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 #include <libubox/uloop.h>
37 #include <libubox/blobmsg.h>
38 #include <libubox/blobmsg_json.h>
40 #include "../syscall-names.h"
42 #define _offsetof(a, b) __builtin_offsetof(a,b)
43 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
46 #define reg_syscall_nr _offsetof(struct user, regs.orig_rax)
47 #elif defined(__i386__)
48 #define reg_syscall_nr _offsetof(struct user, regs.orig_eax)
53 #define reg_syscall_nr (EF_REG2 / 4)
54 #elif defined(__arm__)
55 #include <asm/ptrace.h> /* for PTRACE_SET_SYSCALL */
56 #define reg_syscall_nr _offsetof(struct user, regs.uregs[7])
57 # if defined(__ARM_EABI__)
58 # define reg_retval_nr _offsetof(struct user, regs.uregs[0])
61 #error tracing is not supported on this architecture
69 #define PROC_NAME(mode) (mode == UTRACE ? "utrace" : "seccomp-trace")
71 #define INFO(fmt, ...) do { \
72 fprintf(stderr, "%s: "fmt, PROC_NAME(mode), ## __VA_ARGS__); \
75 #define ERROR(fmt, ...) do { \
76 syslog(LOG_ERR, "%s: "fmt, PROC_NAME(mode), ## __VA_ARGS__); \
77 fprintf(stderr, "%s: "fmt, PROC_NAME(mode), ## __VA_ARGS__); \
80 #define LOGERR(fmt, ...) do { \
81 syslog(LOG_ERR, "%s: "fmt, PROC_NAME(mode), ## __VA_ARGS__); \
85 struct uloop_process proc;
89 static struct tracee tracer;
90 static int syscall_count[SYSCALL_COUNT];
91 static int violation_count;
92 static struct blob_buf b;
97 static void set_syscall(const char *name, int val)
101 for (i = 0; i < SYSCALL_COUNT; i++) {
102 int sc = syscall_index_to_number(i);
103 if (syscall_name(sc) && !strcmp(syscall_name(sc), name)) {
104 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[SYSCALL_COUNT];
135 for (i = 0; i < SYSCALL_COUNT; i++) {
136 sorted[i].syscall = syscall_index_to_number(i);
137 sorted[i].count = syscall_count[i];
140 qsort(sorted, SYSCALL_COUNT, sizeof(sorted[0]), cmp_count);
142 blob_buf_init(&b, 0);
143 c = blobmsg_open_array(&b, "whitelist");
145 for (i = 0; i < SYSCALL_COUNT; i++) {
146 int sc = sorted[i].syscall;
147 if (!sorted[i].count)
149 if (syscall_name(sc)) {
151 printf("syscall %d (%s) was called %d times\n",
152 sc, syscall_name(sc), sorted[i].count);
153 blobmsg_add_string(&b, NULL, syscall_name(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 int i = syscall_index(syscall);
193 LOGERR("%s[%u] tried to call non-whitelisted syscall: %s (see %s)\n",
194 buf, pid, syscall_name(syscall), json);
196 LOGERR("%s[%u] tried to call non-whitelisted syscall: %d (see %s)\n",
197 buf, pid, syscall, json);
201 static void tracer_cb(struct uloop_process *c, int ret)
203 struct tracee *tracee = container_of(c, struct tracee, proc);
204 int inject_signal = 0;
206 /* We explicitely check for events in upper 16 bits, because
207 * musl (as opposed to glibc) does not report
208 * PTRACE_EVENT_STOP as WIFSTOPPED */
209 if (WIFSTOPPED(ret) || (ret >> 16)) {
210 if (WSTOPSIG(ret) & 0x80) {
211 if (!tracee->in_syscall) {
212 int syscall = ptrace(PTRACE_PEEKUSER, c->pid, reg_syscall_nr);
213 int i = syscall_index(syscall);
217 fprintf(stderr, "%s()\n", syscall_name(syscall));
219 fprintf(stderr, "syscal(%d)\n", syscall);
222 tracee->in_syscall = !tracee->in_syscall;
223 } else if ((ret >> 8) == (SIGTRAP | (PTRACE_EVENT_FORK << 8)) ||
224 (ret >> 8) == (SIGTRAP | (PTRACE_EVENT_VFORK << 8)) ||
225 (ret >> 8) == (SIGTRAP | (PTRACE_EVENT_CLONE << 8))) {
226 struct tracee *child = calloc(1, sizeof(struct tracee));
228 ptrace(PTRACE_GETEVENTMSG, c->pid, 0, &child->proc.pid);
229 child->proc.cb = tracer_cb;
230 ptrace(ptrace_restart, child->proc.pid, 0, 0);
231 uloop_process_add(&child->proc);
233 fprintf(stderr, "Tracing new child %d\n", child->proc.pid);
234 } else if ((ret >> 16) == PTRACE_EVENT_STOP) {
235 /* Nothing special to do here */
236 } else if ((ret >> 8) == (SIGTRAP | (PTRACE_EVENT_SECCOMP << 8))) {
237 int syscall = ptrace(PTRACE_PEEKUSER, c->pid, reg_syscall_nr);
239 ptrace(PTRACE_SET_SYSCALL, c->pid, 0, -1);
240 ptrace(PTRACE_POKEUSER, c->pid, reg_retval_nr, -ENOSYS);
242 ptrace(PTRACE_POKEUSER, c->pid, reg_syscall_nr, -1);
244 report_seccomp_vialation(c->pid, syscall);
246 inject_signal = WSTOPSIG(ret);
248 fprintf(stderr, "Injecting signal %d into pid %d\n",
249 inject_signal, tracee->proc.pid);
251 } else if (WIFEXITED(ret) || (WIFSIGNALED(ret) && WTERMSIG(ret))) {
252 if (tracee == &tracer) {
253 uloop_end(); /* Main process exit */
256 fprintf(stderr, "Child %d exited\n", tracee->proc.pid);
262 ptrace(ptrace_restart, c->pid, 0, inject_signal);
263 uloop_process_add(c);
266 static void sigterm_handler(int signum)
268 /* When we receive SIGTERM, we forward it to the tracee. After
269 * the tracee exits, trace_cb() will be called and make us
271 kill(tracer.proc.pid, SIGTERM);
275 int main(int argc, char **argv, char **envp)
277 int status, ch, policy = EPERM;
280 /* When invoked via seccomp-trace symlink, work as seccomp
281 * violation logger rather than as syscall tracer */
282 if (strstr(argv[0], "seccomp-trace"))
283 mode = SECCOMP_TRACE;
285 while ((ch = getopt(argc, argv, "f:p:")) != -1) {
291 policy = atoi(optarg);
297 json = getenv("SECCOMP_FILE");
305 if (getenv("TRACE_DEBUG"))
307 unsetenv("TRACE_DEBUG");
312 char **_argv = calloc(argc + 1, sizeof(char *));
314 char *preload = NULL;
315 const char *old_preload = getenv("LD_PRELOAD");
320 memcpy(_argv, argv, argc * sizeof(char *));
325 _envp = calloc(envc + 2, sizeof(char *));
328 preload = "/lib/libpreload-trace.so";
332 preload = "/lib/libpreload-seccomp.so";
334 asprintf(&_envp[1], "SECCOMP_FILE=%s", json ? json : "");
335 kill(getpid(), SIGSTOP);
338 asprintf(&_envp[0], "LD_PRELOAD=%s%s%s", preload,
339 old_preload ? ":" : "",
340 old_preload ? old_preload : "");
341 memcpy(&_envp[newenv], envp, envc * sizeof(char *));
343 ret = execve(_argv[0], _argv, _envp);
344 ERROR("failed to exec %s: %s\n", _argv[0], strerror(errno));
354 waitpid(child, &status, WUNTRACED);
355 if (!WIFSTOPPED(status)) {
356 ERROR("failed to start %s\n", *argv);
360 int ptrace_options = PTRACE_O_TRACEFORK | PTRACE_O_TRACEVFORK | PTRACE_O_TRACECLONE;
363 ptrace_options |= PTRACE_O_TRACESYSGOOD;
364 ptrace_restart = PTRACE_SYSCALL;
367 ptrace_options |= PTRACE_O_TRACESECCOMP;
368 ptrace_restart = PTRACE_CONT;
371 if (ptrace(PTRACE_SEIZE, child, 0, ptrace_options) == -1)
372 err(1, "PTRACE_SEIZE");
373 if (ptrace(ptrace_restart, child, 0, SIGCONT) == -1)
374 err(1, "ptrace restart");
377 tracer.proc.pid = child;
378 tracer.proc.cb = tracer_cb;
379 uloop_process_add(&tracer.proc);
380 signal(SIGTERM, sigterm_handler); /* Override uloop's SIGTERM handler */
388 if (asprintf(&json, "/tmp/%s.%u.json", basename(*argv), child) < 0)
389 ERROR("failed to allocate output path: %s\n", strerror(errno));
392 if (!violation_count)
394 asprintf(&json, "/tmp/%s.%u.violations.json", basename(*argv), child);
397 print_syscalls(policy, json);