xref: /dragonfly/contrib/dhcpcd/src/privsep.h (revision a85d0907)
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 #define	PS_DAEMONISED		0x0022
59 
60 /* Domains */
61 #define	PS_ROOT			0x0101
62 #define	PS_INET			0x0102
63 #define	PS_CONTROL		0x0103
64 
65 /* BSD Commands */
66 #define	PS_IOCTLLINK		0x0201
67 #define	PS_IOCTL6		0x0202
68 #define	PS_IOCTLINDIRECT	0x0203
69 #define	PS_IP6FORWARDING	0x0204
70 #define	PS_GETIFADDRS		0x0205
71 #define	PS_IFIGNOREGRP		0x0206
72 #define	PS_SYSCTL		0x0207
73 
74 /* Dev Commands */
75 #define	PS_DEV_LISTENING	0x1001
76 #define	PS_DEV_INITTED		0x1002
77 #define	PS_DEV_IFCMD		0x1003
78 
79 /* Dev Interface Commands (via flags) */
80 #define	PS_DEV_IFADDED		0x0001
81 #define	PS_DEV_IFREMOVED	0x0002
82 #define	PS_DEV_IFUPDATED	0x0003
83 
84 /* Control Type (via flags) */
85 #define	PS_CTL_PRIV		0x0004
86 #define	PS_CTL_UNPRIV		0x0005
87 
88 /* Sysctl Needs (via flags) */
89 #define	PS_SYSCTL_OLEN		0x0001
90 #define	PS_SYSCTL_ODATA		0x0002
91 
92 /* Process commands */
93 #define	PS_START		0x4000
94 #define	PS_STOP			0x8000
95 
96 /* Max INET message size + meta data for IPC */
97 #define	PS_BUFLEN		((64 * 1024) +			\
98 				 sizeof(struct ps_msghdr) +	\
99 				 sizeof(struct msghdr) +	\
100 				 CMSG_SPACE(sizeof(struct in6_pktinfo) + \
101 					    sizeof(int)))
102 
103 #define	PSP_NAMESIZE		16 + INET_MAX_ADDRSTRLEN
104 
105 /* Handy macro to work out if in the privsep engine or not. */
106 #define	IN_PRIVSEP(ctx)	\
107 	((ctx)->options & DHCPCD_PRIVSEP)
108 #define	IN_PRIVSEP_SE(ctx)	\
109 	(((ctx)->options & (DHCPCD_PRIVSEP | DHCPCD_FORKED)) == DHCPCD_PRIVSEP)
110 
111 #define	PS_PROCESS_TIMEOUT	5	/* seconds to stop all processes */
112 
113 #if defined(PRIVSEP) && defined(HAVE_CAPSICUM)
114 #define PRIVSEP_RIGHTS
115 #endif
116 
117 #define PS_ROOT_FD(ctx) ((ctx)->ps_root ? (ctx)->ps_root->psp_fd : -1)
118 
119 #if !defined(DISABLE_SECCOMP) && defined(__linux__)
120 # include <linux/version.h>
121 # if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 5, 0)
122 #  define HAVE_SECCOMP
123 # endif
124 #endif
125 
126 #include "config.h"
127 #include "arp.h"
128 #include "dhcp.h"
129 #include "dhcpcd.h"
130 
131 struct ps_addr {
132 	sa_family_t psa_family;
133 	uint8_t psa_pad[4 - sizeof(sa_family_t)];
134 	union {
135 		struct in_addr psau_in_addr;
136 		struct in6_addr psau_in6_addr;
137 	} psa_u;
138 #define	psa_in_addr	psa_u.psau_in_addr
139 #define	psa_in6_addr	psa_u.psau_in6_addr
140 };
141 
142 /* Uniquely identify a process */
143 struct ps_id {
144 	struct ps_addr psi_addr;
145 	unsigned int psi_ifindex;
146 	uint16_t psi_cmd;
147 	uint8_t psi_pad[2];
148 };
149 
150 struct ps_msghdr {
151 	uint16_t ps_cmd;
152 	uint8_t ps_pad[sizeof(unsigned long) - sizeof(uint16_t)];
153 	unsigned long ps_flags;
154 	struct ps_id ps_id;
155 	socklen_t ps_namelen;
156 	socklen_t ps_controllen;
157 	uint8_t ps_pad2[sizeof(size_t) - sizeof(socklen_t)];
158 	size_t ps_datalen;
159 };
160 
161 struct ps_msg {
162 	struct ps_msghdr psm_hdr;
163 	uint8_t psm_data[PS_BUFLEN];
164 };
165 
166 struct bpf;
167 
168 struct ps_process {
169 	TAILQ_ENTRY(ps_process) next;
170 	struct dhcpcd_ctx *psp_ctx;
171 	struct ps_id psp_id;
172 	pid_t psp_pid;
173 	int psp_fd;
174 	int psp_work_fd;
175 	unsigned int psp_ifindex;
176 	char psp_ifname[IF_NAMESIZE];
177 	char psp_name[PSP_NAMESIZE];
178 	uint16_t psp_proto;
179 	const char *psp_protostr;
180 	bool psp_started;
181 
182 #ifdef INET
183 	int (*psp_filter)(const struct bpf *, const struct in_addr *);
184 	struct interface psp_ifp; /* Move BPF gubbins elsewhere */
185 	struct bpf *psp_bpf;
186 #endif
187 
188 #ifdef HAVE_CAPSICUM
189 	int psp_pfd;
190 #endif
191 };
192 TAILQ_HEAD(ps_process_head, ps_process);
193 
194 #include "privsep-control.h"
195 #include "privsep-inet.h"
196 #include "privsep-root.h"
197 #ifdef INET
198 #include "privsep-bpf.h"
199 #endif
200 
201 int ps_init(struct dhcpcd_ctx *);
202 int ps_start(struct dhcpcd_ctx *);
203 int ps_stop(struct dhcpcd_ctx *);
204 int ps_stopwait(struct dhcpcd_ctx *);
205 int ps_entersandbox(const char *, const char **);
206 int ps_managersandbox(struct dhcpcd_ctx *, const char *);
207 ssize_t ps_daemonised(struct dhcpcd_ctx *);
208 
209 int ps_unrollmsg(struct msghdr *, struct ps_msghdr *, const void *, size_t);
210 ssize_t ps_sendpsmmsg(struct dhcpcd_ctx *, int,
211     struct ps_msghdr *, const struct msghdr *);
212 ssize_t ps_sendpsmdata(struct dhcpcd_ctx *, int,
213     struct ps_msghdr *, const void *, size_t);
214 ssize_t ps_sendmsg(struct dhcpcd_ctx *, int, uint16_t, unsigned long,
215     const struct msghdr *);
216 ssize_t ps_sendcmd(struct dhcpcd_ctx *, int, uint16_t, unsigned long,
217     const void *data, size_t len);
218 ssize_t ps_recvmsg(int, unsigned short, uint16_t, int);
219 ssize_t ps_recvpsmsg(struct dhcpcd_ctx *, int, unsigned short,
220     ssize_t (*callback)(void *, struct ps_msghdr *, struct msghdr *), void *);
221 
222 /* Internal privsep functions. */
223 int ps_setbuf_fdpair(int []);
224 
225 #ifdef PRIVSEP_RIGHTS
226 int ps_rights_limit_ioctl(int);
227 int ps_rights_limit_fd_fctnl(int);
228 int ps_rights_limit_fd_rdonly(int);
229 int ps_rights_limit_fd_sockopt(int);
230 int ps_rights_limit_fd(int);
231 int ps_rights_limit_fdpair(int []);
232 #endif
233 
234 #ifdef HAVE_SECCOMP
235 int ps_seccomp_enter(void);
236 #endif
237 
238 pid_t ps_startprocess(struct ps_process *,
239     void (*recv_msg)(void *, unsigned short),
240     void (*recv_unpriv_msg)(void *, unsigned short),
241     int (*callback)(struct ps_process *), void (*)(int, void *),
242     unsigned int);
243 int ps_stopprocess(struct ps_process *);
244 struct ps_process *ps_findprocess(struct dhcpcd_ctx *, struct ps_id *);
245 struct ps_process *ps_findprocesspid(struct dhcpcd_ctx *, pid_t);
246 struct ps_process *ps_newprocess(struct dhcpcd_ctx *, struct ps_id *);
247 bool ps_waitforprocs(struct dhcpcd_ctx *ctx);
248 void ps_process_timeout(void *);
249 void ps_freeprocess(struct ps_process *);
250 void ps_freeprocesses(struct dhcpcd_ctx *, struct ps_process *);
251 #endif
252