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Implement address validation by querying the task's page directory.

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This is way better than walking the region lists. I suppose we could
even let the hardware trigger a page fault and handle that. That'll
be the next step in the evolution here I guess.
This commit is contained in:
Andreas Kling 2018-11-01 12:45:51 +01:00
parent f76fcd1e62
commit 0f70b9105f
5 changed files with 82 additions and 34 deletions
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70
Kernel/Task.cpp
View file

@ -19,10 +19,19 @@
//#define TASK_DEBUG
//#define SCHEDULER_DEBUG
#define VALIDATE_USER_BUFFER(b, s) \
// FIXME: Only do a single validation for accesses that don't span multiple pages.
// FIXME: Some places pass strlen(arg1) as arg2. This doesn't seem entirely perfect..
#define VALIDATE_USER_READ(b, s) \
do { \
LinearAddress laddr((dword)(b)); \
if (!isValidAddressForUser(laddr) || !isValidAddressForUser(laddr.offset((s) - 1))) \
if (!validate_user_read(laddr) || !validate_user_read(laddr.offset((s) - 1))) \
return -EFAULT; \
} while(0)
#define VALIDATE_USER_WRITE(b, s) \
do { \
LinearAddress laddr((dword)(b)); \
if (!validate_user_write(laddr) || !validate_user_write(laddr.offset((s) - 1))) \
return -EFAULT; \
} while(0)
@ -172,7 +181,7 @@ Task::Region* Task::regionFromRange(LinearAddress laddr, size_t size)
int Task::sys$set_mmap_name(void* addr, size_t size, const char* name)
{
VALIDATE_USER_BUFFER(name, strlen(name));
VALIDATE_USER_READ(name, strlen(name));
auto* region = regionFromRange(LinearAddress((dword)addr), size);
if (!region)
return -EINVAL;
@ -205,7 +214,7 @@ int Task::sys$munmap(void* addr, size_t size)
int Task::sys$gethostname(char* buffer, size_t size)
{
VALIDATE_USER_BUFFER(buffer, size);
VALIDATE_USER_WRITE(buffer, size);
auto hostname = getHostname();
if (size < (hostname.length() + 1))
return -ENAMETOOLONG;
@ -217,7 +226,7 @@ int Task::sys$spawn(const char* path, const char** args)
{
if (args) {
for (size_t i = 0; args[i]; ++i) {
VALIDATE_USER_BUFFER(args[i], strlen(args[i]));
VALIDATE_USER_READ(args[i], strlen(args[i]));
}
}
@ -792,7 +801,7 @@ FileHandle* Task::fileHandleIfExists(int fd)
ssize_t Task::sys$get_dir_entries(int fd, void* buffer, size_t size)
{
VALIDATE_USER_BUFFER(buffer, size);
VALIDATE_USER_WRITE(buffer, size);
auto* handle = fileHandleIfExists(fd);
if (!handle)
return -EBADF;
@ -809,7 +818,7 @@ int Task::sys$lseek(int fd, off_t offset, int whence)
int Task::sys$ttyname_r(int fd, char* buffer, size_t size)
{
VALIDATE_USER_BUFFER(buffer, size);
VALIDATE_USER_WRITE(buffer, size);
auto* handle = fileHandleIfExists(fd);
if (!handle)
return -EBADF;
@ -824,7 +833,7 @@ int Task::sys$ttyname_r(int fd, char* buffer, size_t size)
ssize_t Task::sys$write(int fd, const void* data, size_t size)
{
VALIDATE_USER_BUFFER(data, size);
VALIDATE_USER_READ(data, size);
#ifdef DEBUG_IO
kprintf("Task::sys$write: called(%d, %p, %u)\n", fd, data, size);
#endif
@ -843,7 +852,7 @@ ssize_t Task::sys$write(int fd, const void* data, size_t size)
ssize_t Task::sys$read(int fd, void* outbuf, size_t nread)
{
VALIDATE_USER_BUFFER(outbuf, nread);
VALIDATE_USER_WRITE(outbuf, nread);
#ifdef DEBUG_IO
kprintf("Task::sys$read: called(%d, %p, %u)\n", fd, outbuf, nread);
#endif
@ -878,7 +887,7 @@ int Task::sys$close(int fd)
int Task::sys$lstat(const char* path, Unix::stat* statbuf)
{
VALIDATE_USER_BUFFER(statbuf, sizeof(Unix::stat));
VALIDATE_USER_WRITE(statbuf, sizeof(Unix::stat));
int error;
auto handle = VirtualFileSystem::the().open(move(path), error, O_NOFOLLOW_NOERROR, cwdInode());
if (!handle)
@ -889,7 +898,7 @@ int Task::sys$lstat(const char* path, Unix::stat* statbuf)
int Task::sys$stat(const char* path, Unix::stat* statbuf)
{
VALIDATE_USER_BUFFER(statbuf, sizeof(Unix::stat));
VALIDATE_USER_WRITE(statbuf, sizeof(Unix::stat));
int error;
auto handle = VirtualFileSystem::the().open(move(path), error, 0, cwdInode());
if (!handle)
@ -900,8 +909,8 @@ int Task::sys$stat(const char* path, Unix::stat* statbuf)
int Task::sys$readlink(const char* path, char* buffer, size_t size)
{
VALIDATE_USER_BUFFER(path, strlen(path));
VALIDATE_USER_BUFFER(buffer, size);
VALIDATE_USER_READ(path, strlen(path));
VALIDATE_USER_WRITE(buffer, size);
int error;
auto handle = VirtualFileSystem::the().open(path, error, O_RDONLY | O_NOFOLLOW_NOERROR, cwdInode());
@ -923,7 +932,7 @@ int Task::sys$readlink(const char* path, char* buffer, size_t size)
int Task::sys$chdir(const char* path)
{
VALIDATE_USER_BUFFER(path, strlen(path));
VALIDATE_USER_READ(path, strlen(path));
int error;
auto handle = VirtualFileSystem::the().open(path, error, 0, cwdInode());
if (!handle)
@ -936,7 +945,7 @@ int Task::sys$chdir(const char* path)
int Task::sys$getcwd(char* buffer, size_t size)
{
VALIDATE_USER_BUFFER(buffer, size);
VALIDATE_USER_WRITE(buffer, size);
auto path = VirtualFileSystem::the().absolutePath(cwdInode());
if (path.isNull())
return -EINVAL;
@ -951,7 +960,7 @@ int Task::sys$open(const char* path, int options)
#ifdef DEBUG_IO
kprintf("Task::sys$open(): PID=%u, path=%s {%u}\n", m_pid, path, pathLength);
#endif
VALIDATE_USER_BUFFER(path, strlen(path));
VALIDATE_USER_READ(path, strlen(path));
if (m_fileHandles.size() >= m_maxFileHandles)
return -EMFILE;
int error;
@ -969,7 +978,7 @@ int Task::sys$open(const char* path, int options)
int Task::sys$uname(utsname* buf)
{
VALIDATE_USER_BUFFER(buf, sizeof(utsname));
VALIDATE_USER_WRITE(buf, sizeof(utsname));
strcpy(buf->sysname, "Serenity");
strcpy(buf->release, "1.0-dev");
strcpy(buf->version, "FIXME");
@ -1013,7 +1022,7 @@ int Task::sys$sleep(unsigned seconds)
int Task::sys$gettimeofday(timeval* tv)
{
VALIDATE_USER_BUFFER(tv, sizeof(tv));
VALIDATE_USER_WRITE(tv, sizeof(tv));
InterruptDisabler disabler;
auto now = RTC::now();
tv->tv_sec = now;
@ -1039,7 +1048,7 @@ pid_t Task::sys$getpid()
pid_t Task::sys$waitpid(pid_t waitee, int* wstatus, int options)
{
if (wstatus)
VALIDATE_USER_BUFFER(wstatus, sizeof(int));
VALIDATE_USER_WRITE(wstatus, sizeof(int));
InterruptDisabler disabler;
if (!Task::fromPID(waitee))
@ -1115,24 +1124,25 @@ Task::Subregion::~Subregion()
bool Task::isValidAddressForKernel(LinearAddress laddr) const
{
// We check extra carefully here since the first 4MB of the address space is identity-mapped.
// This code allows access outside of the known used address ranges to get caught.
InterruptDisabler disabler;
if (laddr.get() >= ksyms().first().address && laddr.get() <= ksyms().last().address)
return true;
if (is_kmalloc_address((void*)laddr.get()))
return true;
return isValidAddressForUser(laddr);
return validate_user_read(laddr);
}
bool Task::isValidAddressForUser(LinearAddress laddr) const
bool Task::validate_user_read(LinearAddress laddr) const
{
InterruptDisabler disabler;
for (auto& region: m_regions) {
if (laddr >= region->linearAddress && laddr < region->linearAddress.offset(region->size))
return true;
}
for (auto& subregion: m_subregions) {
if (laddr >= subregion->linearAddress && laddr < subregion->linearAddress.offset(subregion->size))
return true;
}
return false;
return MM.validate_user_read(*this, laddr);
}
bool Task::validate_user_write(LinearAddress laddr) const
{
InterruptDisabler disabler;
return MM.validate_user_write(*this, laddr);
}