RGBCube/serenity
1
Fork 0
mirror of https://github.com/RGBCube/serenity synced 2025-05-30 17:48:12 +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

42
Kernel/Net/LocalSocket.cpp
View file

@ -98,7 +98,8 @@ KResult LocalSocket::bind(Userspace<const sockaddr*> user_address, socklen_t add
return KResult(-EINVAL);
sockaddr_un address;
copy_from_user(&address, user_address, sizeof(sockaddr_un));
if (!copy_from_user(&address, user_address, sizeof(sockaddr_un)))
return KResult(-EFAULT);
if (address.sun_family != AF_LOCAL)
return KResult(-EINVAL);
@ -131,19 +132,25 @@ KResult LocalSocket::bind(Userspace<const sockaddr*> user_address, socklen_t add
return KSuccess;
}
KResult LocalSocket::connect(FileDescription& description, const sockaddr* address, socklen_t address_size, ShouldBlock)
KResult LocalSocket::connect(FileDescription& description, Userspace<const sockaddr*> address, socklen_t address_size, ShouldBlock)
{
ASSERT(!m_bound);
if (address_size != sizeof(sockaddr_un))
return KResult(-EINVAL);
if (address->sa_family != AF_LOCAL)
u16 sa_family_copy;
auto* user_address = reinterpret_cast<const sockaddr*>(address.unsafe_userspace_ptr());
if (!copy_from_user(&sa_family_copy, &user_address->sa_family, sizeof(u16)))
return KResult(-EFAULT);
if (sa_family_copy != AF_LOCAL)
return KResult(-EINVAL);
if (is_connected())
return KResult(-EISCONN);
const sockaddr_un& local_address = *reinterpret_cast<const sockaddr_un*>(address);
const auto& local_address = *reinterpret_cast<const sockaddr_un*>(user_address);
char safe_address[sizeof(local_address.sun_path) + 1] = { 0 };
memcpy(safe_address, local_address.sun_path, sizeof(local_address.sun_path));
if (!copy_from_user(&safe_address[0], &local_address.sun_path[0], sizeof(safe_address) - 1))
return KResult(-EFAULT);
safe_address[sizeof(safe_address) - 1] = '\0';
#ifdef DEBUG_LOCAL_SOCKET
dbg() << "LocalSocket{" << this << "} connect(" << safe_address << ")";
@ -159,7 +166,8 @@ KResult LocalSocket::connect(FileDescription& description, const sockaddr* addre
if (!m_file->inode()->socket())
return KResult(-ECONNREFUSED);
m_address = local_address;
m_address.sun_family = sa_family_copy;
memcpy(m_address.sun_path, safe_address, sizeof(m_address.sun_path));
ASSERT(m_connect_side_fd == &description);
m_connect_side_role = Role::Connecting;
@ -260,11 +268,11 @@ bool LocalSocket::can_write(const FileDescription& description, size_t) const
return false;
}
KResultOr<size_t> LocalSocket::sendto(FileDescription& description, const void* data, size_t data_size, int, Userspace<const sockaddr*>, socklen_t)
KResultOr<size_t> LocalSocket::sendto(FileDescription& description, const UserOrKernelBuffer& data, size_t data_size, int, Userspace<const sockaddr*>, socklen_t)
{
if (!has_attached_peer(description))
return KResult(-EPIPE);
ssize_t nwritten = send_buffer_for(description).write((const u8*)data, data_size);
ssize_t nwritten = send_buffer_for(description).write(data, data_size);
if (nwritten > 0)
Thread::current()->did_unix_socket_write(nwritten);
return nwritten;
@ -290,7 +298,7 @@ DoubleBuffer& LocalSocket::send_buffer_for(FileDescription& description)
ASSERT_NOT_REACHED();
}
KResultOr<size_t> LocalSocket::recvfrom(FileDescription& description, void* buffer, size_t buffer_size, int, Userspace<sockaddr*>, Userspace<socklen_t*>)
KResultOr<size_t> LocalSocket::recvfrom(FileDescription& description, UserOrKernelBuffer& buffer, size_t buffer_size, int, Userspace<sockaddr*>, Userspace<socklen_t*>)
{
auto& buffer_for_me = receive_buffer_for(description);
if (!description.is_blocking()) {
@ -306,7 +314,7 @@ KResultOr<size_t> LocalSocket::recvfrom(FileDescription& description, void* buff
if (!has_attached_peer(description) && buffer_for_me.is_empty())
return 0;
ASSERT(!buffer_for_me.is_empty());
int nread = buffer_for_me.read((u8*)buffer, buffer_size);
int nread = buffer_for_me.read(buffer, buffer_size);
if (nread > 0)
Thread::current()->did_unix_socket_read(nread);
return nread;
@ -350,7 +358,7 @@ KResult LocalSocket::getsockopt(FileDescription& description, int level, int opt
return Socket::getsockopt(description, level, option, value, value_size);
socklen_t size;
if (!Process::current()->validate_read_and_copy_typed(&size, value_size))
if (!copy_from_user(&size, value_size.unsafe_userspace_ptr()))
return KResult(-EFAULT);
switch (option) {
@ -359,14 +367,18 @@ KResult LocalSocket::getsockopt(FileDescription& description, int level, int opt
return KResult(-EINVAL);
switch (role(description)) {
case Role::Accepted:
copy_to_user(static_ptr_cast<ucred*>(value), &m_origin);
if (!copy_to_user(static_ptr_cast<ucred*>(value), &m_origin))
return KResult(-EFAULT);
size = sizeof(ucred);
copy_to_user(value_size, &size);
if (!copy_to_user(value_size, &size))
return KResult(-EFAULT);
return KSuccess;
case Role::Connected:
copy_to_user(static_ptr_cast<ucred*>(value), &m_acceptor);
if (!copy_to_user(static_ptr_cast<ucred*>(value), &m_acceptor))
return KResult(-EFAULT);
size = sizeof(ucred);
copy_to_user(value_size, &size);
if (!copy_to_user(value_size, &size))
return KResult(-EFAULT);
return KSuccess;
case Role::Connecting:
return KResult(-ENOTCONN);