1 /* vi: set sw=4 ts=4: */
3 * setpriv implementation for busybox based on linux-utils-ng 2.29
5 * Copyright (C) 2017 by <assafgordon@gmail.com>
7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
9 //config:config SETPRIV
10 //config: bool "setpriv (3.4 kb)"
12 //config: select PLATFORM_LINUX
13 //config: select LONG_OPTS
15 //config: Run a program with different Linux privilege settings.
16 //config: Requires kernel >= 3.5
18 //config:config FEATURE_SETPRIV_DUMP
19 //config: bool "Support dumping current privilege state"
21 //config: depends on SETPRIV
23 //config: Enables the "--dump" switch to print out the current privilege
24 //config: state. This is helpful for diagnosing problems.
26 //config:config FEATURE_SETPRIV_CAPABILITIES
27 //config: bool "Support capabilities"
29 //config: depends on SETPRIV
31 //config: Capabilities can be used to grant processes additional rights
32 //config: without the necessity to always execute as the root user.
33 //config: Enabling this option enables "--dump" to show information on
34 //config: capabilities.
36 //config:config FEATURE_SETPRIV_CAPABILITY_NAMES
37 //config: bool "Support capability names"
39 //config: depends on SETPRIV && FEATURE_SETPRIV_CAPABILITIES
41 //config: Capabilities can be either referenced via a human-readble name,
42 //config: e.g. "net_admin", or using their index, e.g. "cap_12". Enabling
43 //config: this option allows using the human-readable names in addition to
44 //config: the index-based names.
46 //applet:IF_SETPRIV(APPLET(setpriv, BB_DIR_BIN, BB_SUID_DROP))
48 //kbuild:lib-$(CONFIG_SETPRIV) += setpriv.o
50 //usage:#define setpriv_trivial_usage
51 //usage: "[OPTIONS] PROG [ARGS]"
52 //usage:#define setpriv_full_usage "\n\n"
53 //usage: "Run PROG with different privilege settings\n"
54 //usage: IF_FEATURE_SETPRIV_DUMP(
55 //usage: "\n-d,--dump Show current capabilities"
57 //usage: "\n--nnp,--no-new-privs Ignore setuid/setgid bits and file capabilities"
58 //usage: IF_FEATURE_SETPRIV_CAPABILITIES(
59 //usage: "\n--inh-caps CAP,CAP Set inheritable capabilities"
60 //usage: "\n--ambient-caps CAP,CAP Set ambient capabilities"
63 //setpriv from util-linux 2.28:
64 // -d, --dump show current state (and do not exec anything)
65 // --nnp, --no-new-privs disallow granting new privileges
66 // --inh-caps <caps,...> set inheritable capabilities
67 // --bounding-set <caps> set capability bounding set
68 // --ruid <uid> set real uid
69 // --euid <uid> set effective uid
70 // --rgid <gid> set real gid
71 // --egid <gid> set effective gid
72 // --reuid <uid> set real and effective uid
73 // --regid <gid> set real and effective gid
74 // --clear-groups clear supplementary groups
75 // --keep-groups keep supplementary groups
76 // --groups <group,...> set supplementary groups
77 // --securebits <bits> set securebits
78 // --selinux-label <label> set SELinux label
79 // --apparmor-profile <pr> set AppArmor profile
81 #if ENABLE_FEATURE_SETPRIV_CAPABILITIES
82 #include <linux/capability.h>
83 // #include <sys/capability.h>
84 // This header is in libcap, but the functions are in libc.
85 // Comment in the header says this above capset/capget:
86 /* system calls - look to libc for function to system call mapping */
87 extern int capset(cap_user_header_t header, cap_user_data_t data);
88 extern int capget(cap_user_header_t header, const cap_user_data_t data);
89 // so for bbox, let's just repeat the declarations.
90 // This way, libcap needs not be installed in build environment.
92 #include <sys/prctl.h>
95 #ifndef PR_CAPBSET_READ
96 #define PR_CAPBSET_READ 23
99 #ifndef PR_SET_NO_NEW_PRIVS
100 #define PR_SET_NO_NEW_PRIVS 38
103 #ifndef PR_GET_NO_NEW_PRIVS
104 #define PR_GET_NO_NEW_PRIVS 39
107 #ifndef PR_CAP_AMBIENT
108 #define PR_CAP_AMBIENT 47
109 #define PR_CAP_AMBIENT_IS_SET 1
110 #define PR_CAP_AMBIENT_RAISE 2
111 #define PR_CAP_AMBIENT_LOWER 3
115 IF_FEATURE_SETPRIV_DUMP(OPTBIT_DUMP,)
116 IF_FEATURE_SETPRIV_CAPABILITIES(OPTBIT_INH,)
117 IF_FEATURE_SETPRIV_CAPABILITIES(OPTBIT_AMB,)
120 IF_FEATURE_SETPRIV_DUMP(OPT_DUMP = (1 << OPTBIT_DUMP),)
121 IF_FEATURE_SETPRIV_CAPABILITIES(OPT_INH = (1 << OPTBIT_INH),)
122 IF_FEATURE_SETPRIV_CAPABILITIES(OPT_AMB = (1 << OPTBIT_AMB),)
123 OPT_NNP = (1 << OPTBIT_NNP),
126 #if ENABLE_FEATURE_SETPRIV_CAPABILITIES
129 static unsigned parse_cap(const char *cap)
137 bb_error_msg_and_die("invalid capability '%s'", cap);
142 return cap_name_to_number(cap);
145 static void set_inh_caps(char *capstring)
151 capstring = strtok(capstring, ",");
155 cap = parse_cap(capstring);
156 if (CAP_TO_INDEX(cap) >= caps.u32s)
157 bb_error_msg_and_die("invalid capability '%s'", capstring);
159 if (capstring[0] == '+')
160 caps.data[CAP_TO_INDEX(cap)].inheritable |= CAP_TO_MASK(cap);
162 caps.data[CAP_TO_INDEX(cap)].inheritable &= ~CAP_TO_MASK(cap);
163 capstring = strtok(NULL, ",");
166 if (capset(&caps.header, caps.data) != 0)
167 bb_perror_msg_and_die("capset");
170 static void set_ambient_caps(char *string)
174 cap = strtok(string, ",");
178 idx = parse_cap(cap);
180 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, idx, 0, 0) < 0)
181 bb_perror_msg("cap_ambient_raise");
183 if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_LOWER, idx, 0, 0) < 0)
184 bb_perror_msg("cap_ambient_lower");
186 cap = strtok(NULL, ",");
189 #endif /* FEATURE_SETPRIV_CAPABILITIES */
191 #if ENABLE_FEATURE_SETPRIV_DUMP
192 # if !ENABLE_FEATURE_SETPRIV_CAPABILITY_NAMES
193 # define printf_cap(pfx, cap_no) printf("%scap_%u", (pfx), (cap_no))
196 static int dump(void)
198 IF_FEATURE_SETPRIV_CAPABILITIES(struct caps caps;)
200 uid_t ruid, euid, suid;
201 gid_t rgid, egid, sgid;
205 getresuid(&ruid, &euid, &suid); /* never fails in Linux */
206 getresgid(&rgid, &egid, &sgid); /* never fails in Linux */
208 gids = bb_getgroups(&ngids, NULL); /* never fails in Linux */
210 nnp = prctl(PR_GET_NO_NEW_PRIVS, 0, 0, 0, 0);
212 bb_perror_msg_and_die("prctl: %s", "GET_NO_NEW_PRIVS");
214 printf("uid: %u\n", (unsigned)ruid);
215 printf("euid: %u\n", (unsigned)euid);
216 printf("gid: %u\n", (unsigned)rgid);
217 printf("egid: %u\n", (unsigned)egid);
219 printf("Supplementary groups: ");
224 for (i = 0; i < ngids; i++) {
225 printf(fmt, (unsigned)gids[i]);
229 printf("\nno_new_privs: %d\n", nnp);
231 # if ENABLE_FEATURE_SETPRIV_CAPABILITIES
233 printf("Inheritable capabilities: ");
235 for (i = 0; cap_valid(i); i++) {
236 unsigned idx = CAP_TO_INDEX(i);
237 if (idx >= caps.u32s) {
238 printf("\nindex: %u u32s: %u capability: %u\n", idx, caps.u32s, i);
239 bb_error_msg_and_die("unsupported capability");
241 if (caps.data[idx].inheritable & CAP_TO_MASK(i)) {
249 printf("\nAmbient capabilities: ");
251 for (i = 0; cap_valid(i); i++) {
252 int ret = prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, (unsigned long) i, 0UL, 0UL);
254 bb_perror_msg_and_die("prctl: %s", "CAP_AMBIENT_IS_SET");
261 printf("[unsupported]");
265 printf("\nCapability bounding set: ");
267 for (i = 0; cap_valid(i); i++) {
268 int ret = prctl(PR_CAPBSET_READ, (unsigned long) i, 0UL, 0UL, 0UL);
270 bb_perror_msg_and_die("prctl: %s", "CAPBSET_READ");
281 if (ENABLE_FEATURE_CLEAN_UP)
286 #endif /* FEATURE_SETPRIV_DUMP */
288 int setpriv_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
289 int setpriv_main(int argc UNUSED_PARAM, char **argv)
291 static const char setpriv_longopts[] ALIGN1 =
292 IF_FEATURE_SETPRIV_DUMP(
293 "dump\0" No_argument "d"
295 "nnp\0" No_argument "\xff"
296 "no-new-privs\0" No_argument "\xff"
297 IF_FEATURE_SETPRIV_CAPABILITIES(
298 "inh-caps\0" Required_argument "\xfe"
299 "ambient-caps\0" Required_argument "\xfd"
303 IF_FEATURE_SETPRIV_CAPABILITIES(char *inh_caps, *ambient_caps;)
305 opts = getopt32long(argv, "+"
306 IF_FEATURE_SETPRIV_DUMP("d")
307 IF_FEATURE_SETPRIV_CAPABILITIES("\xfe:\xfd:"),
309 IF_FEATURE_SETPRIV_CAPABILITIES(, &inh_caps, &ambient_caps)
313 #if ENABLE_FEATURE_SETPRIV_DUMP
314 if (opts & OPT_DUMP) {
315 if (argv[0] || (opts - OPT_DUMP) != 0)
320 if (opts & OPT_NNP) {
321 if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0))
322 bb_perror_msg_and_die("prctl: %s", "SET_NO_NEW_PRIVS");
325 #if ENABLE_FEATURE_SETPRIV_CAPABILITIES
327 set_inh_caps(inh_caps);
329 set_ambient_caps(ambient_caps);
334 BB_EXECVP_or_die(argv);