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kernel: Make sure argument vectors passed to execve() are not too big

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This commit is contained in:
apio 2023-05-04 16:36:24 +02:00
parent 3eb78aa5f3
commit 44e4ca804a
Signed by: apio
GPG Key ID: B8A7D06E42258954
2 changed files with 29 additions and 4 deletions
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25
kernel/src/sys/exec.cpp
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@ -31,15 +31,36 @@ static Result<Vector<String>> copy_string_vector_from_userspace(u64 address)
return result;
}
static u64 calculate_userspace_stack_size(const Vector<String>& v)
{
u64 total { 0 };
for (const auto& str : v)
{
// The string's byte count + a terminating NUL byte.
total += str.length() + 1;
// The pointer to said string in the userspace array.
total += sizeof(char*);
}
// The NULL pointer at the end of the userspace array.
total += sizeof(char*);
return total;
}
static constexpr usize MAX_ARGV_STACK_SIZE = 2 * ARCH_PAGE_SIZE;
Result<u64> sys_execve(Registers* regs, SyscallArgs args)
{
auto path = TRY(MemoryManager::strdup_from_user(args[0]));
auto argv = TRY(copy_string_vector_from_userspace(args[1]));
auto envp = TRY(copy_string_vector_from_userspace(args[2]));
auto current = Scheduler::current();
if ((calculate_userspace_stack_size(argv) + calculate_userspace_stack_size(envp)) > MAX_ARGV_STACK_SIZE)
return err(E2BIG);
// FIXME: Make sure argv & envp are not too big.
auto current = Scheduler::current();
auto inode = TRY(VFS::resolve_path(path.chars(), current->auth, current->current_directory));

8
kernel/src/thread/ThreadImage.cpp
View File

@ -3,11 +3,15 @@
#include "thread/Thread.h"
#include <luna/CString.h>
static constexpr usize DEFAULT_USER_STACK_PAGES = 6;
static constexpr usize DEFAULT_USER_STACK_SIZE = DEFAULT_USER_STACK_PAGES * ARCH_PAGE_SIZE;
static Result<void> create_stacks(Stack& user_stack, Stack& kernel_stack)
{
const u64 THREAD_STACK_BASE = 0x10000;
TRY(MemoryManager::alloc_at_zeroed(THREAD_STACK_BASE, 4, MMU::ReadWrite | MMU::NoExecute | MMU::User));
TRY(MemoryManager::alloc_at_zeroed(THREAD_STACK_BASE, DEFAULT_USER_STACK_PAGES,
MMU::ReadWrite | MMU::NoExecute | MMU::User));
auto guard = make_scope_guard([&] { MemoryManager::unmap_owned(THREAD_STACK_BASE, 4); });
@ -15,7 +19,7 @@ static Result<void> create_stacks(Stack& user_stack, Stack& kernel_stack)
guard.deactivate();
user_stack = { THREAD_STACK_BASE, 4 * ARCH_PAGE_SIZE };
user_stack = { THREAD_STACK_BASE, DEFAULT_USER_STACK_SIZE };
kernel_stack = { kernel_stack_base, 4 * ARCH_PAGE_SIZE };
return {};