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// MIT License, Copyright (c) 2020 Marvin Borner
#include <cpu.h>
#include <errno.h>
#include <fs.h>
#include <load.h>
#include <mem.h>
#include <mm.h>
#include <random.h>
#include <str.h>
res elf_load(const char *name, struct proc *proc)
{
if (!memory_valid(name))
return -EFAULT;
stac();
char path[64] = { "/apps/" };
strlcat(path, name, sizeof(path));
strlcpy(proc->dir, path, sizeof(proc->dir));
strlcat(path, "/exec", sizeof(path));
strlcpy(proc->name, name, sizeof(proc->name));
clac();
struct stat s = { 0 };
memory_bypass_enable();
res stat = vfs_stat(path, &s);
memory_bypass_disable();
if (stat != EOK)
return stat;
struct elf_header header = { 0 };
stac();
memory_bypass_enable();
res read = vfs_read(path, &header, 0, sizeof(header));
memory_bypass_disable();
clac();
if (read < 0)
return read;
if (read != sizeof(header))
return -ENOEXEC;
// Valid?
u8 *magic = header.ident;
u8 valid_magic = magic[ELF_IDENT_MAG0] == ELF_MAG0 && magic[ELF_IDENT_MAG1] == ELF_MAG1 &&
magic[ELF_IDENT_MAG2] == ELF_MAG2 && magic[ELF_IDENT_MAG3] == ELF_MAG3 &&
magic[ELF_IDENT_CLASS] == ELF_IDENT_CLASS_32 &&
magic[ELF_IDENT_DATA] == ELF_IDENT_DATA_LSB;
if (!valid_magic ||
(header.type != ELF_ETYPE_REL && header.type != ELF_ETYPE_EXEC &&
header.type != ELF_ETYPE_DYN) ||
header.version != 1 || header.machine != ELF_MACHINE_386)
return -ENOEXEC;
if (!memory_valid((void *)header.entry))
return -ENOEXEC;
// ASLR
u32 rand_off = header.type == ELF_ETYPE_DYN ? (rand() & 0xffff) * PAGE_SIZE : 0;
// Loop through programs
for (u32 i = 0; i < header.phnum; i++) {
struct elf_program program = { 0 };
memory_bypass_enable();
if (vfs_read(path, &program, header.phoff + header.phentsize * i,
sizeof(program)) != sizeof(program)) {
memory_bypass_disable();
clac();
return -ENOEXEC;
}
memory_bypass_disable();
if (program.type == ELF_PROGRAM_TYPE_INTERP)
return -ENOEXEC;
if (program.vaddr == 0 || program.type != ELF_PROGRAM_TYPE_LOAD)
continue;
if (!memory_is_user(program.vaddr))
return -ENOEXEC;
struct page_dir *prev;
memory_backup_dir(&prev);
memory_switch_dir(proc->page_dir);
struct memory_range vrange =
memory_range_around(program.vaddr + rand_off, program.memsz);
struct memory_range prange = physical_alloc(vrange.size);
virtual_map(proc->page_dir, prange, vrange.base, MEMORY_CLEAR | MEMORY_USER);
memory_bypass_enable();
if ((u32)vfs_read(path, (void *)((u32)program.vaddr + rand_off), program.offset,
program.filesz) != program.filesz) {
memory_bypass_disable();
memory_switch_dir(prev);
return -ENOEXEC;
}
memory_bypass_disable();
memory_switch_dir(prev);
}
// Find section string table
struct elf_section section_strings = { 0 };
memory_bypass_enable();
if (vfs_read(path, §ion_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, §ion, 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 + rand_off, section.size);
virtual_remap_readonly(proc->page_dir, range);
}
}
struct page_dir *prev;
memory_backup_dir(&prev);
memory_switch_dir(proc->page_dir);
stac();
// Allocate stack with readonly lower and upper page boundary
u32 stack = PAGE_SIZE + (u32)memory_alloc(proc->page_dir, PROC_STACK_SIZE + 2 * PAGE_SIZE,
MEMORY_USER | MEMORY_CLEAR);
virtual_remap_readonly(proc->page_dir, memory_range(stack - PAGE_SIZE, PAGE_SIZE));
virtual_remap_readonly(proc->page_dir, memory_range(stack + PROC_STACK_SIZE, PAGE_SIZE));
proc->regs.ebp = stack + PROC_STACK_SIZE;
proc->regs.useresp = stack + PROC_STACK_SIZE;
proc->regs.eip = header.entry + rand_off;
proc->entry = header.entry + rand_off;
clac();
memory_switch_dir(prev);
return EOK;
}
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