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2541517c AS |
1 | /* Copyright (c) 2011-2015 PLUMgrid, http://plumgrid.com |
2 | * | |
3 | * This program is free software; you can redistribute it and/or | |
4 | * modify it under the terms of version 2 of the GNU General Public | |
5 | * License as published by the Free Software Foundation. | |
6 | */ | |
7 | #include <linux/kernel.h> | |
8 | #include <linux/types.h> | |
9 | #include <linux/slab.h> | |
10 | #include <linux/bpf.h> | |
11 | #include <linux/filter.h> | |
12 | #include <linux/uaccess.h> | |
9c959c86 | 13 | #include <linux/ctype.h> |
2541517c AS |
14 | #include "trace.h" |
15 | ||
2541517c AS |
16 | /** |
17 | * trace_call_bpf - invoke BPF program | |
18 | * @prog: BPF program | |
19 | * @ctx: opaque context pointer | |
20 | * | |
21 | * kprobe handlers execute BPF programs via this helper. | |
22 | * Can be used from static tracepoints in the future. | |
23 | * | |
24 | * Return: BPF programs always return an integer which is interpreted by | |
25 | * kprobe handler as: | |
26 | * 0 - return from kprobe (event is filtered out) | |
27 | * 1 - store kprobe event into ring buffer | |
28 | * Other values are reserved and currently alias to 1 | |
29 | */ | |
30 | unsigned int trace_call_bpf(struct bpf_prog *prog, void *ctx) | |
31 | { | |
32 | unsigned int ret; | |
33 | ||
34 | if (in_nmi()) /* not supported yet */ | |
35 | return 1; | |
36 | ||
37 | preempt_disable(); | |
38 | ||
39 | if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) { | |
40 | /* | |
41 | * since some bpf program is already running on this cpu, | |
42 | * don't call into another bpf program (same or different) | |
43 | * and don't send kprobe event into ring-buffer, | |
44 | * so return zero here | |
45 | */ | |
46 | ret = 0; | |
47 | goto out; | |
48 | } | |
49 | ||
50 | rcu_read_lock(); | |
51 | ret = BPF_PROG_RUN(prog, ctx); | |
52 | rcu_read_unlock(); | |
53 | ||
54 | out: | |
55 | __this_cpu_dec(bpf_prog_active); | |
56 | preempt_enable(); | |
57 | ||
58 | return ret; | |
59 | } | |
60 | EXPORT_SYMBOL_GPL(trace_call_bpf); | |
61 | ||
62 | static u64 bpf_probe_read(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) | |
63 | { | |
64 | void *dst = (void *) (long) r1; | |
65 | int size = (int) r2; | |
66 | void *unsafe_ptr = (void *) (long) r3; | |
67 | ||
68 | return probe_kernel_read(dst, unsafe_ptr, size); | |
69 | } | |
70 | ||
71 | static const struct bpf_func_proto bpf_probe_read_proto = { | |
72 | .func = bpf_probe_read, | |
73 | .gpl_only = true, | |
74 | .ret_type = RET_INTEGER, | |
75 | .arg1_type = ARG_PTR_TO_STACK, | |
76 | .arg2_type = ARG_CONST_STACK_SIZE, | |
77 | .arg3_type = ARG_ANYTHING, | |
78 | }; | |
79 | ||
9c959c86 AS |
80 | /* |
81 | * limited trace_printk() | |
8d3b7dce | 82 | * only %d %u %x %ld %lu %lx %lld %llu %llx %p %s conversion specifiers allowed |
9c959c86 AS |
83 | */ |
84 | static u64 bpf_trace_printk(u64 r1, u64 fmt_size, u64 r3, u64 r4, u64 r5) | |
85 | { | |
86 | char *fmt = (char *) (long) r1; | |
8d3b7dce | 87 | bool str_seen = false; |
9c959c86 AS |
88 | int mod[3] = {}; |
89 | int fmt_cnt = 0; | |
8d3b7dce AS |
90 | u64 unsafe_addr; |
91 | char buf[64]; | |
9c959c86 AS |
92 | int i; |
93 | ||
94 | /* | |
95 | * bpf_check()->check_func_arg()->check_stack_boundary() | |
96 | * guarantees that fmt points to bpf program stack, | |
97 | * fmt_size bytes of it were initialized and fmt_size > 0 | |
98 | */ | |
99 | if (fmt[--fmt_size] != 0) | |
100 | return -EINVAL; | |
101 | ||
102 | /* check format string for allowed specifiers */ | |
103 | for (i = 0; i < fmt_size; i++) { | |
104 | if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i])) | |
105 | return -EINVAL; | |
106 | ||
107 | if (fmt[i] != '%') | |
108 | continue; | |
109 | ||
110 | if (fmt_cnt >= 3) | |
111 | return -EINVAL; | |
112 | ||
113 | /* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */ | |
114 | i++; | |
115 | if (fmt[i] == 'l') { | |
116 | mod[fmt_cnt]++; | |
117 | i++; | |
8d3b7dce | 118 | } else if (fmt[i] == 'p' || fmt[i] == 's') { |
9c959c86 AS |
119 | mod[fmt_cnt]++; |
120 | i++; | |
121 | if (!isspace(fmt[i]) && !ispunct(fmt[i]) && fmt[i] != 0) | |
122 | return -EINVAL; | |
123 | fmt_cnt++; | |
8d3b7dce AS |
124 | if (fmt[i - 1] == 's') { |
125 | if (str_seen) | |
126 | /* allow only one '%s' per fmt string */ | |
127 | return -EINVAL; | |
128 | str_seen = true; | |
129 | ||
130 | switch (fmt_cnt) { | |
131 | case 1: | |
132 | unsafe_addr = r3; | |
133 | r3 = (long) buf; | |
134 | break; | |
135 | case 2: | |
136 | unsafe_addr = r4; | |
137 | r4 = (long) buf; | |
138 | break; | |
139 | case 3: | |
140 | unsafe_addr = r5; | |
141 | r5 = (long) buf; | |
142 | break; | |
143 | } | |
144 | buf[0] = 0; | |
145 | strncpy_from_unsafe(buf, | |
146 | (void *) (long) unsafe_addr, | |
147 | sizeof(buf)); | |
148 | } | |
9c959c86 AS |
149 | continue; |
150 | } | |
151 | ||
152 | if (fmt[i] == 'l') { | |
153 | mod[fmt_cnt]++; | |
154 | i++; | |
155 | } | |
156 | ||
157 | if (fmt[i] != 'd' && fmt[i] != 'u' && fmt[i] != 'x') | |
158 | return -EINVAL; | |
159 | fmt_cnt++; | |
160 | } | |
161 | ||
162 | return __trace_printk(1/* fake ip will not be printed */, fmt, | |
163 | mod[0] == 2 ? r3 : mod[0] == 1 ? (long) r3 : (u32) r3, | |
164 | mod[1] == 2 ? r4 : mod[1] == 1 ? (long) r4 : (u32) r4, | |
165 | mod[2] == 2 ? r5 : mod[2] == 1 ? (long) r5 : (u32) r5); | |
166 | } | |
167 | ||
168 | static const struct bpf_func_proto bpf_trace_printk_proto = { | |
169 | .func = bpf_trace_printk, | |
170 | .gpl_only = true, | |
171 | .ret_type = RET_INTEGER, | |
172 | .arg1_type = ARG_PTR_TO_STACK, | |
173 | .arg2_type = ARG_CONST_STACK_SIZE, | |
174 | }; | |
175 | ||
0756ea3e AS |
176 | const struct bpf_func_proto *bpf_get_trace_printk_proto(void) |
177 | { | |
178 | /* | |
179 | * this program might be calling bpf_trace_printk, | |
180 | * so allocate per-cpu printk buffers | |
181 | */ | |
182 | trace_printk_init_buffers(); | |
183 | ||
184 | return &bpf_trace_printk_proto; | |
185 | } | |
186 | ||
35578d79 KX |
187 | static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5) |
188 | { | |
189 | struct bpf_map *map = (struct bpf_map *) (unsigned long) r1; | |
190 | struct bpf_array *array = container_of(map, struct bpf_array, map); | |
191 | struct perf_event *event; | |
e03e7ee3 | 192 | struct file *file; |
35578d79 KX |
193 | |
194 | if (unlikely(index >= array->map.max_entries)) | |
195 | return -E2BIG; | |
196 | ||
e03e7ee3 AS |
197 | file = (struct file *)array->ptrs[index]; |
198 | if (unlikely(!file)) | |
35578d79 KX |
199 | return -ENOENT; |
200 | ||
e03e7ee3 AS |
201 | event = file->private_data; |
202 | ||
62544ce8 AS |
203 | /* make sure event is local and doesn't have pmu::count */ |
204 | if (event->oncpu != smp_processor_id() || | |
205 | event->pmu->count) | |
206 | return -EINVAL; | |
207 | ||
35578d79 KX |
208 | /* |
209 | * we don't know if the function is run successfully by the | |
210 | * return value. It can be judged in other places, such as | |
211 | * eBPF programs. | |
212 | */ | |
213 | return perf_event_read_local(event); | |
214 | } | |
215 | ||
62544ce8 | 216 | static const struct bpf_func_proto bpf_perf_event_read_proto = { |
35578d79 | 217 | .func = bpf_perf_event_read, |
1075ef59 | 218 | .gpl_only = true, |
35578d79 KX |
219 | .ret_type = RET_INTEGER, |
220 | .arg1_type = ARG_CONST_MAP_PTR, | |
221 | .arg2_type = ARG_ANYTHING, | |
222 | }; | |
223 | ||
a43eec30 AS |
224 | static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 index, u64 r4, u64 size) |
225 | { | |
226 | struct pt_regs *regs = (struct pt_regs *) (long) r1; | |
227 | struct bpf_map *map = (struct bpf_map *) (long) r2; | |
228 | struct bpf_array *array = container_of(map, struct bpf_array, map); | |
229 | void *data = (void *) (long) r4; | |
230 | struct perf_sample_data sample_data; | |
231 | struct perf_event *event; | |
e03e7ee3 | 232 | struct file *file; |
a43eec30 AS |
233 | struct perf_raw_record raw = { |
234 | .size = size, | |
235 | .data = data, | |
236 | }; | |
237 | ||
238 | if (unlikely(index >= array->map.max_entries)) | |
239 | return -E2BIG; | |
240 | ||
e03e7ee3 AS |
241 | file = (struct file *)array->ptrs[index]; |
242 | if (unlikely(!file)) | |
a43eec30 AS |
243 | return -ENOENT; |
244 | ||
e03e7ee3 AS |
245 | event = file->private_data; |
246 | ||
a43eec30 AS |
247 | if (unlikely(event->attr.type != PERF_TYPE_SOFTWARE || |
248 | event->attr.config != PERF_COUNT_SW_BPF_OUTPUT)) | |
249 | return -EINVAL; | |
250 | ||
251 | if (unlikely(event->oncpu != smp_processor_id())) | |
252 | return -EOPNOTSUPP; | |
253 | ||
254 | perf_sample_data_init(&sample_data, 0, 0); | |
255 | sample_data.raw = &raw; | |
256 | perf_event_output(event, &sample_data, regs); | |
257 | return 0; | |
258 | } | |
259 | ||
260 | static const struct bpf_func_proto bpf_perf_event_output_proto = { | |
261 | .func = bpf_perf_event_output, | |
1075ef59 | 262 | .gpl_only = true, |
a43eec30 AS |
263 | .ret_type = RET_INTEGER, |
264 | .arg1_type = ARG_PTR_TO_CTX, | |
265 | .arg2_type = ARG_CONST_MAP_PTR, | |
266 | .arg3_type = ARG_ANYTHING, | |
267 | .arg4_type = ARG_PTR_TO_STACK, | |
268 | .arg5_type = ARG_CONST_STACK_SIZE, | |
269 | }; | |
270 | ||
9fd82b61 | 271 | static const struct bpf_func_proto *tracing_func_proto(enum bpf_func_id func_id) |
2541517c AS |
272 | { |
273 | switch (func_id) { | |
274 | case BPF_FUNC_map_lookup_elem: | |
275 | return &bpf_map_lookup_elem_proto; | |
276 | case BPF_FUNC_map_update_elem: | |
277 | return &bpf_map_update_elem_proto; | |
278 | case BPF_FUNC_map_delete_elem: | |
279 | return &bpf_map_delete_elem_proto; | |
280 | case BPF_FUNC_probe_read: | |
281 | return &bpf_probe_read_proto; | |
d9847d31 AS |
282 | case BPF_FUNC_ktime_get_ns: |
283 | return &bpf_ktime_get_ns_proto; | |
04fd61ab AS |
284 | case BPF_FUNC_tail_call: |
285 | return &bpf_tail_call_proto; | |
ffeedafb AS |
286 | case BPF_FUNC_get_current_pid_tgid: |
287 | return &bpf_get_current_pid_tgid_proto; | |
288 | case BPF_FUNC_get_current_uid_gid: | |
289 | return &bpf_get_current_uid_gid_proto; | |
290 | case BPF_FUNC_get_current_comm: | |
291 | return &bpf_get_current_comm_proto; | |
9c959c86 | 292 | case BPF_FUNC_trace_printk: |
0756ea3e | 293 | return bpf_get_trace_printk_proto(); |
ab1973d3 AS |
294 | case BPF_FUNC_get_smp_processor_id: |
295 | return &bpf_get_smp_processor_id_proto; | |
35578d79 KX |
296 | case BPF_FUNC_perf_event_read: |
297 | return &bpf_perf_event_read_proto; | |
9fd82b61 AS |
298 | default: |
299 | return NULL; | |
300 | } | |
301 | } | |
302 | ||
303 | static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id) | |
304 | { | |
305 | switch (func_id) { | |
a43eec30 AS |
306 | case BPF_FUNC_perf_event_output: |
307 | return &bpf_perf_event_output_proto; | |
d5a3b1f6 AS |
308 | case BPF_FUNC_get_stackid: |
309 | return &bpf_get_stackid_proto; | |
2541517c | 310 | default: |
9fd82b61 | 311 | return tracing_func_proto(func_id); |
2541517c AS |
312 | } |
313 | } | |
314 | ||
315 | /* bpf+kprobe programs can access fields of 'struct pt_regs' */ | |
316 | static bool kprobe_prog_is_valid_access(int off, int size, enum bpf_access_type type) | |
317 | { | |
318 | /* check bounds */ | |
319 | if (off < 0 || off >= sizeof(struct pt_regs)) | |
320 | return false; | |
321 | ||
322 | /* only read is allowed */ | |
323 | if (type != BPF_READ) | |
324 | return false; | |
325 | ||
326 | /* disallow misaligned access */ | |
327 | if (off % size != 0) | |
328 | return false; | |
329 | ||
330 | return true; | |
331 | } | |
332 | ||
27dff4e0 | 333 | static const struct bpf_verifier_ops kprobe_prog_ops = { |
2541517c AS |
334 | .get_func_proto = kprobe_prog_func_proto, |
335 | .is_valid_access = kprobe_prog_is_valid_access, | |
336 | }; | |
337 | ||
338 | static struct bpf_prog_type_list kprobe_tl = { | |
339 | .ops = &kprobe_prog_ops, | |
340 | .type = BPF_PROG_TYPE_KPROBE, | |
341 | }; | |
342 | ||
9940d67c AS |
343 | static u64 bpf_perf_event_output_tp(u64 r1, u64 r2, u64 index, u64 r4, u64 size) |
344 | { | |
345 | /* | |
346 | * r1 points to perf tracepoint buffer where first 8 bytes are hidden | |
347 | * from bpf program and contain a pointer to 'struct pt_regs'. Fetch it | |
348 | * from there and call the same bpf_perf_event_output() helper | |
349 | */ | |
350 | u64 ctx = *(long *)r1; | |
351 | ||
352 | return bpf_perf_event_output(ctx, r2, index, r4, size); | |
353 | } | |
354 | ||
355 | static const struct bpf_func_proto bpf_perf_event_output_proto_tp = { | |
356 | .func = bpf_perf_event_output_tp, | |
357 | .gpl_only = true, | |
358 | .ret_type = RET_INTEGER, | |
359 | .arg1_type = ARG_PTR_TO_CTX, | |
360 | .arg2_type = ARG_CONST_MAP_PTR, | |
361 | .arg3_type = ARG_ANYTHING, | |
362 | .arg4_type = ARG_PTR_TO_STACK, | |
363 | .arg5_type = ARG_CONST_STACK_SIZE, | |
364 | }; | |
365 | ||
366 | static u64 bpf_get_stackid_tp(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) | |
367 | { | |
368 | u64 ctx = *(long *)r1; | |
369 | ||
370 | return bpf_get_stackid(ctx, r2, r3, r4, r5); | |
371 | } | |
372 | ||
373 | static const struct bpf_func_proto bpf_get_stackid_proto_tp = { | |
374 | .func = bpf_get_stackid_tp, | |
375 | .gpl_only = true, | |
376 | .ret_type = RET_INTEGER, | |
377 | .arg1_type = ARG_PTR_TO_CTX, | |
378 | .arg2_type = ARG_CONST_MAP_PTR, | |
379 | .arg3_type = ARG_ANYTHING, | |
380 | }; | |
381 | ||
9fd82b61 AS |
382 | static const struct bpf_func_proto *tp_prog_func_proto(enum bpf_func_id func_id) |
383 | { | |
384 | switch (func_id) { | |
385 | case BPF_FUNC_perf_event_output: | |
9940d67c | 386 | return &bpf_perf_event_output_proto_tp; |
9fd82b61 | 387 | case BPF_FUNC_get_stackid: |
9940d67c | 388 | return &bpf_get_stackid_proto_tp; |
9fd82b61 AS |
389 | default: |
390 | return tracing_func_proto(func_id); | |
391 | } | |
392 | } | |
393 | ||
394 | static bool tp_prog_is_valid_access(int off, int size, enum bpf_access_type type) | |
395 | { | |
396 | if (off < sizeof(void *) || off >= PERF_MAX_TRACE_SIZE) | |
397 | return false; | |
398 | if (type != BPF_READ) | |
399 | return false; | |
400 | if (off % size != 0) | |
401 | return false; | |
402 | return true; | |
403 | } | |
404 | ||
405 | static const struct bpf_verifier_ops tracepoint_prog_ops = { | |
406 | .get_func_proto = tp_prog_func_proto, | |
407 | .is_valid_access = tp_prog_is_valid_access, | |
408 | }; | |
409 | ||
410 | static struct bpf_prog_type_list tracepoint_tl = { | |
411 | .ops = &tracepoint_prog_ops, | |
412 | .type = BPF_PROG_TYPE_TRACEPOINT, | |
413 | }; | |
414 | ||
2541517c AS |
415 | static int __init register_kprobe_prog_ops(void) |
416 | { | |
417 | bpf_register_prog_type(&kprobe_tl); | |
9fd82b61 | 418 | bpf_register_prog_type(&tracepoint_tl); |
2541517c AS |
419 | return 0; |
420 | } | |
421 | late_initcall(register_kprobe_prog_ops); |