5189cfb11290baa18c3897a06ee51223ae2676f7
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>
29 #ifndef PTRACE_EVENT_STOP
30 /* PTRACE_EVENT_STOP is defined in linux/ptrace.h, but this header
31 * collides with musl's sys/ptrace.h */
32 #define PTRACE_EVENT_STOP 128
35 #include <libubox/uloop.h>
36 #include <libubox/blobmsg.h>
37 #include <libubox/blobmsg_json.h>
39 #include "../syscall-names.h"
41 #define _offsetof(a, b) __builtin_offsetof(a,b)
42 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
45 #define reg_syscall_nr _offsetof(struct user, regs.orig_rax)
46 #elif defined(__i386__)
47 #define reg_syscall_nr _offsetof(struct user, regs.orig_eax)
52 #define reg_syscall_nr (EF_REG2 / 4)
53 #elif defined(__arm__)
54 #include <asm/ptrace.h> /* for PTRACE_SET_SYSCALL */
55 #define reg_syscall_nr _offsetof(struct user, regs.uregs[7])
56 # if defined(__ARM_EABI__)
57 # define reg_retval_nr _offsetof(struct user, regs.uregs[0])
60 #error tracing is not supported on this architecture
68 #define PROC_NAME(mode) (mode == UTRACE ? "utrace" : "seccomp-trace")
70 #define INFO(fmt, ...) do { \
71 fprintf(stderr, "%s: "fmt, PROC_NAME(mode), ## __VA_ARGS__); \
74 #define ERROR(fmt, ...) do { \
75 syslog(LOG_ERR, "%s: "fmt, PROC_NAME(mode), ## __VA_ARGS__); \
76 fprintf(stderr, "%s: "fmt, PROC_NAME(mode), ## __VA_ARGS__); \
79 #define LOGERR(fmt, ...) do { \
80 syslog(LOG_ERR, "%s: "fmt, PROC_NAME(mode), ## __VA_ARGS__); \
84 struct uloop_process proc
;
88 static struct tracee tracer
;
89 static int *syscall_count
;
90 static int violation_count
;
91 static struct blob_buf b
;
92 static int syscall_max
;
97 static int max_syscall
= ARRAY_SIZE(syscall_names
);
99 static void set_syscall(const char *name
, int val
)
103 for (i
= 0; i
< max_syscall
; i
++)
104 if (syscall_names
[i
] && !strcmp(syscall_names
[i
], name
)) {
105 syscall_count
[i
] = val
;
115 static int cmp_count(const void *a
, const void *b
)
117 return ((struct syscall
*)b
)->count
- ((struct syscall
*)a
)->count
;
120 static void print_syscalls(int policy
, const char *json
)
125 if (mode
== UTRACE
) {
126 set_syscall("rt_sigaction", 1);
127 set_syscall("sigreturn", 1);
128 set_syscall("rt_sigreturn", 1);
129 set_syscall("exit_group", 1);
130 set_syscall("exit", 1);
133 struct syscall sorted
[ARRAY_SIZE(syscall_names
)];
135 for (i
= 0; i
< ARRAY_SIZE(syscall_names
); i
++) {
136 sorted
[i
].syscall
= i
;
137 sorted
[i
].count
= syscall_count
[i
];
140 qsort(sorted
, ARRAY_SIZE(syscall_names
), sizeof(sorted
[0]), cmp_count
);
142 blob_buf_init(&b
, 0);
143 c
= blobmsg_open_array(&b
, "whitelist");
145 for (i
= 0; i
< ARRAY_SIZE(syscall_names
); i
++) {
146 int sc
= sorted
[i
].syscall
;
147 if (!sorted
[i
].count
)
149 if (syscall_names
[sc
]) {
151 printf("syscall %d (%s) was called %d times\n",
152 sc
, syscall_names
[sc
], sorted
[i
].count
);
153 blobmsg_add_string(&b
, NULL
, syscall_names
[sc
]);
155 ERROR("no name found for syscall(%d)\n", sc
);
158 blobmsg_close_array(&b
, c
);
159 blobmsg_add_u32(&b
, "policy", policy
);
161 FILE *fp
= fopen(json
, "w");
163 fprintf(fp
, "%s", blobmsg_format_json_indent(b
.head
, true, 0));
165 INFO("saving syscall trace to %s\n", json
);
167 ERROR("failed to open %s\n", json
);
171 blobmsg_format_json_indent(b
.head
, true, 0));
176 static void report_seccomp_vialation(pid_t pid
, unsigned syscall
)
179 snprintf(buf
, sizeof(buf
), "/proc/%d/cmdline", pid
);
180 int f
= open(buf
, O_RDONLY
);
181 int r
= read(f
, buf
, sizeof(buf
) - 1);
185 strcpy(buf
, "unknown?");
188 if (violation_count
< INT_MAX
)
190 if (syscall
< ARRAY_SIZE(syscall_names
)) {
191 syscall_count
[syscall
]++;
192 LOGERR("%s[%u] tried to call non-whitelisted syscall: %s (see %s)\n",
193 buf
, pid
, syscall_names
[syscall
], json
);
195 LOGERR("%s[%u] tried to call non-whitelisted syscall: %d (see %s)\n",
196 buf
, pid
, syscall
, json
);
200 static void tracer_cb(struct uloop_process
*c
, int ret
)
202 struct tracee
*tracee
= container_of(c
, struct tracee
, proc
);
203 int inject_signal
= 0;
205 /* We explicitely check for events in upper 16 bits, because
206 * musl (as opposed to glibc) does not report
207 * PTRACE_EVENT_STOP as WIFSTOPPED */
208 if (WIFSTOPPED(ret
) || (ret
>> 16)) {
209 if (WSTOPSIG(ret
) & 0x80) {
210 if (!tracee
->in_syscall
) {
211 int syscall
= ptrace(PTRACE_PEEKUSER
, c
->pid
, reg_syscall_nr
);
213 if (syscall
< syscall_max
) {
214 syscall_count
[syscall
]++;
216 fprintf(stderr
, "%s()\n", syscall_names
[syscall
]);
218 fprintf(stderr
, "syscal(%d)\n", syscall
);
221 tracee
->in_syscall
= !tracee
->in_syscall
;
222 } else if ((ret
>> 8) == (SIGTRAP
| (PTRACE_EVENT_FORK
<< 8)) ||
223 (ret
>> 8) == (SIGTRAP
| (PTRACE_EVENT_VFORK
<< 8)) ||
224 (ret
>> 8) == (SIGTRAP
| (PTRACE_EVENT_CLONE
<< 8))) {
225 struct tracee
*child
= calloc(1, sizeof(struct tracee
));
227 ptrace(PTRACE_GETEVENTMSG
, c
->pid
, 0, &child
->proc
.pid
);
228 child
->proc
.cb
= tracer_cb
;
229 ptrace(ptrace_restart
, child
->proc
.pid
, 0, 0);
230 uloop_process_add(&child
->proc
);
232 fprintf(stderr
, "Tracing new child %d\n", child
->proc
.pid
);
233 } else if ((ret
>> 16) == PTRACE_EVENT_STOP
) {
234 /* Nothing special to do here */
235 } else if ((ret
>> 8) == (SIGTRAP
| (PTRACE_EVENT_SECCOMP
<< 8))) {
236 int syscall
= ptrace(PTRACE_PEEKUSER
, c
->pid
, reg_syscall_nr
);
238 ptrace(PTRACE_SET_SYSCALL
, c
->pid
, 0, -1);
239 ptrace(PTRACE_POKEUSER
, c
->pid
, reg_retval_nr
, -ENOSYS
);
241 ptrace(PTRACE_POKEUSER
, c
->pid
, reg_syscall_nr
, -1);
243 report_seccomp_vialation(c
->pid
, syscall
);
245 inject_signal
= WSTOPSIG(ret
);
247 fprintf(stderr
, "Injecting signal %d into pid %d\n",
248 inject_signal
, tracee
->proc
.pid
);
250 } else if (WIFEXITED(ret
) || (WIFSIGNALED(ret
) && WTERMSIG(ret
))) {
251 if (tracee
== &tracer
) {
252 uloop_end(); /* Main process exit */
255 fprintf(stderr
, "Child %d exited\n", tracee
->proc
.pid
);
261 ptrace(ptrace_restart
, c
->pid
, 0, inject_signal
);
262 uloop_process_add(c
);
265 int main(int argc
, char **argv
, char **envp
)
267 int status
, ch
, policy
= EPERM
;
270 /* When invoked via seccomp-trace symlink, work as seccomp
271 * violation logger rather than as syscall tracer */
272 if (strstr(argv
[0], "seccomp-trace"))
273 mode
= SECCOMP_TRACE
;
275 while ((ch
= getopt(argc
, argv
, "f:p:")) != -1) {
281 policy
= atoi(optarg
);
287 json
= getenv("SECCOMP_FILE");
295 if (getenv("TRACE_DEBUG"))
297 unsetenv("TRACE_DEBUG");
302 char **_argv
= calloc(argc
+ 1, sizeof(char *));
304 char *preload
= NULL
;
305 const char *old_preload
= getenv("LD_PRELOAD");
310 memcpy(_argv
, argv
, argc
* sizeof(char *));
315 _envp
= calloc(envc
+ 2, sizeof(char *));
318 preload
= "/lib/libpreload-trace.so";
322 preload
= "/lib/libpreload-seccomp.so";
324 asprintf(&_envp
[1], "SECCOMP_FILE=%s", json
? json
: "");
325 kill(getpid(), SIGSTOP
);
328 asprintf(&_envp
[0], "LD_PRELOAD=%s%s%s", preload
,
329 old_preload
? ":" : "",
330 old_preload
? old_preload
: "");
331 memcpy(&_envp
[newenv
], envp
, envc
* sizeof(char *));
333 ret
= execve(_argv
[0], _argv
, _envp
);
334 ERROR("failed to exec %s: %s\n", _argv
[0], strerror(errno
));
344 syscall_max
= ARRAY_SIZE(syscall_names
);
345 syscall_count
= calloc(syscall_max
, sizeof(int));
346 waitpid(child
, &status
, WUNTRACED
);
347 if (!WIFSTOPPED(status
)) {
348 ERROR("failed to start %s\n", *argv
);
352 int ptrace_options
= PTRACE_O_TRACEFORK
| PTRACE_O_TRACEVFORK
| PTRACE_O_TRACECLONE
;
355 ptrace_options
|= PTRACE_O_TRACESYSGOOD
;
356 ptrace_restart
= PTRACE_SYSCALL
;
359 ptrace_options
|= PTRACE_O_TRACESECCOMP
;
360 ptrace_restart
= PTRACE_CONT
;
363 ptrace(PTRACE_SEIZE
, child
, 0, ptrace_options
);
364 ptrace(ptrace_restart
, child
, 0, SIGCONT
);
367 tracer
.proc
.pid
= child
;
368 tracer
.proc
.cb
= tracer_cb
;
369 uloop_process_add(&tracer
.proc
);
377 if (asprintf(&json
, "/tmp/%s.%u.json", basename(*argv
), child
) < 0)
378 ERROR("failed to allocate output path: %s\n", strerror(errno
));
381 if (!violation_count
)
383 asprintf(&json
, "/tmp/%s.%u.violations.json", basename(*argv
), child
);
386 print_syscalls(policy
, json
);