1 /*- 2 * Copyright (c) 2012 The FreeBSD Foundation 3 * Copyright (c) 2015 Mariusz Zaborski <oshogbo@FreeBSD.org> 4 * All rights reserved. 5 * 6 * This software was developed by Pawel Jakub Dawidek under sponsorship from 7 * the FreeBSD Foundation. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #include <sys/cdefs.h> 32 __FBSDID("$FreeBSD$"); 33 34 #include <sys/types.h> 35 #include <sys/capsicum.h> 36 #include <sys/procdesc.h> 37 #include <sys/socket.h> 38 #include <sys/nv.h> 39 40 #include <assert.h> 41 #include <err.h> 42 #include <errno.h> 43 #include <stdbool.h> 44 #include <stdlib.h> 45 #include <strings.h> 46 #include <unistd.h> 47 48 #include "zygote.h" 49 50 /* Zygote info. */ 51 static int zygote_sock = -1; 52 53 int 54 zygote_clone(zygote_func_t *func, int *chanfdp, int *procfdp) 55 { 56 nvlist_t *nvl; 57 int error; 58 59 if (zygote_sock == -1) { 60 /* Zygote didn't start. */ 61 errno = ENXIO; 62 return (-1); 63 } 64 65 nvl = nvlist_create(0); 66 nvlist_add_number(nvl, "func", (uint64_t)(uintptr_t)func); 67 nvl = nvlist_xfer(zygote_sock, nvl, 0); 68 if (nvl == NULL) 69 return (-1); 70 if (nvlist_exists_number(nvl, "error")) { 71 error = (int)nvlist_get_number(nvl, "error"); 72 nvlist_destroy(nvl); 73 errno = error; 74 return (-1); 75 } 76 77 *chanfdp = nvlist_take_descriptor(nvl, "chanfd"); 78 *procfdp = nvlist_take_descriptor(nvl, "procfd"); 79 80 nvlist_destroy(nvl); 81 return (0); 82 } 83 84 /* 85 * This function creates sandboxes on-demand whoever has access to it via 86 * 'sock' socket. Function sends two descriptors to the caller: process 87 * descriptor of the sandbox and socket pair descriptor for communication 88 * between sandbox and its owner. 89 */ 90 static void 91 zygote_main(int sock) 92 { 93 int error, procfd; 94 int chanfd[2]; 95 nvlist_t *nvlin, *nvlout; 96 zygote_func_t *func; 97 pid_t pid; 98 99 assert(sock > STDERR_FILENO); 100 101 setproctitle("zygote"); 102 103 for (;;) { 104 nvlin = nvlist_recv(sock, 0); 105 if (nvlin == NULL) { 106 if (errno == ENOTCONN) { 107 /* Casper exited. */ 108 exit(0); 109 } 110 continue; 111 } 112 func = (zygote_func_t *)(uintptr_t)nvlist_get_number(nvlin, 113 "func"); 114 nvlist_destroy(nvlin); 115 116 /* 117 * Someone is requesting a new process, create one. 118 */ 119 procfd = -1; 120 chanfd[0] = -1; 121 chanfd[1] = -1; 122 error = 0; 123 if (socketpair(PF_UNIX, SOCK_STREAM | SOCK_NONBLOCK, 0, 124 chanfd) == -1) { 125 error = errno; 126 goto send; 127 } 128 pid = pdfork(&procfd, 0); 129 switch (pid) { 130 case -1: 131 /* Failure. */ 132 error = errno; 133 break; 134 case 0: 135 /* Child. */ 136 close(sock); 137 close(chanfd[0]); 138 func(chanfd[1]); 139 /* NOTREACHED */ 140 exit(1); 141 default: 142 /* Parent. */ 143 close(chanfd[1]); 144 break; 145 } 146 send: 147 nvlout = nvlist_create(0); 148 if (error != 0) { 149 nvlist_add_number(nvlout, "error", (uint64_t)error); 150 if (chanfd[0] >= 0) 151 close(chanfd[0]); 152 if (procfd >= 0) 153 close(procfd); 154 } else { 155 nvlist_move_descriptor(nvlout, "chanfd", chanfd[0]); 156 nvlist_move_descriptor(nvlout, "procfd", procfd); 157 } 158 (void)nvlist_send(sock, nvlout); 159 nvlist_destroy(nvlout); 160 } 161 /* NOTREACHED */ 162 } 163 164 int 165 zygote_init(void) 166 { 167 int serrno, sp[2]; 168 pid_t pid; 169 170 if (socketpair(PF_UNIX, SOCK_STREAM | SOCK_NONBLOCK, 0, sp) == -1) 171 return (-1); 172 173 pid = fork(); 174 switch (pid) { 175 case -1: 176 /* Failure. */ 177 serrno = errno; 178 close(sp[0]); 179 close(sp[1]); 180 errno = serrno; 181 return (-1); 182 case 0: 183 /* Child. */ 184 close(sp[0]); 185 zygote_main(sp[1]); 186 /* NOTREACHED */ 187 abort(); 188 default: 189 /* Parent. */ 190 zygote_sock = sp[0]; 191 close(sp[1]); 192 return (0); 193 } 194 /* NOTREACHED */ 195 } 196