1 /* SPDX-License-Identifier: BSD-2-Clause */ 2 /* 3 * Privilege Separation for dhcpcd, control proxy 4 * Copyright (c) 2006-2025 Roy Marples <roy (at) marples.name> 5 * All rights reserved 6 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <errno.h> 30 #include <stdlib.h> 31 #include <string.h> 32 33 #include "dhcpcd.h" 34 #include "control.h" 35 #include "eloop.h" 36 #include "logerr.h" 37 #include "privsep.h" 38 39 /* We expect to have open 2 SEQPACKET, 2 STREAM and 2 file STREAM fds */ 40 41 static int 42 ps_ctl_startcb(struct ps_process *psp) 43 { 44 struct dhcpcd_ctx *ctx = psp->psp_ctx; 45 sa_family_t af; 46 47 if (ctx->options & DHCPCD_MANAGER) { 48 setproctitle("[control proxy]"); 49 af = AF_UNSPEC; 50 } else { 51 setproctitle("[control proxy] %s%s%s", 52 ctx->ifv[0], 53 ctx->options & DHCPCD_IPV4 ? " [ip4]" : "", 54 ctx->options & DHCPCD_IPV6 ? " [ip6]" : ""); 55 if ((ctx->options & 56 (DHCPCD_IPV4 | DHCPCD_IPV6)) == DHCPCD_IPV4) 57 af = AF_INET; 58 else if ((ctx->options & 59 (DHCPCD_IPV4 | DHCPCD_IPV6)) == DHCPCD_IPV6) 60 af = AF_INET6; 61 else 62 af = AF_UNSPEC; 63 } 64 65 return control_start(ctx, 66 ctx->options & DHCPCD_MANAGER ? NULL : *ctx->ifv, af); 67 } 68 69 static void 70 ps_ctl_recvmsg(void *arg, unsigned short events) 71 { 72 struct ps_process *psp = arg; 73 74 if (ps_recvpsmsg(psp->psp_ctx, psp->psp_fd, events, NULL, NULL) == -1) 75 logerr(__func__); 76 } 77 78 ssize_t 79 ps_ctl_handleargs(struct fd_list *fd, char *data, size_t len) 80 { 81 82 /* Make any change here in dhcpcd.c as well. */ 83 if (strncmp(data, "--version", 84 MIN(strlen("--version"), len)) == 0) { 85 return control_queue(fd, UNCONST(VERSION), 86 strlen(VERSION) + 1); 87 } else if (strncmp(data, "--getconfigfile", 88 MIN(strlen("--getconfigfile"), len)) == 0) { 89 return control_queue(fd, UNCONST(fd->ctx->cffile), 90 strlen(fd->ctx->cffile) + 1); 91 } else if (strncmp(data, "--listen", 92 MIN(strlen("--listen"), len)) == 0) { 93 fd->flags |= FD_LISTEN; 94 return 0; 95 } 96 97 if (fd->ctx->ps_control_client != NULL && 98 fd->ctx->ps_control_client != fd) 99 { 100 logerrx("%s: cannot handle another client", __func__); 101 return 0; 102 } 103 return 1; 104 } 105 106 static ssize_t 107 ps_ctl_dispatch(void *arg, struct ps_msghdr *psm, struct msghdr *msg) 108 { 109 struct dhcpcd_ctx *ctx = arg; 110 struct iovec *iov = msg->msg_iov; 111 struct fd_list *fd; 112 unsigned int fd_flags = FD_SENDLEN; 113 114 switch (psm->ps_flags) { 115 case PS_CTL_PRIV: 116 break; 117 case PS_CTL_UNPRIV: 118 fd_flags |= FD_UNPRIV; 119 break; 120 } 121 122 switch (psm->ps_cmd) { 123 case PS_CTL: 124 if (msg->msg_iovlen != 1) { 125 errno = EINVAL; 126 return -1; 127 } 128 if (ctx->ps_control_client != NULL) { 129 logerrx("%s: cannot handle another client", __func__); 130 return 0; 131 } 132 fd = control_new(ctx, ctx->ps_ctl->psp_work_fd, fd_flags); 133 if (fd == NULL) 134 return -1; 135 ctx->ps_control_client = fd; 136 control_recvdata(fd, iov->iov_base, iov->iov_len); 137 break; 138 case PS_CTL_EOF: 139 ctx->ps_control_client = NULL; 140 break; 141 default: 142 errno = ENOTSUP; 143 return -1; 144 } 145 return 0; 146 } 147 148 static void 149 ps_ctl_dodispatch(void *arg, unsigned short events) 150 { 151 struct ps_process *psp = arg; 152 153 if (ps_recvpsmsg(psp->psp_ctx, psp->psp_fd, events, 154 ps_ctl_dispatch, psp->psp_ctx) == -1) 155 logerr(__func__); 156 } 157 158 static void 159 ps_ctl_recv(void *arg, unsigned short events) 160 { 161 struct dhcpcd_ctx *ctx = arg; 162 char buf[BUFSIZ]; 163 ssize_t len; 164 165 if (!(events & (ELE_READ | ELE_HANGUP))) 166 logerrx("%s: unexpected event 0x%04x", __func__, events); 167 168 if (events & ELE_READ) { 169 len = read(ctx->ps_ctl->psp_work_fd, buf, sizeof(buf)); 170 if (len == -1) 171 logerr("%s: read", __func__); 172 else if (len == 0) 173 // FIXME: Why does this happen? 174 ; 175 else if (ctx->ps_control_client == NULL) 176 logerrx("%s: clientfd #%d disconnected (len=%zd)", 177 __func__, ctx->ps_ctl->psp_work_fd, len); 178 else { 179 errno = 0; 180 if (control_queue(ctx->ps_control_client, 181 buf, (size_t)len) == -1) 182 logerr("%s: control_queue", __func__); 183 } 184 } 185 } 186 187 static void 188 ps_ctl_listen(void *arg, unsigned short events) 189 { 190 struct dhcpcd_ctx *ctx = arg; 191 char buf[BUFSIZ]; 192 ssize_t len; 193 struct fd_list *fd; 194 195 if (!(events & ELE_READ)) 196 logerrx("%s: unexpected event 0x%04x", __func__, events); 197 198 len = read(ctx->ps_control->fd, buf, sizeof(buf)); 199 if (len == -1) { 200 logerr("%s: read", __func__); 201 eloop_exit(ctx->eloop, EXIT_FAILURE); 202 return; 203 } 204 205 /* Send to our listeners */ 206 TAILQ_FOREACH(fd, &ctx->control_fds, next) { 207 if (!(fd->flags & FD_LISTEN)) 208 continue; 209 if (control_queue(fd, buf, (size_t)len)== -1) 210 logerr("%s: control_queue", __func__); 211 } 212 } 213 214 pid_t 215 ps_ctl_start(struct dhcpcd_ctx *ctx) 216 { 217 struct ps_id id = { 218 .psi_ifindex = 0, 219 .psi_cmd = PS_CTL, 220 }; 221 struct ps_process *psp; 222 int work_fd[2], listen_fd[2]; 223 pid_t pid; 224 225 if_closesockets(ctx); 226 227 if (xsocketpair(AF_UNIX, SOCK_STREAM | SOCK_CXNB, 0, work_fd) == -1 || 228 xsocketpair(AF_UNIX, SOCK_STREAM | SOCK_CXNB, 0, listen_fd) == -1) 229 return -1; 230 #ifdef PRIVSEP_RIGHTS 231 if (ps_rights_limit_fdpair(work_fd) == -1 || 232 ps_rights_limit_fdpair(listen_fd) == -1) 233 return -1; 234 #endif 235 236 psp = ctx->ps_ctl = ps_newprocess(ctx, &id); 237 strlcpy(psp->psp_name, "control proxy", sizeof(psp->psp_name)); 238 pid = ps_startprocess(psp, ps_ctl_recvmsg, ps_ctl_dodispatch, 239 ps_ctl_startcb, PSF_DROPPRIVS); 240 241 if (pid == -1) 242 return -1; 243 else if (pid != 0) { 244 psp->psp_work_fd = work_fd[0]; 245 close(work_fd[1]); 246 close(listen_fd[1]); 247 ctx->ps_control = control_new(ctx, 248 listen_fd[0], FD_SENDLEN | FD_LISTEN); 249 if (ctx->ps_control == NULL) 250 return -1; 251 return pid; 252 } 253 254 close(work_fd[0]); 255 close(listen_fd[0]); 256 257 psp->psp_work_fd = work_fd[1]; 258 if (eloop_event_add(ctx->eloop, psp->psp_work_fd, ELE_READ, 259 ps_ctl_recv, ctx) == -1) 260 return -1; 261 262 ctx->ps_control = control_new(ctx, listen_fd[1], 0); 263 if (ctx->ps_control == NULL) 264 return -1; 265 if (eloop_event_add(ctx->eloop, ctx->ps_control->fd, ELE_READ, 266 ps_ctl_listen, ctx) == -1) 267 return -1; 268 269 ps_entersandbox("stdio inet", NULL); 270 return 0; 271 } 272 273 int 274 ps_ctl_stop(struct dhcpcd_ctx *ctx) 275 { 276 277 return ps_stopprocess(ctx->ps_ctl); 278 } 279 280 ssize_t 281 ps_ctl_sendargs(struct fd_list *fd, void *data, size_t len) 282 { 283 struct dhcpcd_ctx *ctx = fd->ctx; 284 285 if (ctx->ps_control_client != NULL && ctx->ps_control_client != fd) 286 logerrx("%s: cannot deal with another client", __func__); 287 ctx->ps_control_client = fd; 288 return ps_sendcmd(ctx, ctx->ps_ctl->psp_fd, PS_CTL, 289 fd->flags & FD_UNPRIV ? PS_CTL_UNPRIV : PS_CTL_PRIV, 290 data, len); 291 } 292 293 ssize_t 294 ps_ctl_sendeof(struct fd_list *fd) 295 { 296 struct dhcpcd_ctx *ctx = fd->ctx; 297 298 return ps_sendcmd(ctx, ctx->ps_ctl->psp_fd, PS_CTL_EOF, 0, NULL, 0); 299 } 300
Indexes created Mon May 25 00:24:39 UTC 2026