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/* vi: set sw=4 ts=4: */
/*
* setpriv implementation for busybox based on linux-utils-ng 2.29
*
* Copyright (C) 2017 by <assafgordon@gmail.com>
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
//config:config SETPRIV
//config: bool "setpriv (6.6 kb)"
//config: default y
//config: select PLATFORM_LINUX
//config: select LONG_OPTS
//config: help
//config: Run a program with different Linux privilege settings.
//config: Requires kernel >= 3.5
//config:
//config:config FEATURE_SETPRIV_DUMP
//config: bool "Support dumping current privilege state"
//config: default y
//config: depends on SETPRIV
//config: help
//config: Enables the "--dump" switch to print out the current privilege
//config: state. This is helpful for diagnosing problems.
//config:
//config:config FEATURE_SETPRIV_CAPABILITIES
//config: bool "Support capabilities"
//config: default y
//config: depends on SETPRIV
//config: help
//config: Capabilities can be used to grant processes additional rights
//config: without the necessity to always execute as the root user.
//config: Enabling this option enables "--dump" to show information on
//config: capabilities.
//config:
//config:config FEATURE_SETPRIV_CAPABILITY_NAMES
//config: bool "Support capability names"
//config: default y
//config: depends on SETPRIV && FEATURE_SETPRIV_CAPABILITIES
//config: help
//config: Capabilities can be either referenced via a human-readble name,
//config: e.g. "net_admin", or using their index, e.g. "cap_12". Enabling
//config: this option allows using the human-readable names in addition to
//config: the index-based names.
//applet:IF_SETPRIV(APPLET(setpriv, BB_DIR_BIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_SETPRIV) += setpriv.o
//usage:#define setpriv_trivial_usage
//usage: "[OPTIONS] PROG [ARGS]"
//usage:#define setpriv_full_usage "\n\n"
//usage: "Run PROG with different privilege settings\n"
//usage: IF_FEATURE_SETPRIV_DUMP(
//usage: "\n-d,--dump Show current capabilities"
//usage: )
//usage: "\n--nnp,--no-new-privs Ignore setuid/setgid bits and file capabilities"
//usage: IF_FEATURE_SETPRIV_CAPABILITIES(
//usage: "\n--inh-caps CAP,CAP Set inheritable capabilities"
//usage: "\n--ambient-caps CAP,CAP Set ambient capabilities"
//usage: )
//setpriv from util-linux 2.28:
// -d, --dump show current state (and do not exec anything)
// --nnp, --no-new-privs disallow granting new privileges
// --inh-caps <caps,...> set inheritable capabilities
// --bounding-set <caps> set capability bounding set
// --ruid <uid> set real uid
// --euid <uid> set effective uid
// --rgid <gid> set real gid
// --egid <gid> set effective gid
// --reuid <uid> set real and effective uid
// --regid <gid> set real and effective gid
// --clear-groups clear supplementary groups
// --keep-groups keep supplementary groups
// --groups <group,...> set supplementary groups
// --securebits <bits> set securebits
// --selinux-label <label> set SELinux label
// --apparmor-profile <pr> set AppArmor profile
#if ENABLE_FEATURE_SETPRIV_CAPABILITIES
#include <linux/capability.h>
// #include <sys/capability.h>
// This header is in libcap, but the functions are in libc.
// Comment in the header says this above capset/capget:
/* system calls - look to libc for function to system call mapping */
extern int capset(cap_user_header_t header, cap_user_data_t data);
extern int capget(cap_user_header_t header, const cap_user_data_t data);
// so for bbox, let's just repeat the declarations.
// This way, libcap needs not be installed in build environment.
#endif
#include <sys/prctl.h>
#include "libbb.h"
#ifndef PR_CAPBSET_READ
#define PR_CAPBSET_READ 23
#endif
#ifndef PR_SET_NO_NEW_PRIVS
#define PR_SET_NO_NEW_PRIVS 38
#endif
#ifndef PR_GET_NO_NEW_PRIVS
#define PR_GET_NO_NEW_PRIVS 39
#endif
#ifndef PR_CAP_AMBIENT
#define PR_CAP_AMBIENT 47
#define PR_CAP_AMBIENT_IS_SET 1
#define PR_CAP_AMBIENT_RAISE 2
#define PR_CAP_AMBIENT_LOWER 3
#endif
enum {
IF_FEATURE_SETPRIV_DUMP(OPTBIT_DUMP,)
IF_FEATURE_SETPRIV_CAPABILITIES(OPTBIT_INH,)
IF_FEATURE_SETPRIV_CAPABILITIES(OPTBIT_AMB,)
OPTBIT_NNP,
IF_FEATURE_SETPRIV_DUMP(OPT_DUMP = (1 << OPTBIT_DUMP),)
IF_FEATURE_SETPRIV_CAPABILITIES(OPT_INH = (1 << OPTBIT_INH),)
IF_FEATURE_SETPRIV_CAPABILITIES(OPT_AMB = (1 << OPTBIT_AMB),)
OPT_NNP = (1 << OPTBIT_NNP),
};
#if ENABLE_FEATURE_SETPRIV_CAPABILITIES
DEFINE_STRUCT_CAPS;
static unsigned parse_cap(const char *cap)
{
switch (cap[0]) {
case '-':
break;
case '+':
break;
default:
bb_error_msg_and_die("invalid capability '%s'", cap);
break;
}
cap++;
return cap_name_to_number(cap);
}
static void set_inh_caps(char *capstring)
{
struct caps caps;
getcaps(&caps);
capstring = strtok(capstring, ",");
while (capstring) {
unsigned cap;
cap = parse_cap(capstring);
if (CAP_TO_INDEX(cap) >= caps.u32s)
bb_error_msg_and_die("invalid capability '%s'", capstring);
if (capstring[0] == '+')
caps.data[CAP_TO_INDEX(cap)].inheritable |= CAP_TO_MASK(cap);
else
caps.data[CAP_TO_INDEX(cap)].inheritable &= ~CAP_TO_MASK(cap);
capstring = strtok(NULL, ",");
}
if (capset(&caps.header, caps.data) != 0)
bb_perror_msg_and_die("capset");
}
static void set_ambient_caps(char *string)
{
char *cap;
cap = strtok(string, ",");
while (cap) {
unsigned idx;
idx = parse_cap(cap);
if (cap[0] == '+') {
if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, idx, 0, 0) < 0)
bb_perror_msg("cap_ambient_raise");
} else {
if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_LOWER, idx, 0, 0) < 0)
bb_perror_msg("cap_ambient_lower");
}
cap = strtok(NULL, ",");
}
}
#endif /* FEATURE_SETPRIV_CAPABILITIES */
#if ENABLE_FEATURE_SETPRIV_DUMP
# if !ENABLE_FEATURE_SETPRIV_CAPABILITY_NAMES
# define printf_cap(pfx, cap_no) printf("%scap_%u", (pfx), (cap_no))
# endif
static int dump(void)
{
IF_FEATURE_SETPRIV_CAPABILITIES(struct caps caps;)
const char *fmt;
uid_t ruid, euid, suid;
gid_t rgid, egid, sgid;
gid_t *gids;
int i, ngids, nnp;
getresuid(&ruid, &euid, &suid); /* never fails in Linux */
getresgid(&rgid, &egid, &sgid); /* never fails in Linux */
ngids = 0;
gids = bb_getgroups(&ngids, NULL); /* never fails in Linux */
nnp = prctl(PR_GET_NO_NEW_PRIVS, 0, 0, 0, 0);
if (nnp < 0)
bb_perror_msg_and_die("prctl: %s", "GET_NO_NEW_PRIVS");
printf("uid: %u\n", (unsigned)ruid);
printf("euid: %u\n", (unsigned)euid);
printf("gid: %u\n", (unsigned)rgid);
printf("egid: %u\n", (unsigned)egid);
printf("Supplementary groups: ");
if (ngids == 0) {
printf("[none]");
} else {
fmt = ",%u" + 1;
for (i = 0; i < ngids; i++) {
printf(fmt, (unsigned)gids[i]);
fmt = ",%u";
}
}
printf("\nno_new_privs: %d\n", nnp);
# if ENABLE_FEATURE_SETPRIV_CAPABILITIES
getcaps(&caps);
printf("Inheritable capabilities: ");
fmt = "";
for (i = 0; cap_valid(i); i++) {
unsigned idx = CAP_TO_INDEX(i);
if (idx >= caps.u32s) {
printf("\nindex: %u u32s: %u capability: %u\n", idx, caps.u32s, i);
bb_error_msg_and_die("unsupported capability");
}
if (caps.data[idx].inheritable & CAP_TO_MASK(i)) {
printf_cap(fmt, i);
fmt = ",";
}
}
if (!fmt[0])
printf("[none]");
printf("\nAmbient capabilities: ");
fmt = "";
for (i = 0; cap_valid(i); i++) {
int ret = prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, (unsigned long) i, 0UL, 0UL);
if (ret < 0)
bb_perror_msg_and_die("prctl: %s", "CAP_AMBIENT_IS_SET");
if (ret) {
printf_cap(fmt, i);
fmt = ",";
}
}
if (i == 0)
printf("[unsupported]");
else if (!fmt[0])
printf("[none]");
printf("\nCapability bounding set: ");
fmt = "";
for (i = 0; cap_valid(i); i++) {
int ret = prctl(PR_CAPBSET_READ, (unsigned long) i, 0UL, 0UL, 0UL);
if (ret < 0)
bb_perror_msg_and_die("prctl: %s", "CAPBSET_READ");
if (ret) {
printf_cap(fmt, i);
fmt = ",";
}
}
if (!fmt[0])
printf("[none]");
bb_putchar('\n');
# endif
if (ENABLE_FEATURE_CLEAN_UP)
free(gids);
return EXIT_SUCCESS;
}
#endif /* FEATURE_SETPRIV_DUMP */
int setpriv_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int setpriv_main(int argc UNUSED_PARAM, char **argv)
{
static const char setpriv_longopts[] ALIGN1 =
IF_FEATURE_SETPRIV_DUMP(
"dump\0" No_argument "d"
)
"nnp\0" No_argument "\xff"
"no-new-privs\0" No_argument "\xff"
IF_FEATURE_SETPRIV_CAPABILITIES(
"inh-caps\0" Required_argument "\xfe"
"ambient-caps\0" Required_argument "\xfd"
)
;
int opts;
IF_FEATURE_SETPRIV_CAPABILITIES(char *inh_caps, *ambient_caps;)
opts = getopt32long(argv, "+"
IF_FEATURE_SETPRIV_DUMP("d")
IF_FEATURE_SETPRIV_CAPABILITIES("\xfe:\xfd:"),
setpriv_longopts
IF_FEATURE_SETPRIV_CAPABILITIES(, &inh_caps, &ambient_caps)
);
argv += optind;
#if ENABLE_FEATURE_SETPRIV_DUMP
if (opts & OPT_DUMP) {
if (argv[0] || (opts - OPT_DUMP) != 0)
bb_show_usage();
return dump();
}
#endif
if (opts & OPT_NNP) {
if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0))
bb_perror_msg_and_die("prctl: %s", "SET_NO_NEW_PRIVS");
}
#if ENABLE_FEATURE_SETPRIV_CAPABILITIES
if (opts & OPT_INH)
set_inh_caps(inh_caps);
if (opts & OPT_AMB)
set_ambient_caps(ambient_caps);
#endif
if (!argv[0])
bb_show_usage();
BB_EXECVP_or_die(argv);
}