*/
#define _GNU_SOURCE
+#include <fcntl.h>
#include <stddef.h>
#include <sys/ptrace.h>
+#include <sys/stat.h>
#include <sys/types.h>
#include <sys/user.h>
#include <sys/wait.h>
#include <errno.h>
#include <string.h>
#include <syslog.h>
+#include <err.h>
+
+#ifndef PTRACE_EVENT_STOP
+/* PTRACE_EVENT_STOP is defined in linux/ptrace.h, but this header
+ * collides with musl's sys/ptrace.h */
+#define PTRACE_EVENT_STOP 128
+#endif
#include <libubox/uloop.h>
#include <libubox/blobmsg.h>
# endif
#define reg_syscall_nr (EF_REG2 / 4)
#elif defined(__arm__)
+#include <asm/ptrace.h> /* for PTRACE_SET_SYSCALL */
#define reg_syscall_nr _offsetof(struct user, regs.uregs[7])
+# if defined(__ARM_EABI__)
+# define reg_retval_nr _offsetof(struct user, regs.uregs[0])
+# endif
#else
#error tracing is not supported on this architecture
#endif
+enum mode {
+ UTRACE,
+ SECCOMP_TRACE,
+} mode = UTRACE;
+
+#define PROC_NAME(mode) (mode == UTRACE ? "utrace" : "seccomp-trace")
+
#define INFO(fmt, ...) do { \
- fprintf(stderr, "utrace: "fmt, ## __VA_ARGS__); \
+ fprintf(stderr, "%s: "fmt, PROC_NAME(mode), ## __VA_ARGS__); \
} while (0)
#define ERROR(fmt, ...) do { \
- syslog(LOG_ERR, "utrace: "fmt, ## __VA_ARGS__); \
- fprintf(stderr, "utrace: "fmt, ## __VA_ARGS__); \
+ syslog(LOG_ERR, "%s: "fmt, PROC_NAME(mode), ## __VA_ARGS__); \
+ fprintf(stderr, "%s: "fmt, PROC_NAME(mode), ## __VA_ARGS__); \
+} while (0)
+
+#define LOGERR(fmt, ...) do { \
+ syslog(LOG_ERR, "%s: "fmt, PROC_NAME(mode), ## __VA_ARGS__); \
} while (0)
-static struct uloop_process tracer;
-static int *syscall_count;
+struct tracee {
+ struct uloop_process proc;
+ int in_syscall;
+};
+
+static struct tracee tracer;
+static int syscall_count[SYSCALL_COUNT];
+static int violation_count;
static struct blob_buf b;
-static int syscall_max;
-static int in_syscall;
static int debug;
-
-static int max_syscall = ARRAY_SIZE(syscall_names);
+char *json = NULL;
+int ptrace_restart;
static void set_syscall(const char *name, int val)
{
int i;
- for (i = 0; i < max_syscall; i++)
- if (syscall_names[i] && !strcmp(syscall_names[i], name)) {
+ for (i = 0; i < SYSCALL_COUNT; i++) {
+ int sc = syscall_index_to_number(i);
+ if (syscall_name(sc) && !strcmp(syscall_name(sc), name)) {
syscall_count[i] = val;
return;
}
+ }
+}
+
+struct syscall {
+ int syscall;
+ int count;
+};
+
+static int cmp_count(const void *a, const void *b)
+{
+ return ((struct syscall*)b)->count - ((struct syscall*)a)->count;
}
static void print_syscalls(int policy, const char *json)
void *c;
int i;
- set_syscall("rt_sigaction", 1);
- set_syscall("sigreturn", 1);
- set_syscall("rt_sigreturn", 1);
- set_syscall("exit_group", 1);
- set_syscall("exit", 1);
+ if (mode == UTRACE) {
+ set_syscall("rt_sigaction", 1);
+ set_syscall("sigreturn", 1);
+ set_syscall("rt_sigreturn", 1);
+ set_syscall("exit_group", 1);
+ set_syscall("exit", 1);
+ }
+
+ struct syscall sorted[SYSCALL_COUNT];
+
+ for (i = 0; i < SYSCALL_COUNT; i++) {
+ sorted[i].syscall = syscall_index_to_number(i);
+ sorted[i].count = syscall_count[i];
+ }
+
+ qsort(sorted, SYSCALL_COUNT, sizeof(sorted[0]), cmp_count);
blob_buf_init(&b, 0);
c = blobmsg_open_array(&b, "whitelist");
- for (i = 0; i < ARRAY_SIZE(syscall_names); i++) {
- if (!syscall_count[i])
- continue;
- if (syscall_names[i]) {
+ for (i = 0; i < SYSCALL_COUNT; i++) {
+ int sc = sorted[i].syscall;
+ if (!sorted[i].count)
+ break;
+ if (syscall_name(sc)) {
if (debug)
printf("syscall %d (%s) was called %d times\n",
- i, syscall_names[i], syscall_count[i]);
- blobmsg_add_string(&b, NULL, syscall_names[i]);
+ sc, syscall_name(sc), sorted[i].count);
+ blobmsg_add_string(&b, NULL, syscall_name(sc));
} else {
- ERROR("no name found for syscall(%d)\n", i);
+ ERROR("no name found for syscall(%d)\n", sc);
}
}
blobmsg_close_array(&b, c);
}
-static void tracer_cb(struct uloop_process *c, int ret)
+static void report_seccomp_vialation(pid_t pid, unsigned syscall)
{
- if (WIFSTOPPED(ret) && WSTOPSIG(ret) & 0x80) {
- if (!in_syscall) {
- int syscall = ptrace(PTRACE_PEEKUSER, c->pid, reg_syscall_nr);
+ char buf[200];
+ snprintf(buf, sizeof(buf), "/proc/%d/cmdline", pid);
+ int f = open(buf, O_RDONLY);
+ int r = read(f, buf, sizeof(buf) - 1);
+ if (r >= 0)
+ buf[r] = 0;
+ else
+ strcpy(buf, "unknown?");
+ close(f);
+
+ if (violation_count < INT_MAX)
+ violation_count++;
+ int i = syscall_index(syscall);
+ if (i >= 0) {
+ syscall_count[i]++;
+ LOGERR("%s[%u] tried to call non-whitelisted syscall: %s (see %s)\n",
+ buf, pid, syscall_name(syscall), json);
+ } else {
+ LOGERR("%s[%u] tried to call non-whitelisted syscall: %d (see %s)\n",
+ buf, pid, syscall, json);
+ }
+}
- if (syscall < syscall_max) {
- syscall_count[syscall]++;
- if (debug)
- fprintf(stderr, "%s()\n", syscall_names[syscall]);
- } else if (debug) {
- fprintf(stderr, "syscal(%d)\n", syscall);
+static void tracer_cb(struct uloop_process *c, int ret)
+{
+ struct tracee *tracee = container_of(c, struct tracee, proc);
+ int inject_signal = 0;
+
+ /* We explicitely check for events in upper 16 bits, because
+ * musl (as opposed to glibc) does not report
+ * PTRACE_EVENT_STOP as WIFSTOPPED */
+ if (WIFSTOPPED(ret) || (ret >> 16)) {
+ if (WSTOPSIG(ret) & 0x80) {
+ if (!tracee->in_syscall) {
+ int syscall = ptrace(PTRACE_PEEKUSER, c->pid, reg_syscall_nr);
+ int i = syscall_index(syscall);
+ if (i >= 0) {
+ syscall_count[i]++;
+ if (debug)
+ fprintf(stderr, "%s()\n", syscall_name(syscall));
+ } else if (debug) {
+ fprintf(stderr, "syscal(%d)\n", syscall);
+ }
}
+ tracee->in_syscall = !tracee->in_syscall;
+ } else if ((ret >> 8) == (SIGTRAP | (PTRACE_EVENT_FORK << 8)) ||
+ (ret >> 8) == (SIGTRAP | (PTRACE_EVENT_VFORK << 8)) ||
+ (ret >> 8) == (SIGTRAP | (PTRACE_EVENT_CLONE << 8))) {
+ struct tracee *child = calloc(1, sizeof(struct tracee));
+
+ ptrace(PTRACE_GETEVENTMSG, c->pid, 0, &child->proc.pid);
+ child->proc.cb = tracer_cb;
+ ptrace(ptrace_restart, child->proc.pid, 0, 0);
+ uloop_process_add(&child->proc);
+ if (debug)
+ fprintf(stderr, "Tracing new child %d\n", child->proc.pid);
+ } else if ((ret >> 16) == PTRACE_EVENT_STOP) {
+ /* Nothing special to do here */
+ } else if ((ret >> 8) == (SIGTRAP | (PTRACE_EVENT_SECCOMP << 8))) {
+ int syscall = ptrace(PTRACE_PEEKUSER, c->pid, reg_syscall_nr);
+#if defined(__arm__)
+ ptrace(PTRACE_SET_SYSCALL, c->pid, 0, -1);
+ ptrace(PTRACE_POKEUSER, c->pid, reg_retval_nr, -ENOSYS);
+#else
+ ptrace(PTRACE_POKEUSER, c->pid, reg_syscall_nr, -1);
+#endif
+ report_seccomp_vialation(c->pid, syscall);
+ } else {
+ inject_signal = WSTOPSIG(ret);
+ if (debug)
+ fprintf(stderr, "Injecting signal %d into pid %d\n",
+ inject_signal, tracee->proc.pid);
+ }
+ } else if (WIFEXITED(ret) || (WIFSIGNALED(ret) && WTERMSIG(ret))) {
+ if (tracee == &tracer) {
+ uloop_end(); /* Main process exit */
+ } else {
+ if (debug)
+ fprintf(stderr, "Child %d exited\n", tracee->proc.pid);
+ free(tracee);
}
- in_syscall = !in_syscall;
- } else if (WIFEXITED(ret)) {
- uloop_end();
return;
}
- ptrace(PTRACE_SYSCALL, c->pid, 0, 0);
- uloop_process_add(&tracer);
+
+ ptrace(ptrace_restart, c->pid, 0, inject_signal);
+ uloop_process_add(c);
}
+static void sigterm_handler(int signum)
+{
+ /* When we receive SIGTERM, we forward it to the tracee. After
+ * the tracee exits, trace_cb() will be called and make us
+ * exit too. */
+ kill(tracer.proc.pid, SIGTERM);
+}
+
+
int main(int argc, char **argv, char **envp)
{
- char *json = NULL;
int status, ch, policy = EPERM;
pid_t child;
+ /* When invoked via seccomp-trace symlink, work as seccomp
+ * violation logger rather than as syscall tracer */
+ if (strstr(argv[0], "seccomp-trace"))
+ mode = SECCOMP_TRACE;
+
while ((ch = getopt(argc, argv, "f:p:")) != -1) {
switch (ch) {
case 'f':
}
}
+ if (!json)
+ json = getenv("SECCOMP_FILE");
+
argc -= optind;
argv += optind;
if (child == 0) {
char **_argv = calloc(argc + 1, sizeof(char *));
char **_envp;
- char *preload = "LD_PRELOAD=/lib/libpreload-trace.so";
- int envc = 1;
+ char *preload = NULL;
+ const char *old_preload = getenv("LD_PRELOAD");
+ int newenv = 0;
+ int envc = 0;
int ret;
memcpy(_argv, argv, argc * sizeof(char *));
while (envp[envc++])
;
- _envp = calloc(envc, sizeof(char *));
- memcpy(&_envp[1], envp, envc * sizeof(char *));
- *_envp = preload;
+ _envp = calloc(envc + 2, sizeof(char *));
+ switch (mode) {
+ case UTRACE:
+ preload = "/lib/libpreload-trace.so";
+ newenv = 1;
+ break;
+ case SECCOMP_TRACE:
+ preload = "/lib/libpreload-seccomp.so";
+ newenv = 2;
+ asprintf(&_envp[1], "SECCOMP_FILE=%s", json ? json : "");
+ kill(getpid(), SIGSTOP);
+ break;
+ }
+ asprintf(&_envp[0], "LD_PRELOAD=%s%s%s", preload,
+ old_preload ? ":" : "",
+ old_preload ? old_preload : "");
+ memcpy(&_envp[newenv], envp, envc * sizeof(char *));
ret = execve(_argv[0], _argv, _envp);
ERROR("failed to exec %s: %s\n", _argv[0], strerror(errno));
if (child < 0)
return -1;
- syscall_max = ARRAY_SIZE(syscall_names);
- syscall_count = calloc(syscall_max, sizeof(int));
- waitpid(child, &status, 0);
+ waitpid(child, &status, WUNTRACED);
if (!WIFSTOPPED(status)) {
ERROR("failed to start %s\n", *argv);
return -1;
}
- ptrace(PTRACE_SETOPTIONS, child, 0, PTRACE_O_TRACESYSGOOD);
- ptrace(PTRACE_SYSCALL, child, 0, 0);
+ int ptrace_options = PTRACE_O_TRACEFORK | PTRACE_O_TRACEVFORK | PTRACE_O_TRACECLONE;
+ switch (mode) {
+ case UTRACE:
+ ptrace_options |= PTRACE_O_TRACESYSGOOD;
+ ptrace_restart = PTRACE_SYSCALL;
+ break;
+ case SECCOMP_TRACE:
+ ptrace_options |= PTRACE_O_TRACESECCOMP;
+ ptrace_restart = PTRACE_CONT;
+ break;
+ }
+ if (ptrace(PTRACE_SEIZE, child, 0, ptrace_options) == -1)
+ err(1, "PTRACE_SEIZE");
+ if (ptrace(ptrace_restart, child, 0, SIGCONT) == -1)
+ err(1, "ptrace restart");
uloop_init();
- tracer.pid = child;
- tracer.cb = tracer_cb;
- uloop_process_add(&tracer);
+ tracer.proc.pid = child;
+ tracer.proc.cb = tracer_cb;
+ uloop_process_add(&tracer.proc);
+ signal(SIGTERM, sigterm_handler); /* Override uloop's SIGTERM handler */
uloop_run();
uloop_done();
- if (!json)
- if (asprintf(&json, "/tmp/%s.%u.json", basename(*argv), child) < 0)
- ERROR("failed to allocate output path: %s\n", strerror(errno));
+ switch (mode) {
+ case UTRACE:
+ if (!json)
+ if (asprintf(&json, "/tmp/%s.%u.json", basename(*argv), child) < 0)
+ ERROR("failed to allocate output path: %s\n", strerror(errno));
+ break;
+ case SECCOMP_TRACE:
+ if (!violation_count)
+ return 0;
+ asprintf(&json, "/tmp/%s.%u.violations.json", basename(*argv), child);
+ break;
+ }
print_syscalls(policy, json);
-
return 0;
}
projects / project / procd.git / blobdiff