From de1b03c4c28c00f99cefd5097baf3e17648a8f0b Mon Sep 17 00:00:00 2001
From: i-ky <gl.ivanovsky@gmail.com>
Date: Thu, 23 Feb 2023 20:37:11 +0000
Subject: [PATCH] Drop seccomp approach

---
 src/basset.cpp | 102 +------------------------------------------------
 1 file changed, 2 insertions(+), 100 deletions(-)

diff --git a/src/basset.cpp b/src/basset.cpp
index 6b2b272..eeae880 100644
--- a/src/basset.cpp
+++ b/src/basset.cpp
@@ -1,23 +1,15 @@
 #include <stdio.h>
 #include <unistd.h>
 
-#include <sys/prctl.h>
 #include <sys/ptrace.h>
-#include <sys/syscall.h>
 #include <sys/wait.h>
 
-#include <linux/filter.h>
 #include <linux/ptrace.h>
-#include <linux/seccomp.h>
 
 #undef PTRACE_CONT
-#undef PTRACE_GETEVENTMSG
-#undef PTRACE_GET_SYSCALL_INFO
-#undef PTRACE_PEEKDATA
 #undef PTRACE_SETOPTIONS
 #undef PTRACE_TRACEME
 
-#include <cassert>
 #include <csignal>
 #include <iostream>
 #include <string>
@@ -48,7 +40,7 @@ int main(int argc, char *argv[]) {
 
     if (ptrace(PTRACE_SETOPTIONS, pid, nullptr,
                PTRACE_O_TRACECLONE | PTRACE_O_TRACEFORK | PTRACE_O_TRACEVFORK |
-                   PTRACE_O_TRACEEXEC | PTRACE_O_TRACESECCOMP) == -1) {
+                   PTRACE_O_TRACEEXEC) == -1) {
       perror("cannot ptrace(PTRACE_SETOPTIONS)");
       return -1;
     }
@@ -74,80 +66,8 @@ int main(int argc, char *argv[]) {
           case PTRACE_EVENT_CLONE:
           case PTRACE_EVENT_EXEC:
           case PTRACE_EVENT_FORK:
-          case PTRACE_EVENT_VFORK: {
-            unsigned long data;
-
-            if (ptrace(PTRACE_GETEVENTMSG, pid, nullptr, &data) == -1) {
-              perror("cannot ptrace(PTRACE_GETEVENTMSG)");
-              return -1;
-            }
-
-            cerr << "event msg: " << data << '\n';
-            break;
-          }
-          case PTRACE_EVENT_SECCOMP: {
-            unsigned long ret_data;
-
-            if (ptrace(PTRACE_GETEVENTMSG, pid, nullptr, &ret_data) == -1) {
-              perror("cannot ptrace(PTRACE_GETEVENTMSG)");
-              return -1;
-            }
-
-            cerr << "SECCOMP_RET_DATA: " << ret_data << '\n';
-
-            ptrace_syscall_info data;
-            auto res =
-                ptrace(PTRACE_GET_SYSCALL_INFO, pid, sizeof(data), &data);
-
-            if (res == -1) {
-              perror("cannot ptrace(PTRACE_GET_SYSCALL_INFO)");
-              return -1;
-            }
-
-            if (res > sizeof(data)) {
-              cerr << "some data truncated\n";
-            } else {
-              assert(res > 0);
-
-              switch (data.op) {
-              case PTRACE_SYSCALL_INFO_SECCOMP: {
-                cerr << "seccomp " << data.seccomp.nr << '\n';
-
-                for (auto arg : data.seccomp.args) {
-                  cerr << arg << ',';
-                }
-
-                cerr << '\n';
-                assert(ret_data == data.seccomp.ret_data);
-
-                string path;
-                auto *addr = reinterpret_cast<char *>(data.seccomp.args[0]);
-                do {
-                  errno = 0;
-                  const auto peek = ptrace(PTRACE_PEEKDATA, pid, addr, 0);
-
-                  if (peek == -1 && errno != 0) {
-                    perror("cannot ptrace(PTRACE_PEEKDATA)");
-                    return -1;
-                  }
-                  path.append(reinterpret_cast<const char *>(&peek), sizeof(peek));
-                  addr += sizeof(peek);
-                } while (path.find('\0') == string::npos);
-
-                cerr << path << '\n';
-                break;
-              }
-              case PTRACE_SYSCALL_INFO_NONE:
-              case PTRACE_SYSCALL_INFO_ENTRY:
-              case PTRACE_SYSCALL_INFO_EXIT:
-              default:
-                cerr << "unexpected syscall operation: "
-                     << static_cast<int>(data.op) << '\n';
-                return -1;
-              }
-            }
+          case PTRACE_EVENT_VFORK:
             break;
-          }
           default:
             cerr << "unknown stop event, signal: " << (wstatus >> 16) << '\n';
             return -1;
@@ -176,24 +96,6 @@ int main(int argc, char *argv[]) {
     return -1;
   }
 
-  sock_filter filter[] = {
-      BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(seccomp_data, nr)),
-      BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, __NR_chdir, 0, 1),
-      BPF_STMT(BPF_RET + BPF_K, SECCOMP_RET_TRACE),
-      BPF_STMT(BPF_RET + BPF_K, SECCOMP_RET_ALLOW),
-  };
-  sock_fprog prog = {sizeof(filter) / sizeof(*filter), filter};
-
-  if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) != 0) {
-    perror("cannot prctl(PR_SET_NO_NEW_PRIVS)");
-    return -1;
-  }
-
-  if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog, 0, 0) != 0) {
-    perror("cannot prctl(PR_SET_SECCOMP)");
-    return -1;
-  }
-
   // allow parent to ptrace(PTRACE_SETOPTIONS)
   if (raise(SIGSTOP) != 0) {
     perror("cannot raise(SIGSTOP)");