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