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1 /*
2  * Copyright (C) 2016-2018 Netronome Systems, Inc.
3  *
4  * This software is dual licensed under the GNU General License Version 2,
5  * June 1991 as shown in the file COPYING in the top-level directory of this
6  * source tree or the BSD 2-Clause License provided below.  You have the
7  * option to license this software under the complete terms of either license.
8  *
9  * The BSD 2-Clause License:
10  *
11  *     Redistribution and use in source and binary forms, with or
12  *     without modification, are permitted provided that the following
13  *     conditions are met:
14  *
15  *      1. Redistributions of source code must retain the above
16  *         copyright notice, this list of conditions and the following
17  *         disclaimer.
18  *
19  *      2. Redistributions in binary form must reproduce the above
20  *         copyright notice, this list of conditions and the following
21  *         disclaimer in the documentation and/or other materials
22  *         provided with the distribution.
23  *
24  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
25  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
26  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
27  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
28  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
29  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
30  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
31  * SOFTWARE.
32  */
33 
34 #include <linux/bpf.h>
35 #include <linux/bpf_verifier.h>
36 #include <linux/kernel.h>
37 #include <linux/pkt_cls.h>
38 
39 #include "../nfp_app.h"
40 #include "../nfp_main.h"
41 #include "fw.h"
42 #include "main.h"
43 
44 #define pr_vlog(env, fmt, ...)	\
45 	bpf_verifier_log_write(env, "[nfp] " fmt, ##__VA_ARGS__)
46 
47 struct nfp_insn_meta *
nfp_bpf_goto_meta(struct nfp_prog * nfp_prog,struct nfp_insn_meta * meta,unsigned int insn_idx,unsigned int n_insns)48 nfp_bpf_goto_meta(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
49 		  unsigned int insn_idx, unsigned int n_insns)
50 {
51 	unsigned int forward, backward, i;
52 
53 	backward = meta->n - insn_idx;
54 	forward = insn_idx - meta->n;
55 
56 	if (min(forward, backward) > n_insns - insn_idx - 1) {
57 		backward = n_insns - insn_idx - 1;
58 		meta = nfp_prog_last_meta(nfp_prog);
59 	}
60 	if (min(forward, backward) > insn_idx && backward > insn_idx) {
61 		forward = insn_idx;
62 		meta = nfp_prog_first_meta(nfp_prog);
63 	}
64 
65 	if (forward < backward)
66 		for (i = 0; i < forward; i++)
67 			meta = nfp_meta_next(meta);
68 	else
69 		for (i = 0; i < backward; i++)
70 			meta = nfp_meta_prev(meta);
71 
72 	return meta;
73 }
74 
75 static void
nfp_record_adjust_head(struct nfp_app_bpf * bpf,struct nfp_prog * nfp_prog,struct nfp_insn_meta * meta,const struct bpf_reg_state * reg2)76 nfp_record_adjust_head(struct nfp_app_bpf *bpf, struct nfp_prog *nfp_prog,
77 		       struct nfp_insn_meta *meta,
78 		       const struct bpf_reg_state *reg2)
79 {
80 	unsigned int location =	UINT_MAX;
81 	int imm;
82 
83 	/* Datapath usually can give us guarantees on how much adjust head
84 	 * can be done without the need for any checks.  Optimize the simple
85 	 * case where there is only one adjust head by a constant.
86 	 */
87 	if (reg2->type != SCALAR_VALUE || !tnum_is_const(reg2->var_off))
88 		goto exit_set_location;
89 	imm = reg2->var_off.value;
90 	/* Translator will skip all checks, we need to guarantee min pkt len */
91 	if (imm > ETH_ZLEN - ETH_HLEN)
92 		goto exit_set_location;
93 	if (imm > (int)bpf->adjust_head.guaranteed_add ||
94 	    imm < -bpf->adjust_head.guaranteed_sub)
95 		goto exit_set_location;
96 
97 	if (nfp_prog->adjust_head_location) {
98 		/* Only one call per program allowed */
99 		if (nfp_prog->adjust_head_location != meta->n)
100 			goto exit_set_location;
101 
102 		if (meta->arg2.reg.var_off.value != imm)
103 			goto exit_set_location;
104 	}
105 
106 	location = meta->n;
107 exit_set_location:
108 	nfp_prog->adjust_head_location = location;
109 }
110 
nfp_bpf_map_update_value_ok(struct bpf_verifier_env * env)111 static bool nfp_bpf_map_update_value_ok(struct bpf_verifier_env *env)
112 {
113 	const struct bpf_reg_state *reg1 = cur_regs(env) + BPF_REG_1;
114 	const struct bpf_reg_state *reg3 = cur_regs(env) + BPF_REG_3;
115 	struct bpf_offloaded_map *offmap;
116 	struct bpf_func_state *state;
117 	struct nfp_bpf_map *nfp_map;
118 	int off, i;
119 
120 	state = env->cur_state->frame[reg3->frameno];
121 
122 	/* We need to record each time update happens with non-zero words,
123 	 * in case such word is used in atomic operations.
124 	 * Implicitly depend on nfp_bpf_stack_arg_ok(reg3) being run before.
125 	 */
126 
127 	offmap = map_to_offmap(reg1->map_ptr);
128 	nfp_map = offmap->dev_priv;
129 	off = reg3->off + reg3->var_off.value;
130 
131 	for (i = 0; i < offmap->map.value_size; i++) {
132 		struct bpf_stack_state *stack_entry;
133 		unsigned int soff;
134 
135 		soff = -(off + i) - 1;
136 		stack_entry = &state->stack[soff / BPF_REG_SIZE];
137 		if (stack_entry->slot_type[soff % BPF_REG_SIZE] == STACK_ZERO)
138 			continue;
139 
140 		if (nfp_map->use_map[i / 4].type == NFP_MAP_USE_ATOMIC_CNT) {
141 			pr_vlog(env, "value at offset %d/%d may be non-zero, bpf_map_update_elem() is required to initialize atomic counters to zero to avoid offload endian issues\n",
142 				i, soff);
143 			return false;
144 		}
145 		nfp_map->use_map[i / 4].non_zero_update = 1;
146 	}
147 
148 	return true;
149 }
150 
151 static int
nfp_bpf_stack_arg_ok(const char * fname,struct bpf_verifier_env * env,const struct bpf_reg_state * reg,struct nfp_bpf_reg_state * old_arg)152 nfp_bpf_stack_arg_ok(const char *fname, struct bpf_verifier_env *env,
153 		     const struct bpf_reg_state *reg,
154 		     struct nfp_bpf_reg_state *old_arg)
155 {
156 	s64 off, old_off;
157 
158 	if (reg->type != PTR_TO_STACK) {
159 		pr_vlog(env, "%s: unsupported ptr type %d\n",
160 			fname, reg->type);
161 		return false;
162 	}
163 	if (!tnum_is_const(reg->var_off)) {
164 		pr_vlog(env, "%s: variable pointer\n", fname);
165 		return false;
166 	}
167 
168 	off = reg->var_off.value + reg->off;
169 	if (-off % 4) {
170 		pr_vlog(env, "%s: unaligned stack pointer %lld\n", fname, -off);
171 		return false;
172 	}
173 
174 	/* Rest of the checks is only if we re-parse the same insn */
175 	if (!old_arg)
176 		return true;
177 
178 	old_off = old_arg->reg.var_off.value + old_arg->reg.off;
179 	old_arg->var_off |= off != old_off;
180 
181 	return true;
182 }
183 
184 static bool
nfp_bpf_map_call_ok(const char * fname,struct bpf_verifier_env * env,struct nfp_insn_meta * meta,u32 helper_tgt,const struct bpf_reg_state * reg1)185 nfp_bpf_map_call_ok(const char *fname, struct bpf_verifier_env *env,
186 		    struct nfp_insn_meta *meta,
187 		    u32 helper_tgt, const struct bpf_reg_state *reg1)
188 {
189 	if (!helper_tgt) {
190 		pr_vlog(env, "%s: not supported by FW\n", fname);
191 		return false;
192 	}
193 
194 	return true;
195 }
196 
197 static int
nfp_bpf_check_call(struct nfp_prog * nfp_prog,struct bpf_verifier_env * env,struct nfp_insn_meta * meta)198 nfp_bpf_check_call(struct nfp_prog *nfp_prog, struct bpf_verifier_env *env,
199 		   struct nfp_insn_meta *meta)
200 {
201 	const struct bpf_reg_state *reg1 = cur_regs(env) + BPF_REG_1;
202 	const struct bpf_reg_state *reg2 = cur_regs(env) + BPF_REG_2;
203 	const struct bpf_reg_state *reg3 = cur_regs(env) + BPF_REG_3;
204 	struct nfp_app_bpf *bpf = nfp_prog->bpf;
205 	u32 func_id = meta->insn.imm;
206 
207 	switch (func_id) {
208 	case BPF_FUNC_xdp_adjust_head:
209 		if (!bpf->adjust_head.off_max) {
210 			pr_vlog(env, "adjust_head not supported by FW\n");
211 			return -EOPNOTSUPP;
212 		}
213 		if (!(bpf->adjust_head.flags & NFP_BPF_ADJUST_HEAD_NO_META)) {
214 			pr_vlog(env, "adjust_head: FW requires shifting metadata, not supported by the driver\n");
215 			return -EOPNOTSUPP;
216 		}
217 
218 		nfp_record_adjust_head(bpf, nfp_prog, meta, reg2);
219 		break;
220 
221 	case BPF_FUNC_xdp_adjust_tail:
222 		if (!bpf->adjust_tail) {
223 			pr_vlog(env, "adjust_tail not supported by FW\n");
224 			return -EOPNOTSUPP;
225 		}
226 		break;
227 
228 	case BPF_FUNC_map_lookup_elem:
229 		if (!nfp_bpf_map_call_ok("map_lookup", env, meta,
230 					 bpf->helpers.map_lookup, reg1) ||
231 		    !nfp_bpf_stack_arg_ok("map_lookup", env, reg2,
232 					  meta->func_id ? &meta->arg2 : NULL))
233 			return -EOPNOTSUPP;
234 		break;
235 
236 	case BPF_FUNC_map_update_elem:
237 		if (!nfp_bpf_map_call_ok("map_update", env, meta,
238 					 bpf->helpers.map_update, reg1) ||
239 		    !nfp_bpf_stack_arg_ok("map_update", env, reg2,
240 					  meta->func_id ? &meta->arg2 : NULL) ||
241 		    !nfp_bpf_stack_arg_ok("map_update", env, reg3, NULL) ||
242 		    !nfp_bpf_map_update_value_ok(env))
243 			return -EOPNOTSUPP;
244 		break;
245 
246 	case BPF_FUNC_map_delete_elem:
247 		if (!nfp_bpf_map_call_ok("map_delete", env, meta,
248 					 bpf->helpers.map_delete, reg1) ||
249 		    !nfp_bpf_stack_arg_ok("map_delete", env, reg2,
250 					  meta->func_id ? &meta->arg2 : NULL))
251 			return -EOPNOTSUPP;
252 		break;
253 
254 	case BPF_FUNC_get_prandom_u32:
255 		if (bpf->pseudo_random)
256 			break;
257 		pr_vlog(env, "bpf_get_prandom_u32(): FW doesn't support random number generation\n");
258 		return -EOPNOTSUPP;
259 
260 	case BPF_FUNC_perf_event_output:
261 		BUILD_BUG_ON(NFP_BPF_SCALAR_VALUE != SCALAR_VALUE ||
262 			     NFP_BPF_MAP_VALUE != PTR_TO_MAP_VALUE ||
263 			     NFP_BPF_STACK != PTR_TO_STACK ||
264 			     NFP_BPF_PACKET_DATA != PTR_TO_PACKET);
265 
266 		if (!bpf->helpers.perf_event_output) {
267 			pr_vlog(env, "event_output: not supported by FW\n");
268 			return -EOPNOTSUPP;
269 		}
270 
271 		/* Force current CPU to make sure we can report the event
272 		 * wherever we get the control message from FW.
273 		 */
274 		if (reg3->var_off.mask & BPF_F_INDEX_MASK ||
275 		    (reg3->var_off.value & BPF_F_INDEX_MASK) !=
276 		    BPF_F_CURRENT_CPU) {
277 			char tn_buf[48];
278 
279 			tnum_strn(tn_buf, sizeof(tn_buf), reg3->var_off);
280 			pr_vlog(env, "event_output: must use BPF_F_CURRENT_CPU, var_off: %s\n",
281 				tn_buf);
282 			return -EOPNOTSUPP;
283 		}
284 
285 		/* Save space in meta, we don't care about arguments other
286 		 * than 4th meta, shove it into arg1.
287 		 */
288 		reg1 = cur_regs(env) + BPF_REG_4;
289 
290 		if (reg1->type != SCALAR_VALUE /* NULL ptr */ &&
291 		    reg1->type != PTR_TO_STACK &&
292 		    reg1->type != PTR_TO_MAP_VALUE &&
293 		    reg1->type != PTR_TO_PACKET) {
294 			pr_vlog(env, "event_output: unsupported ptr type: %d\n",
295 				reg1->type);
296 			return -EOPNOTSUPP;
297 		}
298 
299 		if (reg1->type == PTR_TO_STACK &&
300 		    !nfp_bpf_stack_arg_ok("event_output", env, reg1, NULL))
301 			return -EOPNOTSUPP;
302 
303 		/* Warn user that on offload NFP may return success even if map
304 		 * is not going to accept the event, since the event output is
305 		 * fully async and device won't know the state of the map.
306 		 * There is also FW limitation on the event length.
307 		 *
308 		 * Lost events will not show up on the perf ring, driver
309 		 * won't see them at all.  Events may also get reordered.
310 		 */
311 		dev_warn_once(&nfp_prog->bpf->app->pf->pdev->dev,
312 			      "bpf: note: return codes and behavior of bpf_event_output() helper differs for offloaded programs!\n");
313 		pr_vlog(env, "warning: return codes and behavior of event_output helper differ for offload!\n");
314 
315 		if (!meta->func_id)
316 			break;
317 
318 		if (reg1->type != meta->arg1.type) {
319 			pr_vlog(env, "event_output: ptr type changed: %d %d\n",
320 				meta->arg1.type, reg1->type);
321 			return -EINVAL;
322 		}
323 		break;
324 
325 	default:
326 		pr_vlog(env, "unsupported function id: %d\n", func_id);
327 		return -EOPNOTSUPP;
328 	}
329 
330 	meta->func_id = func_id;
331 	meta->arg1 = *reg1;
332 	meta->arg2.reg = *reg2;
333 
334 	return 0;
335 }
336 
337 static int
nfp_bpf_check_exit(struct nfp_prog * nfp_prog,struct bpf_verifier_env * env)338 nfp_bpf_check_exit(struct nfp_prog *nfp_prog,
339 		   struct bpf_verifier_env *env)
340 {
341 	const struct bpf_reg_state *reg0 = cur_regs(env) + BPF_REG_0;
342 	u64 imm;
343 
344 	if (nfp_prog->type == BPF_PROG_TYPE_XDP)
345 		return 0;
346 
347 	if (!(reg0->type == SCALAR_VALUE && tnum_is_const(reg0->var_off))) {
348 		char tn_buf[48];
349 
350 		tnum_strn(tn_buf, sizeof(tn_buf), reg0->var_off);
351 		pr_vlog(env, "unsupported exit state: %d, var_off: %s\n",
352 			reg0->type, tn_buf);
353 		return -EINVAL;
354 	}
355 
356 	imm = reg0->var_off.value;
357 	if (nfp_prog->type == BPF_PROG_TYPE_SCHED_CLS &&
358 	    imm <= TC_ACT_REDIRECT &&
359 	    imm != TC_ACT_SHOT && imm != TC_ACT_STOLEN &&
360 	    imm != TC_ACT_QUEUED) {
361 		pr_vlog(env, "unsupported exit state: %d, imm: %llx\n",
362 			reg0->type, imm);
363 		return -EINVAL;
364 	}
365 
366 	return 0;
367 }
368 
369 static int
nfp_bpf_check_stack_access(struct nfp_prog * nfp_prog,struct nfp_insn_meta * meta,const struct bpf_reg_state * reg,struct bpf_verifier_env * env)370 nfp_bpf_check_stack_access(struct nfp_prog *nfp_prog,
371 			   struct nfp_insn_meta *meta,
372 			   const struct bpf_reg_state *reg,
373 			   struct bpf_verifier_env *env)
374 {
375 	s32 old_off, new_off;
376 
377 	if (!tnum_is_const(reg->var_off)) {
378 		pr_vlog(env, "variable ptr stack access\n");
379 		return -EINVAL;
380 	}
381 
382 	if (meta->ptr.type == NOT_INIT)
383 		return 0;
384 
385 	old_off = meta->ptr.off + meta->ptr.var_off.value;
386 	new_off = reg->off + reg->var_off.value;
387 
388 	meta->ptr_not_const |= old_off != new_off;
389 
390 	if (!meta->ptr_not_const)
391 		return 0;
392 
393 	if (old_off % 4 == new_off % 4)
394 		return 0;
395 
396 	pr_vlog(env, "stack access changed location was:%d is:%d\n",
397 		old_off, new_off);
398 	return -EINVAL;
399 }
400 
nfp_bpf_map_use_name(enum nfp_bpf_map_use use)401 static const char *nfp_bpf_map_use_name(enum nfp_bpf_map_use use)
402 {
403 	static const char * const names[] = {
404 		[NFP_MAP_UNUSED]	= "unused",
405 		[NFP_MAP_USE_READ]	= "read",
406 		[NFP_MAP_USE_WRITE]	= "write",
407 		[NFP_MAP_USE_ATOMIC_CNT] = "atomic",
408 	};
409 
410 	if (use >= ARRAY_SIZE(names) || !names[use])
411 		return "unknown";
412 	return names[use];
413 }
414 
415 static int
nfp_bpf_map_mark_used_one(struct bpf_verifier_env * env,struct nfp_bpf_map * nfp_map,unsigned int off,enum nfp_bpf_map_use use)416 nfp_bpf_map_mark_used_one(struct bpf_verifier_env *env,
417 			  struct nfp_bpf_map *nfp_map,
418 			  unsigned int off, enum nfp_bpf_map_use use)
419 {
420 	if (nfp_map->use_map[off / 4].type != NFP_MAP_UNUSED &&
421 	    nfp_map->use_map[off / 4].type != use) {
422 		pr_vlog(env, "map value use type conflict %s vs %s off: %u\n",
423 			nfp_bpf_map_use_name(nfp_map->use_map[off / 4].type),
424 			nfp_bpf_map_use_name(use), off);
425 		return -EOPNOTSUPP;
426 	}
427 
428 	if (nfp_map->use_map[off / 4].non_zero_update &&
429 	    use == NFP_MAP_USE_ATOMIC_CNT) {
430 		pr_vlog(env, "atomic counter in map value may already be initialized to non-zero value off: %u\n",
431 			off);
432 		return -EOPNOTSUPP;
433 	}
434 
435 	nfp_map->use_map[off / 4].type = use;
436 
437 	return 0;
438 }
439 
440 static int
nfp_bpf_map_mark_used(struct bpf_verifier_env * env,struct nfp_insn_meta * meta,const struct bpf_reg_state * reg,enum nfp_bpf_map_use use)441 nfp_bpf_map_mark_used(struct bpf_verifier_env *env, struct nfp_insn_meta *meta,
442 		      const struct bpf_reg_state *reg,
443 		      enum nfp_bpf_map_use use)
444 {
445 	struct bpf_offloaded_map *offmap;
446 	struct nfp_bpf_map *nfp_map;
447 	unsigned int size, off;
448 	int i, err;
449 
450 	if (!tnum_is_const(reg->var_off)) {
451 		pr_vlog(env, "map value offset is variable\n");
452 		return -EOPNOTSUPP;
453 	}
454 
455 	off = reg->var_off.value + meta->insn.off + reg->off;
456 	size = BPF_LDST_BYTES(&meta->insn);
457 	offmap = map_to_offmap(reg->map_ptr);
458 	nfp_map = offmap->dev_priv;
459 
460 	if (off + size > offmap->map.value_size) {
461 		pr_vlog(env, "map value access out-of-bounds\n");
462 		return -EINVAL;
463 	}
464 
465 	for (i = 0; i < size; i += 4 - (off + i) % 4) {
466 		err = nfp_bpf_map_mark_used_one(env, nfp_map, off + i, use);
467 		if (err)
468 			return err;
469 	}
470 
471 	return 0;
472 }
473 
474 static int
nfp_bpf_check_ptr(struct nfp_prog * nfp_prog,struct nfp_insn_meta * meta,struct bpf_verifier_env * env,u8 reg_no)475 nfp_bpf_check_ptr(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
476 		  struct bpf_verifier_env *env, u8 reg_no)
477 {
478 	const struct bpf_reg_state *reg = cur_regs(env) + reg_no;
479 	int err;
480 
481 	if (reg->type != PTR_TO_CTX &&
482 	    reg->type != PTR_TO_STACK &&
483 	    reg->type != PTR_TO_MAP_VALUE &&
484 	    reg->type != PTR_TO_PACKET) {
485 		pr_vlog(env, "unsupported ptr type: %d\n", reg->type);
486 		return -EINVAL;
487 	}
488 
489 	if (reg->type == PTR_TO_STACK) {
490 		err = nfp_bpf_check_stack_access(nfp_prog, meta, reg, env);
491 		if (err)
492 			return err;
493 	}
494 
495 	if (reg->type == PTR_TO_MAP_VALUE) {
496 		if (is_mbpf_load(meta)) {
497 			err = nfp_bpf_map_mark_used(env, meta, reg,
498 						    NFP_MAP_USE_READ);
499 			if (err)
500 				return err;
501 		}
502 		if (is_mbpf_store(meta)) {
503 			pr_vlog(env, "map writes not supported\n");
504 			return -EOPNOTSUPP;
505 		}
506 		if (is_mbpf_xadd(meta)) {
507 			err = nfp_bpf_map_mark_used(env, meta, reg,
508 						    NFP_MAP_USE_ATOMIC_CNT);
509 			if (err)
510 				return err;
511 		}
512 	}
513 
514 	if (meta->ptr.type != NOT_INIT && meta->ptr.type != reg->type) {
515 		pr_vlog(env, "ptr type changed for instruction %d -> %d\n",
516 			meta->ptr.type, reg->type);
517 		return -EINVAL;
518 	}
519 
520 	meta->ptr = *reg;
521 
522 	return 0;
523 }
524 
525 static int
nfp_bpf_check_store(struct nfp_prog * nfp_prog,struct nfp_insn_meta * meta,struct bpf_verifier_env * env)526 nfp_bpf_check_store(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
527 		    struct bpf_verifier_env *env)
528 {
529 	const struct bpf_reg_state *reg = cur_regs(env) + meta->insn.dst_reg;
530 
531 	if (reg->type == PTR_TO_CTX) {
532 		if (nfp_prog->type == BPF_PROG_TYPE_XDP) {
533 			/* XDP ctx accesses must be 4B in size */
534 			switch (meta->insn.off) {
535 			case offsetof(struct xdp_md, rx_queue_index):
536 				if (nfp_prog->bpf->queue_select)
537 					goto exit_check_ptr;
538 				pr_vlog(env, "queue selection not supported by FW\n");
539 				return -EOPNOTSUPP;
540 			}
541 		}
542 		pr_vlog(env, "unsupported store to context field\n");
543 		return -EOPNOTSUPP;
544 	}
545 exit_check_ptr:
546 	return nfp_bpf_check_ptr(nfp_prog, meta, env, meta->insn.dst_reg);
547 }
548 
549 static int
nfp_bpf_check_xadd(struct nfp_prog * nfp_prog,struct nfp_insn_meta * meta,struct bpf_verifier_env * env)550 nfp_bpf_check_xadd(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
551 		   struct bpf_verifier_env *env)
552 {
553 	const struct bpf_reg_state *sreg = cur_regs(env) + meta->insn.src_reg;
554 	const struct bpf_reg_state *dreg = cur_regs(env) + meta->insn.dst_reg;
555 
556 	if (dreg->type != PTR_TO_MAP_VALUE) {
557 		pr_vlog(env, "atomic add not to a map value pointer: %d\n",
558 			dreg->type);
559 		return -EOPNOTSUPP;
560 	}
561 	if (sreg->type != SCALAR_VALUE) {
562 		pr_vlog(env, "atomic add not of a scalar: %d\n", sreg->type);
563 		return -EOPNOTSUPP;
564 	}
565 
566 	meta->xadd_over_16bit |=
567 		sreg->var_off.value > 0xffff || sreg->var_off.mask > 0xffff;
568 	meta->xadd_maybe_16bit |=
569 		(sreg->var_off.value & ~sreg->var_off.mask) <= 0xffff;
570 
571 	return nfp_bpf_check_ptr(nfp_prog, meta, env, meta->insn.dst_reg);
572 }
573 
574 static int
nfp_bpf_check_alu(struct nfp_prog * nfp_prog,struct nfp_insn_meta * meta,struct bpf_verifier_env * env)575 nfp_bpf_check_alu(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
576 		  struct bpf_verifier_env *env)
577 {
578 	const struct bpf_reg_state *sreg =
579 		cur_regs(env) + meta->insn.src_reg;
580 	const struct bpf_reg_state *dreg =
581 		cur_regs(env) + meta->insn.dst_reg;
582 
583 	meta->umin_src = min(meta->umin_src, sreg->umin_value);
584 	meta->umax_src = max(meta->umax_src, sreg->umax_value);
585 	meta->umin_dst = min(meta->umin_dst, dreg->umin_value);
586 	meta->umax_dst = max(meta->umax_dst, dreg->umax_value);
587 
588 	/* NFP supports u16 and u32 multiplication.
589 	 *
590 	 * For ALU64, if either operand is beyond u32's value range, we reject
591 	 * it. One thing to note, if the source operand is BPF_K, then we need
592 	 * to check "imm" field directly, and we'd reject it if it is negative.
593 	 * Because for ALU64, "imm" (with s32 type) is expected to be sign
594 	 * extended to s64 which NFP mul doesn't support.
595 	 *
596 	 * For ALU32, it is fine for "imm" be negative though, because the
597 	 * result is 32-bits and there is no difference on the low halve of
598 	 * the result for signed/unsigned mul, so we will get correct result.
599 	 */
600 	if (is_mbpf_mul(meta)) {
601 		if (meta->umax_dst > U32_MAX) {
602 			pr_vlog(env, "multiplier is not within u32 value range\n");
603 			return -EINVAL;
604 		}
605 		if (mbpf_src(meta) == BPF_X && meta->umax_src > U32_MAX) {
606 			pr_vlog(env, "multiplicand is not within u32 value range\n");
607 			return -EINVAL;
608 		}
609 		if (mbpf_class(meta) == BPF_ALU64 &&
610 		    mbpf_src(meta) == BPF_K && meta->insn.imm < 0) {
611 			pr_vlog(env, "sign extended multiplicand won't be within u32 value range\n");
612 			return -EINVAL;
613 		}
614 	}
615 
616 	/* NFP doesn't have divide instructions, we support divide by constant
617 	 * through reciprocal multiplication. Given NFP support multiplication
618 	 * no bigger than u32, we'd require divisor and dividend no bigger than
619 	 * that as well.
620 	 *
621 	 * Also eBPF doesn't support signed divide and has enforced this on C
622 	 * language level by failing compilation. However LLVM assembler hasn't
623 	 * enforced this, so it is possible for negative constant to leak in as
624 	 * a BPF_K operand through assembly code, we reject such cases as well.
625 	 */
626 	if (is_mbpf_div(meta)) {
627 		if (meta->umax_dst > U32_MAX) {
628 			pr_vlog(env, "dividend is not within u32 value range\n");
629 			return -EINVAL;
630 		}
631 		if (mbpf_src(meta) == BPF_X) {
632 			if (meta->umin_src != meta->umax_src) {
633 				pr_vlog(env, "divisor is not constant\n");
634 				return -EINVAL;
635 			}
636 			if (meta->umax_src > U32_MAX) {
637 				pr_vlog(env, "divisor is not within u32 value range\n");
638 				return -EINVAL;
639 			}
640 		}
641 		if (mbpf_src(meta) == BPF_K && meta->insn.imm < 0) {
642 			pr_vlog(env, "divide by negative constant is not supported\n");
643 			return -EINVAL;
644 		}
645 	}
646 
647 	return 0;
648 }
649 
650 static int
nfp_verify_insn(struct bpf_verifier_env * env,int insn_idx,int prev_insn_idx)651 nfp_verify_insn(struct bpf_verifier_env *env, int insn_idx, int prev_insn_idx)
652 {
653 	struct nfp_prog *nfp_prog = env->prog->aux->offload->dev_priv;
654 	struct nfp_insn_meta *meta = nfp_prog->verifier_meta;
655 
656 	meta = nfp_bpf_goto_meta(nfp_prog, meta, insn_idx, env->prog->len);
657 	nfp_prog->verifier_meta = meta;
658 
659 	if (!nfp_bpf_supported_opcode(meta->insn.code)) {
660 		pr_vlog(env, "instruction %#02x not supported\n",
661 			meta->insn.code);
662 		return -EINVAL;
663 	}
664 
665 	if (meta->insn.src_reg >= MAX_BPF_REG ||
666 	    meta->insn.dst_reg >= MAX_BPF_REG) {
667 		pr_vlog(env, "program uses extended registers - jit hardening?\n");
668 		return -EINVAL;
669 	}
670 
671 	if (meta->insn.code == (BPF_JMP | BPF_CALL))
672 		return nfp_bpf_check_call(nfp_prog, env, meta);
673 	if (meta->insn.code == (BPF_JMP | BPF_EXIT))
674 		return nfp_bpf_check_exit(nfp_prog, env);
675 
676 	if (is_mbpf_load(meta))
677 		return nfp_bpf_check_ptr(nfp_prog, meta, env,
678 					 meta->insn.src_reg);
679 	if (is_mbpf_store(meta))
680 		return nfp_bpf_check_store(nfp_prog, meta, env);
681 
682 	if (is_mbpf_xadd(meta))
683 		return nfp_bpf_check_xadd(nfp_prog, meta, env);
684 
685 	if (is_mbpf_alu(meta))
686 		return nfp_bpf_check_alu(nfp_prog, meta, env);
687 
688 	return 0;
689 }
690 
691 const struct bpf_prog_offload_ops nfp_bpf_analyzer_ops = {
692 	.insn_hook = nfp_verify_insn,
693 };
694