Added readonly remap of readonly elf sections

2 files changed, 75 insertions, 1 deletions

diff --git a/kernel/features/load.c b/kernel/features/load.c
index 0439424..de48be4 100644
--- a/kernel/features/load.c
+++ b/kernel/features/load.c
@@ -49,6 +49,7 @@ res elf_load(const char *path, struct proc *proc)
 	    header.version != 1 || header.machine != ELF_MACHINE_386)
 		return -ENOEXEC;
 
+	// Loop through programs
 	for (u32 i = 0; i < header.phnum; i++) {
 		struct elf_program program = { 0 };
 
@@ -61,7 +62,7 @@ res elf_load(const char *path, struct proc *proc)
 		}
 		memory_bypass_disable();
 
-		if (program.vaddr == 0)
+		if (program.vaddr == 0 || program.type != ELF_PROGRAM_TYPE_LOAD)
 			continue;
 
 		if (!memory_is_user(program.vaddr))
@@ -87,6 +88,56 @@ res elf_load(const char *path, struct proc *proc)
 		memory_switch_dir(prev);
 	}
 
+	// Find section string table
+	struct elf_section section_strings = { 0 };
+	memory_bypass_enable();
+	if (vfs_read(path, &section_strings, header.shoff + header.shentsize * header.shstrndx,
+		     sizeof(section_strings)) != sizeof(section_strings)) {
+		memory_bypass_disable();
+		clac();
+		return -ENOEXEC;
+	}
+	memory_bypass_disable();
+
+	if (section_strings.type != ELF_SECTION_TYPE_STRTAB)
+		return -ENOEXEC;
+
+	// Loop through sections
+	for (u32 i = 0; i < header.shnum; i++) {
+		struct elf_section section = { 0 };
+		memory_bypass_enable();
+		if (vfs_read(path, &section, header.shoff + header.shentsize * i,
+			     sizeof(section)) != sizeof(section)) {
+			memory_bypass_disable();
+			clac();
+			return -ENOEXEC;
+		}
+		memory_bypass_disable();
+
+		// TODO: Use section and symbol name for logging or something? (e.g. in page fault handler)
+		/* u32 offset = section_strings.offset + section.name; */
+		/* if (offset >= s.size) */
+		/* 	return -ENOEXEC; */
+		/* memory_bypass_enable(); */
+		/* char name[64] = { 0 }; // Max length? */
+		/* if (vfs_read(path, &name, offset, sizeof(name)) != sizeof(name)) { */
+		/* 	memory_bypass_disable(); */
+		/* 	clac(); */
+		/* 	return -ENOEXEC; */
+		/* } */
+		/* memory_bypass_disable(); */
+		/* printf("%d\n", section.name); */
+		/* if (section.type == ELF_SECTION_TYPE_SYMTAB) { */
+		/* } else if (section.type == ELF_SECTION_TYPE_STRTAB && i != header.shstrndx) { */
+		/* } */
+
+		// Remap readonly sections
+		if (!(section.flags & ELF_SECTION_FLAG_WRITE)) {
+			struct memory_range range = memory_range_around(section.addr, section.size);
+			virtual_remap_readonly(proc->page_dir, range);
+		}
+	}
+
 	struct page_dir *prev;
 	memory_backup_dir(&prev);
 	memory_switch_dir(proc->page_dir);
diff --git a/kernel/features/mm.c b/kernel/features/mm.c
index 29e07e1..67a5abf 100644
--- a/kernel/features/mm.c
+++ b/kernel/features/mm.c
@@ -257,6 +257,29 @@ void virtual_map(struct page_dir *dir, struct memory_range prange, u32 vaddr, u3
 	paging_invalidate_tlb();
 }
 
+void virtual_remap_readonly(struct page_dir *dir, struct memory_range vrange)
+{
+	for (u32 i = 0; i < vrange.size / PAGE_SIZE; i++) {
+		u32 offset = i * PAGE_SIZE;
+
+		u32 pdi = PDI(vrange.base + offset);
+		union page_dir_entry *dir_entry = &dir->entries[pdi];
+		if (!dir_entry->bits.present)
+			continue;
+
+		struct page_table *table =
+			(struct page_table *)(dir_entry->bits.address * PAGE_SIZE);
+
+		u32 pti = PTI(vrange.base + offset);
+		union page_table_entry *table_entry = &table->entries[pti];
+
+		if (table_entry->bits.present)
+			table_entry->bits.writable = 0;
+	}
+
+	paging_invalidate_tlb();
+}
+
 struct memory_range virtual_alloc(struct page_dir *dir, struct memory_range prange, u32 flags)
 {
 	u8 user = flags & MEMORY_USER;