Kernel: Invoke ELF interpreter instead if it is specified

kernel/arch/i686/Thread.S

@@ -55,14 +55,15 @@ start_userspace_thread:
 	movw %bx, %gs
 	xorw %bx, %bx
 
-	popl %edx
-	popl %esi
 	popl %edi
+	popl %esi
+	popl %edx
 	popl %ecx
+	popl %ebx
 
 	pushl $(0x20 | 3)
 	pushl %eax
 	pushl $0x202
 	pushl $(0x18 | 3)
-	pushl %ecx
+	pushl %ebx
 	iret

kernel/arch/x86_64/Thread.S

@@ -39,14 +39,15 @@ start_userspace_thread:
 
 	call get_userspace_thread_stack_top
 
-	popq %rdx
-	popq %rsi
 	popq %rdi
+	popq %rsi
+	popq %rdx
 	popq %rcx
+	popq %rbx
 
 	pushq $(0x20 | 3)
 	pushq %rax
 	pushq $0x202
 	pushq $(0x18 | 3)
-	pushq %rcx
+	pushq %rbx
 	iretq

kernel/include/kernel/Process.h

@@ -41,6 +41,7 @@ namespace Kernel
 			int argc { 0 };
 			char** argv { nullptr };
 			char** envp { nullptr };
+			int file_fd { -1 };
 		};
 
 	public:

kernel/kernel/Process.cpp

@@ -411,7 +411,7 @@ namespace Kernel
 		}
 
 		auto file = TRY(VirtualFileSystem::get().file_from_absolute_path(credentials, absolute_path, O_EXEC));
-		return TRY(LibELF::LoadableELF::load_from_inode(page_table, file.inode));
+		return TRY(LibELF::LoadableELF::load_from_inode(page_table, credentials, file.inode));
 	}
 
 	BAN::ErrorOr<long> Process::sys_fork(uintptr_t sp, uintptr_t ip)
@@ -515,6 +515,13 @@ namespace Kernel
 			m_loadable_elf->reserve_address_space();
 			m_loadable_elf->update_suid_sgid(m_credentials);
 			m_userspace_info.entry = m_loadable_elf->entry_point();
+			if (m_loadable_elf->has_interpreter())
+			{
+				VirtualFileSystem::File file;
+				TRY(file.canonical_path.append("<self>"));
+				file.inode = m_loadable_elf->inode();
+				m_userspace_info.file_fd = TRY(m_open_file_descriptors.open(BAN::move(file), O_EXEC));
+			}
 
 			for (size_t i = 0; i < sizeof(m_signal_handlers) / sizeof(*m_signal_handlers); i++)
 			{

kernel/kernel/Thread.cpp

@@ -190,22 +190,23 @@ namespace Kernel
 
 		// Signal mask is inherited
 
-		auto& userspace_info = process().userspace_info();
+		const auto& userspace_info = process().userspace_info();
 		ASSERT(userspace_info.entry);
 
 		// Initialize stack for returning
 		PageTable::with_fast_page(process().page_table().physical_address_of(kernel_stack_top() - PAGE_SIZE), [&] {
 			uintptr_t sp = PageTable::fast_page() + PAGE_SIZE;
 			write_to_stack(sp, userspace_info.entry);
-			write_to_stack(sp, userspace_info.argc);
-			write_to_stack(sp, userspace_info.argv);
+			write_to_stack(sp, userspace_info.file_fd);
 			write_to_stack(sp, userspace_info.envp);
+			write_to_stack(sp, userspace_info.argv);
+			write_to_stack(sp, userspace_info.argc);
 		});
 
-		m_interrupt_stack.ip = reinterpret_cast<vaddr_t>(start_userspace_thread);;
+		m_interrupt_stack.ip = reinterpret_cast<vaddr_t>(start_userspace_thread);
 		m_interrupt_stack.cs = 0x08;
 		m_interrupt_stack.flags = 0x002;
-		m_interrupt_stack.sp = kernel_stack_top() - 4 * sizeof(uintptr_t);
+		m_interrupt_stack.sp = kernel_stack_top() - 5 * sizeof(uintptr_t);
 		m_interrupt_stack.ss = 0x10;
 
 		memset(&m_interrupt_registers, 0, sizeof(InterruptRegisters));

userspace/libraries/LibELF/LibELF/LoadableELF.cpp

@@ -1,145 +1,253 @@
 #include <BAN/ScopeGuard.h>
+#include <kernel/FS/VirtualFileSystem.h>
 #include <kernel/Lock/LockGuard.h>
 #include <kernel/Memory/Heap.h>
 #include <kernel/Random.h>
 #include <LibELF/LoadableELF.h>
 #include <LibELF/Values.h>
+#include <fcntl.h>
 
 namespace LibELF
 {
 
 	using namespace Kernel;
 
-	BAN::ErrorOr<BAN::UniqPtr<LoadableELF>> LoadableELF::load_from_inode(PageTable& page_table, BAN::RefPtr<Inode> inode)
+	BAN::ErrorOr<BAN::UniqPtr<LoadableELF>> LoadableELF::load_from_inode(PageTable& page_table, const Credentials& credentials, BAN::RefPtr<Inode> inode)
 	{
-		auto* elf_ptr = new LoadableELF(page_table, inode);
-		if (elf_ptr == nullptr)
-			return BAN::Error::from_errno(ENOMEM);
-		auto elf = BAN::UniqPtr<LoadableELF>::adopt(elf_ptr);
-		TRY(elf->initialize());
-		return BAN::move(elf);
+		auto elf = TRY(BAN::UniqPtr<LoadableELF>::create(page_table));
+		TRY(elf->initialize(credentials, inode));
+		return elf;
 	}
 
-	LoadableELF::LoadableELF(PageTable& page_table, BAN::RefPtr<Inode> inode)
-		: m_inode(inode)
-		, m_page_table(page_table)
+	LoadableELF::LoadableELF(PageTable& page_table)
+		: m_page_table(page_table)
 	{
 	}
 
 	LoadableELF::~LoadableELF()
 	{
-		if (!m_loaded)
-			return;
-		for (const auto& program_header : m_program_headers)
-		{
-			switch (program_header.p_type)
+		const auto cleanup_program_headers =
+			[&](BAN::Span<const ElfNativeProgramHeader> headers)
 			{
-				case PT_NULL:
-					continue;
-				case PT_LOAD:
+				for (const auto& header : headers)
 				{
-					vaddr_t start = program_header.p_vaddr & PAGE_ADDR_MASK;
-					size_t pages = range_page_count(program_header.p_vaddr, program_header.p_memsz);
+					ASSERT(header.p_type == PT_LOAD);
+
+					const vaddr_t vaddr = header.p_vaddr & PAGE_ADDR_MASK;
+					const size_t pages = range_page_count(header.p_vaddr, header.p_memsz);
 					for (size_t i = 0; i < pages; i++)
-					{
-						paddr_t paddr = m_page_table.physical_address_of(start + i * PAGE_SIZE);
-						if (paddr != 0)
+						if (paddr_t paddr = m_page_table.physical_address_of(vaddr + i * PAGE_SIZE))
 							Heap::get().release_page(paddr);
-					}
-					m_page_table.unmap_range(start, pages * PAGE_SIZE);
-					break;
+					m_page_table.unmap_range(vaddr, pages * PAGE_SIZE);
 				}
-				default:
-					ASSERT_NOT_REACHED();
-			}
-		}
+			};
+
+		if (!m_is_loaded)
+			return;
+		cleanup_program_headers(m_executable.program_headers.span());
+		cleanup_program_headers(m_interpreter.program_headers.span());
 	}
 
-	BAN::ErrorOr<void> LoadableELF::initialize()
+	static BAN::ErrorOr<ElfNativeFileHeader> read_and_validate_file_header(BAN::RefPtr<Inode> inode)
 	{
-		if ((size_t)m_inode->size() < sizeof(ElfNativeFileHeader))
+		if ((size_t)inode->size() < sizeof(ElfNativeFileHeader))
 		{
-			dprintln("Too small file");
+			dprintln("File is too small to be ELF");
 			return BAN::Error::from_errno(ENOEXEC);
 		}
 
-		size_t nread = TRY(m_inode->read(0, BAN::ByteSpan::from(m_file_header)));
-		ASSERT(nread == sizeof(m_file_header));
+		ElfNativeFileHeader file_header;
 
-		if (m_file_header.e_ident[EI_MAG0] != ELFMAG0 ||
-			m_file_header.e_ident[EI_MAG1] != ELFMAG1 ||
-			m_file_header.e_ident[EI_MAG2] != ELFMAG2 ||
-			m_file_header.e_ident[EI_MAG3] != ELFMAG3)
+		size_t nread = TRY(inode->read(0, BAN::ByteSpan::from(file_header)));
+		ASSERT(nread == sizeof(file_header));
+
+		if (file_header.e_ident[EI_MAG0] != ELFMAG0 ||
+			file_header.e_ident[EI_MAG1] != ELFMAG1 ||
+			file_header.e_ident[EI_MAG2] != ELFMAG2 ||
+			file_header.e_ident[EI_MAG3] != ELFMAG3)
 		{
-			dprintln("Invalid magic in header");
+			dprintln("Not an ELF file");
 			return BAN::Error::from_errno(ENOEXEC);
 		}
 
-		if (m_file_header.e_ident[EI_DATA] != ELFDATA2LSB)
+		if (file_header.e_ident[EI_DATA] != ELFDATA2LSB)
 		{
-			dprintln("Only little-endian is supported");
+			dprintln("Not in little-endian");
 			return BAN::Error::from_errno(ENOEXEC);
 		}
 
-		if (m_file_header.e_ident[EI_VERSION] != EV_CURRENT)
+		if (file_header.e_ident[EI_VERSION] != EV_CURRENT)
 		{
-			dprintln("Invalid version");
+			dprintln("Unsupported version {}", file_header.e_ident[EI_VERSION]);
 			return BAN::Error::from_errno(ENOEXEC);
 		}
 
 #if ARCH(i686)
-		if (m_file_header.e_ident[EI_CLASS] != ELFCLASS32)
+		if (file_header.e_ident[EI_CLASS] != ELFCLASS32)
 #elif ARCH(x86_64)
-		if (m_file_header.e_ident[EI_CLASS] != ELFCLASS64)
+		if (file_header.e_ident[EI_CLASS] != ELFCLASS64)
 #endif
 		{
 			dprintln("Not in native format");
 			return BAN::Error::from_errno(EINVAL);
 		}
 
-		if (m_file_header.e_type != ET_EXEC && m_file_header.e_type != ET_DYN)
+		if (file_header.e_type != ET_EXEC && file_header.e_type != ET_DYN)
 		{
-			dprintln("Unsupported file header type {}", m_file_header.e_type);
+			dprintln("Unsupported file header type {}", file_header.e_type);
 			return BAN::Error::from_errno(ENOTSUP);
 		}
 
-		if (m_file_header.e_version != EV_CURRENT)
+		if (file_header.e_version != EV_CURRENT)
 		{
-			dprintln("Unsupported version");
+			dprintln("Unsupported version {}", file_header.e_version);
 			return BAN::Error::from_errno(EINVAL);
 		}
 
-		ASSERT(m_file_header.e_phentsize <= sizeof(ElfNativeProgramHeader));
+		if (file_header.e_phentsize < sizeof(ElfNativeProgramHeader))
+		{
+			dprintln("Too small program header size ({} bytes)", file_header.e_phentsize);
+			return BAN::Error::from_errno(EINVAL);
+		}
+
+		return file_header;
+	}
+
+	BAN::ErrorOr<LoadableELF::LoadResult> LoadableELF::load_elf_file(const Credentials& credentials, BAN::RefPtr<Inode> inode) const
+	{
+		auto file_header = TRY(read_and_validate_file_header(inode));
 
 		BAN::Vector<uint8_t> pheader_buffer;
-		TRY(pheader_buffer.resize(m_file_header.e_phnum * m_file_header.e_phentsize));
-		TRY(m_inode->read(m_file_header.e_phoff, BAN::ByteSpan(pheader_buffer.span())));
+		TRY(pheader_buffer.resize(file_header.e_phnum * file_header.e_phentsize));
+		TRY(inode->read(file_header.e_phoff, BAN::ByteSpan(pheader_buffer.span())));
 
-		const vaddr_t dyn_base = (m_file_header.e_type == ET_DYN) ? 0x40000000 + (Random::get_u32() & 0x3FFFF000) : 0;
-		m_file_header.e_entry += dyn_base;
+		BAN::Vector<ElfNativeProgramHeader> program_headers;
+		BAN::RefPtr<Inode> interp;
 
-		for (size_t i = 0; i < m_file_header.e_phnum; i++)
+		for (size_t i = 0; i < file_header.e_phnum; i++)
 		{
-			const auto& pheader = *reinterpret_cast<ElfNativeProgramHeader*>(pheader_buffer.data() + i * m_file_header.e_phentsize);
+			const auto& pheader = *reinterpret_cast<ElfNativeProgramHeader*>(pheader_buffer.data() + i * file_header.e_phentsize);
 			if (pheader.p_memsz < pheader.p_filesz)
 			{
-				dprintln("Invalid program header");
+				dprintln("Invalid program header, memsz less than filesz");
 				return BAN::Error::from_errno(EINVAL);
 			}
 
 			switch (pheader.p_type)
 			{
-				case PT_NULL:
-				case PT_DYNAMIC:
-					break;
 				case PT_LOAD:
-					TRY(m_program_headers.push_back(pheader));
-					m_program_headers.back().p_vaddr += dyn_base;
-					m_virtual_page_count += BAN::Math::div_round_up<size_t>((pheader.p_vaddr % PAGE_SIZE) + pheader.p_memsz, PAGE_SIZE);
+					for (const auto& program_header : program_headers)
+					{
+						const vaddr_t a1 = program_header.p_vaddr & PAGE_ADDR_MASK;
+						const vaddr_t b1 = pheader.p_vaddr        & PAGE_ADDR_MASK;
+						const vaddr_t a2 = (program_header.p_vaddr + program_header.p_memsz + PAGE_SIZE - 1) & PAGE_ADDR_MASK;
+						const vaddr_t b2 = (pheader.p_vaddr        + pheader.p_memsz        + PAGE_SIZE - 1) & PAGE_ADDR_MASK;
+						if (a1 < b2 && b1 < a2)
+						{
+							dwarnln("Overlapping LOAD segments");
+							return BAN::Error::from_errno(EINVAL);
+						}
+					}
+					TRY(program_headers.push_back(pheader));
 					break;
+				case PT_INTERP:
+				{
+					BAN::Vector<uint8_t> buffer;
+					TRY(buffer.resize(pheader.p_memsz, 0));
+					TRY(inode->read(pheader.p_offset, BAN::ByteSpan(buffer.data(), pheader.p_filesz)));
+
+					BAN::StringView path(reinterpret_cast<const char*>(buffer.data()));
+					interp = TRY(VirtualFileSystem::get().file_from_absolute_path(credentials, path, O_EXEC)).inode;
+					break;
+				}
 				default:
-					dprintln("Unsupported program header type {}", pheader.p_type);
-					return BAN::Error::from_errno(ENOTSUP);
+					break;
+			}
+		}
+
+		return LoadResult {
+			.elf_file = {
+				.inode = inode,
+				.file_header = file_header,
+				.program_headers = BAN::move(program_headers),
+				.dynamic_base = 0
+			},
+			.interp = interp
+		};
+	}
+
+	bool LoadableELF::does_executable_and_interpreter_overlap() const
+	{
+		ASSERT(m_executable.inode);
+		ASSERT(m_interpreter.inode);
+
+		for (const auto& epheader : m_executable.program_headers)
+		{
+			for (const auto& ipheader : m_interpreter.program_headers)
+			{
+				const vaddr_t e1 =  epheader.p_vaddr & PAGE_ADDR_MASK;
+				const vaddr_t i1 =  ipheader.p_vaddr & PAGE_ADDR_MASK;
+				const vaddr_t e2 = (epheader.p_vaddr + epheader.p_memsz + PAGE_SIZE - 1) & PAGE_ADDR_MASK;
+				const vaddr_t i2 = (ipheader.p_vaddr + ipheader.p_memsz + PAGE_SIZE - 1) & PAGE_ADDR_MASK;
+				if (e1 < i2 && i1 < e2)
+					return true;
+			}
+		}
+
+		return false;
+	}
+
+	BAN::ErrorOr<void> LoadableELF::initialize(const Credentials& credentials, BAN::RefPtr<Inode> inode)
+	{
+		auto executable_load_result = TRY(load_elf_file(credentials, inode));
+		m_executable = executable_load_result.elf_file;
+
+		if (m_executable.file_header.e_type == ET_DYN)
+		{
+			m_executable.dynamic_base = (Random::get_u32() & 0x7FFFF000) + 0x100000;
+			m_executable.file_header.e_entry += m_executable.dynamic_base;
+			for (auto& program_header : m_executable.program_headers)
+				program_header.p_vaddr += m_executable.dynamic_base;
+		}
+
+		if (executable_load_result.interp)
+		{
+			auto interp_load_result = TRY(load_elf_file(credentials, executable_load_result.interp));
+			m_interpreter = interp_load_result.elf_file;
+
+			if (interp_load_result.interp)
+			{
+				dwarnln("Executable has specified interpreter for its interpreter");
+				return BAN::Error::from_errno(EINVAL);
+			}
+
+			if (m_interpreter.file_header.e_type == ET_DYN)
+			{
+				for (int attempt = 0; attempt < 100; attempt++)
+				{
+					const vaddr_t dynamic_base = (Random::get_u32() & 0x3FFFF000) + 0x40000000;
+					for (auto& program_header : m_interpreter.program_headers)
+						program_header.p_vaddr += dynamic_base;
+					if (does_executable_and_interpreter_overlap())
+					{
+						for (auto& program_header : m_interpreter.program_headers)
+							program_header.p_vaddr -= dynamic_base;
+						continue;
+					}
+					m_interpreter.dynamic_base = dynamic_base;
+					m_interpreter.file_header.e_entry += dynamic_base;
+					break;
+				}
+			}
+
+			const bool can_load_interpreter = (m_interpreter.file_header.e_type == ET_DYN)
+				? (m_interpreter.dynamic_base != 0)
+				: !does_executable_and_interpreter_overlap();
+
+			if (!can_load_interpreter)
+			{
+				dwarnln("Could not find space to load interpreter");
+				return BAN::Error::from_errno(EINVAL);
 			}
 		}
 
@@ -148,149 +256,199 @@ namespace LibELF
 
 	vaddr_t LoadableELF::entry_point() const
 	{
-		return m_file_header.e_entry;
+		if (m_interpreter.inode)
+			return m_interpreter.file_header.e_entry;
+		return m_executable.file_header.e_entry;
 	}
 
 	bool LoadableELF::contains(vaddr_t address) const
 	{
-		for (const auto& program_header : m_program_headers)
-		{
-			ASSERT(program_header.p_type == PT_LOAD);
+		for (const auto& program_header : m_executable.program_headers)
+			if (program_header.p_vaddr <= address && address < program_header.p_vaddr + program_header.p_memsz)
+				return true;
+		for (const auto& program_header : m_interpreter.program_headers)
 			if (program_header.p_vaddr <= address && address < program_header.p_vaddr + program_header.p_memsz)
 				return true;
-		}
 		return false;
 	}
 
 	bool LoadableELF::is_address_space_free() const
 	{
-		for (const auto& program_header : m_program_headers)
-		{
-			ASSERT(program_header.p_type == PT_LOAD);
-			const vaddr_t page_vaddr = program_header.p_vaddr & PAGE_ADDR_MASK;
-			const size_t pages = range_page_count(program_header.p_vaddr, program_header.p_memsz);
-			if (!m_page_table.is_range_free(page_vaddr, pages * PAGE_SIZE))
-				return false;
-		}
+		const auto are_program_headers_free =
+			[&](BAN::Span<const ElfNativeProgramHeader> program_headers) -> bool
+			{
+				for (const auto& program_header : program_headers)
+				{
+					ASSERT(program_header.p_type == PT_LOAD);
+					const vaddr_t page_vaddr = program_header.p_vaddr & PAGE_ADDR_MASK;
+					const size_t pages = range_page_count(program_header.p_vaddr, program_header.p_memsz);
+					if (!m_page_table.is_range_free(page_vaddr, pages * PAGE_SIZE))
+						return false;
+				}
+				return true;
+			};
+		if (!are_program_headers_free(m_executable.program_headers.span()))
+			return false;
+		if (!are_program_headers_free(m_interpreter.program_headers.span()))
+			return false;
 		return true;
 	}
 
 	void LoadableELF::reserve_address_space()
 	{
-		for (const auto& program_header : m_program_headers)
-		{
-			ASSERT(program_header.p_type == PT_LOAD);
-			const vaddr_t page_vaddr = program_header.p_vaddr & PAGE_ADDR_MASK;
-			const size_t pages = range_page_count(program_header.p_vaddr, program_header.p_memsz);
-			if (!m_page_table.reserve_range(page_vaddr, pages * PAGE_SIZE))
-				ASSERT_NOT_REACHED();
-		}
-		m_loaded = true;
+		const auto reserve_program_headers =
+			[&](BAN::Span<const ElfNativeProgramHeader> program_headers)
+			{
+				for (const auto& program_header : program_headers)
+				{
+					ASSERT(program_header.p_type == PT_LOAD);
+					const vaddr_t page_vaddr = program_header.p_vaddr & PAGE_ADDR_MASK;
+					const size_t pages = range_page_count(program_header.p_vaddr, program_header.p_memsz);
+					if (!m_page_table.reserve_range(page_vaddr, pages * PAGE_SIZE))
+						ASSERT_NOT_REACHED();
+					m_virtual_page_count += pages;
+				}
+			};
+		reserve_program_headers(m_executable.program_headers.span());
+		reserve_program_headers(m_interpreter.program_headers.span());
+		m_is_loaded = true;
 	}
 
 	void LoadableELF::update_suid_sgid(Kernel::Credentials& credentials)
 	{
-		if (m_inode->mode().mode & +Inode::Mode::ISUID)
-			credentials.set_euid(m_inode->uid());
-		if (m_inode->mode().mode & +Inode::Mode::ISGID)
-			credentials.set_egid(m_inode->gid());
+		auto inode = m_executable.inode;
+		ASSERT(inode);
+
+		if (inode->mode().mode & +Inode::Mode::ISUID)
+			credentials.set_euid(inode->uid());
+		if (inode->mode().mode & +Inode::Mode::ISGID)
+			credentials.set_egid(inode->gid());
 	}
 
 	BAN::ErrorOr<void> LoadableELF::load_page_to_memory(vaddr_t address)
 	{
-		for (const auto& program_header : m_program_headers)
-		{
-			ASSERT(program_header.p_type == PT_LOAD);
-
-			if (!(program_header.p_vaddr <= address && address < program_header.p_vaddr + program_header.p_memsz))
-				continue;
-
-			PageTable::flags_t flags = PageTable::Flags::UserSupervisor | PageTable::Flags::Present;
-			if (program_header.p_flags & LibELF::PF_W)
-				flags |= PageTable::Flags::ReadWrite;
-			if (program_header.p_flags & LibELF::PF_X)
-				flags |= PageTable::Flags::Execute;
-
-			const vaddr_t vaddr = address & PAGE_ADDR_MASK;
-			const paddr_t paddr = Heap::get().take_free_page();
-			if (paddr == 0)
-				return BAN::Error::from_errno(ENOMEM);
-
-			// Temporarily map page as RW so kernel can write to it
-			m_page_table.map_page_at(paddr, vaddr, PageTable::Flags::ReadWrite | PageTable::Flags::Present);
-			m_physical_page_count++;
-
-			memset((void*)vaddr, 0x00, PAGE_SIZE);
-
-			if (vaddr / PAGE_SIZE < BAN::Math::div_round_up<size_t>(program_header.p_vaddr + program_header.p_filesz, PAGE_SIZE))
+		const auto load_page_from_program_header =
+			[&](BAN::RefPtr<Inode> inode, BAN::Span<const ElfNativeProgramHeader> program_headers) -> BAN::ErrorOr<bool>
 			{
-				size_t vaddr_offset = 0;
-				if (vaddr < program_header.p_vaddr)
-					vaddr_offset = program_header.p_vaddr - vaddr;
+				for (const auto& program_header : program_headers)
+				{
+					ASSERT(program_header.p_type == PT_LOAD);
+					if (!(program_header.p_vaddr <= address && address < program_header.p_vaddr + program_header.p_memsz))
+						continue;
 
-				size_t file_offset = 0;
-				if (vaddr > program_header.p_vaddr)
-					file_offset = vaddr - program_header.p_vaddr;
+					PageTable::flags_t flags = PageTable::Flags::UserSupervisor | PageTable::Flags::Present;
+					if (program_header.p_flags & LibELF::PF_W)
+						flags |= PageTable::Flags::ReadWrite;
+					if (program_header.p_flags & LibELF::PF_X)
+						flags |= PageTable::Flags::Execute;
 
-				size_t bytes = BAN::Math::min<size_t>(PAGE_SIZE - vaddr_offset, program_header.p_filesz - file_offset);
-				TRY(m_inode->read(program_header.p_offset + file_offset, { (uint8_t*)vaddr + vaddr_offset, bytes }));
-			}
+					const vaddr_t vaddr = address & PAGE_ADDR_MASK;
+					const paddr_t paddr = Heap::get().take_free_page();
+					if (paddr == 0)
+						return BAN::Error::from_errno(ENOMEM);
 
-			// Map page with the correct flags
-			m_page_table.map_page_at(paddr, vaddr, flags);
+					// Temporarily map page as RW so kernel can write to it
+					m_page_table.map_page_at(paddr, vaddr, PageTable::Flags::ReadWrite | PageTable::Flags::Present);
+					m_physical_page_count++;
 
+					memset((void*)vaddr, 0x00, PAGE_SIZE);
+
+					if (vaddr / PAGE_SIZE < BAN::Math::div_round_up<size_t>(program_header.p_vaddr + program_header.p_filesz, PAGE_SIZE))
+					{
+						size_t vaddr_offset = 0;
+						if (vaddr < program_header.p_vaddr)
+							vaddr_offset = program_header.p_vaddr - vaddr;
+
+						size_t file_offset = 0;
+						if (vaddr > program_header.p_vaddr)
+							file_offset = vaddr - program_header.p_vaddr;
+
+						size_t bytes = BAN::Math::min<size_t>(PAGE_SIZE - vaddr_offset, program_header.p_filesz - file_offset);
+						TRY(inode->read(program_header.p_offset + file_offset, { (uint8_t*)vaddr + vaddr_offset, bytes }));
+					}
+
+					// Map page with the correct flags
+					m_page_table.map_page_at(paddr, vaddr, flags);
+
+					return true;
+				}
+
+				return false;
+			};
+
+		if (TRY(load_page_from_program_header(m_executable.inode, m_executable.program_headers.span())))
+			return {};
+		if (TRY(load_page_from_program_header(m_interpreter.inode, m_interpreter.program_headers.span())))
 			return {};
-		}
 		ASSERT_NOT_REACHED();
 	}
 
 	BAN::ErrorOr<BAN::UniqPtr<LoadableELF>> LoadableELF::clone(Kernel::PageTable& new_page_table)
 	{
-		auto* elf_ptr = new LoadableELF(new_page_table, m_inode);
-		if (elf_ptr == nullptr)
-			return BAN::Error::from_errno(ENOMEM);
-		auto elf = BAN::UniqPtr<LoadableELF>::adopt(elf_ptr);
+		auto elf = TRY(BAN::UniqPtr<LoadableELF>::create(new_page_table));
 
-		memcpy(&elf->m_file_header, &m_file_header, sizeof(ElfNativeFileHeader));
+		const auto clone_loadable_file =
+			[](const LoadableElfFile& source, LoadableElfFile& destination) -> BAN::ErrorOr<void>
+			{
+				if (!source.inode)
+					return {};
 
-		TRY(elf->m_program_headers.resize(m_program_headers.size()));
-		memcpy(elf->m_program_headers.data(), m_program_headers.data(), m_program_headers.size() * sizeof(ElfNativeProgramHeader));
+				destination.inode = source.inode;
+				destination.file_header = source.file_header;
+				destination.dynamic_base = source.dynamic_base;
+
+				TRY(destination.program_headers.reserve(source.program_headers.size()));
+				for (const auto& program_header : source.program_headers)
+					MUST(destination.program_headers.emplace_back(program_header));
+
+				return {};
+			};
+
+		const auto map_loadable_file =
+			[&](BAN::Span<const ElfNativeProgramHeader> program_headers) -> BAN::ErrorOr<void>
+			{
+				for (const auto& program_header : program_headers)
+				{
+					ASSERT(program_header.p_type == PT_LOAD);
+					if (!(program_header.p_flags & LibELF::PF_W))
+						continue;
+
+					PageTable::flags_t flags = PageTable::Flags::UserSupervisor | PageTable::Flags::Present;
+					if (program_header.p_flags & LibELF::PF_W)
+						flags |= PageTable::Flags::ReadWrite;
+					if (program_header.p_flags & LibELF::PF_X)
+						flags |= PageTable::Flags::Execute;
+
+					vaddr_t start = program_header.p_vaddr & PAGE_ADDR_MASK;
+					size_t pages = range_page_count(program_header.p_vaddr, program_header.p_memsz);
+
+					for (size_t i = 0; i < pages; i++)
+					{
+						if (m_page_table.physical_address_of(start + i * PAGE_SIZE) == 0)
+							continue;
+
+						paddr_t paddr = Heap::get().take_free_page();
+						if (paddr == 0)
+							return BAN::Error::from_errno(ENOMEM);
+
+						PageTable::with_fast_page(paddr, [&] {
+							memcpy(PageTable::fast_page_as_ptr(), (void*)(start + i * PAGE_SIZE), PAGE_SIZE);
+						});
+
+						new_page_table.map_page_at(paddr, start + i * PAGE_SIZE, flags);
+						elf->m_physical_page_count++;
+					}
+				}
+				return {};
+			};
+
+		TRY(clone_loadable_file(m_executable, elf->m_executable));
+		TRY(clone_loadable_file(m_interpreter, elf->m_interpreter));
 
 		elf->reserve_address_space();
 
-		for (const auto& program_header : m_program_headers)
-		{
-			ASSERT(program_header.p_type == PT_LOAD);
-
-			if (!(program_header.p_flags & LibELF::PF_W))
-				continue;
-
-			PageTable::flags_t flags = PageTable::Flags::UserSupervisor | PageTable::Flags::Present;
-			if (program_header.p_flags & LibELF::PF_W)
-				flags |= PageTable::Flags::ReadWrite;
-			if (program_header.p_flags & LibELF::PF_X)
-				flags |= PageTable::Flags::Execute;
-
-			vaddr_t start = program_header.p_vaddr & PAGE_ADDR_MASK;
-			size_t pages = range_page_count(program_header.p_vaddr, program_header.p_memsz);
-
-			for (size_t i = 0; i < pages; i++)
-			{
-				if (m_page_table.physical_address_of(start + i * PAGE_SIZE) == 0)
-					continue;
-
-				paddr_t paddr = Heap::get().take_free_page();
-				if (paddr == 0)
-					return BAN::Error::from_errno(ENOMEM);
-
-				PageTable::with_fast_page(paddr, [&] {
-					memcpy(PageTable::fast_page_as_ptr(), (void*)(start + i * PAGE_SIZE), PAGE_SIZE);
-				});
-
-				new_page_table.map_page_at(paddr, start + i * PAGE_SIZE, flags);
-				elf->m_physical_page_count++;
-			}
-		}
+		TRY(map_loadable_file(elf->m_executable.program_headers.span()));
+		TRY(map_loadable_file(elf->m_interpreter.program_headers.span()));
 
 		return elf;
 	}

userspace/libraries/LibELF/include/LibELF/LoadableELF.h

@@ -22,11 +22,14 @@ namespace LibELF
 		BAN_NON_MOVABLE(LoadableELF);
 
 	public:
-		static BAN::ErrorOr<BAN::UniqPtr<LoadableELF>> load_from_inode(Kernel::PageTable&, BAN::RefPtr<Kernel::Inode>);
+		static BAN::ErrorOr<BAN::UniqPtr<LoadableELF>> load_from_inode(Kernel::PageTable&, const Kernel::Credentials&, BAN::RefPtr<Kernel::Inode>);
 		~LoadableELF();
 
 		Kernel::vaddr_t entry_point() const;
 
+		bool has_interpreter() const { return !!m_interpreter.inode; }
+		BAN::RefPtr<Kernel::Inode> inode() { return m_executable.inode; }
+
 		bool contains(Kernel::vaddr_t address) const;
 		bool is_address_space_free() const;
 		void reserve_address_space();
@@ -41,17 +44,36 @@ namespace LibELF
 		size_t physical_page_count() const { return m_physical_page_count; }
 
 	private:
-		LoadableELF(Kernel::PageTable&, BAN::RefPtr<Kernel::Inode>);
-		BAN::ErrorOr<void> initialize();
+		struct LoadableElfFile
+		{
+			BAN::RefPtr<Kernel::Inode> inode;
+			ElfNativeFileHeader file_header;
+			BAN::Vector<ElfNativeProgramHeader>	program_headers;
+			Kernel::vaddr_t dynamic_base;
+		};
+
+		struct LoadResult
+		{
+			LoadableElfFile elf_file;
+			BAN::RefPtr<Kernel::Inode> interp;
+		};
 
 	private:
-		BAN::RefPtr<Kernel::Inode>			m_inode;
-		Kernel::PageTable&					m_page_table;
-		ElfNativeFileHeader					m_file_header;
-		BAN::Vector<ElfNativeProgramHeader>	m_program_headers;
-		size_t m_virtual_page_count = 0;
-		size_t m_physical_page_count = 0;
-		bool m_loaded { false };
+		LoadableELF(Kernel::PageTable&);
+		BAN::ErrorOr<void> initialize(const Kernel::Credentials&, BAN::RefPtr<Kernel::Inode>);
+
+		bool does_executable_and_interpreter_overlap() const;
+		BAN::ErrorOr<LoadResult> load_elf_file(const Kernel::Credentials&, BAN::RefPtr<Kernel::Inode>) const;
+
+	private:
+		LoadableElfFile    m_executable;
+		LoadableElfFile    m_interpreter;
+		Kernel::PageTable& m_page_table;
+		size_t             m_virtual_page_count  { 0 };
+		size_t             m_physical_page_count { 0 };
+		bool               m_is_loaded           { false };
+
+		friend class BAN::UniqPtr<LoadableELF>;
 	};
 
 }