/*
   *  linux/fs/binfmt_aout.c
   *
   *  Copyright (C) 1991, 1992, 1996  Linus Torvalds
   */
  
  #include <linux/module.h>
  
  #include <linux/time.h>
  #include <linux/kernel.h>
  #include <linux/mm.h>
  #include <linux/mman.h>
  #include <linux/a.out.h>
  #include <linux/errno.h>
  #include <linux/signal.h>
  #include <linux/string.h>
  #include <linux/fs.h>
  #include <linux/file.h>
  #include <linux/stat.h>
  #include <linux/fcntl.h>
  #include <linux/ptrace.h>
  #include <linux/user.h>

  #include <linux/binfmts.h>
  #include <linux/personality.h>
  #include <linux/init.h>

  #include <linux/coredump.h>

  #include <linux/slab.h>

  #include <linux/sched/task_stack.h>

  #include <linux/uaccess.h>

  #include <asm/cacheflush.h>

  #include <asm/a.out-core.h>

  static int load_aout_binary(struct linux_binprm *);

  static int load_aout_library(struct file*);

  #ifdef CONFIG_COREDUMP

  /*

   * Routine writes a core dump image in the current directory.
   * Currently only a stub-function.
   *
   * Note that setuid/setgid files won't make a core-dump if the uid/gid
   * changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
   * field, which also makes sure the core-dumps won't be recursive if the
   * dumping of the process results in another error..
   */

  static int aout_core_dump(struct coredump_params *cprm)

  {
  	mm_segment_t fs;
  	int has_dumped = 0;

  	void __user *dump_start;
  	int dump_size;

  	struct user dump;

  #ifdef __alpha__

  #       define START_DATA(u)	((void __user *)u.start_data)

  #else

  #	define START_DATA(u)	((void __user *)((u.u_tsize << PAGE_SHIFT) + \
  				 u.start_code))

  #endif

  #       define START_STACK(u)   ((void __user *)u.start_stack)

  
  	fs = get_fs();
  	set_fs(KERNEL_DS);
  	has_dumped = 1;

         	strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));

  	dump.u_ar0 = offsetof(struct user, regs);

  	dump.signal = cprm->siginfo->si_signo;

  	aout_dump_thread(cprm->regs, &dump);

  
  /* If the size of the dump file exceeds the rlimit, then see what would happen
     if we wrote the stack, but not the data area.  */

  	if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > cprm->limit)

  		dump.u_dsize = 0;

  
  /* Make sure we have enough room to write the stack and data areas. */

  	if ((dump.u_ssize + 1) * PAGE_SIZE > cprm->limit)

  		dump.u_ssize = 0;

  
  /* make sure we actually have a data and stack area to dump */
  	set_fs(USER_DS);

  	if (!access_ok(VERIFY_READ, START_DATA(dump), dump.u_dsize << PAGE_SHIFT))

  		dump.u_dsize = 0;

  	if (!access_ok(VERIFY_READ, START_STACK(dump), dump.u_ssize << PAGE_SHIFT))

  		dump.u_ssize = 0;

  
  	set_fs(KERNEL_DS);
  /* struct user */

  	if (!dump_emit(cprm, &dump, sizeof(dump)))

  		goto end_coredump;

  /* Now dump all of the user data.  Include malloced stuff as well */

  	if (!dump_skip(cprm, PAGE_SIZE - sizeof(dump)))

  		goto end_coredump;

  /* now we start writing out the user space info */
  	set_fs(USER_DS);
  /* Dump the data area */
  	if (dump.u_dsize != 0) {
  		dump_start = START_DATA(dump);

  		dump_size = dump.u_dsize << PAGE_SHIFT;

  		if (!dump_emit(cprm, dump_start, dump_size))

  			goto end_coredump;

  	}
  /* Now prepare to dump the stack area */
  	if (dump.u_ssize != 0) {
  		dump_start = START_STACK(dump);

  		dump_size = dump.u_ssize << PAGE_SHIFT;

  		if (!dump_emit(cprm, dump_start, dump_size))

  			goto end_coredump;

  	}

  end_coredump:
  	set_fs(fs);
  	return has_dumped;
  }

  #else
  #define aout_core_dump NULL
  #endif
  
  static struct linux_binfmt aout_format = {
  	.module		= THIS_MODULE,
  	.load_binary	= load_aout_binary,
  	.load_shlib	= load_aout_library,
  	.core_dump	= aout_core_dump,
  	.min_coredump	= PAGE_SIZE
  };
  
  #define BAD_ADDR(x)	((unsigned long)(x) >= TASK_SIZE)
  
  static int set_brk(unsigned long start, unsigned long end)
  {
  	start = PAGE_ALIGN(start);
  	end = PAGE_ALIGN(end);

  	if (end > start)
  		return vm_brk(start, end - start);

  	return 0;
  }

  
  /*
   * create_aout_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", returning the new stack pointer value.
   */
  static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
  {
  	char __user * __user *argv;
  	char __user * __user *envp;
  	unsigned long __user *sp;
  	int argc = bprm->argc;
  	int envc = bprm->envc;
  
  	sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);

  #ifdef __alpha__
  /* whee.. test-programs are so much fun. */
  	put_user(0, --sp);
  	put_user(0, --sp);
  	if (bprm->loader) {
  		put_user(0, --sp);

  		put_user(1003, --sp);

  		put_user(bprm->loader, --sp);

  		put_user(1002, --sp);

  	}
  	put_user(bprm->exec, --sp);

  	put_user(1001, --sp);

  #endif
  	sp -= envc+1;
  	envp = (char __user * __user *) sp;
  	sp -= argc+1;
  	argv = (char __user * __user *) sp;

  #ifndef __alpha__

  	put_user((unsigned long) envp,--sp);
  	put_user((unsigned long) argv,--sp);
  #endif
  	put_user(argc,--sp);
  	current->mm->arg_start = (unsigned long) p;
  	while (argc-->0) {
  		char c;
  		put_user(p,argv++);
  		do {
  			get_user(c,p++);
  		} while (c);
  	}
  	put_user(NULL,argv);
  	current->mm->arg_end = current->mm->env_start = (unsigned long) p;
  	while (envc-->0) {
  		char c;
  		put_user(p,envp++);
  		do {
  			get_user(c,p++);
  		} while (c);
  	}
  	put_user(NULL,envp);
  	current->mm->env_end = (unsigned long) p;
  	return sp;
  }
  
  /*
   * These are the functions used to load a.out style executables and shared
   * libraries.  There is no binary dependent code anywhere else.
   */

  static int load_aout_binary(struct linux_binprm * bprm)

  {

  	struct pt_regs *regs = current_pt_regs();

  	struct exec ex;
  	unsigned long error;
  	unsigned long fd_offset;
  	unsigned long rlim;
  	int retval;
  
  	ex = *((struct exec *) bprm->buf);		/* exec-header */
  	if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
  	     N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
  	    N_TRSIZE(ex) || N_DRSIZE(ex) ||

  	    i_size_read(file_inode(bprm->file)) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {

  		return -ENOEXEC;
  	}

  	/*
  	 * Requires a mmap handler. This prevents people from using a.out
  	 * as part of an exploit attack against /proc-related vulnerabilities.
  	 */

  	if (!bprm->file->f_op->mmap)

  		return -ENOEXEC;

  	fd_offset = N_TXTOFF(ex);
  
  	/* Check initial limits. This avoids letting people circumvent
  	 * size limits imposed on them by creating programs with large
  	 * arrays in the data or bss.
  	 */

  	rlim = rlimit(RLIMIT_DATA);

  	if (rlim >= RLIM_INFINITY)
  		rlim = ~0;
  	if (ex.a_data + ex.a_bss > rlim)
  		return -ENOMEM;
  
  	/* Flush all traces of the currently running executable */
  	retval = flush_old_exec(bprm);
  	if (retval)
  		return retval;
  
  	/* OK, This is the point of no return */

  #ifdef __alpha__

  	SET_AOUT_PERSONALITY(bprm, ex);

  #else
  	set_personality(PER_LINUX);
  #endif

  	setup_new_exec(bprm);

  
  	current->mm->end_code = ex.a_text +
  		(current->mm->start_code = N_TXTADDR(ex));
  	current->mm->end_data = ex.a_data +
  		(current->mm->start_data = N_DATADDR(ex));
  	current->mm->brk = ex.a_bss +
  		(current->mm->start_brk = N_BSSADDR(ex));

  	retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);

  	if (retval < 0)

  		return retval;

  	install_exec_creds(bprm);

  
  	if (N_MAGIC(ex) == OMAGIC) {
  		unsigned long text_addr, map_size;
  		loff_t pos;
  
  		text_addr = N_TXTADDR(ex);

  #ifdef __alpha__

  		pos = fd_offset;
  		map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
  #else
  		pos = 32;
  		map_size = ex.a_text+ex.a_data;
  #endif

  		error = vm_brk(text_addr & PAGE_MASK, map_size);

  		if (error)

  			return error;

  		error = read_code(bprm->file, text_addr, pos,
  				  ex.a_text+ex.a_data);

  		if ((signed long)error < 0)

  			return error;

  	} else {

  		if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&

  		    (N_MAGIC(ex) != NMAGIC) && printk_ratelimit())

  		{
  			printk(KERN_NOTICE "executable not page aligned
  ");

  		}

  		if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())

  		{
  			printk(KERN_WARNING 

  			       "fd_offset is not page aligned. Please convert program: %pD
  ",
  			       bprm->file);

  		}
  
  		if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {

  			error = vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);

  			if (error)

  				return error;

  			read_code(bprm->file, N_TXTADDR(ex), fd_offset,
  				  ex.a_text + ex.a_data);

  			goto beyond_if;
  		}

  		error = vm_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,

  			PROT_READ | PROT_EXEC,
  			MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
  			fd_offset);

  		if (error != N_TXTADDR(ex))

  			return error;

  		error = vm_mmap(bprm->file, N_DATADDR(ex), ex.a_data,

  				PROT_READ | PROT_WRITE | PROT_EXEC,
  				MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
  				fd_offset + ex.a_text);

  		if (error != N_DATADDR(ex))

  			return error;

  	}
  beyond_if:
  	set_binfmt(&aout_format);
  
  	retval = set_brk(current->mm->start_brk, current->mm->brk);

  	if (retval < 0)

  		return retval;

  	current->mm->start_stack =
  		(unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
  #ifdef __alpha__
  	regs->gp = ex.a_gpvalue;
  #endif
  	start_thread(regs, ex.a_entry, current->mm->start_stack);

  	return 0;
  }
  
  static int load_aout_library(struct file *file)
  {
  	struct inode * inode;
  	unsigned long bss, start_addr, len;
  	unsigned long error;
  	int retval;
  	struct exec ex;

  	loff_t pos = 0;

  	inode = file_inode(file);

  
  	retval = -ENOEXEC;

  	error = kernel_read(file, &ex, sizeof(ex), &pos);

  	if (error != sizeof(ex))
  		goto out;
  
  	/* We come in here for the regular a.out style of shared libraries */
  	if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
  	    N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
  	    i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
  		goto out;
  	}

  	/*
  	 * Requires a mmap handler. This prevents people from using a.out
  	 * as part of an exploit attack against /proc-related vulnerabilities.
  	 */

  	if (!file->f_op->mmap)

  		goto out;

  	if (N_FLAGS(ex))
  		goto out;
  
  	/* For  QMAGIC, the starting address is 0x20 into the page.  We mask
  	   this off to get the starting address for the page */
  
  	start_addr =  ex.a_entry & 0xfffff000;
  
  	if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {

  		if (printk_ratelimit())

  		{
  			printk(KERN_WARNING 

  			       "N_TXTOFF is not page aligned. Please convert library: %pD
  ",
  			       file);

  		}

  		retval = vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);

  		if (retval)

  			goto out;

  		read_code(file, start_addr, N_TXTOFF(ex),
  			  ex.a_text + ex.a_data);

  		retval = 0;
  		goto out;
  	}
  	/* Now use mmap to map the library into memory. */

  	error = vm_mmap(file, start_addr, ex.a_text + ex.a_data,

  			PROT_READ | PROT_WRITE | PROT_EXEC,
  			MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
  			N_TXTOFF(ex));

  	retval = error;
  	if (error != start_addr)
  		goto out;
  
  	len = PAGE_ALIGN(ex.a_text + ex.a_data);
  	bss = ex.a_text + ex.a_data + ex.a_bss;
  	if (bss > len) {

  		retval = vm_brk(start_addr + len, bss - len);
  		if (retval)

  			goto out;
  	}
  	retval = 0;
  out:
  	return retval;
  }
  
  static int __init init_aout_binfmt(void)
  {

  	register_binfmt(&aout_format);
  	return 0;

  }
  
  static void __exit exit_aout_binfmt(void)
  {
  	unregister_binfmt(&aout_format);
  }
  
  core_initcall(init_aout_binfmt);
  module_exit(exit_aout_binfmt);
  MODULE_LICENSE("GPL");