path: root/fs/binfmt_flat.c

// SPDX-License-Identifier: GPL-2.0
/****************************************************************************/
/*
 *  linux/fs/binfmt_flat.c
 *
 *	Copyright (C) 2000-2003 David McCullough <davidm@snapgear.com>
 *	Copyright (C) 2002 Greg Ungerer <gerg@snapgear.com>
 *	Copyright (C) 2002 SnapGear, by Paul Dale <pauli@snapgear.com>
 *	Copyright (C) 2000, 2001 Lineo, by David McCullough <davidm@lineo.com>
 *  based heavily on:
 *
 *  linux/fs/binfmt_aout.c:
 *      Copyright (C) 1991, 1992, 1996  Linus Torvalds
 *  linux/fs/binfmt_flat.c for 2.0 kernel
 *	    Copyright (C) 1998  Kenneth Albanowski <kjahds@kjahds.com>
 *	JAN/99 -- coded full program relocation (gerg@snapgear.com)
 */

#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/slab.h>
#include <linux/binfmts.h>
#include <linux/personality.h>
#include <linux/init.h>
#include <linux/flat.h>
#include <linux/uaccess.h>
#include <linux/vmalloc.h>
#include <linux/coredump.h>

#include <asm/byteorder.h>
#include <asm/unaligned.h>
#include <asm/cacheflush.h>
#include <asm/page.h>
#include <asm/flat.h>

#ifndef flat_get_relocate_addr
#define flat_get_relocate_addr(rel)	(rel)
#endif

/****************************************************************************/

/*
 * User data (data section and bss) needs to be aligned.
 * We pick 0x20 here because it is the max value elf2flt has always
 * used in producing FLAT files, and because it seems to be large
 * enough to make all the gcc alignment related tests happy.
 */
#define FLAT_DATA_ALIGN	(0x20)

/*
 * User data (stack) also needs to be aligned.
 * Here we can be a bit looser than the data sections since this
 * needs to only meet arch ABI requirements.
 */
#define FLAT_STACK_ALIGN	max_t(unsigned long, sizeof(void *), ARCH_SLAB_MINALIGN)

#define RELOC_FAILED 0xff00ff01		/* Relocation incorrect somewhere */
#define UNLOADED_LIB 0x7ff000ff		/* Placeholder for unused library */

#ifdef CONFIG_BINFMT_SHARED_FLAT
#define	MAX_SHARED_LIBS			(4)
#else
#define	MAX_SHARED_LIBS			(1)
#endif

#ifdef CONFIG_BINFMT_FLAT_NO_DATA_START_OFFSET
#define DATA_START_OFFSET_WORDS		(0)
#else
#define DATA_START_OFFSET_WORDS		(MAX_SHARED_LIBS)
#endif

struct lib_info {
	struct {
		unsigned long start_code;		/* Start of text segment */
		unsigned long start_data;		/* Start of data segment */
		unsigned long start_brk;		/* End of data segment */
		unsigned long text_len;			/* Length of text segment */
		unsigned long entry;			/* Start address for this module */
		unsigned long build_date;		/* When this one was compiled */
		bool loaded;				/* Has this library been loaded? */
	} lib_list[MAX_SHARED_LIBS];
};

#ifdef CONFIG_BINFMT_SHARED_FLAT
static int load_flat_shared_library(int id, struct lib_info *p);
#endif

static int load_flat_binary(struct linux_binprm *);
#ifdef CONFIG_COREDUMP
static int flat_core_dump(struct coredump_params *cprm);
#endif

static struct linux_binfmt flat_format = {
	.module		= THIS_MODULE,
	.load_binary	= load_flat_binary,
#ifdef CONFIG_COREDUMP
	.core_dump	= flat_core_dump,
	.min_coredump	= PAGE_SIZE
#endif
};

/****************************************************************************/
/*
 * Routine writes a core dump image in the current directory.
 * Currently only a stub-function.
 */

#ifdef CONFIG_COREDUMP
static int flat_core_dump(struct coredump_params *cprm)
{
	pr_warn("Process %s:%d received signr %d and should have core dumped\n",
		current->comm, current->pid, cprm->siginfo->si_signo);
	return 1;
}
#endif

/****************************************************************************/
/*
 * create_flat_tables() parses the env- and arg-strings in new user
 * memory and creates the pointer tables from them, and puts their
 * addresses on the "stack", recording the new stack pointer value.
 */

static int create_flat_tables(struct linux_binprm *bprm, unsigned long arg_start)
{
	char __user *p;
	unsigned long __user *sp;
	long i, len;

	p = (char __user *)arg_start;
	sp = (unsigned long __user *)current->mm->start_stack;

	sp -= bprm->envc + 1;
	sp -= bprm->argc + 1;
	if (IS_ENABLED(CONFIG_BINFMT_FLAT_ARGVP_ENVP_ON_STACK))
		sp -= 2; /* argvp + envp */
	sp -= 1;  /* &argc */

	current->mm->start_stack = (unsigned long)sp & -FLAT_STACK_ALIGN;
	sp = (unsigned long __user *)current->mm->start_stack;

	if (put_user(bprm->argc, sp++))
		return -EFAULT;
	if (IS_ENABLED(CONFIG_BINFMT_FLAT_ARGVP_ENVP_ON_STACK)) {
		unsigned long argv, envp;
		argv = (unsigned long)(sp + 2);
		envp = (unsigned long)(sp + 2 + bprm->argc + 1);
		if (put_user(argv, sp++) || put_user(envp, sp++))
			return -EFAULT;
	}

	current->mm->arg_start = (unsigned long)p;
	for (i = bprm->argc; i > 0; i--) {
		if (put_user((unsigned long)p, sp++))
			return -EFAULT;
		len = strnlen_user(p, MAX_ARG_STRLEN);
		if (!len || len > MAX_ARG_STRLEN)
			return -EINVAL;
		p += len;
	}
	if (put_user(0, sp++))
		return -EFAULT;
	current->mm->arg_end = (unsigned long)p;

	current->mm->env_start = (unsigned long) p;
	for (i = bprm->envc; i > 0; i--) {
		if (put_user((unsigned long)p, sp++))
			return -EFAULT;
		len = strnlen_user(p, MAX_ARG_STRLEN);