2 * Copyright (C) 2015 John Crispin <blogic@openwrt.org>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU Lesser General Public License version 2.1
6 * as published by the Free Software Foundation
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
17 #include <sys/ptrace.h>
19 #include <sys/types.h>
30 #ifndef PTRACE_EVENT_STOP
31 /* PTRACE_EVENT_STOP is defined in linux/ptrace.h, but this header
32 * collides with musl's sys/ptrace.h */
33 #define PTRACE_EVENT_STOP 128
36 #ifndef PTRACE_EVENT_SECCOMP
37 /* undefined with uClibc-ng */
38 #define PTRACE_EVENT_SECCOMP 7
41 #include <libubox/ulog.h>
42 #include <libubox/uloop.h>
43 #include <libubox/blobmsg.h>
44 #include <libubox/blobmsg_json.h>
46 #include "../syscall-names.h"
48 #define _offsetof(a, b) __builtin_offsetof(a,b)
49 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
51 #if defined (__aarch64__)
52 #include <linux/ptrace.h>
53 #elif defined(__amd64__)
54 #define reg_syscall_nr _offsetof(struct user, regs.orig_rax)
55 #elif defined(__arm__)
56 #include <asm/ptrace.h> /* for PTRACE_SET_SYSCALL */
57 #define reg_syscall_nr _offsetof(struct user, regs.uregs[7])
58 # if defined(__ARM_EABI__)
59 # define reg_retval_nr _offsetof(struct user, regs.uregs[0])
61 #elif defined(__i386__)
62 #define reg_syscall_nr _offsetof(struct user, regs.orig_eax)
67 #define reg_syscall_nr (EF_REG2 / 4)
68 #elif defined(__PPC__)
69 #define reg_syscall_nr _offsetof(struct user, regs.gpr[0])
70 #define reg_retval_nr _offsetof(struct user, regs.gpr[3])
72 #error tracing is not supported on this architecture
81 struct uloop_process proc
;
85 static struct tracee tracer
;
86 static int syscall_count
[SYSCALL_COUNT
];
87 static int violation_count
;
88 static struct blob_buf b
;
93 static void set_syscall(const char *name
, int val
)
97 for (i
= 0; i
< SYSCALL_COUNT
; i
++) {
98 int sc
= syscall_index_to_number(i
);
99 if (syscall_name(sc
) && !strcmp(syscall_name(sc
), name
)) {
100 syscall_count
[i
] = val
;
111 static int cmp_count(const void *a
, const void *b
)
113 return ((struct syscall
*)b
)->count
- ((struct syscall
*)a
)->count
;
116 static void print_syscalls(int policy
, const char *json
)
121 if (mode
== UTRACE
) {
122 set_syscall("rt_sigaction", 1);
123 set_syscall("sigreturn", 1);
124 set_syscall("rt_sigreturn", 1);
125 set_syscall("exit_group", 1);
126 set_syscall("exit", 1);
129 struct syscall sorted
[SYSCALL_COUNT
];
131 for (i
= 0; i
< SYSCALL_COUNT
; i
++) {
132 sorted
[i
].syscall
= syscall_index_to_number(i
);
133 sorted
[i
].count
= syscall_count
[i
];
136 qsort(sorted
, SYSCALL_COUNT
, sizeof(sorted
[0]), cmp_count
);
138 blob_buf_init(&b
, 0);
139 blobmsg_add_string(&b
, "defaultAction", "SCMP_ACT_KILL_PROCESS");
140 c
= blobmsg_open_array(&b
, "syscalls");
141 d
= blobmsg_open_table(&b
, "");
142 e
= blobmsg_open_array(&b
, "names");
144 for (i
= 0; i
< SYSCALL_COUNT
; i
++) {
145 int sc
= sorted
[i
].syscall
;
146 if (!sorted
[i
].count
)
148 if (syscall_name(sc
)) {
150 printf("syscall %d (%s) was called %d times\n",
151 sc
, syscall_name(sc
), sorted
[i
].count
);
152 blobmsg_add_string(&b
, NULL
, syscall_name(sc
));
154 ULOG_ERR("no name found for syscall(%d)\n", sc
);
157 blobmsg_close_array(&b
, e
);
158 blobmsg_add_string(&b
, "action", "SCMP_ACT_ALLOW");
159 blobmsg_close_table(&b
, d
);
160 blobmsg_close_array(&b
, c
);
162 FILE *fp
= fopen(json
, "w");
164 fprintf(fp
, "%s\n", blobmsg_format_json_indent(b
.head
, true, 0));
166 ULOG_INFO("saving syscall trace to %s\n", json
);
168 ULOG_ERR("failed to open %s\n", json
);
172 blobmsg_format_json_indent(b
.head
, true, 0));
177 static void report_seccomp_vialation(pid_t pid
, unsigned syscall
)
180 snprintf(buf
, sizeof(buf
), "/proc/%d/cmdline", pid
);
181 int f
= open(buf
, O_RDONLY
);
182 int r
= read(f
, buf
, sizeof(buf
) - 1);
186 strcpy(buf
, "unknown?");
189 if (violation_count
< INT_MAX
)
191 int i
= syscall_index(syscall
);
194 ULOG_ERR("%s[%u] tried to call non-whitelisted syscall: %s (see %s)\n",
195 buf
, pid
, syscall_name(syscall
), json
);
197 ULOG_ERR("%s[%u] tried to call non-whitelisted syscall: %d (see %s)\n",
198 buf
, pid
, syscall
, json
);
202 static void tracer_cb(struct uloop_process
*c
, int ret
)
204 struct tracee
*tracee
= container_of(c
, struct tracee
, proc
);
205 int inject_signal
= 0;
207 /* We explicitely check for events in upper 16 bits, because
208 * musl (as opposed to glibc) does not report
209 * PTRACE_EVENT_STOP as WIFSTOPPED */
210 if (WIFSTOPPED(ret
) || (ret
>> 16)) {
211 if (WSTOPSIG(ret
) & 0x80) {
212 if (!tracee
->in_syscall
) {
215 struct ptrace_syscall_info ptsi
= {.op
=PTRACE_SYSCALL_INFO_ENTRY
};
216 if (ptrace(PTRACE_GET_SYSCALL_INFO
, c
->pid
, sizeof(ptsi
), &ptsi
) != -1)
217 syscall
= ptsi
.entry
.nr
;
219 int syscall
= ptrace(PTRACE_PEEKUSER
, c
->pid
, reg_syscall_nr
);
221 int i
= syscall_index(syscall
);
225 fprintf(stderr
, "%s()\n", syscall_name(syscall
));
227 fprintf(stderr
, "syscal(%d)\n", syscall
);
230 tracee
->in_syscall
= !tracee
->in_syscall
;
231 } else if ((ret
>> 8) == (SIGTRAP
| (PTRACE_EVENT_FORK
<< 8)) ||
232 (ret
>> 8) == (SIGTRAP
| (PTRACE_EVENT_VFORK
<< 8)) ||
233 (ret
>> 8) == (SIGTRAP
| (PTRACE_EVENT_CLONE
<< 8))) {
234 struct tracee
*child
= calloc(1, sizeof(struct tracee
));
237 ptrace(PTRACE_GETEVENTMSG
, c
->pid
, 0, &msg
);
238 child
->proc
.pid
= msg
;
239 child
->proc
.cb
= tracer_cb
;
240 ptrace(ptrace_restart
, child
->proc
.pid
, 0, 0);
241 uloop_process_add(&child
->proc
);
243 fprintf(stderr
, "Tracing new child %d\n", child
->proc
.pid
);
244 } else if ((ret
>> 16) == PTRACE_EVENT_STOP
) {
245 /* Nothing special to do here */
246 } else if ((ret
>> 8) == (SIGTRAP
| (PTRACE_EVENT_SECCOMP
<< 8))) {
249 struct ptrace_syscall_info ptsi
= {.op
=PTRACE_SYSCALL_INFO_SECCOMP
};
250 if (ptrace(PTRACE_GET_SYSCALL_INFO
, c
->pid
, sizeof(ptsi
), &ptsi
) != -1)
251 syscall
= ptsi
.entry
.nr
;
253 int syscall
= ptrace(PTRACE_PEEKUSER
, c
->pid
, reg_syscall_nr
);
255 ptrace(PTRACE_SET_SYSCALL
, c
->pid
, 0, -1);
256 ptrace(PTRACE_POKEUSER
, c
->pid
, reg_retval_nr
, -ENOSYS
);
258 ptrace(PTRACE_POKEUSER
, c
->pid
, reg_syscall_nr
, -1);
261 report_seccomp_vialation(c
->pid
, syscall
);
263 inject_signal
= WSTOPSIG(ret
);
265 fprintf(stderr
, "Injecting signal %d into pid %d\n",
266 inject_signal
, tracee
->proc
.pid
);
268 } else if (WIFEXITED(ret
) || (WIFSIGNALED(ret
) && WTERMSIG(ret
))) {
269 if (tracee
== &tracer
) {
270 uloop_end(); /* Main process exit */
273 fprintf(stderr
, "Child %d exited\n", tracee
->proc
.pid
);
279 ptrace(ptrace_restart
, c
->pid
, 0, inject_signal
);
280 uloop_process_add(c
);
283 static void sigterm_handler(int signum
)
285 /* When we receive SIGTERM, we forward it to the tracee. After
286 * the tracee exits, trace_cb() will be called and make us
288 kill(tracer
.proc
.pid
, SIGTERM
);
292 int main(int argc
, char **argv
, char **envp
)
294 int status
, ch
, policy
= EPERM
;
297 /* When invoked via seccomp-trace symlink, work as seccomp
298 * violation logger rather than as syscall tracer */
299 if (strstr(argv
[0], "seccomp-trace"))
300 mode
= SECCOMP_TRACE
;
302 while ((ch
= getopt(argc
, argv
, "f:p:")) != -1) {
308 policy
= atoi(optarg
);
314 json
= getenv("SECCOMP_FILE");
322 if (getenv("TRACE_DEBUG"))
324 unsetenv("TRACE_DEBUG");
329 char **_argv
= calloc(argc
+ 1, sizeof(char *));
331 char *preload
= NULL
;
332 const char *old_preload
= getenv("LD_PRELOAD");
337 memcpy(_argv
, argv
, argc
* sizeof(char *));
342 _envp
= calloc(envc
+ 2, sizeof(char *));
345 preload
= "/lib/libpreload-trace.so";
349 preload
= "/lib/libpreload-seccomp.so";
351 if (asprintf(&_envp
[1], "SECCOMP_FILE=%s", json
? json
: "") < 0)
352 ULOG_ERR("failed to allocate SECCOMP_FILE env: %m\n");
354 kill(getpid(), SIGSTOP
);
357 if (asprintf(&_envp
[0], "LD_PRELOAD=%s%s%s", preload
,
358 old_preload
? ":" : "",
359 old_preload
? old_preload
: "") < 0)
360 ULOG_ERR("failed to allocate LD_PRELOAD env: %m\n");
362 memcpy(&_envp
[newenv
], envp
, envc
* sizeof(char *));
364 ret
= execve(_argv
[0], _argv
, _envp
);
365 ULOG_ERR("failed to exec %s: %m\n", _argv
[0]);
375 waitpid(child
, &status
, WUNTRACED
);
376 if (!WIFSTOPPED(status
)) {
377 ULOG_ERR("failed to start %s\n", *argv
);
381 /* Initialize uloop to catch all ptrace stops from now on. */
384 int ptrace_options
= PTRACE_O_TRACEFORK
| PTRACE_O_TRACEVFORK
| PTRACE_O_TRACECLONE
;
387 ptrace_options
|= PTRACE_O_TRACESYSGOOD
;
388 ptrace_restart
= PTRACE_SYSCALL
;
391 ptrace_options
|= PTRACE_O_TRACESECCOMP
;
392 ptrace_restart
= PTRACE_CONT
;
395 if (ptrace(PTRACE_SEIZE
, child
, 0, ptrace_options
) == -1) {
396 ULOG_ERR("PTRACE_SEIZE: %m\n");
399 if (ptrace(ptrace_restart
, child
, 0, SIGCONT
) == -1) {
400 ULOG_ERR("ptrace_restart: %m\n");
404 tracer
.proc
.pid
= child
;
405 tracer
.proc
.cb
= tracer_cb
;
406 uloop_process_add(&tracer
.proc
);
407 signal(SIGTERM
, sigterm_handler
); /* Override uloop's SIGTERM handler */
415 if (asprintf(&json
, "/tmp/%s.%u.json", basename(*argv
), child
) < 0)
416 ULOG_ERR("failed to allocate output path: %m\n");
419 if (!violation_count
)
421 if (asprintf(&json
, "/tmp/%s.%u.violations.json", basename(*argv
), child
) < 0)
422 ULOG_ERR("failed to allocate violations output path: %m\n");
425 print_syscalls(policy
, json
);