1 /* SPDX-License-Identifier: BSD-2-Clause */ 2 /* 3 * Privilege Separation for dhcpcd 4 * Copyright (c) 2006-2020 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 37 /* Protocols */ 38 #define PS_BOOTP 0x0001 39 #define PS_ND 0x0002 40 #define PS_DHCP6 0x0003 41 #define PS_BPF_BOOTP 0x0004 42 #define PS_BPF_ARP 0x0005 43 44 /* Generic commands */ 45 #define PS_IOCTL 0x0010 46 #define PS_ROUTE 0x0011 /* Also used for NETLINK */ 47 #define PS_SCRIPT 0x0012 48 #define PS_UNLINK 0x0013 49 #define PS_READFILE 0x0014 50 #define PS_WRITEFILE 0x0015 51 #define PS_FILEMTIME 0x0016 52 #define PS_AUTH_MONORDM 0x0017 53 #define PS_CTL 0x0018 54 #define PS_CTL_EOF 0x0019 55 56 /* BSD Commands */ 57 #define PS_IOCTLLINK 0x0101 58 #define PS_IOCTL6 0x0102 59 #define PS_IOCTLINDIRECT 0x0103 60 #define PS_IP6FORWARDING 0x0104 61 #define PS_GETIFADDRS 0x0105 62 #define PS_IFIGNOREGRP 0x0106 63 64 /* Dev Commands */ 65 #define PS_DEV_LISTENING 0x1001 66 #define PS_DEV_INITTED 0x1002 67 #define PS_DEV_IFCMD 0x1003 68 69 /* Dev Interface Commands (via flags) */ 70 #define PS_DEV_IFADDED 0x0001 71 #define PS_DEV_IFREMOVED 0x0002 72 #define PS_DEV_IFUPDATED 0x0003 73 74 /* Control Type (via flags) */ 75 #define PS_CTL_PRIV 0x0004 76 #define PS_CTL_UNPRIV 0x0005 77 78 /* Process commands */ 79 #define PS_START 0x4000 80 #define PS_STOP 0x8000 81 82 /* Max INET message size + meta data for IPC */ 83 #define PS_BUFLEN ((64 * 1024) + \ 84 sizeof(struct ps_msghdr) + \ 85 sizeof(struct msghdr) + \ 86 CMSG_SPACE(sizeof(struct in6_pktinfo) + \ 87 sizeof(int))) 88 89 /* Handy macro to work out if in the privsep engine or not. */ 90 #define IN_PRIVSEP(ctx) \ 91 ((ctx)->options & DHCPCD_PRIVSEP) 92 #define IN_PRIVSEP_SE(ctx) \ 93 (((ctx)->options & (DHCPCD_PRIVSEP | DHCPCD_FORKED)) == DHCPCD_PRIVSEP) 94 95 #if defined(PRIVSEP) && defined(HAVE_CAPSICUM) 96 #define PRIVSEP_RIGHTS 97 #endif 98 99 #ifdef __linux__ 100 # include <linux/version.h> 101 # if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 5, 0) 102 # define HAVE_SECCOMP 103 # endif 104 #endif 105 106 #include "config.h" 107 #include "arp.h" 108 #include "dhcp.h" 109 #include "dhcpcd.h" 110 111 struct ps_addr { 112 sa_family_t psa_family; 113 uint8_t psa_pad[4 - sizeof(sa_family_t)]; 114 union { 115 struct in_addr psau_in_addr; 116 struct in6_addr psau_in6_addr; 117 } psa_u; 118 #define psa_in_addr psa_u.psau_in_addr 119 #define psa_in6_addr psa_u.psau_in6_addr 120 }; 121 122 /* Uniquely identify a process */ 123 struct ps_id { 124 struct ps_addr psi_addr; 125 unsigned int psi_ifindex; 126 uint16_t psi_cmd; 127 uint8_t psi_pad[2]; 128 }; 129 130 struct ps_msghdr { 131 uint16_t ps_cmd; 132 uint8_t ps_pad[sizeof(unsigned long) - sizeof(uint16_t)]; 133 unsigned long ps_flags; 134 struct ps_id ps_id; 135 socklen_t ps_namelen; 136 socklen_t ps_controllen; 137 uint8_t ps_pad2[sizeof(size_t) - sizeof(socklen_t)]; 138 size_t ps_datalen; 139 }; 140 141 struct ps_msg { 142 struct ps_msghdr psm_hdr; 143 uint8_t psm_data[PS_BUFLEN]; 144 }; 145 146 struct bpf; 147 struct ps_process { 148 TAILQ_ENTRY(ps_process) next; 149 struct dhcpcd_ctx *psp_ctx; 150 struct ps_id psp_id; 151 pid_t psp_pid; 152 int psp_fd; 153 int psp_work_fd; 154 unsigned int psp_ifindex; 155 char psp_ifname[IF_NAMESIZE]; 156 uint16_t psp_proto; 157 const char *psp_protostr; 158 159 #ifdef INET 160 int (*psp_filter)(const struct bpf *, const struct in_addr *); 161 struct interface psp_ifp; /* Move BPF gubbins elsewhere */ 162 struct bpf *psp_bpf; 163 #endif 164 }; 165 TAILQ_HEAD(ps_process_head, ps_process); 166 167 #include "privsep-control.h" 168 #include "privsep-inet.h" 169 #include "privsep-root.h" 170 #ifdef INET 171 #include "privsep-bpf.h" 172 #endif 173 174 int ps_init(struct dhcpcd_ctx *); 175 int ps_start(struct dhcpcd_ctx *); 176 int ps_stop(struct dhcpcd_ctx *); 177 int ps_entersandbox(const char *, const char **); 178 int ps_mastersandbox(struct dhcpcd_ctx *, const char *); 179 180 int ps_unrollmsg(struct msghdr *, struct ps_msghdr *, const void *, size_t); 181 ssize_t ps_sendpsmmsg(struct dhcpcd_ctx *, int, 182 struct ps_msghdr *, const struct msghdr *); 183 ssize_t ps_sendpsmdata(struct dhcpcd_ctx *, int, 184 struct ps_msghdr *, const void *, size_t); 185 ssize_t ps_sendmsg(struct dhcpcd_ctx *, int, uint16_t, unsigned long, 186 const struct msghdr *); 187 ssize_t ps_sendcmd(struct dhcpcd_ctx *, int, uint16_t, unsigned long, 188 const void *data, size_t len); 189 ssize_t ps_recvmsg(struct dhcpcd_ctx *, int, uint16_t, int); 190 ssize_t ps_recvpsmsg(struct dhcpcd_ctx *, int, 191 ssize_t (*callback)(void *, struct ps_msghdr *, struct msghdr *), void *); 192 193 /* Internal privsep functions. */ 194 int ps_setbuf_fdpair(int []); 195 196 #ifdef PRIVSEP_RIGHTS 197 int ps_rights_limit_ioctl(int); 198 int ps_rights_limit_fd_fctnl(int); 199 int ps_rights_limit_fd_rdonly(int); 200 int ps_rights_limit_fd_sockopt(int); 201 int ps_rights_limit_fd(int); 202 int ps_rights_limit_fdpair(int []); 203 #endif 204 205 #ifdef HAVE_SECCOMP 206 int ps_seccomp_enter(void); 207 #endif 208 209 pid_t ps_dostart(struct dhcpcd_ctx * ctx, 210 pid_t *priv_pid, int *priv_fd, 211 void (*recv_msg)(void *), void (*recv_unpriv_msg), 212 void *recv_ctx, int (*callback)(void *), void (*)(int, void *), 213 unsigned int); 214 int ps_dostop(struct dhcpcd_ctx *ctx, pid_t *pid, int *fd); 215 216 struct ps_process *ps_findprocess(struct dhcpcd_ctx *, struct ps_id *); 217 struct ps_process *ps_newprocess(struct dhcpcd_ctx *, struct ps_id *); 218 void ps_freeprocess(struct ps_process *); 219 void ps_freeprocesses(struct dhcpcd_ctx *, struct ps_process *); 220 #endif 221