Line data Source code
1 : /* SPDX-License-Identifier: GPL-2.0-only */
2 : /*
3 : * Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
4 : */
5 :
6 : #include "bpfilter/cgen/matcher/meta.h"
7 :
8 : #include <linux/bpf.h>
9 : #include <linux/bpf_common.h>
10 : #include <linux/in.h> // NOLINT
11 : #include <linux/tcp.h>
12 : #include <linux/udp.h>
13 :
14 : #include <endian.h>
15 : #include <errno.h>
16 : #include <stddef.h>
17 : #include <stdint.h>
18 :
19 : #include "bpfilter/cgen/program.h"
20 : #include "bpfilter/cgen/swich.h"
21 : #include "core/logger.h"
22 : #include "core/matcher.h"
23 :
24 : #include "external/filter.h"
25 :
26 0 : static int _bf_matcher_generate_meta_ifindex(struct bf_program *program,
27 : const struct bf_matcher *matcher)
28 : {
29 0 : EMIT(program,
30 : BPF_LDX_MEM(BPF_H, BPF_REG_1, BPF_REG_10, BF_PROG_CTX_OFF(ifindex)));
31 0 : EMIT_FIXUP_JMP_NEXT_RULE(
32 : program,
33 : BPF_JMP_IMM(BPF_JNE, BPF_REG_1, *(uint32_t *)&matcher->payload, 0));
34 :
35 0 : return 0;
36 : }
37 :
38 0 : static int _bf_matcher_generate_meta_l3_proto(struct bf_program *program,
39 : const struct bf_matcher *matcher)
40 : {
41 0 : EMIT_FIXUP_JMP_NEXT_RULE(
42 : program, BPF_JMP_IMM(BPF_JNE, BPF_REG_7,
43 : htobe16(*(uint16_t *)&matcher->payload), 0));
44 :
45 0 : return 0;
46 : }
47 :
48 0 : static int _bf_matcher_generate_meta_l4_proto(struct bf_program *program,
49 : const struct bf_matcher *matcher)
50 : {
51 0 : EMIT_FIXUP_JMP_NEXT_RULE(
52 : program,
53 : BPF_JMP_IMM(BPF_JNE, BPF_REG_8, *(uint8_t *)&matcher->payload, 0));
54 :
55 0 : return 0;
56 : }
57 :
58 0 : static int _bf_matcher_generate_meta_port(struct bf_program *program,
59 : const struct bf_matcher *matcher)
60 : {
61 0 : _clean_bf_swich_ struct bf_swich swich;
62 : uint16_t *port = (uint16_t *)&matcher->payload;
63 : int r;
64 :
65 : // Load L4 header address into r6
66 0 : EMIT(program,
67 : BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_10, BF_PROG_CTX_OFF(l4_hdr)));
68 :
69 : // Get the packet's port into r1
70 0 : swich = bf_swich_get(program, BPF_REG_8);
71 0 : EMIT_SWICH_OPTION(&swich, IPPROTO_TCP,
72 : BPF_LDX_MEM(BPF_H, BPF_REG_1, BPF_REG_6,
73 : matcher->type == BF_MATCHER_META_SPORT ?
74 : offsetof(struct tcphdr, source) :
75 : offsetof(struct tcphdr, dest)));
76 0 : EMIT_SWICH_OPTION(&swich, IPPROTO_UDP,
77 : BPF_LDX_MEM(BPF_H, BPF_REG_1, BPF_REG_6,
78 : matcher->type == BF_MATCHER_META_SPORT ?
79 : offsetof(struct udphdr, source) :
80 : offsetof(struct udphdr, dest)));
81 0 : EMIT_SWICH_DEFAULT(&swich, BPF_MOV64_IMM(BPF_REG_1, 0));
82 :
83 0 : r = bf_swich_generate(&swich);
84 0 : if (r)
85 0 : return bf_err_r(r, "failed to generate swich for meta.(s|d)port");
86 :
87 : // If r1 == 0: no TCP nor UDP header found, jump to the next rule
88 0 : EMIT_FIXUP_JMP_NEXT_RULE(program, BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 0));
89 :
90 0 : switch (matcher->op) {
91 0 : case BF_MATCHER_EQ:
92 0 : EMIT_FIXUP_JMP_NEXT_RULE(
93 : program, BPF_JMP_IMM(BPF_JNE, BPF_REG_1, htobe16(*port), 0));
94 0 : break;
95 0 : case BF_MATCHER_NE:
96 0 : EMIT_FIXUP_JMP_NEXT_RULE(
97 : program, BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, htobe16(*port), 0));
98 0 : break;
99 0 : case BF_MATCHER_RANGE:
100 : /* Convert the big-endian value stored in the packet into a
101 : * little-endian value for x86 and arm before comparing it to the
102 : * reference value. This is a JLT/JGT comparison, we need to have the
103 : * MSB where the machine expects then. */
104 0 : EMIT(program, BPF_BSWAP(BPF_REG_1, 16));
105 0 : EMIT_FIXUP_JMP_NEXT_RULE(program,
106 : BPF_JMP_IMM(BPF_JLT, BPF_REG_1, port[0], 0));
107 0 : EMIT_FIXUP_JMP_NEXT_RULE(program,
108 : BPF_JMP_IMM(BPF_JGT, BPF_REG_1, port[1], 0));
109 0 : break;
110 0 : default:
111 0 : return bf_err_r(-EINVAL, "unknown matcher operator '%s' (%d)",
112 : bf_matcher_op_to_str(matcher->op), matcher->op);
113 : }
114 :
115 : return 0;
116 : }
117 :
118 0 : int bf_matcher_generate_meta(struct bf_program *program,
119 : const struct bf_matcher *matcher)
120 : {
121 : int r;
122 :
123 0 : switch (matcher->type) {
124 0 : case BF_MATCHER_META_IFINDEX:
125 0 : r = _bf_matcher_generate_meta_ifindex(program, matcher);
126 0 : break;
127 0 : case BF_MATCHER_META_L3_PROTO:
128 0 : r = _bf_matcher_generate_meta_l3_proto(program, matcher);
129 0 : break;
130 0 : case BF_MATCHER_META_L4_PROTO:
131 0 : r = _bf_matcher_generate_meta_l4_proto(program, matcher);
132 0 : break;
133 0 : case BF_MATCHER_META_SPORT:
134 : case BF_MATCHER_META_DPORT:
135 0 : r = _bf_matcher_generate_meta_port(program, matcher);
136 0 : break;
137 0 : default:
138 0 : return bf_err_r(-EINVAL, "unknown matcher type %d", matcher->type);
139 : };
140 :
141 : if (r)
142 : return r;
143 :
144 : return 0;
145 : }
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