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 #ifdef __linux__ 117 # include <linux/version.h> 118 # if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 5, 0) 119 # define HAVE_SECCOMP 120 # endif 121 #endif 122 123 #include "config.h" 124 #include "arp.h" 125 #include "dhcp.h" 126 #include "dhcpcd.h" 127 128 struct ps_addr { 129 sa_family_t psa_family; 130 uint8_t psa_pad[4 - sizeof(sa_family_t)]; 131 union { 132 struct in_addr psau_in_addr; 133 struct in6_addr psau_in6_addr; 134 } psa_u; 135 #define psa_in_addr psa_u.psau_in_addr 136 #define psa_in6_addr psa_u.psau_in6_addr 137 }; 138 139 /* Uniquely identify a process */ 140 struct ps_id { 141 struct ps_addr psi_addr; 142 unsigned int psi_ifindex; 143 uint16_t psi_cmd; 144 uint8_t psi_pad[2]; 145 }; 146 147 struct ps_msghdr { 148 uint16_t ps_cmd; 149 uint8_t ps_pad[sizeof(unsigned long) - sizeof(uint16_t)]; 150 unsigned long ps_flags; 151 struct ps_id ps_id; 152 socklen_t ps_namelen; 153 socklen_t ps_controllen; 154 uint8_t ps_pad2[sizeof(size_t) - sizeof(socklen_t)]; 155 size_t ps_datalen; 156 }; 157 158 struct ps_msg { 159 struct ps_msghdr psm_hdr; 160 uint8_t psm_data[PS_BUFLEN]; 161 }; 162 163 struct bpf; 164 165 struct ps_process { 166 TAILQ_ENTRY(ps_process) next; 167 struct dhcpcd_ctx *psp_ctx; 168 struct ps_id psp_id; 169 pid_t psp_pid; 170 int psp_fd; 171 int psp_work_fd; 172 unsigned int psp_ifindex; 173 char psp_ifname[IF_NAMESIZE]; 174 char psp_name[PSP_NAMESIZE]; 175 uint16_t psp_proto; 176 const char *psp_protostr; 177 bool psp_started; 178 179 #ifdef INET 180 int (*psp_filter)(const struct bpf *, const struct in_addr *); 181 struct interface psp_ifp; /* Move BPF gubbins elsewhere */ 182 struct bpf *psp_bpf; 183 #endif 184 185 #ifdef HAVE_CAPSICUM 186 int psp_pfd; 187 #endif 188 }; 189 TAILQ_HEAD(ps_process_head, ps_process); 190 191 #include "privsep-control.h" 192 #include "privsep-inet.h" 193 #include "privsep-root.h" 194 #ifdef INET 195 #include "privsep-bpf.h" 196 #endif 197 198 int ps_init(struct dhcpcd_ctx *); 199 int ps_start(struct dhcpcd_ctx *); 200 int ps_stop(struct dhcpcd_ctx *); 201 int ps_stopwait(struct dhcpcd_ctx *); 202 int ps_entersandbox(const char *, const char **); 203 int ps_managersandbox(struct dhcpcd_ctx *, const char *); 204 205 int ps_unrollmsg(struct msghdr *, struct ps_msghdr *, const void *, size_t); 206 ssize_t ps_sendpsmmsg(struct dhcpcd_ctx *, int, 207 struct ps_msghdr *, const struct msghdr *); 208 ssize_t ps_sendpsmdata(struct dhcpcd_ctx *, int, 209 struct ps_msghdr *, const void *, size_t); 210 ssize_t ps_sendmsg(struct dhcpcd_ctx *, int, uint16_t, unsigned long, 211 const struct msghdr *); 212 ssize_t ps_sendcmd(struct dhcpcd_ctx *, int, uint16_t, unsigned long, 213 const void *data, size_t len); 214 ssize_t ps_recvmsg(struct dhcpcd_ctx *, int, unsigned short, uint16_t, int); 215 ssize_t ps_recvpsmsg(struct dhcpcd_ctx *, int, unsigned short, 216 ssize_t (*callback)(void *, struct ps_msghdr *, struct msghdr *), void *); 217 218 /* Internal privsep functions. */ 219 int ps_setbuf_fdpair(int []); 220 221 #ifdef PRIVSEP_RIGHTS 222 int ps_rights_limit_ioctl(int); 223 int ps_rights_limit_fd_fctnl(int); 224 int ps_rights_limit_fd_rdonly(int); 225 int ps_rights_limit_fd_sockopt(int); 226 int ps_rights_limit_fd(int); 227 int ps_rights_limit_fdpair(int []); 228 #endif 229 230 #ifdef HAVE_SECCOMP 231 int ps_seccomp_enter(void); 232 #endif 233 234 pid_t ps_startprocess(struct ps_process *, 235 void (*recv_msg)(void *, unsigned short), 236 void (*recv_unpriv_msg)(void *, unsigned short), 237 int (*callback)(struct ps_process *), void (*)(int, void *), 238 unsigned int); 239 int ps_stopprocess(struct ps_process *); 240 struct ps_process *ps_findprocess(struct dhcpcd_ctx *, struct ps_id *); 241 struct ps_process *ps_findprocesspid(struct dhcpcd_ctx *, pid_t); 242 struct ps_process *ps_newprocess(struct dhcpcd_ctx *, struct ps_id *); 243 bool ps_waitforprocs(struct dhcpcd_ctx *ctx); 244 void ps_process_timeout(void *); 245 void ps_freeprocess(struct ps_process *); 246 void ps_freeprocesses(struct dhcpcd_ctx *, struct ps_process *); 247 #endif 248