binfmt_elf_fdpic.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* binfmt_elf_fdpic.c: FDPIC ELF binary format
 *
 * Copyright (C) 2003, 2004, 2006 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 * Derived from binfmt_elf.c
 */

#include <linux/module.h>

#include <linux/fs.h>
#include <linux/stat.h>
#include <linux/sched.h>
#include <linux/sched/coredump.h>
#include <linux/sched/task_stack.h>
#include <linux/sched/cputime.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/binfmts.h>
#include <linux/string.h>
#include <linux/file.h>
#include <linux/fcntl.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/security.h>
#include <linux/highmem.h>
#include <linux/highuid.h>
#include <linux/personality.h>
#include <linux/ptrace.h>
#include <linux/init.h>
#include <linux/elf.h>
#include <linux/elf-fdpic.h>
#include <linux/elfcore.h>
#include <linux/coredump.h>
#include <linux/dax.h>
#include <linux/regset.h>

#include <linux/uaccess.h>
#include <asm/param.h>

typedef char *elf_caddr_t;

#if 0
#define kdebug(fmt, ...) printk("FDPIC "fmt"\n" ,##__VA_ARGS__ )
#else
#define kdebug(fmt, ...) do {} while(0)
#endif

#if 0
#define kdcore(fmt, ...) printk("FDPIC "fmt"\n" ,##__VA_ARGS__ )
#else
#define kdcore(fmt, ...) do {} while(0)
#endif

MODULE_LICENSE("GPL");

static int load_elf_fdpic_binary(struct linux_binprm *);
static int elf_fdpic_fetch_phdrs(struct elf_fdpic_params *, struct file *);
static int elf_fdpic_map_file(struct elf_fdpic_params *, struct file *,
			      struct mm_struct *, const char *);

static int create_elf_fdpic_tables(struct linux_binprm *, struct mm_struct *,
				   struct elf_fdpic_params *,
				   struct elf_fdpic_params *);

#ifndef CONFIG_MMU
static int elf_fdpic_map_file_constdisp_on_uclinux(struct elf_fdpic_params *,
						   struct file *,
						   struct mm_struct *);
#endif

static int elf_fdpic_map_file_by_direct_mmap(struct elf_fdpic_params *,
					     struct file *, struct mm_struct *);

#ifdef CONFIG_ELF_CORE
static int elf_fdpic_core_dump(struct coredump_params *cprm);
#endif

static struct linux_binfmt elf_fdpic_format = {
	.module		= THIS_MODULE,
	.load_binary	= load_elf_fdpic_binary,
#ifdef CONFIG_ELF_CORE
	.core_dump	= elf_fdpic_core_dump,
	.min_coredump	= ELF_EXEC_PAGESIZE,
#endif
};

static int __init init_elf_fdpic_binfmt(void)
{
	register_binfmt(&elf_fdpic_format);
	return 0;
}

static void __exit exit_elf_fdpic_binfmt(void)
{
	unregister_binfmt(&elf_fdpic_format);
}

core_initcall(init_elf_fdpic_binfmt);
module_exit(exit_elf_fdpic_binfmt);

static int is_elf(struct elfhdr *hdr, struct file *file)
{
	if (memcmp(hdr->e_ident, ELFMAG, SELFMAG) != 0)
		return 0;
	if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN)
		return 0;
	if (!elf_check_arch(hdr))
		return 0;
	if (!file->f_op->mmap)
		return 0;
	return 1;
}

#ifndef elf_check_fdpic
#define elf_check_fdpic(x) 0
#endif

#ifndef elf_check_const_displacement
#define elf_check_const_displacement(x) 0
#endif

static int is_constdisp(struct elfhdr *hdr)
{
	if (!elf_check_fdpic(hdr))
		return 1;
	if (elf_check_const_displacement(hdr))
		return 1;
	return 0;
}

/*****************************************************************************/
/*
 * read the program headers table into memory
 */
static int elf_fdpic_fetch_phdrs(struct elf_fdpic_params *params,
				 struct file *file)
{
	struct elf32_phdr *phdr;
	unsigned long size;
	int retval, loop;
	loff_t pos = params->hdr.e_phoff;

	if (params->hdr.e_phentsize != sizeof(struct elf_phdr))
		return -ENOMEM;
	if (params->hdr.e_phnum > 65536U / sizeof(struct elf_phdr))
		return -ENOMEM;

	size = params->hdr.e_phnum * sizeof(struct elf_phdr);
	params->phdrs = kmalloc(size, GFP_KERNEL);
	if (!params->phdrs)
		return -ENOMEM;

	retval = kernel_read(file, params->phdrs, size, &pos);
	if (unlikely(retval != size))
		return retval < 0 ? retval : -ENOEXEC;

	/* determine stack size for this binary */
	phdr = params->phdrs;
	for (loop = 0; loop < params->hdr.e_phnum; loop++, phdr++) {
		if (phdr->p_type != PT_GNU_STACK)
			continue;

		if (phdr->p_flags & PF_X)
			params->flags |= ELF_FDPIC_FLAG_EXEC_STACK;
		else
			params->flags |= ELF_FDPIC_FLAG_NOEXEC_STACK;

		params->stack_size = phdr->p_memsz;
		break;
	}

	return 0;
}

/*****************************************************************************/
/*
 * load an fdpic binary into various bits of memory
 */
static int load_elf_fdpic_binary(struct linux_binprm *bprm)
{
	struct elf_fdpic_params exec_params, interp_params;
	struct pt_regs *regs = current_pt_regs();
	struct elf_phdr *phdr;
	unsigned long stack_size, entryaddr;
#ifdef ELF_FDPIC_PLAT_INIT
	unsigned long dynaddr;
#endif
#ifndef CONFIG_MMU
	unsigned long stack_prot;
#endif
	struct file *interpreter = NULL; /* to shut gcc up */
	char *interpreter_name = NULL;
	int executable_stack;
	int retval, i;
	loff_t pos;

	kdebug("____ LOAD %d ____", current->pid);

	memset(&exec_params, 0, sizeof(exec_params));
	memset(&interp_params, 0, sizeof(interp_params));

	exec_params.hdr = *(struct elfhdr *) bprm->buf;
	exec_params.flags = ELF_FDPIC_FLAG_PRESENT | ELF_FDPIC_FLAG_EXECUTABLE;

	/* check that this is a binary we know how to deal with */
	retval = -ENOEXEC;
	if (!is_elf(&exec_params.hdr, bprm->file))
		goto error;
	if (!elf_check_fdpic(&exec_params.hdr)) {
#ifdef CONFIG_MMU
		/* binfmt_elf handles non-fdpic elf except on nommu */
		goto error;
#else
		/* nommu can only load ET_DYN (PIE) ELF */
		if (exec_params.hdr.e_type != ET_DYN)
			goto error;
#endif
	}

	/* read the program header table */
	retval = elf_fdpic_fetch_phdrs(&exec_params, bprm->file);
	if (retval < 0)
		goto error;

	/* scan for a program header that specifies an interpreter */
	phdr = exec_params.phdrs;

	for (i = 0; i < exec_params.hdr.e_phnum; i++, phdr++) {
		switch (phdr->p_type) {
		case PT_INTERP:
			retval = -ENOMEM;
			if (phdr->p_filesz > PATH_MAX)
				goto error;
			retval = -ENOENT;
			if (phdr->p_filesz < 2)
				goto error;

			/* read the name of the interpreter into memory */
			interpreter_name = kmalloc(phdr->p_filesz, GFP_KERNEL);
			if (!interpreter_name)
				goto error;

			pos = phdr->p_offset;
			retval = kernel_read(bprm->file, interpreter_name,
					     phdr->p_filesz, &pos);
			if (unlikely(retval != phdr->p_filesz)) {
				if (retval >= 0)
					retval = -ENOEXEC;
				goto error;
			}

			retval = -ENOENT;
			if (interpreter_name[phdr->p_filesz - 1] != '\0')
				goto error;

			kdebug("Using ELF interpreter %s", interpreter_name);

			/* replace the program with the interpreter */
			interpreter = open_exec(interpreter_name);
			retval = PTR_ERR(interpreter);
			if (IS_ERR(interpreter)) {
				interpreter = NULL;
				goto error;
			}

			/*
			 * If the binary is not readable then enforce
			 * mm->dumpable = 0 regardless of the interpreter's
			 * permissions.
			 */
			would_dump(bprm, interpreter);

			pos = 0;
			retval = kernel_read(interpreter, bprm->buf,
					BINPRM_BUF_SIZE, &pos);
			if (unlikely(retval != BINPRM_BUF_SIZE)) {
				if (retval >= 0)
					retval = -ENOEXEC;
				goto error;
			}

			interp_params.hdr = *((struct elfhdr *) bprm->buf);
			break;

		case PT_LOAD:
#ifdef CONFIG_MMU
			if (exec_params.load_addr == 0)
				exec_params.load_addr = phdr->p_vaddr;
#endif
			break;
		}

	}

	if (is_constdisp(&exec_params.hdr))
		exec_params.flags |= ELF_FDPIC_FLAG_CONSTDISP;

	/* perform insanity checks on the interpreter */
	if (interpreter_name) {
		retval = -ELIBBAD;
		if (!is_elf(&interp_params.hdr, interpreter))
			goto error;

		interp_params.flags = ELF_FDPIC_FLAG_PRESENT;

		/* read the interpreter's program header table */
		retval = elf_fdpic_fetch_phdrs(&interp_params, interpreter);
		if (retval < 0)
			goto error;
	}

	stack_size = exec_params.stack_size;
	if (exec_params.flags & ELF_FDPIC_FLAG_EXEC_STACK)
		executable_stack = EXSTACK_ENABLE_X;
	else if (exec_params.flags & ELF_FDPIC_FLAG_NOEXEC_STACK)
		executable_stack = EXSTACK_DISABLE_X;
	else
		executable_stack = EXSTACK_DEFAULT;

	if (stack_size == 0) {
		stack_size = interp_params.stack_size;
		if (interp_params.flags & ELF_FDPIC_FLAG_EXEC_STACK)
			executable_stack = EXSTACK_ENABLE_X;
		else if (interp_params.flags & ELF_FDPIC_FLAG_NOEXEC_STACK)
			executable_stack = EXSTACK_DISABLE_X;
		else
			executable_stack = EXSTACK_DEFAULT;
	}

	retval = -ENOEXEC;
	if (stack_size == 0)
		stack_size = 131072UL; /* same as exec.c's default commit */

	if (is_constdisp(&interp_params.hdr))
		interp_params.flags |= ELF_FDPIC_FLAG_CONSTDISP;

	/* flush all traces of the currently running executable */
	retval = begin_new_exec(bprm);
	if (retval)
		goto error;

	/* there's now no turning back... the old userspace image is dead,
	 * defunct, deceased, etc.
	 */
	if (elf_check_fdpic(&exec_params.hdr))
		set_personality(PER_LINUX_FDPIC);
	else
		set_personality(PER_LINUX);
	if (elf_read_implies_exec(&exec_params.hdr, executable_stack))
		current->personality |= READ_IMPLIES_EXEC;

	setup_new_exec(bprm);

	set_binfmt(&elf_fdpic_format);

	current->mm->start_code = 0;
	current->mm->end_code = 0;
	current->mm->start_stack = 0;
	current->mm->start_data = 0;
	current->mm->end_data = 0;
	current->mm->context.exec_fdpic_loadmap = 0;
	current->mm->context.interp_fdpic_loadmap = 0;

#ifdef CONFIG_MMU
	elf_fdpic_arch_lay_out_mm(&exec_params,
				  &interp_params,
				  &current->mm->start_stack,
				  &current->mm->start_brk);

	retval = setup_arg_pages(bprm, current->mm->start_stack,
				 executable_stack);
	if (retval < 0)
		goto error;
#ifdef ARCH_HAS_SETUP_ADDITIONAL_PAGES
	retval = arch_setup_additional_pages(bprm, !!interpreter_name);
	if (retval < 0)
		goto error;
#endif
#endif

	/* load the executable and interpreter into memory */
	retval = elf_fdpic_map_file(&exec_params, bprm->file, current->mm,
				    "executable");
	if (retval < 0)
		goto error;

	if (interpreter_name) {
		retval = elf_fdpic_map_file(&interp_params, interpreter,
					    current->mm, "interpreter");
		if (retval < 0) {
			printk(KERN_ERR "Unable to load interpreter\n");
			goto error;
		}

		allow_write_access(interpreter);
		fput(interpreter);
		interpreter = NULL;
	}

#ifdef CONFIG_MMU
	if (!current->mm->start_brk)
		current->mm->start_brk = current->mm->end_data;

	current->mm->brk = current->mm->start_brk =
		PAGE_ALIGN(current->mm->start_brk);

#else
	/* create a stack area and zero-size brk area */
	stack_size = (stack_size + PAGE_SIZE - 1) & PAGE_MASK;
	if (stack_size < PAGE_SIZE * 2)
		stack_size = PAGE_SIZE * 2;

	stack_prot = PROT_READ | PROT_WRITE;
	if (executable_stack == EXSTACK_ENABLE_X ||
	    (executable_stack == EXSTACK_DEFAULT && VM_STACK_FLAGS & VM_EXEC))
		stack_prot |= PROT_EXEC;

	current->mm->start_brk = vm_mmap(NULL, 0, stack_size, stack_prot,
					 MAP_PRIVATE | MAP_ANONYMOUS |
					 MAP_UNINITIALIZED | MAP_GROWSDOWN,
					 0);

	if (IS_ERR_VALUE(current->mm->start_brk)) {
		retval = current->mm->start_brk;
		current->mm->start_brk = 0;
		goto error;
	}

	current->mm->brk = current->mm->start_brk;
	current->mm->context.end_brk = current->mm->start_brk;
	current->mm->start_stack = current->mm->start_brk + stack_size;
#endif

	if (create_elf_fdpic_tables(bprm, current->mm,
				    &exec_params, &interp_params) < 0)
		goto error;

	kdebug("- start_code  %lx", current->mm->start_code);
	kdebug("- end_code    %lx", current->mm->end_code);
	kdebug("- start_data  %lx", current->mm->start_data);
	kdebug("- end_data    %lx", current->mm->end_data);
	kdebug("- start_brk   %lx", current->mm->start_brk);
	kdebug("- brk         %lx", current->mm->brk);
	kdebug("- start_stack %lx", current->mm->start_stack);

#ifdef ELF_FDPIC_PLAT_INIT
	/*
	 * The ABI may specify that certain registers be set up in special
	 * ways (on i386 %edx is the address of a DT_FINI function, for
	 * example.  This macro performs whatever initialization to
	 * the regs structure is required.
	 */
	dynaddr = interp_params.dynamic_addr ?: exec_params.dynamic_addr;
	ELF_FDPIC_PLAT_INIT(regs, exec_params.map_addr, interp_params.map_addr,
			    dynaddr);
#endif

	finalize_exec(bprm);
	/* everything is now ready... get the userspace context ready to roll */
	entryaddr = interp_params.entry_addr ?: exec_params.entry_addr;
	start_thread(regs, entryaddr, current->mm->start_stack);

	retval = 0;

error:
	if (interpreter) {
		allow_write_access(interpreter);
		fput(interpreter);
	}
	kfree(interpreter_name);
	kfree(exec_params.phdrs);
	kfree(exec_params.loadmap);
	kfree(interp_params.phdrs);
	kfree(interp_params.loadmap);
	return retval;
}

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

#ifndef ELF_BASE_PLATFORM
/*
 * AT_BASE_PLATFORM indicates the "real" hardware/microarchitecture.
 * If the arch defines ELF_BASE_PLATFORM (in asm/elf.h), the value
 * will be copied to the user stack in the same manner as AT_PLATFORM.
 */
#define ELF_BASE_PLATFORM NULL
#endif

/*
 * present useful information to the program by shovelling it onto the new
 * process's stack
 */
static int create_elf_fdpic_tables(struct linux_binprm *bprm,
				   struct mm_struct *mm,
				   struct elf_fdpic_params *exec_params,
				   struct elf_fdpic_params *interp_params)
{
	const struct cred *cred = current_cred();
	unsigned long sp, csp, nitems;
	elf_caddr_t __user *argv, *envp;
	size_t platform_len = 0, len;
	char *k_platform, *k_base_platform;
	char __user *u_platform, *u_base_platform, *p;
	int loop;
	int nr;	/* reset for each csp adjustment */
	unsigned long flags = 0;

#ifdef CONFIG_MMU
	/* In some cases (e.g. Hyper-Threading), we want to avoid L1 evictions
	 * by the processes running on the same package. One thing we can do is
	 * to shuffle the initial stack for them, so we give the architecture
	 * an opportunity to do so here.
	 */
	sp = arch_align_stack(bprm->p);
#else
	sp = mm->start_stack;

	/* stack the program arguments and environment */
	if (transfer_args_to_stack(bprm, &sp) < 0)
		return -EFAULT;
	sp &= ~15;
#endif

	/*
	 * If this architecture has a platform capability string, copy it
	 * to userspace.  In some cases (Sparc), this info is impossible
	 * for userspace to get any other way, in others (i386) it is
	 * merely difficult.
	 */
	k_platform = ELF_PLATFORM;
	u_platform = NULL;

	if (k_platform) {
		platform_len = strlen(k_platform) + 1;
		sp -= platform_len;
		u_platform = (char __user *) sp;
		if (copy_to_user(u_platform, k_platform, platform_len) != 0)
			return -EFAULT;
	}

	/*
	 * If this architecture has a "base" platform capability
	 * string, copy it to userspace.
	 */
	k_base_platform = ELF_BASE_PLATFORM;
	u_base_platform = NULL;

	if (k_base_platform) {
		platform_len = strlen(k_base_platform) + 1;
		sp -= platform_len;
		u_base_platform = (char __user *) sp;
		if (copy_to_user(u_base_platform, k_base_platform, platform_len) != 0)
			return -EFAULT;
	}

	sp &= ~7UL;

	/* stack the load map(s) */
	len = sizeof(struct elf32_fdpic_loadmap);
	len += sizeof(struct elf32_fdpic_loadseg) * exec_params->loadmap->nsegs;
	sp = (sp - len) & ~7UL;
	exec_params->map_addr = sp;

	if (copy_to_user((void __user *) sp, exec_params->loadmap, len) != 0)
		return -EFAULT;

	current->mm->context.exec_fdpic_loadmap = (unsigned long) sp;

	if (interp_params->loadmap) {
		len = sizeof(struct elf32_fdpic_loadmap);
		len += sizeof(struct elf32_fdpic_loadseg) *
			interp_params->loadmap->nsegs;
		sp = (sp - len) & ~7UL;
		interp_params->map_addr = sp;

		if (copy_to_user((void __user *) sp, interp_params->loadmap,
				 len) != 0)
			return -EFAULT;

		current->mm->context.interp_fdpic_loadmap = (unsigned long) sp;
	}

	/* force 16 byte _final_ alignment here for generality */
#define DLINFO_ITEMS 15

	nitems = 1 + DLINFO_ITEMS + (k_platform ? 1 : 0) +
		(k_base_platform ? 1 : 0) + AT_VECTOR_SIZE_ARCH;

	if (bprm->have_execfd)
		nitems++;

	csp = sp;
	sp -= nitems * 2 * sizeof(unsigned long);
	sp -= (bprm->envc + 1) * sizeof(char *);	/* envv[] */
	sp -= (bprm->argc + 1) * sizeof(char *);	/* argv[] */
	sp -= 1 * sizeof(unsigned long);		/* argc */

	csp -= sp & 15UL;
	sp -= sp & 15UL;

	/* put the ELF interpreter info on the stack */
#define NEW_AUX_ENT(id, val)						\
	do {								\
		struct { unsigned long _id, _val; } __user *ent, v;	\
									\
		ent = (void __user *) csp;				\
		v._id = (id);						\
		v._val = (val);						\
		if (copy_to_user(ent + nr, &v, sizeof(v)))		\
			return -EFAULT;					\
		nr++;							\
	} while (0)

	nr = 0;
	csp -= 2 * sizeof(unsigned long);
	NEW_AUX_ENT(AT_NULL, 0);
	if (k_platform) {
		nr = 0;
		csp -= 2 * sizeof(unsigned long);
		NEW_AUX_ENT(AT_PLATFORM,
			    (elf_addr_t) (unsigned long) u_platform);
	}

	if (k_base_platform) {
		nr = 0;
		csp -= 2 * sizeof(unsigned long);
		NEW_AUX_ENT(AT_BASE_PLATFORM,
			    (elf_addr_t) (unsigned long) u_base_platform);
	}

	if (bprm->have_execfd) {
		nr = 0;
		csp -= 2 * sizeof(unsigned long);
		NEW_AUX_ENT(AT_EXECFD, bprm->execfd);
	}

	nr = 0;
	csp -= DLINFO_ITEMS * 2 * sizeof(unsigned long);
	NEW_AUX_ENT(AT_HWCAP,	ELF_HWCAP);
#ifdef ELF_HWCAP2
	NEW_AUX_ENT(AT_HWCAP2,	ELF_HWCAP2);
#endif
	NEW_AUX_ENT(AT_PAGESZ,	PAGE_SIZE);
	NEW_AUX_ENT(AT_CLKTCK,	CLOCKS_PER_SEC);
	NEW_AUX_ENT(AT_PHDR,	exec_params->ph_addr);
	NEW_AUX_ENT(AT_PHENT,	sizeof(struct elf_phdr));
	NEW_AUX_ENT(AT_PHNUM,	exec_params->hdr.e_phnum);
	NEW_AUX_ENT(AT_BASE,	interp_params->elfhdr_addr);
	if (bprm->interp_flags & BINPRM_FLAGS_PRESERVE_ARGV0)
		flags |= AT_FLAGS_PRESERVE_ARGV0;
	NEW_AUX_ENT(AT_FLAGS,	flags);
	NEW_AUX_ENT(AT_ENTRY,	exec_params->entry_addr);
	NEW_AUX_ENT(AT_UID,	(elf_addr_t) from_kuid_munged(cred->user_ns, cred->uid));
	NEW_AUX_ENT(AT_EUID,	(elf_addr_t) from_kuid_munged(cred->user_ns, cred->euid));
	NEW_AUX_ENT(AT_GID,	(elf_addr_t) from_kgid_munged(cred->user_ns, cred->gid));
	NEW_AUX_ENT(AT_EGID,	(elf_addr_t) from_kgid_munged(cred->user_ns, cred->egid));
	NEW_AUX_ENT(AT_SECURE,	bprm->secureexec);
	NEW_AUX_ENT(AT_EXECFN,	bprm->exec);

#ifdef ARCH_DLINFO
	nr = 0;
	csp -= AT_VECTOR_SIZE_ARCH * 2 * sizeof(unsigned long);

	/* ARCH_DLINFO must come last so platform specific code can enforce
	 * special alignment requirements on the AUXV if necessary (eg. PPC).
	 */
	ARCH_DLINFO;
#endif
#undef NEW_AUX_ENT

	/* allocate room for argv[] and envv[] */
	csp -= (bprm->envc + 1) * sizeof(elf_caddr_t);
	envp = (elf_caddr_t __user *) csp;
	csp -= (bprm->argc + 1) * sizeof(elf_caddr_t);
	argv = (elf_caddr_t __user *) csp;

	/* stack argc */
	csp -= sizeof(unsigned long);
	if (put_user(bprm->argc, (unsigned long __user *) csp))
		return -EFAULT;

	BUG_ON(csp != sp);

	/* fill in the argv[] array */
#ifdef CONFIG_MMU
	current->mm->arg_start = bprm->p;
#else
	current->mm->arg_start = current->mm->start_stack -
		(MAX_ARG_PAGES * PAGE_SIZE - bprm->p);
#endif

	p = (char __user *) current->mm->arg_start;
	for (loop = bprm->argc; loop > 0; loop--) {
		if (put_user((elf_caddr_t) p, argv++))
			return -EFAULT;
		len = strnlen_user(p, MAX_ARG_STRLEN);
		if (!len || len > MAX_ARG_STRLEN)
			return -EINVAL;
		p += len;
	}
	if (put_user(NULL, argv))
		return -EFAULT;
	current->mm->arg_end = (unsigned long) p;

	/* fill in the envv[] array */
	current->mm->env_start = (unsigned long) p;
	for (loop = bprm->envc; loop > 0; loop--) {
		if (put_user((elf_caddr_t)(unsigned long) p, envp++))
			return -EFAULT;
		len = strnlen_user(p, MAX_ARG_STRLEN);
		if (!len || len > MAX_ARG_STRLEN)
			return -EINVAL;
		p += len;
	}
	if (put_user(NULL, envp))
		return -EFAULT;
	current->mm->env_end = (unsigned long) p;

	mm->start_stack = (unsigned long) sp;
	return 0;
}

/*****************************************************************************/
/*
 * load the appropriate binary image (executable or interpreter) into memory
 * - we assume no MMU is available
 * - if no other PIC bits are set in params->hdr->e_flags
 *   - we assume that the LOADable segments in the binary are independently relocatable
 *   - we assume R/O executable segments are shareable
 * - else
 *   - we assume the loadable parts of the image to require fixed displacement
 *   - the image is not shareable
 */
static int elf_fdpic_map_file(struct elf_fdpic_params *params,
			      struct file *file,
			      struct mm_struct *mm,
			      const char *what)
{
	struct elf32_fdpic_loadmap *loadmap;
#ifdef CONFIG_MMU
	struct elf32_fdpic_loadseg *mseg;
#endif
	struct elf32_fdpic_loadseg *seg;
	struct elf32_phdr *phdr;
	unsigned long load_addr, stop;
	unsigned nloads, tmp;
	size_t size;
	int loop, ret;

	/* allocate a load map table */
	nloads = 0;
	for (loop = 0; loop < params->hdr.e_phnum; loop++)
		if (params->phdrs[loop].p_type == PT_LOAD)
			nloads++;

	if (nloads == 0)
		return -ELIBBAD;

	size = sizeof(*loadmap) + nloads * sizeof(*seg);
	loadmap = kzalloc(size, GFP_KERNEL);
	if (!loadmap)
		return -ENOMEM;

	params->loadmap = loadmap;

	loadmap->version = ELF32_FDPIC_LOADMAP_VERSION;
	loadmap->nsegs = nloads;

	load_addr = params->load_addr;
	seg = loadmap->segs;

	/* map the requested LOADs into the memory space */
	switch (params->flags & ELF_FDPIC_FLAG_ARRANGEMENT) {
	case ELF_FDPIC_FLAG_CONSTDISP:
	case ELF_FDPIC_FLAG_CONTIGUOUS:
#ifndef CONFIG_MMU
		ret = elf_fdpic_map_file_constdisp_on_uclinux(params, file, mm);
		if (ret < 0)
			return ret;
		break;
#endif
	default:
		ret = elf_fdpic_map_file_by_direct_mmap(params, file, mm);
		if (ret < 0)
			return ret;
		break;
	}

	/* map the entry point */
	if (params->hdr.e_entry) {
		seg = loadmap->segs;
		for (loop = loadmap->nsegs; loop > 0; loop--, seg++) {
			if (params->hdr.e_entry >= seg->p_vaddr &&
			    params->hdr.e_entry < seg->p_vaddr + seg->p_memsz) {
				params->entry_addr =
					(params->hdr.e_entry - seg->p_vaddr) +
					seg->addr;
				break;
			}
		}
	}

	/* determine where the program header table has wound up if mapped */
	stop = params->hdr.e_phoff;
	stop += params->hdr.e_phnum * sizeof (struct elf_phdr);
	phdr = params->phdrs;

	for (loop = 0; loop < params->hdr.e_phnum; loop++, phdr++) {
		if (phdr->p_type != PT_LOAD)
			continue;

		if (phdr->p_offset > params->hdr.e_phoff ||
		    phdr->p_offset + phdr->p_filesz < stop)
			continue;

		seg = loadmap->segs;
		for (loop = loadmap->nsegs; loop > 0; loop--, seg++) {
			if (phdr->p_vaddr >= seg->p_vaddr &&
			    phdr->p_vaddr + phdr->p_filesz <=
			    seg->p_vaddr + seg->p_memsz) {
				params->ph_addr =
					(phdr->p_vaddr - seg->p_vaddr) +
					seg->addr +
					params->hdr.e_phoff - phdr->p_offset;
				break;
			}
		}
		break;
	}

	/* determine where the dynamic section has wound up if there is one */
	phdr = params->phdrs;
	for (loop = 0; loop < params->hdr.e_phnum; loop++, phdr++) {
		if (phdr->p_type != PT_DYNAMIC)
			continue;

		seg = loadmap->segs;
		for (loop = loadmap->nsegs; loop > 0; loop--, seg++) {
			if (phdr->p_vaddr >= seg->p_vaddr &&
			    phdr->p_vaddr + phdr->p_memsz <=
			    seg->p_vaddr + seg->p_memsz) {
				Elf32_Dyn __user *dyn;
				Elf32_Sword d_tag;

				params->dynamic_addr =
					(phdr->p_vaddr - seg->p_vaddr) +
					seg->addr;

				/* check the dynamic section contains at least
				 * one item, and that the last item is a NULL
				 * entry */
				if (phdr->p_memsz == 0 ||
				    phdr->p_memsz % sizeof(Elf32_Dyn) != 0)
					goto dynamic_error;

				tmp = phdr->p_memsz / sizeof(Elf32_Dyn);
				dyn = (Elf32_Dyn __user *)params->dynamic_addr;
				if (get_user(d_tag, &dyn[tmp - 1].d_tag) ||
				    d_tag != 0)
					goto dynamic_error;
				break;
			}
		}
		break;
	}

	/* now elide adjacent segments in the load map on MMU linux
	 * - on uClinux the holes between may actually be filled with system
	 *   stuff or stuff from other processes
	 */
#ifdef CONFIG_MMU
	nloads = loadmap->nsegs;
	mseg = loadmap->segs;
	seg = mseg + 1;
	for (loop = 1; loop < nloads; loop++) {
		/* see if we have a candidate for merging */
		if (seg->p_vaddr - mseg->p_vaddr == seg->addr - mseg->addr) {
			load_addr = PAGE_ALIGN(mseg->addr + mseg->p_memsz);
			if (load_addr == (seg->addr & PAGE_MASK)) {
				mseg->p_memsz +=
					load_addr -
					(mseg->addr + mseg->p_memsz);
				mseg->p_memsz += seg->addr & ~PAGE_MASK;
				mseg->p_memsz += seg->p_memsz;
				loadmap->nsegs--;
				continue;
			}
		}

		mseg++;
		if (mseg != seg)
			*mseg = *seg;
	}
#endif

	kdebug("Mapped Object [%s]:", what);
	kdebug("- elfhdr   : %lx", params->elfhdr_addr);
	kdebug("- entry    : %lx", params->entry_addr);
	kdebug("- PHDR[]   : %lx", params->ph_addr);
	kdebug("- DYNAMIC[]: %lx", params->dynamic_addr);
	seg = loadmap->segs;
	for (loop = 0; loop < loadmap->nsegs; loop++, seg++)
		kdebug("- LOAD[%d] : %08x-%08x [va=%x ms=%x]",
		       loop,
		       seg->addr, seg->addr + seg->p_memsz - 1,
		       seg->p_vaddr, seg->p_memsz);

	return 0;

dynamic_error:
	printk("ELF FDPIC %s with invalid DYNAMIC section (inode=%lu)\n",
	       what, file_inode(file)->i_ino);
	return -ELIBBAD;
}

/*****************************************************************************/
/*
 * map a file with constant displacement under uClinux
 */
#ifndef CONFIG_MMU
static int elf_fdpic_map_file_constdisp_on_uclinux(
	struct elf_fdpic_params *params,
	struct file *file,
	struct mm_struct *mm)
{
	struct elf32_fdpic_loadseg *seg;
	struct elf32_phdr *phdr;
	unsigned long load_addr, base = ULONG_MAX, top = 0, maddr = 0;
	int loop, ret;

	load_addr = params->load_addr;
	seg = params->loadmap->segs;

	/* determine the bounds of the contiguous overall allocation we must
	 * make */
	phdr = params->phdrs;
	for (loop = 0; loop < params->hdr.e_phnum; loop++, phdr++) {
		if (params->phdrs[loop].p_type != PT_LOAD)
			continue;

		if (base > phdr->p_vaddr)
			base = phdr->p_vaddr;
		if (top < phdr->p_vaddr + phdr->p_memsz)
			top = phdr->p_vaddr + phdr->p_memsz;
	}

	/* allocate one big anon block for everything */
	maddr = vm_mmap(NULL, load_addr, top - base,
			PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, 0);
	if (IS_ERR_VALUE(maddr))
		return (int) maddr;

	if (load_addr != 0)
		load_addr += PAGE_ALIGN(top - base);

	/* and then load the file segments into it */
	phdr = params->phdrs;
	for (loop = 0; loop < params->hdr.e_phnum; loop++, phdr++) {
		if (params->phdrs[loop].p_type != PT_LOAD)
			continue;

		seg->addr = maddr + (phdr->p_vaddr - base);
		seg->p_vaddr = phdr->p_vaddr;
		seg->p_memsz = phdr->p_memsz;

		ret = read_code(file, seg->addr, phdr->p_offset,
				       phdr->p_filesz);
		if (ret < 0)
			return ret;

		/* map the ELF header address if in this segment */
		if (phdr->p_offset == 0)
			params->elfhdr_addr = seg->addr;

		/* clear any space allocated but not loaded */
		if (phdr->p_filesz < phdr->p_memsz) {
			if (clear_user((void *) (seg->addr + phdr->p_filesz),
				       phdr->p_memsz - phdr->p_filesz))
				return -EFAULT;
		}

		if (mm) {
			if (phdr->p_flags & PF_X) {
				if (!mm->start_code) {
					mm->start_code = seg->addr;
					mm->end_code = seg->addr +
						phdr->p_memsz;
				}
			} else if (!mm->start_data) {
				mm->start_data = seg->addr;
				mm->end_data = seg->addr + phdr->p_memsz;
			}
		}

		seg++;
	}