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Kernel: Remove SmapDisablers in open(), openat() and set_thread_name()

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This patch introduces a helpful copy_string_from_user() function
that takes a bounded null-terminated string from userspace memory
and copies it into a String object.
This commit is contained in:
Andreas Kling 2020-01-05 21:51:06 +01:00
parent c4a1ea34c2
commit 80cbb72f2f
3 changed files with 37 additions and 33 deletions
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56
Kernel/Process.cpp
View file

@ -1600,34 +1600,22 @@ int Process::number_of_open_file_descriptors() const
return count; return count;
} }
int Process::sys$open(const Syscall::SC_open_params* params) int Process::sys$open(const Syscall::SC_open_params* user_params)
{ {
if (!validate_read_typed(params)) if (!validate_read_typed(user_params))
return -EFAULT; return -EFAULT;
const char* path_data; Syscall::SC_open_params params;
int path_length; copy_from_user(&params, user_params, sizeof(params));
int options; auto options = params.options;
u16 mode; auto mode = params.mode;
{ if (params.path_length <= 0)
SmapDisabler disabler;
path_data = params->path;
path_length = params->path_length;
options = params->options;
mode = params->mode;
}
if (!path_length)
return -EINVAL; return -EINVAL;
if (!validate_read(path_data, path_length)) if (!validate_read(params.path, params.path_length))
return -EFAULT; return -EFAULT;
String path; String path = copy_string_from_user(params.path, params.path_length);
{
SmapDisabler disabler;
path = String(path_data, path_length);
}
int fd = alloc_fd(); int fd = alloc_fd();
#ifdef DEBUG_IO #ifdef DEBUG_IO
dbgprintf("%s(%u) sys$open(\"%s\") -> %d\n", name().characters(), pid(), path, fd); dbgprintf("%s(%u) sys$open(\"%s\") -> %d\n", name().characters(), pid(), path, fd);
@ -1645,20 +1633,22 @@ int Process::sys$open(const Syscall::SC_open_params* params)
return fd; return fd;
} }
int Process::sys$openat(const Syscall::SC_openat_params* params) int Process::sys$openat(const Syscall::SC_openat_params* user_params)
{ {
if (!validate_read_typed(params)) if (!validate_read_typed(user_params))
return -EFAULT; return -EFAULT;
SmapDisabler disabler; Syscall::SC_openat_params params;
int dirfd = params->dirfd; copy_from_user(&params, user_params, sizeof(params));
const char* path = params->path; int dirfd = params.dirfd;
int path_length = params->path_length; int options = params.options;
int options = params->options; u16 mode = params.mode;
u16 mode = params->mode;
if (!validate_read(path, path_length)) if (params.path_length <= 0)
return -EINVAL;
if (!validate_read(params.path, params.path_length))
return -EFAULT; return -EFAULT;
auto path = copy_string_from_user(params.path, params.path_length);
#ifdef DEBUG_IO #ifdef DEBUG_IO
dbgprintf("%s(%u) sys$openat(%d, \"%s\")\n", dirfd, name().characters(), pid(), path); dbgprintf("%s(%u) sys$openat(%d, \"%s\")\n", dirfd, name().characters(), pid(), path);
#endif #endif
@ -3377,17 +3367,17 @@ int Process::sys$set_thread_name(int tid, const char* buffer, int buffer_size)
if (!validate_read(buffer, buffer_size)) if (!validate_read(buffer, buffer_size))
return -EFAULT; return -EFAULT;
SmapDisabler disabler; auto name = copy_string_from_user(buffer, buffer_size);
const size_t max_thread_name_size = 64; const size_t max_thread_name_size = 64;
if (strnlen(buffer, (size_t)buffer_size) > max_thread_name_size) if (name.length() > max_thread_name_size)
return -EINVAL; return -EINVAL;
auto* thread = Thread::from_tid(tid); auto* thread = Thread::from_tid(tid);
if (!thread || thread->pid() != pid()) if (!thread || thread->pid() != pid())
return -ESRCH; return -ESRCH;
thread->set_name({ buffer, (size_t)buffer_size }); thread->set_name(name);
return 0; return 0;
} }
int Process::sys$get_thread_name(int tid, char* buffer, int buffer_size) int Process::sys$get_thread_name(int tid, char* buffer, int buffer_size)

8
Kernel/StdLib.cpp
View file

@ -1,9 +1,17 @@
#include <AK/Assertions.h> #include <AK/Assertions.h>
#include <AK/String.h>
#include <AK/Types.h> #include <AK/Types.h>
#include <Kernel/Arch/i386/CPU.h> #include <Kernel/Arch/i386/CPU.h>
#include <Kernel/Heap/kmalloc.h> #include <Kernel/Heap/kmalloc.h>
#include <Kernel/StdLib.h> #include <Kernel/StdLib.h>
String copy_string_from_user(const char* user_str, size_t user_str_size)
{
SmapDisabler disabler;
size_t length = strnlen(user_str, user_str_size);
return String(user_str, length);
}
extern "C" { extern "C" {
void* copy_to_user(void* dest_ptr, const void* src_ptr, size_t n) void* copy_to_user(void* dest_ptr, const void* src_ptr, size_t n)

6
Kernel/StdLib.h
View file

@ -2,6 +2,12 @@
#include <AK/Types.h> #include <AK/Types.h>
namespace AK {
class String;
}
AK::String copy_string_from_user(const char*, size_t);
extern "C" { extern "C" {
static_assert(sizeof(size_t) == 4); static_assert(sizeof(size_t) == 4);