contrib/dhcpcd/src/privsep.h

   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
  96 #if defined(PRIVSEP) && defined(HAVE_CAPSICUM)
  97 #define PRIVSEP_RIGHTS
  98 #endif
  99
 100 #include "config.h"
 101 #include "arp.h"
 102 #include "dhcp.h"
 103 #include "dhcpcd.h"
 104
 105 struct ps_addr {
 106         sa_family_t psa_family;
 107         uint8_t psa_pad[4 - sizeof(sa_family_t)];
 108         union {
 109                 struct in_addr psau_in_addr;
 110                 struct in6_addr psau_in6_addr;
 111         } psa_u;
 112 #define psa_in_addr     psa_u.psau_in_addr
 113 #define psa_in6_addr    psa_u.psau_in6_addr
 114 };
 115
 116 /* Uniquely identify a process */
 117 struct ps_id {
 118         struct ps_addr psi_addr;
 119         unsigned int psi_ifindex;
 120         uint16_t psi_cmd;
 121         uint8_t psi_pad[2];
 122 };
 123
 124 struct ps_msghdr {
 125         uint16_t ps_cmd;
 126         uint8_t ps_pad[sizeof(unsigned long) - sizeof(uint16_t)];
 127         unsigned long ps_flags;
 128         struct ps_id ps_id;
 129         socklen_t ps_namelen;
 130         socklen_t ps_controllen;
 131         uint8_t ps_pad2[sizeof(size_t) - sizeof(socklen_t)];
 132         size_t ps_datalen;
 133 };
 134
 135 struct ps_msg {
 136         struct ps_msghdr psm_hdr;
 137         uint8_t psm_data[PS_BUFLEN];
 138 };
 139
 140 struct bpf;
 141 struct ps_process {
 142         TAILQ_ENTRY(ps_process) next;
 143         struct dhcpcd_ctx *psp_ctx;
 144         struct ps_id psp_id;
 145         pid_t psp_pid;
 146         int psp_fd;
 147         int psp_work_fd;
 148         unsigned int psp_ifindex;
 149         char psp_ifname[IF_NAMESIZE];
 150         uint16_t psp_proto;
 151         const char *psp_protostr;
 152
 153 #ifdef INET
 154         int (*psp_filter)(const struct bpf *, const struct in_addr *);
 155         struct interface psp_ifp; /* Move BPF gubbins elsewhere */
 156         struct bpf *psp_bpf;
 157 #endif
 158 };
 159 TAILQ_HEAD(ps_process_head, ps_process);
 160
 161 #include "privsep-control.h"
 162 #include "privsep-inet.h"
 163 #include "privsep-root.h"
 164 #ifdef INET
 165 #include "privsep-bpf.h"
 166 #endif
 167
 168 int ps_init(struct dhcpcd_ctx *);
 169 int ps_start(struct dhcpcd_ctx *);
 170 int ps_stop(struct dhcpcd_ctx *);
 171 int ps_mastersandbox(struct dhcpcd_ctx *);
 172
 173 int ps_unrollmsg(struct msghdr *, struct ps_msghdr *, const void *, size_t);
 174 ssize_t ps_sendpsmmsg(struct dhcpcd_ctx *, int,
 175     struct ps_msghdr *, const struct msghdr *);
 176 ssize_t ps_sendpsmdata(struct dhcpcd_ctx *, int,
 177     struct ps_msghdr *, const void *, size_t);
 178 ssize_t ps_sendmsg(struct dhcpcd_ctx *, int, uint16_t, unsigned long,
 179     const struct msghdr *);
 180 ssize_t ps_sendcmd(struct dhcpcd_ctx *, int, uint16_t, unsigned long,
 181     const void *data, size_t len);
 182 ssize_t ps_recvmsg(struct dhcpcd_ctx *, int, uint16_t, int);
 183 ssize_t ps_recvpsmsg(struct dhcpcd_ctx *, int,
 184     ssize_t (*callback)(void *, struct ps_msghdr *, struct msghdr *), void *);
 185
 186 /* Internal privsep functions. */
 187 int ps_setbuf_fdpair(int []);
 188 #ifdef PRIVSEP_RIGHTS
 189 int ps_rights_limit_ioctl(int);
 190 int ps_rights_limit_fd_fctnl(int);
 191 int ps_rights_limit_fd_rdonly(int);
 192 int ps_rights_limit_fd(int);
 193 int ps_rights_limit_fdpair(int []);
 194 #endif
 195 pid_t ps_dostart(struct dhcpcd_ctx * ctx,
 196     pid_t *priv_pid, int *priv_fd,
 197     void (*recv_msg)(void *), void (*recv_unpriv_msg),
 198     void *recv_ctx, int (*callback)(void *), void (*)(int, void *),
 199     unsigned int);
 200 int ps_dostop(struct dhcpcd_ctx *ctx, pid_t *pid, int *fd);
 201
 202 struct ps_process *ps_findprocess(struct dhcpcd_ctx *, struct ps_id *);
 203 struct ps_process *ps_newprocess(struct dhcpcd_ctx *, struct ps_id *);
 204 void ps_freeprocess(struct ps_process *);
 205 void ps_freeprocesses(struct dhcpcd_ctx *, struct ps_process *);
 206 #endif