From 0150f21be9739ad3fc8d5ce7cee2a2ff4a09326f Mon Sep 17 00:00:00 2001
From: Karel Zak <kzak@redhat.com>
Date: Wed, 22 Aug 2018 11:43:32 +0200
Subject: [PATCH] setpriv: add --reset-env
Clear environment in way like su(1), but PATH is set to hard-coded
defaults and /etc/login.defs is not used at all (I guess we want to
keep setpriv(1) simple).
If you need anything more advanced than use env(1).
Addresses: https://github.com/karelzak/util-linux/issues/325
Signed-off-by: Karel Zak <kzak@redhat.com>
---
sys-utils/setpriv.1 | 9 ++++++++
sys-utils/setpriv.c | 54 ++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 62 insertions(+), 1 deletion(-)
diff --git a/sys-utils/setpriv.1 b/sys-utils/setpriv.1
index b900f6e08..45bc5a23b 100644
--- a/sys-utils/setpriv.1
+++ b/sys-utils/setpriv.1
@@ -159,6 +159,15 @@ to abort if AppArmor is not in use, and the transition may be ignored or cause
.BR execve (2)
to fail at AppArmor's whim.
.TP
+.BI \-\-reset\-env
+Clears all the environment variables except TERM; initializes the environment variables HOME, SHELL, USER, LOGNAME
+according to the user's passwd entry; sets PATH to \fI/usr/local/bin:/bin:/usr/bin\fR for a regual user and to
+\fI/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin\fR for root.
+.sp
+The environment variable PATH may be different on systems where /bin and /sbin
+are merged into /usr. The environment variable SHELL defaults to \fI/bin/sh\fR if none is given in the user's
+passwd entry.
+.TP
.BR \-V , " \-\-version"
Display version information and exit.
.TP
diff --git a/sys-utils/setpriv.c b/sys-utils/setpriv.c
index 4147978cc..30f8f9b15 100644
--- a/sys-utils/setpriv.c
+++ b/sys-utils/setpriv.c
@@ -38,6 +38,7 @@
#include "strutils.h"
#include "xalloc.h"
#include "pathnames.h"
+#include "env.h"
#ifndef PR_SET_NO_NEW_PRIVS
# define PR_SET_NO_NEW_PRIVS 38
@@ -55,6 +56,9 @@
#define SETPRIV_EXIT_PRIVERR 127 /* how we exit when we fail to set privs */
+/* The shell to set SHELL env.variable if none is given in the user's passwd entry. */
+#define DEFAULT_SHELL "/bin/sh"
+
enum cap_type {
CAP_TYPE_EFFECTIVE = CAPNG_EFFECTIVE,
CAP_TYPE_PERMITTED = CAPNG_PERMITTED,
@@ -82,6 +86,7 @@ struct privctx {
keep_groups:1, /* keep groups */
clear_groups:1, /* remove groups */
init_groups:1, /* initialize groups */
+ reset_env:1, /* reset environment */
have_securebits:1; /* remove groups */
/* uids and gids */
@@ -137,6 +142,8 @@ static void __attribute__((__noreturn__)) usage(void)
fputs(_(" --securebits <bits> set securebits\n"), out);
fputs(_(" --selinux-label <label> set SELinux label\n"), out);
fputs(_(" --apparmor-profile <pr> set AppArmor profile\n"), out);
+ fputs(_(" --reset-env clear all environment and initialize\n"
+ " HOME, SHELL, USER, LOGNAME and PATH\n"), out);
fputs(USAGE_SEPARATOR, out);
printf(USAGE_HELP_OPTIONS(29));
@@ -643,6 +650,36 @@ static void do_apparmor_profile(const char *label)
_("write failed: %s"), _PATH_PROC_ATTR_EXEC);
}
+
+static void do_reset_environ(struct passwd *pw)
+{
+ char *term = getenv("TERM");
+
+ if (term)
+ term = xstrdup(term);
+#ifdef HAVE_CLEARENV
+ clearenv();
+#else
+ environ = NULL;
+#endif
+ if (term)
+ xsetenv("TERM", term, 1);
+
+ if (pw->pw_shell && *pw->pw_shell)
+ xsetenv("SHELL", pw->pw_shell, 1);
+ else
+ xsetenv("SHELL", DEFAULT_SHELL, 1);
+
+ xsetenv("HOME", pw->pw_dir, 1);
+ xsetenv("USER", pw->pw_name, 1);
+ xsetenv("LOGNAME", pw->pw_name, 1);
+
+ if (pw->pw_uid)
+ xsetenv("PATH", _PATH_DEFPATH, 1);
+ else
+ xsetenv("PATH", _PATH_DEFPATH_ROOT, 1);
+}
+
static uid_t get_user(const char *s, const char *err)
{
struct passwd *pw;
@@ -712,7 +749,8 @@ int main(int argc, char **argv)
CAPBSET,
SECUREBITS,
SELINUX_LABEL,
- APPARMOR_PROFILE
+ APPARMOR_PROFILE,
+ RESET_ENV
};
static const struct option longopts[] = {
@@ -737,6 +775,7 @@ int main(int argc, char **argv)
{ "selinux-label", required_argument, NULL, SELINUX_LABEL },
{ "apparmor-profile", required_argument, NULL, APPARMOR_PROFILE },
{ "help", no_argument, NULL, 'h' },
+ { "reset-env", no_argument, NULL, RESET_ENV, },
{ "version", no_argument, NULL, 'V' },
{ NULL, 0, NULL, 0 }
};
@@ -883,6 +922,9 @@ int main(int argc, char **argv)
_("duplicate --apparmor-profile option"));
opts.apparmor_profile = optarg;
break;
+ case RESET_ENV:
+ opts.reset_env = 1;
+ break;
case 'h':
usage();
case 'V':
@@ -928,6 +970,16 @@ int main(int argc, char **argv)
"can be found on the system"),
(long) opts.ruid);
+ if (opts.reset_env) {
+ if (opts.have_passwd)
+ /* pwd according to --ruid or --reuid */
+ pw = &opts.passwd;
+ else
+ /* pwd for the current user */
+ pw = getpwuid(getuid());
+ do_reset_environ(pw);
+ }
+
if (opts.nnp && prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) == -1)
err(EXIT_FAILURE, _("disallow granting new privileges failed"));
--
2.30.2