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);