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inject.c
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inject.c
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/*
* Copyright (C) 2011 IITiS PAN Gliwice <www.iitis.pl>
* Author: Paweł Foremski <pjf@iitis.pl>
* Licensed under GNU GPL v. 3
*/
#include <stdbool.h>
#include <stdint.h>
#include <sys/socket.h>
#include <linux/net.h>
#include <netinet/in.h>
#include <stdarg.h>
#include "tracedump.h"
int32_t inject_socketcall(struct tracedump *td, struct pid *sp, uint32_t sc_code, ...)
{
/* int 0x80, int3 */
unsigned char code[4] = { 0xcd, 0x80, 0xcc, 0 };
char backup[4];
struct user_regs_struct regs, regs2;
int ss_vals, ss_mem, ss;
va_list vl;
enum arg_type type;
uint32_t sv;
void *ptr;
uint8_t *stack, *stack_mem;
uint32_t *stack32;
int i, j;
/*
* get the required amount of stack space
*/
ss_vals = 0;
ss_mem = 0;
va_start(vl, sc_code);
do {
type = va_arg(vl, enum arg_type);
if (type == AT_LAST) break;
sv = va_arg(vl, uint32_t);
/* each socketcall argument takes 4 bytes */
ss_vals += 4;
/* if its memory, it takes additional sv bytes */
if (type == AT_MEM_IN || type == AT_MEM_INOUT) {
ss_mem += sv;
ptr = va_arg(vl, void *);
}
} while (true);
va_end(vl);
ss = ss_vals + ss_mem;
/*
* backup
*/
ptrace_getregs(sp, ®s);
memcpy(®s2, ®s, sizeof regs);
ptrace_read(sp, regs.eip, backup, sizeof backup);
/*
* write the stack
*/
stack = mmatic_zalloc(td->mm, ss);
stack32 = (uint32_t *) stack;
stack_mem = stack + ss_vals;
va_start(vl, sc_code);
i = 0; j = 0;
do {
type = va_arg(vl, enum arg_type);
if (type == AT_LAST) break;
sv = va_arg(vl, uint32_t);
if (type == AT_VALUE) {
stack32[i++] = sv;
} else { /* i.e. its a memory arg */
stack32[i++] = regs.esp - ss_mem + j;
/* copy the memory */
ptr = va_arg(vl, void *);
memcpy(stack_mem + j, ptr, sv);
j += sv;
}
} while (true);
va_end(vl);
ptrace_write(sp, regs.esp - ss, stack, ss);
/*
* write the code and run
*/
regs2.eax = 102; // socketcall
regs2.ebx = sc_code;
regs2.ecx = regs.esp - ss;
ptrace_write(sp, regs.eip, code, sizeof code);
ptrace_setregs(sp, ®s2);
ptrace_cont(sp, 0, true);
/*
* read back
*/
ptrace_getregs(sp, ®s2);
ptrace_read(sp, regs.esp - ss_mem, stack_mem, ss_mem);
va_start(vl, sc_code);
do {
type = va_arg(vl, enum arg_type);
if (type == AT_LAST) break;
sv = va_arg(vl, uint32_t);
if (type == AT_VALUE) continue;
ptr = va_arg(vl, void *);
if (type == AT_MEM_IN) continue;
memcpy(ptr, stack_mem, sv);
stack_mem += sv;
} while (true);
va_end(vl);
/* restore */
ptrace_write(sp, regs.eip, backup, sizeof backup);
ptrace_setregs(sp, ®s);
mmatic_free(stack);
return regs2.eax;
}
void inject_escape_socketcall(struct tracedump *td, struct pid *sp)
{
struct user_regs_struct regs;
/* make backup */
ptrace_getregs(sp, ®s);
memcpy(&sp->regs, ®s, sizeof regs);
/* update EBX so it is invalid */
regs.ebx = 0;
ptrace_setregs(sp, ®s);
/* run the invalid socketcall and wait */
ptrace_cont_syscall(sp, 0, true);
/* -> now the process is in user mode */
}
void inject_restore_socketcall(struct tracedump *td, struct pid *sp)
{
/* int 0x80, int3 */
unsigned char code[4] = { 0xcd, 0x80, 0xcc, 0 };
char backup[4];
struct user_regs_struct regs2;
/* backup */
ptrace_read(sp, sp->regs.eip, backup, 4);
/* exec */
sp->regs.eax = sp->regs.orig_eax;
ptrace_setregs(sp, &sp->regs);
ptrace_write(sp, sp->regs.eip, code, 4);
ptrace_cont(sp, 0, true);
/* read the return code */
ptrace_getregs(sp, ®s2);
sp->regs.eax = regs2.eax;
/* restore */
ptrace_setregs(sp, &sp->regs);
ptrace_write(sp, sp->regs.eip, backup, 4);
}