Line data Source code
1 : /* SPDX-License-Identifier: GPL-2.0-only */
2 : /*
3 : * Copyright (c) 2023 Meta Platforms, Inc. and affiliates.
4 : */
5 :
6 : #include "bpfilter/cgen/stub.h"
7 :
8 : #include <linux/bpf.h>
9 : #include <linux/bpf_common.h>
10 : #include <linux/icmp.h>
11 : #include <linux/icmpv6.h>
12 : #include <linux/if_ether.h>
13 : #include <linux/in.h> // NOLINT
14 : #include <linux/in6.h>
15 : #include <linux/ip.h>
16 : #include <linux/ipv6.h>
17 : #include <linux/tcp.h>
18 : #include <linux/udp.h>
19 :
20 : #include <endian.h>
21 : #include <stddef.h>
22 :
23 : #include "bpfilter/cgen/elfstub.h"
24 : #include "bpfilter/cgen/jmp.h"
25 : #include "bpfilter/cgen/printer.h"
26 : #include "bpfilter/cgen/program.h"
27 : #include "bpfilter/cgen/swich.h"
28 : #include "bpfilter/opts.h"
29 : #include "core/flavor.h"
30 : #include "core/helper.h"
31 : #include "core/matcher.h"
32 : #include "core/verdict.h"
33 :
34 : #include "external/filter.h"
35 :
36 : #define _BF_LOW_EH_BITMASK 0x1801800000000801ULL
37 :
38 : /**
39 : * Generate stub to create a dynptr.
40 : *
41 : * @param program Program to generate the stub for. Must not be NULL.
42 : * @param arg_reg Register where the first argument to the dynptr creation
43 : * function is located (SKB or xdp_md structure).
44 : * @param kfunc Name of the kfunc to use to create the dynamic pointer.
45 : * @return 0 on success, or negative errno value on error.
46 : */
47 0 : static int _bf_stub_make_ctx_dynptr(struct bf_program *program, int arg_reg,
48 : const char *kfunc)
49 : {
50 0 : bf_assert(program && kfunc);
51 :
52 : // Call bpf_dynptr_from_xxx()
53 0 : if (arg_reg != BPF_REG_1)
54 0 : EMIT(program, BPF_MOV64_IMM(BPF_REG_1, arg_reg));
55 0 : EMIT(program, BPF_MOV64_IMM(BPF_REG_2, 0));
56 0 : EMIT(program, BPF_MOV64_REG(BPF_REG_3, BPF_REG_10));
57 0 : EMIT(program, BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, BF_PROG_CTX_OFF(dynptr)));
58 0 : EMIT_KFUNC_CALL(program, kfunc);
59 :
60 : // If the function call failed, quit the program
61 : {
62 0 : _clean_bf_jmpctx_ struct bf_jmpctx _ =
63 0 : bf_jmpctx_get(program, BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 0));
64 :
65 : // Update the error counter
66 0 : EMIT(program, BPF_MOV64_REG(BPF_REG_1, BPF_REG_10));
67 0 : EMIT(program, BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, BF_PROG_CTX_OFF(arg)));
68 0 : EMIT_LOAD_COUNTERS_FD_FIXUP(program, BPF_REG_2);
69 0 : EMIT(program,
70 : BPF_MOV32_IMM(BPF_REG_3, bf_program_error_counter_idx(program)));
71 0 : EMIT_FIXUP_ELFSTUB(program, BF_ELFSTUB_UPDATE_COUNTERS);
72 :
73 0 : if (bf_opts_is_verbose(BF_VERBOSE_BPF))
74 0 : EMIT_PRINT(program, "failed to create a new dynamic pointer");
75 :
76 0 : EMIT(program,
77 : BPF_MOV64_IMM(BPF_REG_0, program->runtime.ops->get_verdict(
78 : BF_VERDICT_ACCEPT)));
79 0 : EMIT(program, BPF_EXIT_INSN());
80 : }
81 :
82 0 : return 0;
83 : }
84 :
85 0 : int bf_stub_make_ctx_xdp_dynptr(struct bf_program *program, int md_reg)
86 : {
87 0 : bf_assert(program);
88 :
89 0 : return _bf_stub_make_ctx_dynptr(program, md_reg, "bpf_dynptr_from_xdp");
90 : }
91 :
92 0 : int bf_stub_make_ctx_skb_dynptr(struct bf_program *program, int skb_reg)
93 : {
94 0 : bf_assert(program);
95 :
96 0 : return _bf_stub_make_ctx_dynptr(program, skb_reg, "bpf_dynptr_from_skb");
97 : }
98 :
99 0 : int bf_stub_parse_l2_ethhdr(struct bf_program *program)
100 : {
101 0 : bf_assert(program);
102 :
103 : // Call bpf_dynptr_slice()
104 0 : EMIT(program, BPF_MOV64_REG(BPF_REG_1, BPF_REG_10));
105 0 : EMIT(program, BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, BF_PROG_CTX_OFF(dynptr)));
106 0 : EMIT(program, BPF_MOV64_IMM(BPF_REG_2, 0));
107 0 : EMIT(program, BPF_MOV64_REG(BPF_REG_3, BPF_REG_10));
108 0 : EMIT(program, BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, BF_PROG_CTX_OFF(l2)));
109 0 : EMIT(program, BPF_MOV64_IMM(BPF_REG_4, sizeof(struct ethhdr)));
110 :
111 0 : EMIT(program,
112 : BPF_STX_MEM(BPF_B, BPF_REG_10, BPF_REG_4, BF_PROG_CTX_OFF(l2_size)));
113 :
114 0 : EMIT_KFUNC_CALL(program, "bpf_dynptr_slice");
115 :
116 : // If the function call failed, quit the program
117 : {
118 0 : _clean_bf_jmpctx_ struct bf_jmpctx _ =
119 0 : bf_jmpctx_get(program, BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 0));
120 :
121 : // Update the error counter
122 0 : EMIT(program, BPF_MOV64_REG(BPF_REG_1, BPF_REG_10));
123 0 : EMIT(program, BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, BF_PROG_CTX_OFF(arg)));
124 0 : EMIT_LOAD_COUNTERS_FD_FIXUP(program, BPF_REG_2);
125 0 : EMIT(program,
126 : BPF_MOV32_IMM(BPF_REG_3, bf_program_error_counter_idx(program)));
127 0 : EMIT_FIXUP_ELFSTUB(program, BF_ELFSTUB_UPDATE_COUNTERS);
128 :
129 0 : if (bf_opts_is_verbose(BF_VERBOSE_BPF))
130 0 : EMIT_PRINT(program, "failed to create L2 dynamic pointer slice");
131 :
132 0 : EMIT(program,
133 : BPF_MOV64_IMM(BPF_REG_0, program->runtime.ops->get_verdict(
134 : BF_VERDICT_ACCEPT)));
135 0 : EMIT(program, BPF_EXIT_INSN());
136 : }
137 :
138 : // Store the L2 header address into the runtime context
139 0 : EMIT(program,
140 : BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0, BF_PROG_CTX_OFF(l2_hdr)));
141 :
142 : // Store the L3 protocol ID in r7
143 0 : EMIT(program, BPF_LDX_MEM(BPF_H, BPF_REG_7, BPF_REG_0,
144 : offsetof(struct ethhdr, h_proto)));
145 :
146 : // Set bf_runtime.l3_offset
147 0 : EMIT(program, BPF_ST_MEM(BPF_W, BPF_REG_10, BF_PROG_CTX_OFF(l3_offset),
148 : sizeof(struct ethhdr)));
149 :
150 0 : return 0;
151 : }
152 :
153 0 : int bf_stub_parse_l3_hdr(struct bf_program *program)
154 : {
155 0 : _clean_bf_jmpctx_ struct bf_jmpctx _ = bf_jmpctx_default();
156 : int r;
157 :
158 0 : bf_assert(program);
159 :
160 : /* Store the size of the L3 protocol header in r4, depending on the protocol
161 : * ID stored in r7. If the protocol is not supported, we store 0 into r7
162 : * and we skip the instructions below. */
163 : {
164 0 : _clean_bf_swich_ struct bf_swich swich =
165 0 : bf_swich_get(program, BPF_REG_7);
166 :
167 0 : EMIT_SWICH_OPTION(&swich, htobe16(ETH_P_IP),
168 : BPF_MOV64_IMM(BPF_REG_4, sizeof(struct iphdr)));
169 0 : EMIT_SWICH_OPTION(&swich, htobe16(ETH_P_IPV6),
170 : BPF_MOV64_IMM(BPF_REG_4, sizeof(struct ipv6hdr)));
171 0 : EMIT_SWICH_DEFAULT(&swich, BPF_MOV64_IMM(BPF_REG_7, 0));
172 :
173 0 : r = bf_swich_generate(&swich);
174 0 : if (r)
175 : return r;
176 : }
177 0 : _ = bf_jmpctx_get(program, BPF_JMP_IMM(BPF_JEQ, BPF_REG_7, 0, 0));
178 :
179 0 : EMIT(program,
180 : BPF_STX_MEM(BPF_B, BPF_REG_10, BPF_REG_4, BF_PROG_CTX_OFF(l3_size)));
181 :
182 : // Call bpf_dynptr_slice()
183 0 : EMIT(program, BPF_MOV64_REG(BPF_REG_1, BPF_REG_10));
184 0 : EMIT(program, BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, BF_PROG_CTX_OFF(dynptr)));
185 0 : EMIT(program,
186 : BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_10, BF_PROG_CTX_OFF(l3_offset)));
187 0 : EMIT(program, BPF_MOV64_REG(BPF_REG_3, BPF_REG_10));
188 0 : EMIT(program, BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, BF_PROG_CTX_OFF(l2)));
189 0 : EMIT_KFUNC_CALL(program, "bpf_dynptr_slice");
190 :
191 : // If the function call failed, quit the program
192 : {
193 0 : _clean_bf_jmpctx_ struct bf_jmpctx _ =
194 0 : bf_jmpctx_get(program, BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 0));
195 :
196 0 : EMIT(program, BPF_MOV64_REG(BPF_REG_1, BPF_REG_10));
197 0 : EMIT(program, BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, BF_PROG_CTX_OFF(arg)));
198 0 : EMIT_LOAD_COUNTERS_FD_FIXUP(program, BPF_REG_2);
199 0 : EMIT(program,
200 : BPF_MOV32_IMM(BPF_REG_3, bf_program_error_counter_idx(program)));
201 0 : EMIT_FIXUP_ELFSTUB(program, BF_ELFSTUB_UPDATE_COUNTERS);
202 :
203 0 : if (bf_opts_is_verbose(BF_VERBOSE_BPF))
204 0 : EMIT_PRINT(program, "failed to create L3 dynamic pointer slice");
205 :
206 0 : EMIT(program,
207 : BPF_MOV64_IMM(BPF_REG_0, program->runtime.ops->get_verdict(
208 : BF_VERDICT_ACCEPT)));
209 0 : EMIT(program, BPF_EXIT_INSN());
210 : }
211 :
212 : // Store the L3 header address into the runtime context
213 0 : EMIT(program,
214 : BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0, BF_PROG_CTX_OFF(l3_hdr)));
215 :
216 : /* Unsupported L3 protocols have been filtered out at the beginning of this
217 : * function and would jump over the block below, so there is no need to
218 : * worry about them here. */
219 : {
220 : // IPv4
221 0 : _clean_bf_jmpctx_ struct bf_jmpctx _ = bf_jmpctx_get(
222 : program, BPF_JMP_IMM(BPF_JNE, BPF_REG_7, htobe16(ETH_P_IP), 0));
223 :
224 0 : EMIT(program, BPF_LDX_MEM(BPF_B, BPF_REG_1, BPF_REG_0, 0));
225 0 : EMIT(program, BPF_ALU64_IMM(BPF_AND, BPF_REG_1, 0x0f));
226 0 : EMIT(program, BPF_ALU64_IMM(BPF_LSH, BPF_REG_1, 2));
227 0 : EMIT(program, BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_10,
228 : BF_PROG_CTX_OFF(l3_offset)));
229 0 : EMIT(program, BPF_ALU64_REG(BPF_ADD, BPF_REG_1, BPF_REG_2));
230 0 : EMIT(program, BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_1,
231 : BF_PROG_CTX_OFF(l4_offset)));
232 0 : EMIT(program, BPF_LDX_MEM(BPF_B, BPF_REG_8, BPF_REG_0,
233 : offsetof(struct iphdr, protocol)));
234 : }
235 :
236 : {
237 : // IPv6
238 : struct bf_jmpctx tcpjmp, udpjmp, noehjmp, ehjmp;
239 0 : struct bpf_insn ld64[2] = {BPF_LD_IMM64(BPF_REG_2, _BF_LOW_EH_BITMASK)};
240 0 : _clean_bf_jmpctx_ struct bf_jmpctx _ = bf_jmpctx_get(
241 : program, BPF_JMP_IMM(BPF_JNE, BPF_REG_7, htobe16(ETH_P_IPV6), 0));
242 :
243 0 : EMIT(program, BPF_LDX_MEM(BPF_B, BPF_REG_8, BPF_REG_0,
244 : offsetof(struct ipv6hdr, nexthdr)));
245 :
246 : /* Fast path for TCP and UDP: quickly recognize the most used protocol
247 : * to process them as fast as possible. */
248 0 : tcpjmp = bf_jmpctx_get(program,
249 : BPF_JMP_IMM(BPF_JEQ, BPF_REG_8, IPPROTO_TCP, 0));
250 0 : udpjmp = bf_jmpctx_get(program,
251 : BPF_JMP_IMM(BPF_JEQ, BPF_REG_8, IPPROTO_UDP, 0));
252 :
253 : /* For all the EH protocol numbers <64, use a bitmask:
254 : * mask = (1<<0) | (1<<43) | (1<<44) | (1<<50) | (1<<51) | (1<<60)
255 : *
256 : * Pseudo-code:
257 : * - r3 = 1 << r8 (nexthdr)
258 : * - r3 = r3 & mask
259 : * - if r3 != 0: go to slow path (EH present) */
260 0 : EMIT(program, ld64[0]);
261 0 : EMIT(program, ld64[1]);
262 0 : EMIT(program, BPF_JMP_IMM(BPF_JGE, BPF_REG_8, 64, 4));
263 0 : EMIT(program, BPF_MOV64_IMM(BPF_REG_3, 1));
264 0 : EMIT(program, BPF_ALU64_REG(BPF_LSH, BPF_REG_3, BPF_REG_8));
265 0 : EMIT(program, BPF_ALU64_REG(BPF_AND, BPF_REG_3, BPF_REG_2));
266 0 : EMIT(program, BPF_JMP_IMM(BPF_JNE, BPF_REG_3, 0, 4));
267 :
268 : // EH with protocol numbers >64 are processed individually
269 0 : EMIT(program, BPF_JMP_IMM(BPF_JEQ, BPF_REG_8, 135, 3));
270 0 : EMIT(program, BPF_JMP_IMM(BPF_JEQ, BPF_REG_8, 139, 2));
271 0 : EMIT(program, BPF_JMP_IMM(BPF_JEQ, BPF_REG_8, 140, 1));
272 :
273 : // If no EH matched, nexthdr is L4, skip EH processing
274 0 : noehjmp = bf_jmpctx_get(program, BPF_JMP_A(0));
275 :
276 : // Process EH
277 0 : EMIT(program, BPF_MOV64_REG(BPF_REG_1, BPF_REG_10));
278 0 : EMIT(program, BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, BF_PROG_CTX_OFF(arg)));
279 : // If any rule filters on ipv6.nexthdr, store the EH in the runtime context
280 : // during process, so we won't have to process the EH again.
281 0 : if (program->runtime.chain->flags & BF_FLAG(BF_CHAIN_STORE_NEXTHDR))
282 0 : EMIT_FIXUP_ELFSTUB(program, BF_ELFSTUB_PARSE_IPV6_NH);
283 : else
284 0 : EMIT_FIXUP_ELFSTUB(program, BF_ELFSTUB_PARSE_IPV6_EH);
285 0 : EMIT(program, BPF_MOV64_REG(BPF_REG_8, BPF_REG_0));
286 :
287 0 : ehjmp = bf_jmpctx_get(program, BPF_JMP_A(0));
288 :
289 : // If no EH found, all the jmp will end up here
290 0 : bf_jmpctx_cleanup(&tcpjmp);
291 0 : bf_jmpctx_cleanup(&udpjmp);
292 0 : bf_jmpctx_cleanup(&noehjmp);
293 :
294 : // Process IPv6 header, no EH (BPF_REG_8 already contains nexthdr)
295 0 : EMIT(program, BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_10,
296 : BF_PROG_CTX_OFF(l3_offset)));
297 0 : EMIT(program,
298 : BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, sizeof(struct ipv6hdr)));
299 0 : EMIT(program, BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_2,
300 : BF_PROG_CTX_OFF(l4_offset)));
301 :
302 0 : bf_jmpctx_cleanup(&ehjmp);
303 : }
304 :
305 0 : return 0;
306 : }
307 :
308 0 : int bf_stub_parse_l4_hdr(struct bf_program *program)
309 : {
310 0 : _clean_bf_jmpctx_ struct bf_jmpctx _ = bf_jmpctx_default();
311 : int r;
312 :
313 0 : bf_assert(program);
314 :
315 : /* Parse the L4 protocol and handle unuspported protocol, similarly to
316 : * bf_stub_parse_l3_hdr() above. */
317 : {
318 0 : _clean_bf_swich_ struct bf_swich swich =
319 0 : bf_swich_get(program, BPF_REG_8);
320 :
321 0 : EMIT_SWICH_OPTION(&swich, IPPROTO_TCP,
322 : BPF_MOV64_IMM(BPF_REG_4, sizeof(struct tcphdr)));
323 0 : EMIT_SWICH_OPTION(&swich, IPPROTO_UDP,
324 : BPF_MOV64_IMM(BPF_REG_4, sizeof(struct udphdr)));
325 0 : EMIT_SWICH_OPTION(&swich, IPPROTO_ICMP,
326 : BPF_MOV64_IMM(BPF_REG_4, sizeof(struct icmphdr)));
327 0 : EMIT_SWICH_OPTION(&swich, IPPROTO_ICMPV6,
328 : BPF_MOV64_IMM(BPF_REG_4, sizeof(struct icmp6hdr)));
329 0 : EMIT_SWICH_DEFAULT(&swich, BPF_MOV64_IMM(BPF_REG_8, 0));
330 :
331 0 : r = bf_swich_generate(&swich);
332 0 : if (r)
333 : return r;
334 : }
335 0 : _ = bf_jmpctx_get(program, BPF_JMP_IMM(BPF_JEQ, BPF_REG_8, 0, 0));
336 :
337 0 : EMIT(program,
338 : BPF_STX_MEM(BPF_B, BPF_REG_10, BPF_REG_4, BF_PROG_CTX_OFF(l4_size)));
339 :
340 : // Call bpf_dynptr_slice()
341 0 : EMIT(program, BPF_MOV64_REG(BPF_REG_1, BPF_REG_10));
342 0 : EMIT(program, BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, BF_PROG_CTX_OFF(dynptr)));
343 0 : EMIT(program,
344 : BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_10, BF_PROG_CTX_OFF(l4_offset)));
345 0 : EMIT(program, BPF_MOV64_REG(BPF_REG_3, BPF_REG_10));
346 0 : EMIT(program, BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, BF_PROG_CTX_OFF(l4)));
347 0 : EMIT_KFUNC_CALL(program, "bpf_dynptr_slice");
348 :
349 : // If the function call failed, quit the program
350 : {
351 0 : _clean_bf_jmpctx_ struct bf_jmpctx _ =
352 0 : bf_jmpctx_get(program, BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 0));
353 :
354 0 : EMIT(program, BPF_MOV64_REG(BPF_REG_1, BPF_REG_10));
355 0 : EMIT(program, BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, BF_PROG_CTX_OFF(arg)));
356 0 : EMIT_LOAD_COUNTERS_FD_FIXUP(program, BPF_REG_2);
357 0 : EMIT(program,
358 : BPF_MOV32_IMM(BPF_REG_3, bf_program_error_counter_idx(program)));
359 0 : EMIT_FIXUP_ELFSTUB(program, BF_ELFSTUB_UPDATE_COUNTERS);
360 :
361 0 : if (bf_opts_is_verbose(BF_VERBOSE_BPF))
362 0 : EMIT_PRINT(program, "failed to create L4 dynamic pointer slice");
363 :
364 0 : EMIT(program,
365 : BPF_MOV64_IMM(BPF_REG_0, program->runtime.ops->get_verdict(
366 : BF_VERDICT_ACCEPT)));
367 0 : EMIT(program, BPF_EXIT_INSN());
368 : }
369 :
370 : // Store the L4 header address into the runtime context
371 0 : EMIT(program,
372 : BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0, BF_PROG_CTX_OFF(l4_hdr)));
373 :
374 0 : return 0;
375 : }
376 :
377 0 : int bf_stub_rule_check_protocol(struct bf_program *program,
378 : const struct bf_matcher_meta *meta)
379 : {
380 0 : bf_assert(program && meta);
381 :
382 0 : switch (meta->layer) {
383 0 : case BF_MATCHER_LAYER_3:
384 0 : EMIT_FIXUP_JMP_NEXT_RULE(
385 : program, BPF_JMP_IMM(BPF_JNE, BPF_REG_7,
386 : htobe16((uint16_t)meta->hdr_id), 0));
387 0 : break;
388 0 : case BF_MATCHER_LAYER_4:
389 0 : EMIT_FIXUP_JMP_NEXT_RULE(
390 : program, BPF_JMP_IMM(BPF_JNE, BPF_REG_8, (uint8_t)meta->hdr_id, 0));
391 0 : break;
392 0 : default:
393 0 : return bf_err_r(-EINVAL, "rule can't check for layer ID %d",
394 : meta->layer);
395 : }
396 :
397 : return 0;
398 : }
399 :
400 0 : int bf_stub_load_header(struct bf_program *program,
401 : const struct bf_matcher_meta *meta, int reg)
402 : {
403 0 : bf_assert(program && meta);
404 :
405 0 : switch (meta->layer) {
406 0 : case BF_MATCHER_LAYER_3:
407 0 : EMIT(program,
408 : BPF_LDX_MEM(BPF_DW, reg, BPF_REG_10, BF_PROG_CTX_OFF(l3_hdr)));
409 0 : break;
410 0 : case BF_MATCHER_LAYER_4:
411 0 : EMIT(program,
412 : BPF_LDX_MEM(BPF_DW, reg, BPF_REG_10, BF_PROG_CTX_OFF(l4_hdr)));
413 0 : break;
414 0 : default:
415 0 : return bf_err_r(-EINVAL,
416 : "layer ID %d is not a valid layer to load header for",
417 : meta->layer);
418 : }
419 :
420 : return 0;
421 : }
422 :
423 0 : int bf_stub_stx_payload(struct bf_program *program,
424 : const struct bf_matcher_meta *meta, size_t offset)
425 : {
426 0 : bf_assert(program && meta);
427 :
428 0 : size_t remaining_size = meta->hdr_payload_size;
429 : size_t src_offset = 0;
430 : size_t dst_offset = offset;
431 :
432 0 : while (remaining_size) {
433 : int bpf_size = BPF_B;
434 : size_t copy_bytes = 1;
435 :
436 0 : if (BF_ALIGNED_64(offset) && remaining_size >= 8) {
437 : bpf_size = BPF_DW;
438 : copy_bytes = 8;
439 0 : } else if (BF_ALIGNED_32(offset) && remaining_size >= 4) {
440 : bpf_size = BPF_W;
441 : copy_bytes = 4;
442 0 : } else if (BF_ALIGNED_16(offset) && remaining_size >= 2) {
443 : bpf_size = BPF_H;
444 : copy_bytes = 2;
445 : }
446 :
447 0 : EMIT(program, BPF_LDX_MEM(bpf_size, BPF_REG_1, BPF_REG_6,
448 : meta->hdr_payload_offset + src_offset));
449 0 : EMIT(program, BPF_STX_MEM(bpf_size, BPF_REG_10, BPF_REG_1,
450 : BF_PROG_SCR_OFF(dst_offset)));
451 :
452 0 : remaining_size -= copy_bytes;
453 0 : src_offset += copy_bytes;
454 0 : dst_offset += copy_bytes;
455 : }
456 :
457 : return 0;
458 : }
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