Commit ebc23cb9 authored by Ramon Nou's avatar Ramon Nou
Browse files

fix syscall tls recursion

parent 73227dff

src/client/intercept.cpp

+48 −25
Original line number Diff line number Diff line
@@ -36,7 +36,7 @@ 


  SPDX-License-Identifier: LGPL-3.0-or-later

*/



#include <pthread.h>

#include <client/intercept.hpp>

#include <client/preload.hpp>

#include <client/hooks.hpp>
@@ -74,7 +74,13 @@ void (*intercept_hook_point_post_kernel)(long syscall_number, long arg0, 
#endif

namespace {



thread_local bool reentrance_guard_flag;

static pthread_key_t reentrance_guard_key;

static pthread_once_t key_once_control = PTHREAD_ONCE_INIT;

static void make_key() {

    // This function will be called exactly once per process.

    pthread_key_create(&reentrance_guard_key, NULL);

}



thread_local gkfs::syscall::info saved_syscall_info;



constexpr void
@@ -533,7 +539,8 @@ hook(long syscall_number, long arg0, long arg1, long arg2, long arg3, long arg4, 


        case SYS_execve:

            // If we do not set this to false, we are in trouble with vforks

            reentrance_guard_flag = false;

pthread_once(&key_once_control, make_key);

            pthread_setspecific(reentrance_guard_key, NULL);

    		*result = syscall_no_intercept_wrapper(

                    syscall_number, reinterpret_cast<const char*>(arg0),

                    reinterpret_cast<const char* const*>(arg1),
@@ -543,7 +550,8 @@ hook(long syscall_number, long arg0, long arg1, long arg2, long arg3, long arg4, 
#ifdef SYS_execveat

        case SYS_execveat:

            // If we do not set this to false, we are in trouble with vforks

            reentrance_guard_flag = false;

pthread_once(&key_once_control, make_key);

            pthread_setspecific(reentrance_guard_key, NULL);

	    *result = syscall_no_intercept_wrapper(

                    syscall_number, arg0, reinterpret_cast<const char*>(arg1),

                    reinterpret_cast<const char* const*>(arg2),
@@ -1011,12 +1019,19 @@ socketcall_wrapper(long syscall_number, long& arg0, long& arg1, long& arg2, 
}

#endif





void

hook_forwarded_syscall(long syscall_number, long arg0, long arg1, long arg2,

                       long arg3, long arg4, long arg5, long result) {

    

    pthread_once(&key_once_control, make_key);

    if (pthread_getspecific(reentrance_guard_key) != NULL) {

        return;

    }

    pthread_setspecific(reentrance_guard_key, (void*) 1);





    if(::get_current_syscall_info() == gkfs::syscall::no_info) {

        pthread_setspecific(reentrance_guard_key, NULL);

        return;

    }
@@ -1029,6 +1044,8 @@ hook_forwarded_syscall(long syscall_number, long arg0, long arg1, long arg2, 
        syscall_number, args, result);



    ::reset_current_syscall_info();

    

    pthread_setspecific(reentrance_guard_key, NULL);

}



void
@@ -1042,12 +1059,13 @@ hook_clone_at_child(unsigned long flags, void* child_stack, int* ptid, 
            static_cast<long>(newtls),    0};

#endif



    reentrance_guard_flag = true;

    pthread_once(&key_once_control, make_key);

    pthread_setspecific(reentrance_guard_key, (void*) 1);



    LOG(SYSCALL, ::get_current_syscall_info() | gkfs::syscall::executed,

        SYS_clone, args, 0);



    reentrance_guard_flag = false;

    pthread_setspecific(reentrance_guard_key, NULL);

}



void
@@ -1061,18 +1079,20 @@ hook_clone_at_parent(unsigned long flags, void* child_stack, int* ptid, 
            static_cast<long>(newtls),    0};

#endif



    reentrance_guard_flag = true;

    pthread_once(&key_once_control, make_key);

    pthread_setspecific(reentrance_guard_key, (void*) 1);



    LOG(SYSCALL, ::get_current_syscall_info() | gkfs::syscall::executed,

        SYS_clone, args, returned_pid);



    reentrance_guard_flag = false;

    pthread_setspecific(reentrance_guard_key, NULL);

}



} // namespace



namespace gkfs::preload {



// This function is inside 'namespace gkfs::preload'

int

internal_hook_guard_wrapper(long syscall_number, long arg0, long arg1,

                            long arg2, long arg3, long arg4, long arg5,
@@ -1085,7 +1105,8 @@ internal_hook_guard_wrapper(long syscall_number, long arg0, long arg1, 
                                            arg3, arg4, arg5);

#endif



    if(reentrance_guard_flag) {

    pthread_once(&key_once_control, make_key);

    if (pthread_getspecific(reentrance_guard_key) != NULL) {

        ::save_current_syscall_info(gkfs::syscall::from_internal_code |

                                    gkfs::syscall::to_kernel |

                                    gkfs::syscall::not_executed);
@@ -1094,15 +1115,14 @@ internal_hook_guard_wrapper(long syscall_number, long arg0, long arg1, 


    int was_hooked = 0;



    reentrance_guard_flag = true;

    pthread_setspecific(reentrance_guard_key, (void*) 1);

    was_hooked = hook_internal(syscall_number, arg0, arg1, arg2, arg3, arg4,

                               arg5, syscall_return_value);

    reentrance_guard_flag = false;

    pthread_setspecific(reentrance_guard_key, NULL);



    return was_hooked;

}





/*

 * hook_guard_wrapper -- a wrapper which can notice reentrance.

 *
@@ -1122,6 +1142,17 @@ hook_guard_wrapper(long syscall_number, long arg0, long arg1, long arg2, 
                   long arg3, long arg4, long arg5,

                   long* syscall_return_value) {



    // --- START OF REVISED FIX for hook_guard_wrapper ---

    pthread_once(&key_once_control, make_key); // Ensure the key is created

    if (pthread_getspecific(reentrance_guard_key) != NULL) {

        // If the guard is set, forward the syscall to the kernel and return.

        return gkfs::syscall::forward_to_kernel;

    }

    // Set the guard to a non-NULL value.

    pthread_setspecific(reentrance_guard_key, (void*) 1);

    // --- END OF REVISED FIX for hook_guard_wrapper ---





    assert(CTX->interception_enabled());



#ifdef SYS_socketcall
@@ -1132,19 +1163,11 @@ hook_guard_wrapper(long syscall_number, long arg0, long arg1, long arg2, 


    int was_hooked = 0;



    if(reentrance_guard_flag) {



        was_hooked = hook_internal(syscall_number, arg0, arg1, arg2, arg3, arg4,

                                   arg5, syscall_return_value);

        return was_hooked;

    }



    reentrance_guard_flag = true;



    was_hooked = ::hook(syscall_number, arg0, arg1, arg2, arg3, arg4, arg5,

                        syscall_return_value);



    reentrance_guard_flag = false;

    // Unset the guard before returning

    pthread_setspecific(reentrance_guard_key, NULL);



    return was_hooked;

}