blob: 4f568c3768f6aea85e36f7531ac1ad38fa1162fb [file] [log] [blame]
/*
* Copyright (c) 2008-11,16,19,2020 Andrew G. Morgan <morgan@kernel.org>
*
* This is a multifunction shell wrapper tool that can be used to
* launch capable files in various ways with a variety of settings. It
* also supports some testing modes, which are used extensively as
* part of the libcap build system.
*
* The --print option can be used as a quick test whether various
* capability manipulations work as expected (or not).
*/
#ifndef _DEFAULT_SOURCE
#define _DEFAULT_SOURCE
#endif
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <pwd.h>
#include <grp.h>
#include <errno.h>
#include <ctype.h>
#include <sys/capability.h>
#include <sys/prctl.h>
#include <sys/securebits.h>
#include <sys/wait.h>
#include <unistd.h>
#ifndef SHELL
#define SHELL "/bin/bash"
#endif /* ndef SHELL */
#include "./capshdoc.h"
#define MAX_GROUPS 100 /* max number of supplementary groups for user */
/* parse a non-negative integer with some error handling */
static unsigned long nonneg_uint(const char *text, const char *prefix, int *ok)
{
char *remains;
unsigned long value;
ssize_t len = strlen(text);
if (len == 0 || *text == '-') {
goto fail;
}
value = strtoul(text, &remains, 0);
if (*remains) {
goto fail;
}
if (ok != NULL) {
*ok = 1;
}
return value;
fail:
if (ok == NULL) {
fprintf(stderr, "%s: want non-negative integer, got \"%s\"\n",
prefix, text);
exit(1);
}
*ok = 0;
return 0;
}
static char *binary(unsigned long value)
{
static char string[8*sizeof(unsigned long) + 1];
unsigned i;
i = sizeof(string);
string[--i] = '\0';
do {
string[--i] = (value & 1) ? '1' : '0';
value >>= 1;
} while ((i > 0) && value);
return string + i;
}
static void display_prctl_set(const char *name, int (*fn)(cap_value_t))
{
unsigned cap;
const char *sep;
int set;
printf("%s set =", name);
for (sep = "", cap=0; (set = fn(cap)) >= 0; cap++) {
char *ptr;
if (!set) {
continue;
}
ptr = cap_to_name(cap);
if (ptr == NULL) {
printf("%s%u", sep, cap);
} else {
printf("%s%s", sep, ptr);
cap_free(ptr);
}
sep = ",";
}
if (!cap) {
printf(" <unsupported>\n");
} else {
printf("\n");
}
}
static void display_current(void)
{
cap_t all;
char *text;
all = cap_get_proc();
if (all == NULL) {
perror("failed to get process capabilities");
exit(1);
}
text = cap_to_text(all, NULL);
printf("Current: %s\n", text);
cap_free(text);
cap_free(all);
}
static void display_current_iab(void)
{
cap_iab_t iab;
char *text;
iab = cap_iab_get_proc();
if (iab == NULL) {
perror("failed to get IAB for process");
exit(1);
}
text = cap_iab_to_text(iab);
if (text == NULL) {
perror("failed to obtain text for IAB");
cap_free(iab);
exit(1);
}
printf("Current IAB: %s\n", text);
cap_free(text);
cap_free(iab);
}
/* arg_print displays the current capability state of the process */
static void arg_print(void)
{
long set;
int status, j;
const char *sep;
struct group *g;
gid_t groups[MAX_GROUPS], gid;
uid_t uid, euid;
struct passwd *u, *eu;
display_current();
display_prctl_set("Bounding", cap_get_bound);
display_prctl_set("Ambient", cap_get_ambient);
display_current_iab();
set = cap_get_secbits();
if (set >= 0) {
const char *b = binary(set); /* verilog convention for binary string */
printf("Securebits: 0%lo/0x%lx/%u'b%s (no-new-privs=%d)\n", set, set,
(unsigned) strlen(b), b,
prctl(PR_GET_NO_NEW_PRIVS, 0, 0, 0, 0, 0));
printf(" secure-noroot: %s (%s)\n",
(set & SECBIT_NOROOT) ? "yes":"no",
(set & SECBIT_NOROOT_LOCKED) ? "locked":"unlocked");
printf(" secure-no-suid-fixup: %s (%s)\n",
(set & SECBIT_NO_SETUID_FIXUP) ? "yes":"no",
(set & SECBIT_NO_SETUID_FIXUP_LOCKED) ? "locked":"unlocked");
printf(" secure-keep-caps: %s (%s)\n",
(set & SECBIT_KEEP_CAPS) ? "yes":"no",
(set & SECBIT_KEEP_CAPS_LOCKED) ? "locked":"unlocked");
if (CAP_AMBIENT_SUPPORTED()) {
printf(" secure-no-ambient-raise: %s (%s)\n",
(set & SECBIT_NO_CAP_AMBIENT_RAISE) ? "yes":"no",
(set & SECBIT_NO_CAP_AMBIENT_RAISE_LOCKED) ?
"locked":"unlocked");
}
} else {
printf("[Securebits ABI not supported]\n");
set = prctl(PR_GET_KEEPCAPS);
if (set >= 0) {
printf(" prctl-keep-caps: %s (locking not supported)\n",
set ? "yes":"no");
} else {
printf("[Keepcaps ABI not supported]\n");
}
}
uid = getuid();
u = getpwuid(uid);
euid = geteuid();
eu = getpwuid(euid);
printf("uid=%u(%s) euid=%u(%s)\n", uid, u ? u->pw_name : "???", euid, eu ? eu->pw_name : "???");
gid = getgid();
g = getgrgid(gid);
printf("gid=%u(%s)\n", gid, g ? g->gr_name : "???");
printf("groups=");
status = getgroups(MAX_GROUPS, groups);
sep = "";
for (j=0; j < status; j++) {
g = getgrgid(groups[j]);
printf("%s%u(%s)", sep, groups[j], g ? g->gr_name : "???");
sep = ",";
}
printf("\n");
cap_mode_t mode = cap_get_mode();
printf("Guessed mode: %s (%d)\n", cap_mode_name(mode), mode);
}
static const cap_value_t raise_setpcap[1] = { CAP_SETPCAP };
static const cap_value_t raise_chroot[1] = { CAP_SYS_CHROOT };
static cap_t will_need_setpcap(int strict)
{
cap_flag_value_t enabled;
cap_t raised = NULL;
if (strict) {
return NULL;
}
raised = cap_get_proc();
if (raised == NULL) {
perror("Capabilities not available");
exit(1);
}
if (cap_get_flag(raised, CAP_SETPCAP, CAP_EFFECTIVE, &enabled) != 0) {
perror("Unable to check CAP_EFFECTIVE CAP_SETPCAP value");
exit(1);
}
if (enabled != CAP_SET) {
cap_set_flag(raised, CAP_EFFECTIVE, 1, raise_setpcap, CAP_SET);
} else {
/* no need to raise - since already raised */
cap_free(raised);
raised = NULL;
}
return raised;
}
static void push_pcap(int strict, cap_t *orig_p, cap_t *raised_for_setpcap_p)
{
*orig_p = cap_get_proc();
if (NULL == *orig_p) {
perror("Capabilities not available");
exit(1);
}
*raised_for_setpcap_p = will_need_setpcap(strict);
}
static void pop_pcap(cap_t orig, cap_t raised_for_setpcap)
{
cap_free(raised_for_setpcap);
cap_free(orig);
}
static void arg_drop(int strict, const char *arg_names)
{
char *ptr;
cap_t orig, raised_for_setpcap;
char *names;
push_pcap(strict, &orig, &raised_for_setpcap);
if (strcmp("all", arg_names) == 0) {
unsigned j = 0;
while (CAP_IS_SUPPORTED(j)) {
int status;
if (raised_for_setpcap != NULL &&
cap_set_proc(raised_for_setpcap) != 0) {
perror("unable to raise CAP_SETPCAP for BSET changes");
exit(1);
}
status = cap_drop_bound(j);
if (raised_for_setpcap != NULL && cap_set_proc(orig) != 0) {
perror("unable to lower CAP_SETPCAP post BSET change");
exit(1);
}
if (status != 0) {
char *name_ptr;
name_ptr = cap_to_name(j);
fprintf(stderr, "Unable to drop bounding capability [%s]\n",
name_ptr);
cap_free(name_ptr);
exit(1);
}
j++;
}
pop_pcap(orig, raised_for_setpcap);
return;
}
names = strdup(arg_names);
if (NULL == names) {
fprintf(stderr, "failed to allocate names\n");
exit(1);
}
for (ptr = names; (ptr = strtok(ptr, ",")); ptr = NULL) {
/* find name for token */
cap_value_t cap;
int status;
if (cap_from_name(ptr, &cap) != 0) {
fprintf(stderr, "capability [%s] is unknown to libcap\n", ptr);
exit(1);
}
if (raised_for_setpcap != NULL &&
cap_set_proc(raised_for_setpcap) != 0) {
perror("unable to raise CAP_SETPCAP for BSET changes");
exit(1);
}
status = cap_drop_bound(cap);
if (raised_for_setpcap != NULL && cap_set_proc(orig) != 0) {
perror("unable to lower CAP_SETPCAP post BSET change");
exit(1);
}
if (status != 0) {
fprintf(stderr, "failed to drop [%s=%u]\n", ptr, cap);
exit(1);
}
}
pop_pcap(orig, raised_for_setpcap);
free(names);
}
static void arg_change_amb(const char *arg_names, cap_flag_value_t set)
{
char *ptr;
cap_t orig;
char *names;
orig = cap_get_proc();
if (strcmp("all", arg_names) == 0) {
unsigned j = 0;
while (CAP_IS_SUPPORTED(j)) {
int status;
status = cap_set_ambient(j, set);
if (status != 0) {
char *name_ptr;
name_ptr = cap_to_name(j);
fprintf(stderr, "Unable to %s ambient capability [%s]\n",
set == CAP_CLEAR ? "clear":"raise", name_ptr);
cap_free(name_ptr);
exit(1);
}
j++;
}
cap_free(orig);
return;
}
names = strdup(arg_names);
if (NULL == names) {
fprintf(stderr, "failed to allocate names\n");
exit(1);
}
for (ptr = names; (ptr = strtok(ptr, ",")); ptr = NULL) {
/* find name for token */
cap_value_t cap;
int status;
if (cap_from_name(ptr, &cap) != 0) {
fprintf(stderr, "capability [%s] is unknown to libcap\n", ptr);
exit(1);
}
status = cap_set_ambient(cap, set);
if (status != 0) {
fprintf(stderr, "failed to %s ambient [%s=%u]\n",
set == CAP_CLEAR ? "clear":"raise", ptr, cap);
exit(1);
}
}
cap_free(orig);
free(names);
}
/*
* find_self locates and returns the full pathname of the named binary
* that is running. Importantly, it looks in the context of the
* prevailing CHROOT. Further, it does not fail over to invoking a
* shell if the target binary looks like something other than a
* executable. If an executable is not found, the function terminates
* the program with an error.
*/
static char *find_self(const char *arg0)
{
int i, status=1;
char *p = NULL, *parts, *dir, *scratch;
const char *path;
for (i = strlen(arg0)-1; i >= 0 && arg0[i] != '/'; i--);
if (i >= 0) {
return strdup(arg0);
}
path = getenv("PATH");
if (path == NULL) {
fprintf(stderr, "no PATH environment variable found for re-execing\n");
exit(1);
}
parts = strdup(path);
if (parts == NULL) {
fprintf(stderr, "insufficient memory for parts of path\n");
exit(1);
}
scratch = malloc(2+strlen(path)+strlen(arg0));
if (scratch == NULL) {
fprintf(stderr, "insufficient memory for path building\n");
goto free_parts;
}
for (p = parts; (dir = strtok(p, ":")); p = NULL) {
sprintf(scratch, "%s/%s", dir, arg0);
if (access(scratch, X_OK) == 0) {
status = 0;
break;
}
}
if (status) {
fprintf(stderr, "unable to find executable '%s' in PATH\n", arg0);
free(scratch);
}
free_parts:
free(parts);
if (status) {
exit(status);
}
return scratch;
}
static long safe_sysconf(int name)
{
long ans = sysconf(name);
if (ans <= 0) {
fprintf(stderr, "sysconf(%d) returned a non-positive number: %ld\n", name, ans);
exit(1);
}
return ans;
}
static void describe(cap_value_t cap) {
int j;
const char **lines = explanations[cap];
char *name = cap_to_name(cap);
if (cap < cap_max_bits()) {
printf("%s (%d)", name, cap);
} else {
printf("<reserved for> %s (%d)", name, cap);
}
cap_free(name);
printf(" [/proc/self/status:CapXXX: 0x%016llx]\n\n", 1ULL<<cap);
for (j=0; lines[j]; j++) {
printf(" %s\n", lines[j]);
}
}
__attribute__ ((noreturn))
static void do_launch(char *args[], char *envp[])
{
cap_launch_t lau;
pid_t child;
int ret, result;
lau = cap_new_launcher(args[0], (void *) args, (void *) envp);
if (lau == NULL) {
perror("failed to create launcher");
exit(1);
}
child = cap_launch(lau, NULL);
if (child <= 0) {
perror("child failed to start");
exit(1);
}
cap_free(lau);
ret = waitpid(child, &result, 0);
if (ret != child) {
fprintf(stderr, "failed to wait for PID=%d, result=%x: ",
child, result);
perror("");
exit(1);
}
if (WIFEXITED(result)) {
exit(WEXITSTATUS(result));
}
if (WIFSIGNALED(result)) {
fprintf(stderr, "child PID=%d terminated by signo=%d\n",
child, WTERMSIG(result));
exit(1);
}
fprintf(stderr, "child PID=%d generated result=%0x\n", child, result);
exit(1);
}
int main(int argc, char *argv[], char *envp[])
{
pid_t child = 0;
unsigned i;
int strict = 0, quiet_start = 0;
const char *shell = SHELL;
for (i=1; i<argc; ++i) {
if (!strcmp("--quiet", argv[i])) {
quiet_start = 1;
continue;
}
if (i == 1) {
char *temp_name = cap_to_name(cap_max_bits() - 1);
if (temp_name == NULL) {
perror("obtaining highest capability name");
exit(1);
}
if (temp_name[0] != 'c') {
printf("WARNING: libcap needs an update"
" (cap=%d should have a name).\n",
cap_max_bits() - 1);
}
cap_free(temp_name);
}
if (!strncmp("--drop=", argv[i], 7)) {
arg_drop(strict, argv[i]+7);
} else if (!strncmp("--dropped=", argv[i], 10)) {
cap_value_t cap;
if (cap_from_name(argv[i]+10, &cap) < 0) {
fprintf(stderr, "cap[%s] not recognized by library\n",
argv[i] + 10);
exit(1);
}
if (cap_get_bound(cap) > 0) {
fprintf(stderr, "cap[%s] raised in bounding vector\n",
argv[i]+10);
exit(1);
}
} else if (!strcmp("--has-ambient", argv[i])) {
if (!CAP_AMBIENT_SUPPORTED()) {
perror("ambient set not supported");
exit(1);
}
} else if (!strncmp("--addamb=", argv[i], 9)) {
arg_change_amb(argv[i]+9, CAP_SET);
} else if (!strncmp("--delamb=", argv[i], 9)) {
arg_change_amb(argv[i]+9, CAP_CLEAR);
} else if (!strncmp("--noamb", argv[i], 7)) {
if (cap_reset_ambient() != 0) {
perror("failed to reset ambient set");
exit(1);
}
} else if (!strncmp("--inh=", argv[i], 6)) {
cap_t all, raised_for_setpcap;
char *text;
char *ptr;
push_pcap(strict, &all, &raised_for_setpcap);
if (cap_clear_flag(all, CAP_INHERITABLE) != 0) {
perror("libcap:cap_clear_flag() internal error");
exit(1);
}
text = cap_to_text(all, NULL);
cap_free(all);
if (text == NULL) {
perror("Fatal error concerning process capabilities");
exit(1);
}
ptr = malloc(10 + strlen(argv[i]+6) + strlen(text));
if (ptr == NULL) {
perror("Out of memory for inh set");
exit(1);
}
if (argv[i][6] && strcmp("none", argv[i]+6)) {
sprintf(ptr, "%s %s+i", text, argv[i]+6);
} else {
strcpy(ptr, text);
}
cap_free(text);
all = cap_from_text(ptr);
if (all == NULL) {
perror("Fatal error internalizing capabilities");
exit(1);
}
free(ptr);
if (raised_for_setpcap != NULL) {
/*
* This is only for the case that pP does not contain
* the requested change to pI.. Failing here is not
* indicative of the cap_set_proc(all) failing (always).
*/
(void) cap_set_proc(raised_for_setpcap);
cap_free(raised_for_setpcap);
raised_for_setpcap = NULL;
}
if (cap_set_proc(all) != 0) {
perror("Unable to set inheritable capabilities");
exit(1);
}
cap_free(all);
} else if (!strcmp("--strict", argv[i])) {
strict = !strict;
} else if (!strncmp("--caps=", argv[i], 7)) {
cap_t all, raised_for_setpcap;
raised_for_setpcap = will_need_setpcap(strict);
all = cap_from_text(argv[i]+7);
if (all == NULL) {
fprintf(stderr, "unable to interpret [%s]\n", argv[i]);
exit(1);
}
if (raised_for_setpcap != NULL) {
/*
* This is actually only for the case that pP does not
* contain the requested change to pI.. Failing here
* is not always indicative of the cap_set_proc(all)
* failing.
*/
(void) cap_set_proc(raised_for_setpcap);
cap_free(raised_for_setpcap);
raised_for_setpcap = NULL;
}
if (cap_set_proc(all) != 0) {
fprintf(stderr, "Unable to set capabilities [%s]\n", argv[i]);
exit(1);
}
/*
* Since status is based on orig, we don't want to restore
* the previous value of 'all' again here!
*/
cap_free(all);
} else if (!strcmp("--modes", argv[i])) {
cap_mode_t c;
printf("Supported modes:");
for (c = 1; ; c++) {
const char *m = cap_mode_name(c);
if (strcmp("UNKNOWN", m) == 0) {
break;
}
printf(" %s", m);
}
printf("\n");
} else if (!strncmp("--mode", argv[i], 6)) {
if (argv[i][6] == '=') {
const char *target = argv[i]+7;
cap_mode_t c;
int found = 0;
for (c = 1; ; c++) {
const char *m = cap_mode_name(c);
if (!strcmp("UNKNOWN", m)) {
found = 0;
break;
}
if (!strcmp(m, target)) {
found = 1;
break;
}
}
if (!found) {
printf("unsupported mode: %s\n", target);
exit(1);
}
int ret = cap_set_mode(c);
if (ret != 0) {
printf("failed to set mode [%s]: %s\n",
target, strerror(errno));
exit(1);
}
} else if (argv[i][6]) {
printf("unrecognized command [%s]\n", argv[i]);
goto usage;
} else {
cap_mode_t m = cap_get_mode();
printf("Mode: %s\n", cap_mode_name(m));
}
} else if (!strncmp("--inmode=", argv[i], 9)) {
const char *target = argv[i]+9;
cap_mode_t c = cap_get_mode();
const char *m = cap_mode_name(c);
if (strcmp(m, target)) {
printf("mismatched mode got=%s want=%s\n", m, target);
exit(1);
}
} else if (!strncmp("--keep=", argv[i], 7)) {
unsigned value;
int set;
value = nonneg_uint(argv[i]+7, "invalid --keep value", NULL);
set = prctl(PR_SET_KEEPCAPS, value);
if (set < 0) {
fprintf(stderr, "prctl(PR_SET_KEEPCAPS, %u) failed: %s\n",
value, strerror(errno));
exit(1);
}
} else if (!strncmp("--chroot=", argv[i], 9)) {
int status;
cap_t orig, raised_for_chroot;
orig = cap_get_proc();
if (orig == NULL) {
perror("Capabilities not available");
exit(1);
}
raised_for_chroot = cap_dup(orig);
if (raised_for_chroot == NULL) {
perror("Unable to duplicate capabilities");
exit(1);
}
if (cap_set_flag(raised_for_chroot, CAP_EFFECTIVE, 1, raise_chroot,
CAP_SET) != 0) {
perror("unable to select CAP_SET_SYS_CHROOT");
exit(1);
}
if (cap_set_proc(raised_for_chroot) != 0) {
perror("unable to raise CAP_SYS_CHROOT");
exit(1);
}
cap_free(raised_for_chroot);
status = chroot(argv[i]+9);
if (cap_set_proc(orig) != 0) {
perror("unable to lower CAP_SYS_CHROOT");
exit(1);
}
/*
* Given we are now in a new directory tree, its good practice
* to start off in a sane location
*/
if (status == 0) {
status = chdir("/");
}
cap_free(orig);
if (status != 0) {
fprintf(stderr, "Unable to chroot/chdir to [%s]", argv[i]+9);
exit(1);
}
} else if (!strncmp("--secbits=", argv[i], 10)) {
unsigned value;
int status;
value = nonneg_uint(argv[i]+10, "invalid --secbits value", NULL);
status = cap_set_secbits(value);
if (status < 0) {
fprintf(stderr, "failed to set securebits to 0%o/0x%x\n",
value, value);
exit(1);
}
} else if (!strncmp("--forkfor=", argv[i], 10)) {
unsigned value;
if (child != 0) {
fprintf(stderr, "already forked\n");
exit(1);
}
value = nonneg_uint(argv[i]+10, "invalid --forkfor value", NULL);
if (value == 0) {
fprintf(stderr, "require non-zero --forkfor value\n");
goto usage;
}
child = fork();
if (child < 0) {
perror("unable to fork()");
} else if (!child) {
sleep(value);
exit(0);
}
} else if (!strncmp("--killit=", argv[i], 9)) {
int retval, status;
pid_t result;
unsigned value;
value = nonneg_uint(argv[i]+9, "invalid --killit signo value",
NULL);
if (!child) {
fprintf(stderr, "no forked process to kill\n");
exit(1);
}
retval = kill(child, value);
if (retval != 0) {
perror("Unable to kill child process");
exit(1);
}
result = waitpid(child, &status, 0);
if (result != child) {
fprintf(stderr, "waitpid didn't match child: %u != %u\n",
child, result);
exit(1);
}
if (WTERMSIG(status) != value) {
fprintf(stderr, "child terminated with odd signal (%d != %d)\n"
, value, WTERMSIG(status));
exit(1);
}
child = 0;
} else if (!strncmp("--uid=", argv[i], 6)) {
unsigned value;
int status;
value = nonneg_uint(argv[i]+6, "invalid --uid value", NULL);
status = setuid(value);
if (status < 0) {
fprintf(stderr, "Failed to set uid=%u: %s\n",
value, strerror(errno));
exit(1);
}
} else if (!strncmp("--cap-uid=", argv[i], 10)) {
unsigned value;
int status;
value = nonneg_uint(argv[i]+10, "invalid --cap-uid value", NULL);
status = cap_setuid(value);
if (status < 0) {
fprintf(stderr, "Failed to cap_setuid(%u): %s\n",
value, strerror(errno));
exit(1);
}
} else if (!strncmp("--gid=", argv[i], 6)) {
unsigned value;
int status;
value = nonneg_uint(argv[i]+6, "invalid --gid value", NULL);
status = setgid(value);
if (status < 0) {
fprintf(stderr, "Failed to set gid=%u: %s\n",
value, strerror(errno));
exit(1);
}
} else if (!strncmp("--groups=", argv[i], 9)) {
char *ptr, *buf;
long length, max_groups;
gid_t *group_list;
int g_count;
length = safe_sysconf(_SC_GETGR_R_SIZE_MAX);
buf = calloc(1, length);
if (NULL == buf) {
fprintf(stderr, "No memory for [%s] operation\n", argv[i]);
exit(1);
}
max_groups = safe_sysconf(_SC_NGROUPS_MAX);
group_list = calloc(max_groups, sizeof(gid_t));
if (NULL == group_list) {
fprintf(stderr, "No memory for gid list\n");
exit(1);
}
g_count = 0;
for (ptr = argv[i] + 9; (ptr = strtok(ptr, ","));
ptr = NULL, g_count++) {
if (max_groups <= g_count) {
fprintf(stderr, "Too many groups specified (%d)\n", g_count);
exit(1);
}
if (!isdigit(*ptr)) {
struct group *g, grp;
if (getgrnam_r(ptr, &grp, buf, length, &g) || NULL == g) {
fprintf(stderr, "Failed to identify gid for group [%s]\n", ptr);
exit(1);
}
group_list[g_count] = g->gr_gid;
} else {
group_list[g_count] = strtoul(ptr, NULL, 0);
}
}
free(buf);
if (setgroups(g_count, group_list) != 0) {
fprintf(stderr, "Failed to setgroups.\n");
exit(1);
}
free(group_list);
} else if (!strncmp("--user=", argv[i], 7)) {
struct passwd *pwd;
const char *user;
gid_t groups[MAX_GROUPS];
int status, ngroups;
user = argv[i] + 7;
pwd = getpwnam(user);
if (pwd == NULL) {
fprintf(stderr, "User [%s] not known\n", user);
exit(1);
}
ngroups = MAX_GROUPS;
status = getgrouplist(user, pwd->pw_gid, groups, &ngroups);
if (status < 1) {
perror("Unable to get group list for user");
exit(1);
}
status = cap_setgroups(pwd->pw_gid, ngroups, groups);
if (status != 0) {
perror("Unable to set group list for user");
exit(1);
}
status = cap_setuid(pwd->pw_uid);
if (status < 0) {
fprintf(stderr, "Failed to set uid=%u(user=%s): %s\n",
pwd->pw_uid, user, strerror(errno));
exit(1);
}
} else if (!strncmp("--decode=", argv[i], 9)) {
unsigned long long value;
unsigned cap;
const char *sep = "";
/* Note, if capabilities become longer than 64-bits we'll need
to fixup the following code.. */
value = strtoull(argv[i]+9, NULL, 16);
printf("0x%016llx=", value);
for (cap=0; (cap < 64) && (value >> cap); ++cap) {
if (value & (1ULL << cap)) {
char *ptr;
ptr = cap_to_name(cap);
if (ptr != NULL) {
printf("%s%s", sep, ptr);
cap_free(ptr);
} else {
printf("%s%u", sep, cap);
}
sep = ",";
}
}
printf("\n");
} else if (!strncmp("--supports=", argv[i], 11)) {
cap_value_t cap;
if (cap_from_name(argv[i] + 11, &cap) < 0) {
fprintf(stderr, "cap[%s] not recognized by library\n",
argv[i] + 11);
exit(1);
}
if (!CAP_IS_SUPPORTED(cap)) {
fprintf(stderr, "cap[%s=%d] not supported by kernel\n",
argv[i] + 11, cap);
exit(1);
}
} else if (!strcmp("--print", argv[i])) {
arg_print();
} else if ((!strcmp("--", argv[i])) || (!strcmp("==", argv[i]))
|| (!strcmp("-+", argv[i])) || (!strcmp("=+", argv[i]))) {
int launch = argv[i][1] == '+';
if (argv[i][0] == '=') {
if (quiet_start) {
argv[i--] = strdup("--quiet");
}
argv[i] = find_self(argv[0]);
} else {
argv[i] = strdup(shell);
}
argv[argc] = NULL;
/* Two ways to chain load - use cap_launch() or execve() */
if (launch) {
do_launch(argv+i, envp);
}
execve(argv[i], argv+i, envp);
fprintf(stderr, "execve '%s' failed!\n", argv[i]);
free(argv[i]);
exit(1);
} else if (!strncmp("--shell=", argv[i], 8)) {
shell = argv[i]+8;
} else if (!strncmp("--has-p=", argv[i], 8)) {
cap_value_t cap;
cap_flag_value_t enabled;
cap_t orig;
if (cap_from_name(argv[i]+8, &cap) < 0) {
fprintf(stderr, "cap[%s] not recognized by library\n",
argv[i] + 8);
exit(1);
}
orig = cap_get_proc();
if (orig == NULL) {
perror("failed to get process capabilities");
exit(1);
}
if (cap_get_flag(orig, cap, CAP_PERMITTED, &enabled) || !enabled) {
fprintf(stderr, "cap[%s] not permitted\n", argv[i]+8);
exit(1);
}
cap_free(orig);
} else if (!strncmp("--has-i=", argv[i], 8)) {
cap_value_t cap;
cap_flag_value_t enabled;
cap_t orig;
if (cap_from_name(argv[i]+8, &cap) < 0) {
fprintf(stderr, "cap[%s] not recognized by library\n",
argv[i] + 8);
exit(1);
}
orig = cap_get_proc();
if (orig == NULL) {
perror("failed to get process capabilities");
exit(1);
}
if (cap_get_flag(orig, cap, CAP_INHERITABLE, &enabled)
|| !enabled) {
fprintf(stderr, "cap[%s] not inheritable\n", argv[i]+8);
exit(1);
}
cap_free(orig);
} else if (!strncmp("--has-a=", argv[i], 8)) {
cap_value_t cap;
if (cap_from_name(argv[i]+8, &cap) < 0) {
fprintf(stderr, "cap[%s] not recognized by library\n",
argv[i] + 8);
exit(1);
}
if (!cap_get_ambient(cap)) {
fprintf(stderr, "cap[%s] not in ambient vector\n", argv[i]+8);
exit(1);
}
} else if (!strncmp("--has-b=", argv[i], 8)) {
cap_value_t cap;
if (cap_from_name(argv[i]+8, &cap) < 0) {
fprintf(stderr, "cap[%s] not recognized by library\n",
argv[i] + 8);
exit(1);
}
if (!cap_get_bound(cap)) {
fprintf(stderr, "cap[%s] not in bounding vector\n", argv[i]+8);
exit(1);
}
} else if (!strncmp("--is-uid=", argv[i], 9)) {
unsigned value;
uid_t uid;
value = nonneg_uint(argv[i]+9, "invalid --is-uid value", NULL);
uid = getuid();
if (uid != value) {
fprintf(stderr, "uid: got=%d, want=%d\n", uid, value);
exit(1);
}
} else if (!strncmp("--is-gid=", argv[i], 9)) {
unsigned value;
gid_t gid;
value = nonneg_uint(argv[i]+9, "invalid --is-gid value", NULL);
gid = getgid();
if (gid != value) {
fprintf(stderr, "gid: got=%d, want=%d\n", gid, value);
exit(1);
}
} else if (!strncmp("--iab=", argv[i], 6)) {
cap_iab_t iab = cap_iab_from_text(argv[i]+6);
if (iab == NULL) {
fprintf(stderr, "iab: '%s' malformed\n", argv[i]+6);
exit(1);
}
if (cap_iab_set_proc(iab)) {
perror("unable to set IAB tuple");
exit(1);
}
cap_free(iab);
} else if (!strcmp("--no-new-privs", argv[i])) {
if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0, 0) != 0) {
perror("unable to set no-new-privs");
exit(1);
}
} else if (!strcmp("--has-no-new-privs", argv[i])) {
if (prctl(PR_GET_NO_NEW_PRIVS, 0, 0, 0, 0, 0) != 1) {
fprintf(stderr, "no-new-privs not set\n");
exit(1);
}
} else if (!strcmp("--license", argv[i])) {
printf(
"%s see License file for details.\n"
"Copyright (c) 2008-11,16,19-21 Andrew G. Morgan"
" <morgan@kernel.org>\n", argv[0]);
exit(0);
} else if (!strncmp("--explain=", argv[i], 10)) {
cap_value_t cap;
if (cap_from_name(argv[i]+10, &cap) != 0) {
fprintf(stderr, "unrecognised value '%s'\n", argv[i]+10);
exit(1);
}
if (cap < 0) {
fprintf(stderr, "negative capability (%d) invalid\n", cap);
exit(1);
}
if (cap < capsh_doc_limit) {
describe(cap);
continue;
}
if (cap < cap_max_bits()) {
printf("<unnamed in libcap> (%d)", cap);
} else {
printf("<unsupported> (%d)", cap);
}
printf(" [/proc/self/status:CapXXX: 0x%016llx]\n", 1ULL<<cap);
} else if (!strncmp("--suggest=", argv[i], 10)) {
cap_value_t cap;
int hits = 0;
for (cap=0; cap < capsh_doc_limit; cap++) {
const char **lines = explanations[cap];
int j;
char *name = cap_to_name(cap);
if (name == NULL) {
perror("invalid named cap");
exit(1);
}
char *match = strcasestr(name, argv[i]+10);
cap_free(name);
if (match != NULL) {
if (hits++) {
printf("\n");
}
describe(cap);
continue;
}
for (j=0; lines[j]; j++) {
if (strcasestr(lines[j], argv[i]+10) != NULL) {
if (hits++) {
printf("\n");
}
describe(cap);
break;
}
}
}
} else if (strcmp("--current", argv[i]) == 0) {
display_current();
display_current_iab();
} else {
usage:
printf("usage: %s [args ...]\n"
" --addamb=xxx add xxx,... capabilities to ambient set\n"
" --cap-uid=<n> use libcap cap_setuid() to change uid\n"
" --caps=xxx set caps as per cap_from_text()\n"
" --chroot=path chroot(2) to this path\n"
" --current show current caps and IAB vectors\n"
" --decode=xxx decode a hex string to a list of caps\n"
" --delamb=xxx remove xxx,... capabilities from ambient\n"
" --drop=xxx drop xxx,... caps from bounding set\n"
" --explain=xxx explain what capability xxx permits\n"
" --forkfor=<n> fork and make child sleep for <n> sec\n"
" --gid=<n> set gid to <n> (hint: id <username>)\n"
" --groups=g,... set the supplemental groups\n"
" --has-a=xxx exit 1 if capability xxx not ambient\n"
" --has-b=xxx exit 1 if capability xxx not dropped\n"
" --has-ambient exit 1 unless ambient vector supported\n"
" --has-i=xxx exit 1 if capability xxx not inheritable\n"
" --has-p=xxx exit 1 if capability xxx not permitted\n"
" --has-no-new-privs exit 1 if privs not limited\n"
" --help, -h this message (or try 'man capsh')\n"
" --iab=... use cap_iab_from_text() to set iab\n"
" --inh=xxx set xxx,.. inheritable set\n"
" --inmode=<xxx> exit 1 if current mode is not <xxx>\n"
" --is-uid=<n> exit 1 if uid != <n>\n"
" --is-gid=<n> exit 1 if gid != <n>\n"
" --keep=<n> set keep-capability bit to <n>\n"
" --killit=<n> send signal(n) to child\n"
" --license display license info\n"
" --mode display current libcap mode\n"
" --mode=<xxx> set libcap mode to <xxx>\n"
" --modes list libcap named modes\n"
" --no-new-privs set sticky process privilege limiter\n"
" --noamb reset (drop) all ambient capabilities\n"
" --print display capability relevant state\n"
" --quiet if first argument skip max cap check\n"
" --secbits=<n> write a new value for securebits\n"
" --shell=/xx/yy use /xx/yy instead of " SHELL " for --\n"
" --strict toggle --caps, --drop and --inh fixups\n"
" --suggest=text search cap descriptions for text\n"
" --supports=xxx exit 1 if capability xxx unsupported\n"
" --uid=<n> set uid to <n> (hint: id <username>)\n"
" --user=<name> set uid,gid and groups to that of user\n"
" == re-exec(capsh) with args as for --\n"
" =+ cap_launch capsh with args as for -+\n"
" -- remaining arguments are for " SHELL "\n"
" -+ cap_launch " SHELL " with remaining args\n"
" (without -- [%s] will simply exit(0))\n",
argv[0], argv[0]);
if (strcmp("--help", argv[1]) && strcmp("-h", argv[1])) {
exit(1);
}
exit(0);
}
}
exit(0);
}