Verified Commit 92cdbe05 authored by Tommaso Tocci's avatar Tommaso Tocci
Browse files

intercept basic syscalls

parent d0e8d84a

ifs/include/preload/adafs_functions.hpp

+2 −0
Original line number Diff line number Diff line
@@ -52,6 +52,8 @@ int adafs_dup(int oldfd); 


int adafs_dup2(int oldfd, int newfd);



ssize_t adafs_write(int fd, void* buf, size_t count);



ssize_t adafs_pwrite_ws(int fd, const void* buf, size_t count, off64_t offset);



ssize_t adafs_read(int fd, void* buf, size_t count);

ifs/include/preload/hooks.hpp

+6 −0
Original line number Diff line number Diff line
@@ -5,5 +5,11 @@ 




int hook_openat(int dirfd, const char *cpath, int flags, mode_t mode);

int hook_close(int fd);

int hook_stat(const char* path, struct stat* buf);

int hook_read(int fd, void* buf, size_t count);

int hook_write(int fd, void* buf, size_t count);

int hook_unlink(const char* path);





#endif

ifs/src/preload/adafs_functions.cpp

+12 −0
Original line number Diff line number Diff line
@@ -284,6 +284,18 @@ int adafs_dup2(const int oldfd, const int newfd) { 
    return CTX->file_map()->dup2(oldfd, newfd);

}



ssize_t adafs_write(int fd, void* buf, size_t count) {

            auto adafs_fd = CTX->file_map()->get(fd);

            auto pos = adafs_fd->pos(); //retrieve the current offset

            if (adafs_fd->get_flag(OpenFile_flags::append))

                adafs_lseek(adafs_fd, 0, SEEK_END);

            auto ret = adafs_pwrite_ws(fd, buf, count, pos);

            // Update offset in file descriptor in the file map

            if (ret > 0) {

                adafs_fd->pos(pos + count);

            }

            return ret;

}



ssize_t adafs_pwrite_ws(int fd, const void* buf, size_t count, off64_t offset) {

    auto adafs_fd = CTX->file_map()->get(fd);

ifs/src/preload/hooks.cpp

+60 −3
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ int hook_openat(int dirfd, const char *cpath, int flags, mode_t mode) { 
            if(ret < 0) {

                return -errno;

            }

            return ret;

        }

    } else {

        // cpath is relative
@@ -44,8 +45,7 @@ int hook_openat(int dirfd, const char *cpath, int flags, mode_t mode) { 
        auto dir = CTX->file_map()->get_dir(dirfd);

        if(dir == nullptr) {

            CTX->log()->error("{}() dirfd is not a directory ", __func__);

            errno = ENOTDIR;

            return -1;

            return -ENOTDIR;

        }



        std::string path = CTX->mountdir();
@@ -57,7 +57,64 @@ int hook_openat(int dirfd, const char *cpath, int flags, mode_t mode) { 
            if(ret < 0) {

                return -errno;

            }

            return ret;

        }

    }

    return syscall_no_intercept(SYS_openat, dirfd, resolved.c_str(), flags, mode);

}



int hook_close(int fd) {

    CTX->log()->trace("{}() called with fd {}", __func__, fd);

    if(CTX->file_map()->exist(fd)) {

        // No call to the daemon is required

        CTX->file_map()->remove(fd);

        return 0;

    }

    return syscall_no_intercept(SYS_close, fd);

}



int hook_stat(const char* path, struct stat* buf) {

    CTX->log()->trace("{}() called with path '{}'", __func__, path);

    std::string rel_path;

    if (CTX->relativize_path(path, rel_path)) {

            return with_errno(adafs_stat(rel_path, buf));

    }

    return syscall_no_intercept(SYS_stat, rel_path.c_str(), buf);

}



int hook_read(int fd, void* buf, size_t count) {

    CTX->log()->trace("{}() called with fd {}, count {}", __func__, fd, count);

    if (CTX->file_map()->exist(fd)) {

        auto ret = adafs_read(fd, buf, count);

        if(ret < 0) {

            return -errno;

        }

        return ret;

    }

    return syscall_no_intercept(SYS_read, fd, buf, count);

}



int hook_write(int fd, void* buf, size_t count) {

    CTX->log()->trace("{}() called with fd {}, count {}", __func__, fd, count);

    if (CTX->file_map()->exist(fd)) {

        auto ret = adafs_write(fd, buf, count);

        if(ret < 0) {

            return -errno;

        }

        return ret;

    }

    return syscall_no_intercept(SYS_write, fd, buf, count);

}



int hook_unlink(const char* path) {

    CTX->log()->trace("{}() called with path '{}'", __func__, path);

    std::string rel_path;

    if (CTX->relativize_path(path, rel_path)) {

        auto ret = adafs_rm_node(rel_path);

        if(ret < 0) {

            return -errno;

        }

        return ret;

    }

    return syscall_no_intercept(SYS_unlink, rel_path.c_str());

}

ifs/src/preload/intercept.cpp

+32 −0
Original line number Diff line number Diff line
@@ -30,6 +30,38 @@ static inline int hook(long syscall_number, 
                              static_cast<mode_t>(arg2));

        break;



    case SYS_openat:

        *result = hook_openat(static_cast<int>(arg0),

                              reinterpret_cast<const char*>(arg1),

                              static_cast<int>(arg2),

                              static_cast<mode_t>(arg3));

        break;



    case SYS_close:

        *result = hook_close(static_cast<int>(arg0));

        break;



    case SYS_stat:

        *result = hook_stat(reinterpret_cast<char*>(arg0),

                            reinterpret_cast<struct stat*>(arg1));

        break;



    case SYS_read:

        *result = hook_read(static_cast<int>(arg0),

                            reinterpret_cast<void*>(arg1),

                            static_cast<size_t>(arg2));

        break;



    case SYS_write:

        *result = hook_write(static_cast<int>(arg0),

                             reinterpret_cast<void*>(arg1),

                             static_cast<size_t>(arg2));

        break;



    case SYS_unlink:

        *result = hook_unlink(reinterpret_cast<char*>(arg0));

        break;



    default:

        /*

         * Ignore any other syscalls