1 /* SPDX-License-Identifier: BSD-2-Clause */ 2 /* 3 * Privilege Separation for dhcpcd 4 * Copyright (c) 2006-2023 Roy Marples <roy@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 #ifndef PRIVSEP_H 30 #define PRIVSEP_H 31 32 //#define PRIVSEP_DEBUG 33 34 /* Start flags */ 35 #define PSF_DROPPRIVS 0x01 36 #define PSF_ELOOP 0x02 37 38 /* Protocols */ 39 #define PS_BOOTP 0x0001 40 #define PS_ND 0x0002 41 #define PS_DHCP6 0x0003 42 #define PS_BPF_BOOTP 0x0004 43 #define PS_BPF_ARP 0x0005 44 45 /* Generic commands */ 46 #define PS_IOCTL 0x0010 47 #define PS_ROUTE 0x0011 /* Also used for NETLINK */ 48 #define PS_SCRIPT 0x0012 49 #define PS_UNLINK 0x0013 50 #define PS_READFILE 0x0014 51 #define PS_WRITEFILE 0x0015 52 #define PS_FILEMTIME 0x0016 53 #define PS_AUTH_MONORDM 0x0017 54 #define PS_CTL 0x0018 55 #define PS_CTL_EOF 0x0019 56 #define PS_LOGREOPEN 0x0020 57 #define PS_STOPPROCS 0x0021 58 #define PS_DAEMONISED 0x0022 59 60 /* Domains */ 61 #define PS_ROOT 0x0101 62 #define PS_INET 0x0102 63 #define PS_CONTROL 0x0103 64 65 /* BSD Commands */ 66 #define PS_IOCTLLINK 0x0201 67 #define PS_IOCTL6 0x0202 68 #define PS_IOCTLINDIRECT 0x0203 69 #define PS_IP6FORWARDING 0x0204 70 #define PS_GETIFADDRS 0x0205 71 #define PS_IFIGNOREGRP 0x0206 72 #define PS_SYSCTL 0x0207 73 74 /* Dev Commands */ 75 #define PS_DEV_LISTENING 0x1001 76 #define PS_DEV_INITTED 0x1002 77 #define PS_DEV_IFCMD 0x1003 78 79 /* Dev Interface Commands (via flags) */ 80 #define PS_DEV_IFADDED 0x0001 81 #define PS_DEV_IFREMOVED 0x0002 82 #define PS_DEV_IFUPDATED 0x0003 83 84 /* Control Type (via flags) */ 85 #define PS_CTL_PRIV 0x0004 86 #define PS_CTL_UNPRIV 0x0005 87 88 /* Sysctl Needs (via flags) */ 89 #define PS_SYSCTL_OLEN 0x0001 90 #define PS_SYSCTL_ODATA 0x0002 91 92 /* Process commands */ 93 #define PS_START 0x4000 94 #define PS_STOP 0x8000 95 96 /* Max INET message size + meta data for IPC */ 97 #define PS_BUFLEN ((64 * 1024) + \ 98 sizeof(struct ps_msghdr) + \ 99 sizeof(struct msghdr) + \ 100 CMSG_SPACE(sizeof(struct in6_pktinfo) + \ 101 sizeof(int))) 102 103 #define PSP_NAMESIZE 16 + INET_MAX_ADDRSTRLEN 104 105 /* Handy macro to work out if in the privsep engine or not. */ 106 #define IN_PRIVSEP(ctx) \ 107 ((ctx)->options & DHCPCD_PRIVSEP) 108 #define IN_PRIVSEP_SE(ctx) \ 109 (((ctx)->options & (DHCPCD_PRIVSEP | DHCPCD_FORKED)) == DHCPCD_PRIVSEP) 110 111 #define PS_PROCESS_TIMEOUT 5 /* seconds to stop all processes */ 112 113 #if defined(PRIVSEP) && defined(HAVE_CAPSICUM) 114 #define PRIVSEP_RIGHTS 115 #endif 116 117 #define PS_ROOT_FD(ctx) ((ctx)->ps_root ? (ctx)->ps_root->psp_fd : -1) 118 119 #if !defined(DISABLE_SECCOMP) && defined(__linux__) 120 # include <linux/version.h> 121 # if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 5, 0) 122 # define HAVE_SECCOMP 123 # endif 124 #endif 125 126 #include "config.h" 127 #include "arp.h" 128 #include "dhcp.h" 129 #include "dhcpcd.h" 130 131 struct ps_addr { 132 sa_family_t psa_family; 133 uint8_t psa_pad[4 - sizeof(sa_family_t)]; 134 union { 135 struct in_addr psau_in_addr; 136 struct in6_addr psau_in6_addr; 137 } psa_u; 138 #define psa_in_addr psa_u.psau_in_addr 139 #define psa_in6_addr psa_u.psau_in6_addr 140 }; 141 142 /* Uniquely identify a process */ 143 struct ps_id { 144 struct ps_addr psi_addr; 145 unsigned int psi_ifindex; 146 uint16_t psi_cmd; 147 uint8_t psi_pad[2]; 148 }; 149 150 struct ps_msghdr { 151 uint16_t ps_cmd; 152 uint8_t ps_pad[sizeof(unsigned long) - sizeof(uint16_t)]; 153 unsigned long ps_flags; 154 struct ps_id ps_id; 155 socklen_t ps_namelen; 156 socklen_t ps_controllen; 157 uint8_t ps_pad2[sizeof(size_t) - sizeof(socklen_t)]; 158 size_t ps_datalen; 159 }; 160 161 struct ps_msg { 162 struct ps_msghdr psm_hdr; 163 uint8_t psm_data[PS_BUFLEN]; 164 }; 165 166 struct bpf; 167 168 struct ps_process { 169 TAILQ_ENTRY(ps_process) next; 170 struct dhcpcd_ctx *psp_ctx; 171 struct ps_id psp_id; 172 pid_t psp_pid; 173 int psp_fd; 174 int psp_work_fd; 175 unsigned int psp_ifindex; 176 char psp_ifname[IF_NAMESIZE]; 177 char psp_name[PSP_NAMESIZE]; 178 uint16_t psp_proto; 179 const char *psp_protostr; 180 bool psp_started; 181 182 #ifdef INET 183 int (*psp_filter)(const struct bpf *, const struct in_addr *); 184 struct interface psp_ifp; /* Move BPF gubbins elsewhere */ 185 struct bpf *psp_bpf; 186 #endif 187 188 #ifdef HAVE_CAPSICUM 189 int psp_pfd; 190 #endif 191 }; 192 TAILQ_HEAD(ps_process_head, ps_process); 193 194 #include "privsep-control.h" 195 #include "privsep-inet.h" 196 #include "privsep-root.h" 197 #ifdef INET 198 #include "privsep-bpf.h" 199 #endif 200 201 int ps_init(struct dhcpcd_ctx *); 202 int ps_start(struct dhcpcd_ctx *); 203 int ps_stop(struct dhcpcd_ctx *); 204 int ps_stopwait(struct dhcpcd_ctx *); 205 int ps_entersandbox(const char *, const char **); 206 int ps_managersandbox(struct dhcpcd_ctx *, const char *); 207 ssize_t ps_daemonised(struct dhcpcd_ctx *); 208 209 int ps_unrollmsg(struct msghdr *, struct ps_msghdr *, const void *, size_t); 210 ssize_t ps_sendpsmmsg(struct dhcpcd_ctx *, int, 211 struct ps_msghdr *, const struct msghdr *); 212 ssize_t ps_sendpsmdata(struct dhcpcd_ctx *, int, 213 struct ps_msghdr *, const void *, size_t); 214 ssize_t ps_sendmsg(struct dhcpcd_ctx *, int, uint16_t, unsigned long, 215 const struct msghdr *); 216 ssize_t ps_sendcmd(struct dhcpcd_ctx *, int, uint16_t, unsigned long, 217 const void *data, size_t len); 218 ssize_t ps_recvmsg(int, unsigned short, uint16_t, int); 219 ssize_t ps_recvpsmsg(struct dhcpcd_ctx *, int, unsigned short, 220 ssize_t (*callback)(void *, struct ps_msghdr *, struct msghdr *), void *); 221 222 /* Internal privsep functions. */ 223 int ps_setbuf_fdpair(int []); 224 225 #ifdef PRIVSEP_RIGHTS 226 int ps_rights_limit_ioctl(int); 227 int ps_rights_limit_fd_fctnl(int); 228 int ps_rights_limit_fd_rdonly(int); 229 int ps_rights_limit_fd_sockopt(int); 230 int ps_rights_limit_fd(int); 231 int ps_rights_limit_fdpair(int []); 232 #endif 233 234 #ifdef HAVE_SECCOMP 235 int ps_seccomp_enter(void); 236 #endif 237 238 pid_t ps_startprocess(struct ps_process *, 239 void (*recv_msg)(void *, unsigned short), 240 void (*recv_unpriv_msg)(void *, unsigned short), 241 int (*callback)(struct ps_process *), void (*)(int, void *), 242 unsigned int); 243 int ps_stopprocess(struct ps_process *); 244 struct ps_process *ps_findprocess(struct dhcpcd_ctx *, struct ps_id *); 245 struct ps_process *ps_findprocesspid(struct dhcpcd_ctx *, pid_t); 246 struct ps_process *ps_newprocess(struct dhcpcd_ctx *, struct ps_id *); 247 bool ps_waitforprocs(struct dhcpcd_ctx *ctx); 248 void ps_process_timeout(void *); 249 void ps_freeprocess(struct ps_process *); 250 void ps_freeprocesses(struct dhcpcd_ctx *, struct ps_process *); 251 #endif 252