jexec.c revision 185435
1/*- 2 * Copyright (c) 2003 Mike Barcroft <mike@FreeBSD.org> 3 * Copyright (c) 2008 Bjoern A. Zeeb <bz@FreeBSD.org> 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 * 27 * $FreeBSD: head/usr.sbin/jexec/jexec.c 185435 2008-11-29 14:32:14Z bz $ 28 */ 29 30#include <sys/param.h> 31#include <sys/jail.h> 32#include <sys/sysctl.h> 33 34#include <netinet/in.h> 35 36#include <err.h> 37#include <errno.h> 38#include <login_cap.h> 39#include <stdio.h> 40#include <stdlib.h> 41#include <string.h> 42#include <pwd.h> 43#include <unistd.h> 44 45static void usage(void); 46 47#ifdef SUPPORT_OLD_XPRISON 48static 49char *lookup_xprison_v1(void *p, char *end, int *id) 50{ 51 struct xprison_v1 *xp; 52 53 if (id == NULL) 54 errx(1, "Internal error. Invalid ID pointer."); 55 56 if ((char *)p + sizeof(struct xprison_v1) > end) 57 errx(1, "Invalid length for jail"); 58 59 xp = (struct xprison_v1 *)p; 60 61 *id = xp->pr_id; 62 return ((char *)(xp + 1)); 63} 64#endif 65 66static 67char *lookup_xprison_v3(void *p, char *end, int *id, char *jailname) 68{ 69 struct xprison *xp; 70 char *q; 71 int ok; 72 73 if (id == NULL) 74 errx(1, "Internal error. Invalid ID pointer."); 75 76 if ((char *)p + sizeof(struct xprison) > end) 77 errx(1, "Invalid length for jail"); 78 79 xp = (struct xprison *)p; 80 ok = 1; 81 82 /* Jail state and name. */ 83 if (xp->pr_state < 0 || xp->pr_state > 84 (int)((sizeof(prison_states) / sizeof(struct prison_state)))) 85 errx(1, "Invalid jail state."); 86 else if (xp->pr_state != PRISON_STATE_ALIVE) 87 ok = 0; 88 if (jailname != NULL) { 89 if (xp->pr_name == NULL) 90 ok = 0; 91 else if (strcmp(jailname, xp->pr_name) != 0) 92 ok = 0; 93 } 94 95 q = (char *)(xp + 1); 96 /* IPv4 addresses. */ 97 q += (xp->pr_ip4s * sizeof(struct in_addr)); 98 if ((char *)q > end) 99 errx(1, "Invalid length for jail"); 100 /* IPv6 addresses. */ 101 q += (xp->pr_ip6s * sizeof(struct in6_addr)); 102 if ((char *)q > end) 103 errx(1, "Invalid length for jail"); 104 105 if (ok) 106 *id = xp->pr_id; 107 return (q); 108} 109 110static int 111lookup_jail(int jid, char *jailname) 112{ 113 size_t i, j, len; 114 void *p, *q; 115 int version, id, xid, count; 116 117 if (sysctlbyname("security.jail.list", NULL, &len, NULL, 0) == -1) 118 err(1, "sysctlbyname(): security.jail.list"); 119 120 j = len; 121 for (i = 0; i < 4; i++) { 122 if (len <= 0) 123 exit(0); 124 p = q = malloc(len); 125 if (p == NULL) 126 err(1, "malloc()"); 127 128 if (sysctlbyname("security.jail.list", q, &len, NULL, 0) == -1) { 129 if (errno == ENOMEM) { 130 free(p); 131 p = NULL; 132 len += j; 133 continue; 134 } 135 err(1, "sysctlbyname(): security.jail.list"); 136 } 137 break; 138 } 139 if (p == NULL) 140 err(1, "sysctlbyname(): security.jail.list"); 141 if (len < sizeof(int)) 142 errx(1, "This is no prison. Kernel and userland out of sync?"); 143 version = *(int *)p; 144 if (version > XPRISON_VERSION) 145 errx(1, "Sci-Fi prison. Kernel/userland out of sync?"); 146 147 count = 0; 148 xid = -1; 149 for (; q != NULL && (char *)q + sizeof(int) < (char *)p + len;) { 150 version = *(int *)q; 151 if (version > XPRISON_VERSION) 152 errx(1, "Sci-Fi prison. Kernel/userland out of sync?"); 153 id = -1; 154 switch (version) { 155#ifdef SUPPORT_OLD_XPRISON 156 case 1: 157 if (jailname != NULL) 158 errx(1, "Version 1 prisons did not " 159 "support jail names."); 160 q = lookup_xprison_v1(q, (char *)p + len, &id); 161 break; 162 case 2: 163 errx(1, "Version 2 was used by multi-IPv4 jail " 164 "implementations that never made it into the " 165 "official kernel."); 166 /* NOTREACHED */ 167 break; 168#endif 169 case 3: 170 q = lookup_xprison_v3(q, (char *)p + len, &id, jailname); 171 break; 172 default: 173 errx(1, "Prison unknown. Kernel/userland out of sync?"); 174 /* NOTREACHED */ 175 break; 176 } 177 /* Possible match. */ 178 if (id > 0) { 179 /* Do we have a jail ID to match as well? */ 180 if (jid > 0) { 181 if (jid == id) { 182 xid = id; 183 count++; 184 } 185 } else { 186 xid = id; 187 count++; 188 } 189 } 190 } 191 192 free(p); 193 194 if (count != 1) 195 errx(1, "Could not uniquely identify the jail."); 196 197 return (xid); 198} 199 200#define GET_USER_INFO do { \ 201 pwd = getpwnam(username); \ 202 if (pwd == NULL) { \ 203 if (errno) \ 204 err(1, "getpwnam: %s", username); \ 205 else \ 206 errx(1, "%s: no such user", username); \ 207 } \ 208 lcap = login_getpwclass(pwd); \ 209 if (lcap == NULL) \ 210 err(1, "getpwclass: %s", username); \ 211 ngroups = NGROUPS; \ 212 if (getgrouplist(username, pwd->pw_gid, groups, &ngroups) != 0) \ 213 err(1, "getgrouplist: %s", username); \ 214} while (0) 215 216int 217main(int argc, char *argv[]) 218{ 219 int jid; 220 login_cap_t *lcap = NULL; 221 struct passwd *pwd = NULL; 222 gid_t groups[NGROUPS]; 223 int ch, ngroups, uflag, Uflag; 224 char *jailname, *username; 225 226 ch = uflag = Uflag = 0; 227 jailname = username = NULL; 228 jid = -1; 229 230 while ((ch = getopt(argc, argv, "i:n:u:U:")) != -1) { 231 switch (ch) { 232 case 'n': 233 jailname = optarg; 234 break; 235 case 'u': 236 username = optarg; 237 uflag = 1; 238 break; 239 case 'U': 240 username = optarg; 241 Uflag = 1; 242 break; 243 default: 244 usage(); 245 } 246 } 247 argc -= optind; 248 argv += optind; 249 if (argc < 2) 250 usage(); 251 if (strlen(argv[0]) > 0) { 252 jid = (int)strtol(argv[0], NULL, 10); 253 if (errno) 254 err(1, "Unable to parse jail ID."); 255 } 256 if (jid <= 0 && jailname == NULL) { 257 fprintf(stderr, "Neither jail ID nor jail name given.\n"); 258 usage(); 259 } 260 if (uflag && Uflag) 261 usage(); 262 if (uflag) 263 GET_USER_INFO; 264 jid = lookup_jail(jid, jailname); 265 if (jid <= 0) 266 errx(1, "Cannot identify jail."); 267 if (jail_attach(jid) == -1) 268 err(1, "jail_attach(): %d", jid); 269 if (chdir("/") == -1) 270 err(1, "chdir(): /"); 271 if (username != NULL) { 272 if (Uflag) 273 GET_USER_INFO; 274 if (setgroups(ngroups, groups) != 0) 275 err(1, "setgroups"); 276 if (setgid(pwd->pw_gid) != 0) 277 err(1, "setgid"); 278 if (setusercontext(lcap, pwd, pwd->pw_uid, 279 LOGIN_SETALL & ~LOGIN_SETGROUP & ~LOGIN_SETLOGIN) != 0) 280 err(1, "setusercontext"); 281 login_close(lcap); 282 } 283 if (execvp(argv[1], argv + 1) == -1) 284 err(1, "execvp(): %s", argv[1]); 285 exit(0); 286} 287 288static void 289usage(void) 290{ 291 292 fprintf(stderr, "%s%s\n", 293 "usage: jexec [-u username | -U username]", 294 " [-n jailname] jid command ..."); 295 exit(1); 296} 297