Files
PSFree/kpatch/80x.c
T
2024-01-27 20:25:49 -06:00

138 lines
3.7 KiB
C

/* Copyright (C) 2024 anonymous
This file is part of PSFree.
PSFree is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as
published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.
PSFree is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
#include <stddef.h>
#include "types.h"
void enable_cr0_wp(void) {
asm(
"mov rax, cr0\n"
"or rax, 0x10000\n"
"mov cr0, rax\n"
);
}
void disable_cr0_wp(void) {
asm(
"mov rax, cr0\n"
"and rax, ~0x10000\n"
"mov cr0, rax\n"
);
}
inline void write8(void *addr, size_t offset, u8 value) {
*(u8 *)(addr + offset) = value;
}
inline void write16(void *addr, size_t offset, u16 value) {
*(u16 *)(addr + offset) = value;
}
inline void write32(void *addr, size_t offset, u32 value) {
*(u32 *)(addr + offset) = value;
}
inline void write64(void *addr, size_t offset, u64 value) {
*(u64 *)(addr + offset) = value;
}
// Args:
// kbase: kernel base address
// res:
// Needed value to return (as to not crash) if the caller of the hijacked
// function is expecting some valid value.
// error:
// Address to return an error. 0 for success.
__attribute__((section (".text.start")))
u64 kpatch(void *kbase, u64 res, u64 *error) {
if (kbase == NULL) {
if (error != NULL) {
*error = -1;
}
goto end;
}
disable_cr0_wp();
// patch amd64_syscall() to allow calling syscalls everywhere
write32(kbase, 0x490, 0);
write16(kbase, 0x4b5, 0x9090);
write16(kbase, 0x4b9, 0x9090);
write8(kbase, 0x4c2, 0xeb);
// patch sys_mmap() to allow rwx mappings
// patch maximum cpu mem protection: 0x33 -> 0x37
// the ps4 added custom protections for their gpu memory accesses
// GPU R: 0x10, W: 0x20, X:, 0x40
// that's why you see other bits set
write8(kbase, 0xfd03a, 0x37);
write8(kbase, 0xfd03d, 0x37);
// patch vm_map_protect() (called by sys_mprotect()) to allow rwx mappings
write32(kbase, 0x3ec68d, 0);
// patch sys_dynlib_dlsym() to allow dynamic symbol resolution everywhere
// patch to alway jump regardless of the check before
write8(kbase, 0x31953f, 0xeb);
// patch called function to always return 0
write32(kbase, 0x951c0, 0xC3C03148);
// patch sys_setuid() to allow freely changing the effective user ID
// patch to alway jump regardless of the check before
write8(kbase, 0x34d696, 0xeb);
// overwrite the entry of syscall 11 (unimplemented) in sysent
//
// struct args {
// u64 rdi;
// u64 rsi;
// u64 rdx;
// u64 rdx;
// u64 r8;
// u64 r9;
// }
//
// jumps to uap->rdi
// u64 sys_kexec(struct thread td, struct args *uap)
// sysent[11]
const size_t offset_sysent_11 = 0x10fc6e0;
// .sy_narg = 2
write32(kbase, offset_sysent_11, 2);
// .sy_call = gadgets['jmp qword ptr [rsi]']
write64(kbase, offset_sysent_11 + 8, kbase + 0xe629c);
// .sy_thrcnt = SY_THR_STATIC
write32(kbase, offset_sysent_11 + 0x2c, 1);
// restore socketops.fo_chmod
// it was used to initially to perform kernel code execution
write64(kbase, 0x1a76060, kbase + 0x3d0a60);
enable_cr0_wp();
if (error != NULL) {
*error = 0;
}
end:
return res;
}