Loading...
Note: File does not exist in v3.5.6.
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Augment the raw_syscalls tracepoints with the contents of the pointer arguments.
4 *
5 * Test it with:
6 *
7 * perf trace -e tools/perf/examples/bpf/augmented_raw_syscalls.c cat /etc/passwd > /dev/null
8 *
9 * This exactly matches what is marshalled into the raw_syscall:sys_enter
10 * payload expected by the 'perf trace' beautifiers.
11 *
12 * For now it just uses the existing tracepoint augmentation code in 'perf
13 * trace', in the next csets we'll hook up these with the sys_enter/sys_exit
14 * code that will combine entry/exit in a strace like way.
15 */
16
17#include <linux/bpf.h>
18#include <bpf/bpf_helpers.h>
19#include <linux/limits.h>
20
21// FIXME: These should come from system headers
22typedef char bool;
23typedef int pid_t;
24typedef long long int __s64;
25typedef __s64 time64_t;
26
27struct timespec64 {
28 time64_t tv_sec;
29 long int tv_nsec;
30};
31
32/* bpf-output associated map */
33struct __augmented_syscalls__ {
34 __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
35 __type(key, int);
36 __type(value, __u32);
37 __uint(max_entries, __NR_CPUS__);
38} __augmented_syscalls__ SEC(".maps");
39
40/*
41 * What to augment at entry?
42 *
43 * Pointer arg payloads (filenames, etc) passed from userspace to the kernel
44 */
45struct syscalls_sys_enter {
46 __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
47 __type(key, __u32);
48 __type(value, __u32);
49 __uint(max_entries, 512);
50} syscalls_sys_enter SEC(".maps");
51
52/*
53 * What to augment at exit?
54 *
55 * Pointer arg payloads returned from the kernel (struct stat, etc) to userspace.
56 */
57struct syscalls_sys_exit {
58 __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
59 __type(key, __u32);
60 __type(value, __u32);
61 __uint(max_entries, 512);
62} syscalls_sys_exit SEC(".maps");
63
64struct syscall_enter_args {
65 unsigned long long common_tp_fields;
66 long syscall_nr;
67 unsigned long args[6];
68};
69
70struct syscall_exit_args {
71 unsigned long long common_tp_fields;
72 long syscall_nr;
73 long ret;
74};
75
76struct augmented_arg {
77 unsigned int size;
78 int err;
79 char value[PATH_MAX];
80};
81
82struct pids_filtered {
83 __uint(type, BPF_MAP_TYPE_HASH);
84 __type(key, pid_t);
85 __type(value, bool);
86 __uint(max_entries, 64);
87} pids_filtered SEC(".maps");
88
89/*
90 * Desired design of maximum size and alignment (see RFC2553)
91 */
92#define SS_MAXSIZE 128 /* Implementation specific max size */
93
94typedef unsigned short sa_family_t;
95
96/*
97 * FIXME: Should come from system headers
98 *
99 * The definition uses anonymous union and struct in order to control the
100 * default alignment.
101 */
102struct sockaddr_storage {
103 union {
104 struct {
105 sa_family_t ss_family; /* address family */
106 /* Following field(s) are implementation specific */
107 char __data[SS_MAXSIZE - sizeof(unsigned short)];
108 /* space to achieve desired size, */
109 /* _SS_MAXSIZE value minus size of ss_family */
110 };
111 void *__align; /* implementation specific desired alignment */
112 };
113};
114
115struct augmented_args_payload {
116 struct syscall_enter_args args;
117 union {
118 struct {
119 struct augmented_arg arg, arg2;
120 };
121 struct sockaddr_storage saddr;
122 char __data[sizeof(struct augmented_arg)];
123 };
124};
125
126// We need more tmp space than the BPF stack can give us
127struct augmented_args_tmp {
128 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
129 __type(key, int);
130 __type(value, struct augmented_args_payload);
131 __uint(max_entries, 1);
132} augmented_args_tmp SEC(".maps");
133
134static inline struct augmented_args_payload *augmented_args_payload(void)
135{
136 int key = 0;
137 return bpf_map_lookup_elem(&augmented_args_tmp, &key);
138}
139
140static inline int augmented__output(void *ctx, struct augmented_args_payload *args, int len)
141{
142 /* If perf_event_output fails, return non-zero so that it gets recorded unaugmented */
143 return bpf_perf_event_output(ctx, &__augmented_syscalls__, BPF_F_CURRENT_CPU, args, len);
144}
145
146static inline
147unsigned int augmented_arg__read_str(struct augmented_arg *augmented_arg, const void *arg, unsigned int arg_len)
148{
149 unsigned int augmented_len = sizeof(*augmented_arg);
150 int string_len = bpf_probe_read_str(&augmented_arg->value, arg_len, arg);
151
152 augmented_arg->size = augmented_arg->err = 0;
153 /*
154 * probe_read_str may return < 0, e.g. -EFAULT
155 * So we leave that in the augmented_arg->size that userspace will
156 */
157 if (string_len > 0) {
158 augmented_len -= sizeof(augmented_arg->value) - string_len;
159 augmented_len &= sizeof(augmented_arg->value) - 1;
160 augmented_arg->size = string_len;
161 } else {
162 /*
163 * So that username notice the error while still being able
164 * to skip this augmented arg record
165 */
166 augmented_arg->err = string_len;
167 augmented_len = offsetof(struct augmented_arg, value);
168 }
169
170 return augmented_len;
171}
172
173SEC("!raw_syscalls:unaugmented")
174int syscall_unaugmented(struct syscall_enter_args *args)
175{
176 return 1;
177}
178
179/*
180 * These will be tail_called from SEC("raw_syscalls:sys_enter"), so will find in
181 * augmented_args_tmp what was read by that raw_syscalls:sys_enter and go
182 * on from there, reading the first syscall arg as a string, i.e. open's
183 * filename.
184 */
185SEC("!syscalls:sys_enter_connect")
186int sys_enter_connect(struct syscall_enter_args *args)
187{
188 struct augmented_args_payload *augmented_args = augmented_args_payload();
189 const void *sockaddr_arg = (const void *)args->args[1];
190 unsigned int socklen = args->args[2];
191 unsigned int len = sizeof(augmented_args->args);
192
193 if (augmented_args == NULL)
194 return 1; /* Failure: don't filter */
195
196 if (socklen > sizeof(augmented_args->saddr))
197 socklen = sizeof(augmented_args->saddr);
198
199 bpf_probe_read(&augmented_args->saddr, socklen, sockaddr_arg);
200
201 return augmented__output(args, augmented_args, len + socklen);
202}
203
204SEC("!syscalls:sys_enter_sendto")
205int sys_enter_sendto(struct syscall_enter_args *args)
206{
207 struct augmented_args_payload *augmented_args = augmented_args_payload();
208 const void *sockaddr_arg = (const void *)args->args[4];
209 unsigned int socklen = args->args[5];
210 unsigned int len = sizeof(augmented_args->args);
211
212 if (augmented_args == NULL)
213 return 1; /* Failure: don't filter */
214
215 if (socklen > sizeof(augmented_args->saddr))
216 socklen = sizeof(augmented_args->saddr);
217
218 bpf_probe_read(&augmented_args->saddr, socklen, sockaddr_arg);
219
220 return augmented__output(args, augmented_args, len + socklen);
221}
222
223SEC("!syscalls:sys_enter_open")
224int sys_enter_open(struct syscall_enter_args *args)
225{
226 struct augmented_args_payload *augmented_args = augmented_args_payload();
227 const void *filename_arg = (const void *)args->args[0];
228 unsigned int len = sizeof(augmented_args->args);
229
230 if (augmented_args == NULL)
231 return 1; /* Failure: don't filter */
232
233 len += augmented_arg__read_str(&augmented_args->arg, filename_arg, sizeof(augmented_args->arg.value));
234
235 return augmented__output(args, augmented_args, len);
236}
237
238SEC("!syscalls:sys_enter_openat")
239int sys_enter_openat(struct syscall_enter_args *args)
240{
241 struct augmented_args_payload *augmented_args = augmented_args_payload();
242 const void *filename_arg = (const void *)args->args[1];
243 unsigned int len = sizeof(augmented_args->args);
244
245 if (augmented_args == NULL)
246 return 1; /* Failure: don't filter */
247
248 len += augmented_arg__read_str(&augmented_args->arg, filename_arg, sizeof(augmented_args->arg.value));
249
250 return augmented__output(args, augmented_args, len);
251}
252
253SEC("!syscalls:sys_enter_rename")
254int sys_enter_rename(struct syscall_enter_args *args)
255{
256 struct augmented_args_payload *augmented_args = augmented_args_payload();
257 const void *oldpath_arg = (const void *)args->args[0],
258 *newpath_arg = (const void *)args->args[1];
259 unsigned int len = sizeof(augmented_args->args), oldpath_len;
260
261 if (augmented_args == NULL)
262 return 1; /* Failure: don't filter */
263
264 oldpath_len = augmented_arg__read_str(&augmented_args->arg, oldpath_arg, sizeof(augmented_args->arg.value));
265 len += oldpath_len + augmented_arg__read_str((void *)(&augmented_args->arg) + oldpath_len, newpath_arg, sizeof(augmented_args->arg.value));
266
267 return augmented__output(args, augmented_args, len);
268}
269
270SEC("!syscalls:sys_enter_renameat")
271int sys_enter_renameat(struct syscall_enter_args *args)
272{
273 struct augmented_args_payload *augmented_args = augmented_args_payload();
274 const void *oldpath_arg = (const void *)args->args[1],
275 *newpath_arg = (const void *)args->args[3];
276 unsigned int len = sizeof(augmented_args->args), oldpath_len;
277
278 if (augmented_args == NULL)
279 return 1; /* Failure: don't filter */
280
281 oldpath_len = augmented_arg__read_str(&augmented_args->arg, oldpath_arg, sizeof(augmented_args->arg.value));
282 len += oldpath_len + augmented_arg__read_str((void *)(&augmented_args->arg) + oldpath_len, newpath_arg, sizeof(augmented_args->arg.value));
283
284 return augmented__output(args, augmented_args, len);
285}
286
287#define PERF_ATTR_SIZE_VER0 64 /* sizeof first published struct */
288
289// we need just the start, get the size to then copy it
290struct perf_event_attr_size {
291 __u32 type;
292 /*
293 * Size of the attr structure, for fwd/bwd compat.
294 */
295 __u32 size;
296};
297
298SEC("!syscalls:sys_enter_perf_event_open")
299int sys_enter_perf_event_open(struct syscall_enter_args *args)
300{
301 struct augmented_args_payload *augmented_args = augmented_args_payload();
302 const struct perf_event_attr_size *attr = (const struct perf_event_attr_size *)args->args[0], *attr_read;
303 unsigned int len = sizeof(augmented_args->args);
304
305 if (augmented_args == NULL)
306 goto failure;
307
308 if (bpf_probe_read(&augmented_args->__data, sizeof(*attr), attr) < 0)
309 goto failure;
310
311 attr_read = (const struct perf_event_attr_size *)augmented_args->__data;
312
313 __u32 size = attr_read->size;
314
315 if (!size)
316 size = PERF_ATTR_SIZE_VER0;
317
318 if (size > sizeof(augmented_args->__data))
319 goto failure;
320
321 // Now that we read attr->size and tested it against the size limits, read it completely
322 if (bpf_probe_read(&augmented_args->__data, size, attr) < 0)
323 goto failure;
324
325 return augmented__output(args, augmented_args, len + size);
326failure:
327 return 1; /* Failure: don't filter */
328}
329
330SEC("!syscalls:sys_enter_clock_nanosleep")
331int sys_enter_clock_nanosleep(struct syscall_enter_args *args)
332{
333 struct augmented_args_payload *augmented_args = augmented_args_payload();
334 const void *rqtp_arg = (const void *)args->args[2];
335 unsigned int len = sizeof(augmented_args->args);
336 __u32 size = sizeof(struct timespec64);
337
338 if (augmented_args == NULL)
339 goto failure;
340
341 if (size > sizeof(augmented_args->__data))
342 goto failure;
343
344 bpf_probe_read(&augmented_args->__data, size, rqtp_arg);
345
346 return augmented__output(args, augmented_args, len + size);
347failure:
348 return 1; /* Failure: don't filter */
349}
350
351static pid_t getpid(void)
352{
353 return bpf_get_current_pid_tgid();
354}
355
356static bool pid_filter__has(struct pids_filtered *pids, pid_t pid)
357{
358 return bpf_map_lookup_elem(pids, &pid) != NULL;
359}
360
361SEC("raw_syscalls:sys_enter")
362int sys_enter(struct syscall_enter_args *args)
363{
364 struct augmented_args_payload *augmented_args;
365 /*
366 * We start len, the amount of data that will be in the perf ring
367 * buffer, if this is not filtered out by one of pid_filter__has(),
368 * syscall->enabled, etc, with the non-augmented raw syscall payload,
369 * i.e. sizeof(augmented_args->args).
370 *
371 * We'll add to this as we add augmented syscalls right after that
372 * initial, non-augmented raw_syscalls:sys_enter payload.
373 */
374 unsigned int len = sizeof(augmented_args->args);
375
376 if (pid_filter__has(&pids_filtered, getpid()))
377 return 0;
378
379 augmented_args = augmented_args_payload();
380 if (augmented_args == NULL)
381 return 1;
382
383 bpf_probe_read(&augmented_args->args, sizeof(augmented_args->args), args);
384
385 /*
386 * Jump to syscall specific augmenter, even if the default one,
387 * "!raw_syscalls:unaugmented" that will just return 1 to return the
388 * unaugmented tracepoint payload.
389 */
390 bpf_tail_call(args, &syscalls_sys_enter, augmented_args->args.syscall_nr);
391
392 // If not found on the PROG_ARRAY syscalls map, then we're filtering it:
393 return 0;
394}
395
396SEC("raw_syscalls:sys_exit")
397int sys_exit(struct syscall_exit_args *args)
398{
399 struct syscall_exit_args exit_args;
400
401 if (pid_filter__has(&pids_filtered, getpid()))
402 return 0;
403
404 bpf_probe_read(&exit_args, sizeof(exit_args), args);
405 /*
406 * Jump to syscall specific return augmenter, even if the default one,
407 * "!raw_syscalls:unaugmented" that will just return 1 to return the
408 * unaugmented tracepoint payload.
409 */
410 bpf_tail_call(args, &syscalls_sys_exit, exit_args.syscall_nr);
411 /*
412 * If not found on the PROG_ARRAY syscalls map, then we're filtering it:
413 */
414 return 0;
415}
416
417char _license[] SEC("license") = "GPL";