1 /*-
2 * Copyright (c) 2009-2013 The NetBSD Foundation, Inc.
3 * All rights reserved.
4 *
5 * This material is based upon work partially supported by The
6 * NetBSD Foundation under a contract with Mindaugas Rasiukevicius.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
18 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
19 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
20 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
21 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
22 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
23 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
24 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
25 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
26 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
27 * POSSIBILITY OF SUCH DAMAGE.
28 */
29
30 /*
31 * NPF byte-code processing.
32 */
33
34 #ifdef _KERNEL
35 #include <sys/cdefs.h>
36 __KERNEL_RCSID(0, "$NetBSD: npf_bpf.c,v 1.14 2018/09/29 14:41:36 rmind Exp $");
37
38 #include <sys/types.h>
39 #include <sys/param.h>
40
41 #include <sys/bitops.h>
42 #include <sys/mbuf.h>
43 #include <net/bpf.h>
44 #endif
45
46 #define NPF_BPFCOP
47 #include "npf_impl.h"
48
49 #if defined(_NPF_STANDALONE)
50 #define m_length(m) (nbuf)->nb_mops->getchainlen(m)
51 #endif
52
53 /*
54 * BPF context and the coprocessor.
55 */
56
57 static bpf_ctx_t *npf_bpfctx __read_mostly;
58
59 static uint32_t npf_cop_l3(const bpf_ctx_t *, bpf_args_t *, uint32_t);
60 static uint32_t npf_cop_table(const bpf_ctx_t *, bpf_args_t *, uint32_t);
61
62 static const bpf_copfunc_t npf_bpfcop[] = {
63 [NPF_COP_L3] = npf_cop_l3,
64 [NPF_COP_TABLE] = npf_cop_table,
65 };
66
67 #define BPF_MW_ALLMASK \
68 ((1U << BPF_MW_IPVER) | (1U << BPF_MW_L4OFF) | (1U << BPF_MW_L4PROTO))
69
70 void
npf_bpf_sysinit(void)71 npf_bpf_sysinit(void)
72 {
73 npf_bpfctx = bpf_create();
74 bpf_set_cop(npf_bpfctx, npf_bpfcop, __arraycount(npf_bpfcop));
75 bpf_set_extmem(npf_bpfctx, NPF_BPF_NWORDS, BPF_MW_ALLMASK);
76 }
77
78 void
npf_bpf_sysfini(void)79 npf_bpf_sysfini(void)
80 {
81 bpf_destroy(npf_bpfctx);
82 }
83
84 void
npf_bpf_prepare(npf_cache_t * npc,bpf_args_t * args,uint32_t * M)85 npf_bpf_prepare(npf_cache_t *npc, bpf_args_t *args, uint32_t *M)
86 {
87 nbuf_t *nbuf = npc->npc_nbuf;
88 const struct mbuf *mbuf = nbuf_head_mbuf(nbuf);
89 const size_t pktlen = m_length(mbuf);
90
91 /* Prepare the arguments for the BPF programs. */
92 #ifdef _NPF_STANDALONE
93 args->pkt = (const uint8_t *)nbuf_dataptr(nbuf);
94 args->wirelen = args->buflen = pktlen;
95 #else
96 args->pkt = (const uint8_t *)mbuf;
97 args->wirelen = pktlen;
98 args->buflen = 0;
99 #endif
100 args->mem = M;
101 args->arg = npc;
102
103 /*
104 * Convert address length to IP version. Just mask out
105 * number 4 or set 6 if higher bits set, such that:
106 *
107 * 0 => 0
108 * 4 => 4 (IPVERSION)
109 * 16 => 6 (IPV6_VERSION >> 4)
110 */
111 const u_int alen = npc->npc_alen;
112 const uint32_t ver = (alen & 4) | ((alen >> 4) * 6);
113
114 /*
115 * Output words in the memory store:
116 * BPF_MW_IPVER IP version (4 or 6).
117 * BPF_MW_L4OFF L4 header offset.
118 * BPF_MW_L4PROTO L4 protocol.
119 */
120 M[BPF_MW_IPVER] = ver;
121 M[BPF_MW_L4OFF] = npc->npc_hlen;
122 M[BPF_MW_L4PROTO] = npc->npc_proto;
123 }
124
125 int
npf_bpf_filter(bpf_args_t * args,const void * code,bpfjit_func_t jcode)126 npf_bpf_filter(bpf_args_t *args, const void *code, bpfjit_func_t jcode)
127 {
128 /* Execute JIT-compiled code. */
129 if (__predict_true(jcode)) {
130 return jcode(npf_bpfctx, args);
131 }
132
133 /* Execute BPF byte-code. */
134 return bpf_filter_ext(npf_bpfctx, code, args);
135 }
136
137 void *
npf_bpf_compile(void * code,size_t size)138 npf_bpf_compile(void *code, size_t size)
139 {
140 return bpf_jit_generate(npf_bpfctx, code, size);
141 }
142
143 bool
npf_bpf_validate(const void * code,size_t len)144 npf_bpf_validate(const void *code, size_t len)
145 {
146 const size_t icount = len / sizeof(struct bpf_insn);
147 return bpf_validate_ext(npf_bpfctx, code, icount) != 0;
148 }
149
150 /*
151 * NPF_COP_L3: fetches layer 3 information.
152 */
153 static uint32_t
npf_cop_l3(const bpf_ctx_t * bc,bpf_args_t * args,uint32_t A)154 npf_cop_l3(const bpf_ctx_t *bc, bpf_args_t *args, uint32_t A)
155 {
156 const npf_cache_t * const npc = (const npf_cache_t *)args->arg;
157 const uint32_t ver = (npc->npc_alen & 4) | ((npc->npc_alen >> 4) * 6);
158 uint32_t * const M = args->mem;
159
160 M[BPF_MW_IPVER] = ver;
161 M[BPF_MW_L4OFF] = npc->npc_hlen;
162 M[BPF_MW_L4PROTO] = npc->npc_proto;
163 return ver; /* A <- IP version */
164 }
165
166 #define SRC_FLAG_BIT (1U << 31)
167
168 /*
169 * NPF_COP_TABLE: perform NPF table lookup.
170 *
171 * A <- non-zero (true) if found and zero (false) otherwise
172 */
173 static uint32_t
npf_cop_table(const bpf_ctx_t * bc,bpf_args_t * args,uint32_t A)174 npf_cop_table(const bpf_ctx_t *bc, bpf_args_t *args, uint32_t A)
175 {
176 const npf_cache_t * const npc = (const npf_cache_t *)args->arg;
177 npf_tableset_t *tblset = npf_config_tableset(npc->npc_ctx);
178 const uint32_t tid = A & (SRC_FLAG_BIT - 1);
179 const npf_addr_t *addr;
180 npf_table_t *t;
181
182 if (!npf_iscached(npc, NPC_IP46)) {
183 return 0;
184 }
185 t = npf_tableset_getbyid(tblset, tid);
186 if (__predict_false(!t)) {
187 return 0;
188 }
189 addr = npc->npc_ips[(A & SRC_FLAG_BIT) ? NPF_SRC : NPF_DST];
190 return npf_table_lookup(t, npc->npc_alen, addr) == 0;
191 }
192