contrib/dhcpcd/src/privsep.h

   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