This makes it easier to handle initial ptrace-stops (after
fork/clone/...), because we don't need to distinguish whether SIGSTOP
is from user or from ptrace. Also execve() does not deliver an extra
SIGTRAP, which we would have to handle.
Signed-off-by: Michal Sojka <sojk...@fel.cvut.cz>
---
trace/preload.c | 1 -
trace/trace.c | 19 +++++++++++++++----
2 files changed, 15 insertions(+), 5 deletions(-)
diff --git a/trace/preload.c b/trace/preload.c
index 99dd906..ee97429 100644
--- a/trace/preload.c
+++ b/trace/preload.c
@@ -32,7 +32,6 @@ static main_t __main__;
static int __preload_main__(int argc, char **argv, char **envp)
{
unsetenv("LD_PRELOAD");
- ptrace(PTRACE_TRACEME);
kill(getpid(), SIGSTOP);
return (*__main__)(argc, argv, envp);
diff --git a/trace/trace.c b/trace/trace.c
index cad2d37..9d3cd0a 100644
--- a/trace/trace.c
+++ b/trace/trace.c
@@ -24,6 +24,12 @@
#include <string.h>
#include <syslog.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>
#include <libubox/blobmsg_json.h>
@@ -150,7 +156,10 @@ static void tracer_cb(struct uloop_process *c, int ret)
struct tracee *tracee = container_of(c, struct tracee, proc);
int inject_signal = 0;
- if (WIFSTOPPED(ret)) {
+ /* 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);
@@ -175,6 +184,8 @@ static void tracer_cb(struct uloop_process *c, int ret)
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 {
inject_signal = WSTOPSIG(ret);
if (debug)
@@ -254,18 +265,18 @@ int main(int argc, char **argv, char **envp)
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(PTRACE_SEIZE, child, 0,
PTRACE_O_TRACESYSGOOD |
PTRACE_O_TRACEFORK |
PTRACE_O_TRACEVFORK |
PTRACE_O_TRACECLONE);
- ptrace(PTRACE_SYSCALL, child, 0, 0);
+ ptrace(PTRACE_SYSCALL, child, 0, SIGCONT);
uloop_init();
tracer.proc.pid = child;
--
2.14.1
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