data;
- /* Parse arguments. We don't understand many, so no sense in breaking
- * this into a separate function. */
+ /* Parse arguments. We don't understand many, so
+ * no sense in breaking this into a separate function. */
for (i = 0; i < argc; i++) {
if (strcmp(argv[i], "debug") == 0) {
debug = 1;
@@ -714,19 +764,26 @@ pam_sm_close_session (pam_handle_t *pamh
argv[i]);
}
- /* Try to retrieve the name of a file we created when the session was
- * opened. */
- if (pam_get_data(pamh, DATANAME, (const void**) &cookiefile) == PAM_SUCCESS) {
- /* We'll only try to remove the file once. */
- if (strlen((char*)cookiefile) > 0) {
- if (debug) {
- pam_syslog(pamh, LOG_DEBUG, "removing `%s'",
- (char*)cookiefile);
- }
- unlink((char*)cookiefile);
- *((char*)cookiefile) = '\0';
- }
+ if (pam_get_user(pamh, &user, NULL) != PAM_SUCCESS) {
+ pam_syslog(pamh, LOG_ERR,
+ "error determining target user's name");
+ return PAM_SESSION_ERR;
+ }
+ if (!(tpwd = pam_modutil_getpwnam(pamh, user))) {
+ pam_syslog(pamh, LOG_ERR,
+ "error determining target user's UID");
+ return PAM_SESSION_ERR;
}
+
+ if (debug)
+ pam_syslog(pamh, LOG_DEBUG, "removing `%s'", cookiefile);
+ if (pam_modutil_drop_priv(pamh, &privs, tpwd))
+ return PAM_SESSION_ERR;
+ if (unlink(cookiefile) == -1 && errno != ENOENT)
+ pam_syslog(pamh, LOG_WARNING, "Couldn't remove `%s': %m", cookiefile);
+ if (pam_modutil_regain_priv(pamh, &privs))
+ return PAM_SESSION_ERR;
+
return PAM_SUCCESS;
}
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