RGBCube/serenity
1
Fork 0
mirror of https://github.com/RGBCube/serenity synced 2025-05-31 09:38:11 +00:00
Code Issues Activity Actions

Kernel: Make copy_to/from_user safe and remove unnecessary checks

Browse source 
Since the CPU already does almost all necessary validation steps
for us, we don't really need to attempt to do this. Doing it
ourselves doesn't really work very reliably, because we'd have to
account for other processors modifying virtual memory, and we'd
have to account for e.g. pages not being able to be allocated
due to insufficient resources.

So change the copy_to/from_user (and associated helper functions)
to use the new safe_memcpy, which will return whether it succeeded
or not. The only manual validation step needed (which the CPU
can't perform for us) is making sure the pointers provided by user
mode aren't pointing to kernel mappings.

To make it easier to read/write from/to either kernel or user mode
data add the UserOrKernelBuffer helper class, which will internally
either use copy_from/to_user or directly memcpy, or pass the data
through directly using a temporary buffer on the stack.

Last but not least we need to keep syscall params trivial as we
need to copy them from/to user mode using copy_from/to_user.
This commit is contained in:
Tom 2020-09-11 21:11:07 -06:00 • committed by Andreas Kling
parent 7d1b8417bd
commit c8d9f1b9c9
149 changed files with 1585 additions and 1244 deletions
Download patch file Download diff file Expand all files Collapse all files

36
Kernel/Devices/PATADiskDevice.cpp
View file

@ -55,19 +55,19 @@ const char* PATADiskDevice::class_name() const
return "PATADiskDevice";
}
bool PATADiskDevice::read_blocks(unsigned index, u16 count, u8* out)
bool PATADiskDevice::read_blocks(unsigned index, u16 count, UserOrKernelBuffer& out)
{
if (!m_channel.m_bus_master_base.is_null() && m_channel.m_dma_enabled.resource())
return read_sectors_with_dma(index, count, out);
return read_sectors(index, count, out);
}
bool PATADiskDevice::write_blocks(unsigned index, u16 count, const u8* data)
bool PATADiskDevice::write_blocks(unsigned index, u16 count, const UserOrKernelBuffer& data)
{
if (!m_channel.m_bus_master_base.is_null() && m_channel.m_dma_enabled.resource())
return write_sectors_with_dma(index, count, data);
for (unsigned i = 0; i < count; ++i) {
if (!write_sectors(index + i, 1, data + i * 512))
if (!write_sectors(index + i, 1, data.offset(i * 512)))
return false;
}
return true;
@ -80,7 +80,7 @@ void PATADiskDevice::set_drive_geometry(u16 cyls, u16 heads, u16 spt)
m_sectors_per_track = spt;
}
KResultOr<size_t> PATADiskDevice::read(FileDescription&, size_t offset, u8* outbuf, size_t len)
KResultOr<size_t> PATADiskDevice::read(FileDescription&, size_t offset, UserOrKernelBuffer& outbuf, size_t len)
{
unsigned index = offset / block_size();
u16 whole_blocks = len / block_size();
@ -107,10 +107,12 @@ KResultOr<size_t> PATADiskDevice::read(FileDescription&, size_t offset, u8* outb
off_t pos = whole_blocks * block_size();
if (remaining > 0) {
auto buf = ByteBuffer::create_uninitialized(block_size());
if (!read_blocks(index + whole_blocks, 1, buf.data()))
auto data = ByteBuffer::create_uninitialized(block_size());
auto data_buffer = UserOrKernelBuffer::for_kernel_buffer(data.data());
if (!read_blocks(index + whole_blocks, 1, data_buffer))
return pos;
memcpy(&outbuf[pos], buf.data(), remaining);
if (!outbuf.write(data.data(), pos, remaining))
return KResult(-EFAULT);
}
return pos + remaining;
@ -121,7 +123,7 @@ bool PATADiskDevice::can_read(const FileDescription&, size_t offset) const
return offset < (m_cylinders * m_heads * m_sectors_per_track * block_size());
}
KResultOr<size_t> PATADiskDevice::write(FileDescription&, size_t offset, const u8* inbuf, size_t len)
KResultOr<size_t> PATADiskDevice::write(FileDescription&, size_t offset, const UserOrKernelBuffer& inbuf, size_t len)
{
unsigned index = offset / block_size();
u16 whole_blocks = len / block_size();
@ -151,11 +153,13 @@ KResultOr<size_t> PATADiskDevice::write(FileDescription&, size_t offset, const u
// partial write, we have to read the block's content first, modify it,
// then write the whole block back to the disk.
if (remaining > 0) {
auto buf = ByteBuffer::create_zeroed(block_size());
if (!read_blocks(index + whole_blocks, 1, buf.data()))
auto data = ByteBuffer::create_zeroed(block_size());
auto data_buffer = UserOrKernelBuffer::for_kernel_buffer(data.data());
if (!read_blocks(index + whole_blocks, 1, data_buffer))
return pos;
memcpy(buf.data(), &inbuf[pos], remaining);
if (!write_blocks(index + whole_blocks, 1, buf.data()))
if (!inbuf.read(data.data(), pos, remaining))
return KResult(-EFAULT);
if (!write_blocks(index + whole_blocks, 1, data_buffer))
return pos;
}
@ -167,22 +171,22 @@ bool PATADiskDevice::can_write(const FileDescription&, size_t offset) const
return offset < (m_cylinders * m_heads * m_sectors_per_track * block_size());
}
bool PATADiskDevice::read_sectors_with_dma(u32 lba, u16 count, u8* outbuf)
bool PATADiskDevice::read_sectors_with_dma(u32 lba, u16 count, UserOrKernelBuffer& outbuf)
{
return m_channel.ata_read_sectors_with_dma(lba, count, outbuf, is_slave());
}
bool PATADiskDevice::read_sectors(u32 start_sector, u16 count, u8* outbuf)
bool PATADiskDevice::read_sectors(u32 start_sector, u16 count, UserOrKernelBuffer& outbuf)
{
return m_channel.ata_read_sectors(start_sector, count, outbuf, is_slave());
}
bool PATADiskDevice::write_sectors_with_dma(u32 lba, u16 count, const u8* inbuf)
bool PATADiskDevice::write_sectors_with_dma(u32 lba, u16 count, const UserOrKernelBuffer& inbuf)
{
return m_channel.ata_write_sectors_with_dma(lba, count, inbuf, is_slave());
}
bool PATADiskDevice::write_sectors(u32 start_sector, u16 count, const u8* inbuf)
bool PATADiskDevice::write_sectors(u32 start_sector, u16 count, const UserOrKernelBuffer& inbuf)
{
return m_channel.ata_write_sectors(start_sector, count, inbuf, is_slave());
}