prosper0gdb: add sigaction20

Allows to set signal handlers to SIGKILL and SIGSTOP

prosper0gdb/r0gdb.c

@@ -10,6 +10,7 @@
 #include <sys/ptrace.h>
 #include <sys/ucontext.h>
 #include <sys/cpuset.h>
+#include <sys/syscall.h>
 #include <machine/sysarch.h>
 #include <signal.h>
 #include <netinet/in.h>
@@ -539,6 +540,35 @@ void* mmap20(void* addr, size_t sz, int prot, int flags, int fd, off_t offset)
     return ans;
 }
 
+static uint64_t sys_write;
+static uint64_t sys_sigaction;
+
+static void fix_sigaction_17_9(uint64_t* regs)
+{
+    SKIP_SCHEDULER
+    if(regs[0] == sys_write)
+        regs[0] = sys_sigaction;
+    else if(regs[0] == kdata_base - 0x6c2989)
+        regs[0] = kdata_base - 0x6c2933;
+}
+
+int sigaction20(int sig, const struct sigaction* neww, struct sigaction* oldd)
+{
+    if(sig != SIGKILL && sig != SIGSTOP)
+        return sigaction(sig, neww, oldd);
+    r0gdb_instrument(0);
+    int(*p_write)(int, const void*, void*) = dlsym((void*)0x2001, "_write");
+    trace_prog = fix_sigaction_17_9;
+    if(!sys_write)
+        kmemcpy(&sys_write, (void*)(kdata_base + 0x1709c0 + 48*SYS_write + 8), 8);
+    if(!sys_sigaction)
+        kmemcpy(&sys_sigaction, (void*)(kdata_base + 0x1709c0 + 48*SYS_sigaction + 8), 8);
+    set_trace();
+    int ans = p_write(sig, neww, oldd);
+    trace_prog = 0;
+    return ans;
+}
+
 static uint64_t fncall_fn = 0;
 static uint64_t fncall_args[6];
 static uint64_t fncall_ans = 0;

prosper0gdb/r0gdb.h

@@ -48,6 +48,10 @@ int mprotect20(void* addr, size_t sz, int prot);
 //mmap with map_self
 void* mmap20(void* addr, size_t sz, int prot, int flags, int fd, off_t offset);
 
+//sigaction with sigstop/sigkill
+struct sigaction;
+int sigaction20(int sig, const struct sigaction* neww, struct sigaction* oldd);
+
 //kernel function call
 uint64_t r0gdb_kfncall(uint64_t kfn, ...);