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MemoryManager: Add helper functions to validate arbitrary ranges of userspace memory

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This commit is contained in:
apio 2023-01-07 01:39:33 +01:00
parent 7fb2807d0c
commit 29bd8a69fa
Signed by: apio
GPG Key ID: B8A7D06E42258954
2 changed files with 72 additions and 5 deletions
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61
kernel/src/memory/MemoryManager.cpp
View File

@ -347,23 +347,74 @@ namespace MemoryManager
return false;
}
// FIXME: Replace this with some kind of strdup_from_user() function.
bool validate_user_readable_page(u64 address)
{
auto rc = MMU::get_flags(address);
if (rc.has_error()) return false;
if (rc.value() & MMU::User) return true;
return false;
}
bool validate_user_writable_page(u64 address)
{
auto rc = MMU::get_flags(address);
if (rc.has_error()) return false;
if ((rc.value() & MMU::User) && (rc.value() && MMU::ReadWrite)) return true;
return false;
}
bool validate_userspace_string(u64 address)
{
if (!validate_readable_page(address)) return false;
if (!validate_user_readable_page(address)) return false;
while (*(char*)address != 0)
{
address++;
if (address % ARCH_PAGE_SIZE)
{
if (!validate_readable_page(address)) return false;
if (!validate_user_readable_page(address)) return false;
}
}
return true;
}
bool validate_user_write(void* user, usize size)
{
uintptr_t user_ptr = (uintptr_t)user;
uintptr_t user_page = align_down<ARCH_PAGE_SIZE>(user_ptr);
uintptr_t diff = user_ptr - user_page;
usize pages = get_blocks_from_size(size + diff, ARCH_PAGE_SIZE);
while (pages--)
{
if (!validate_user_writable_page(user_page)) return false;
user_page += ARCH_PAGE_SIZE;
}
return true;
}
bool validate_user_read(const void* user, usize size)
{
uintptr_t user_ptr = (uintptr_t)user;
uintptr_t user_page = align_down<ARCH_PAGE_SIZE>(user_ptr);
uintptr_t diff = user_ptr - user_page;
usize pages = get_blocks_from_size(size + diff, ARCH_PAGE_SIZE);
while (pages--)
{
if (!validate_user_readable_page(user_page)) return false;
user_page += ARCH_PAGE_SIZE;
}
return true;
}
bool copy_to_user(void* user, const void* kernel, usize size)
{
uintptr_t user_ptr = (uintptr_t)user;
@ -375,7 +426,7 @@ namespace MemoryManager
if (user_ptr != user_page)
{
// FIXME: Validate that this page is writable by the user, not just the kernel.
if (!validate_writable_page(user_page)) return false;
if (!validate_user_writable_page(user_page)) return false;
}
while (size--)
@ -383,7 +434,7 @@ namespace MemoryManager
// Crossed a page boundary, gotta check the page tables again before touching any memory!!
if (user_ptr % ARCH_PAGE_SIZE)
{
if (!validate_writable_page(user_ptr)) return false;
if (!validate_user_writable_page(user_ptr)) return false;
}
*(char*)user_ptr = *kernel_ptr++;

16
kernel/src/memory/MemoryManager.h
View File

@ -20,8 +20,24 @@ namespace MemoryManager
bool validate_readable_page(u64 address);
bool validate_writable_page(u64 address);
bool validate_user_readable_page(u64 address);
bool validate_user_writable_page(u64 address);
bool validate_userspace_string(u64 address);
bool validate_user_write(void* user, usize size);
bool validate_user_read(const void* user, usize size);
template <typename T> bool validate_user_write_typed(T* user)
{
return validate_user_write(user, sizeof(T));
}
template <typename T> bool validate_user_read_typed(const T* user)
{
return validate_user_read(user, sizeof(T));
}
bool copy_to_user(void* user, const void* kernel, usize size);
template <typename T> bool copy_to_user_typed(T* user, const T* kernel)