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;
91 static int violation_count;
92 static struct blob_buf b;
93 static int syscall_max;
98 static int max_syscall = ARRAY_SIZE(syscall_names);
100 static void set_syscall(const char *name, int val)
104 for (i = 0; i < max_syscall; i++)
105 if (syscall_names[i] && !strcmp(syscall_names[i], name)) {
106 syscall_count[i] = val;
116 static int cmp_count(const void *a, const void *b)
118 return ((struct syscall*)b)->count - ((struct syscall*)a)->count;
121 static void print_syscalls(int policy, const char *json)
126 if (mode == UTRACE) {
127 set_syscall("rt_sigaction", 1);
128 set_syscall("sigreturn", 1);
129 set_syscall("rt_sigreturn", 1);
130 set_syscall("exit_group", 1);
131 set_syscall("exit", 1);
134 struct syscall sorted[ARRAY_SIZE(syscall_names)];
136 for (i = 0; i < ARRAY_SIZE(syscall_names); i++) {
137 sorted[i].syscall = i;
138 sorted[i].count = syscall_count[i];
141 qsort(sorted, ARRAY_SIZE(syscall_names), sizeof(sorted[0]), cmp_count);
143 blob_buf_init(&b, 0);
144 c = blobmsg_open_array(&b, "whitelist");
146 for (i = 0; i < ARRAY_SIZE(syscall_names); i++) {
147 int sc = sorted[i].syscall;
148 if (!sorted[i].count)
150 if (syscall_names[sc]) {
152 printf("syscall %d (%s) was called %d times\n",
153 sc, syscall_names[sc], sorted[i].count);
154 blobmsg_add_string(&b, NULL, syscall_names[sc]);
156 ERROR("no name found for syscall(%d)\n", sc);
159 blobmsg_close_array(&b, c);
160 blobmsg_add_u32(&b, "policy", policy);
162 FILE *fp = fopen(json, "w");
164 fprintf(fp, "%s", blobmsg_format_json_indent(b.head, true, 0));
166 INFO("saving syscall trace to %s\n", json);
168 ERROR("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 if (syscall < ARRAY_SIZE(syscall_names)) {
192 syscall_count[syscall]++;
193 LOGERR("%s[%u] tried to call non-whitelisted syscall: %s (see %s)\n",
194 buf, pid, syscall_names[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);
214 if (syscall < syscall_max) {
215 syscall_count[syscall]++;
217 fprintf(stderr, "%s()\n", syscall_names[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 int main(int argc, char **argv, char **envp)
268 int status, ch, policy = EPERM;
271 /* When invoked via seccomp-trace symlink, work as seccomp
272 * violation logger rather than as syscall tracer */
273 if (strstr(argv[0], "seccomp-trace"))
274 mode = SECCOMP_TRACE;
276 while ((ch = getopt(argc, argv, "f:p:")) != -1) {
282 policy = atoi(optarg);
288 json = getenv("SECCOMP_FILE");
296 if (getenv("TRACE_DEBUG"))
298 unsetenv("TRACE_DEBUG");
303 char **_argv = calloc(argc + 1, sizeof(char *));
305 char *preload = NULL;
306 const char *old_preload = getenv("LD_PRELOAD");
311 memcpy(_argv, argv, argc * sizeof(char *));
316 _envp = calloc(envc + 2, sizeof(char *));
319 preload = "/lib/libpreload-trace.so";
323 preload = "/lib/libpreload-seccomp.so";
325 asprintf(&_envp[1], "SECCOMP_FILE=%s", json ? json : "");
326 kill(getpid(), SIGSTOP);
329 asprintf(&_envp[0], "LD_PRELOAD=%s%s%s", preload,
330 old_preload ? ":" : "",
331 old_preload ? old_preload : "");
332 memcpy(&_envp[newenv], envp, envc * sizeof(char *));
334 ret = execve(_argv[0], _argv, _envp);
335 ERROR("failed to exec %s: %s\n", _argv[0], strerror(errno));
345 syscall_max = ARRAY_SIZE(syscall_names);
346 syscall_count = calloc(syscall_max, sizeof(int));
347 waitpid(child, &status, WUNTRACED);
348 if (!WIFSTOPPED(status)) {
349 ERROR("failed to start %s\n", *argv);
353 int ptrace_options = PTRACE_O_TRACEFORK | PTRACE_O_TRACEVFORK | PTRACE_O_TRACECLONE;
356 ptrace_options |= PTRACE_O_TRACESYSGOOD;
357 ptrace_restart = PTRACE_SYSCALL;
360 ptrace_options |= PTRACE_O_TRACESECCOMP;
361 ptrace_restart = PTRACE_CONT;
364 if (ptrace(PTRACE_SEIZE, child, 0, ptrace_options) == -1)
365 err(1, "PTRACE_SEIZE");
366 if (ptrace(ptrace_restart, child, 0, SIGCONT) == -1)
367 err(1, "ptrace restart");
370 tracer.proc.pid = child;
371 tracer.proc.cb = tracer_cb;
372 uloop_process_add(&tracer.proc);
380 if (asprintf(&json, "/tmp/%s.%u.json", basename(*argv), child) < 0)
381 ERROR("failed to allocate output path: %s\n", strerror(errno));
384 if (!violation_count)
386 asprintf(&json, "/tmp/%s.%u.violations.json", basename(*argv), child);
389 print_syscalls(policy, json);