binfmt_aout.c

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/*
 *  linux/fs/binfmt_aout.c
 *
 *  Copyright (C) 1991, 1992, 1996  Linus Torvalds
 */

#include <linux/module.h>

#include <linux/fs.h>
#include <linux/sched.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/stat.h>
#include <linux/fcntl.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/malloc.h>
#include <linux/binfmts.h>
#include <linux/personality.h>

#include <asm/system.h>
#include <asm/segment.h>
#include <asm/pgtable.h>

static int load_aout_binary(struct linux_binprm *, struct pt_regs * regs);
static int load_aout_library(int fd);
static int aout_core_dump(long signr, struct pt_regs * regs);

extern void dump_thread(struct pt_regs *, struct user *);

static struct linux_binfmt aout_format = {
#ifndef MODULE
	NULL, NULL, load_aout_binary, load_aout_library, aout_core_dump
#else
	NULL, &mod_use_count_, load_aout_binary, load_aout_library, aout_core_dump
#endif
};

static void set_brk(unsigned long start, unsigned long end)
{
	start = PAGE_ALIGN(start);
	end = PAGE_ALIGN(end);
	if (end <= start)
		return;
	do_mmap(NULL, start, end - start,
		PROT_READ | PROT_WRITE | PROT_EXEC,
		MAP_FIXED | MAP_PRIVATE, 0);
}

/*
 * These are the only things you should do on a core-file: use only these
 * macros to write out all the necessary info.
 */
#define DUMP_WRITE(addr,nr) \
while (file.f_op->write(inode,&file,(char *)(addr),(nr)) != (nr)) goto close_coredump

#define DUMP_SEEK(offset) \
if (file.f_op->lseek) { \
	if (file.f_op->lseek(inode,&file,(offset),0) != (offset)) \
 		goto close_coredump; \
} else file.f_pos = (offset)		

/*
 * 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->dumpable"
 * field, which also makes sure the core-dumps won't be recursive if the
 * dumping of the process results in another error..
 */

static inline int
do_aout_core_dump(long signr, struct pt_regs * regs)
{
	struct inode * inode = NULL;
	struct file file;
	unsigned short fs;
	int has_dumped = 0;
	char corefile[6+sizeof(current->comm)];
	unsigned long dump_start, dump_size;
	struct user dump;
#ifdef __alpha__
#       define START_DATA(u)	(u.start_data)
#else
#       define START_DATA(u)	(u.u_tsize << PAGE_SHIFT)
#endif

	if (!current->dumpable || current->mm->count != 1)
		return 0;
	current->dumpable = 0;

/* See if we have enough room to write the upage.  */
	if (current->rlim[RLIMIT_CORE].rlim_cur < PAGE_SIZE)
		return 0;
	fs = get_fs();
	set_fs(KERNEL_DS);
	memcpy(corefile,"core.",5);
#if 0
	memcpy(corefile+5,current->comm,sizeof(current->comm));
#else
	corefile[4] = '\0';
#endif
	if (open_namei(corefile,O_CREAT | 2 | O_TRUNC,0600,&inode,NULL)) {
		inode = NULL;
		goto end_coredump;
	}
	if (!S_ISREG(inode->i_mode))
		goto end_coredump;
	if (!inode->i_op || !inode->i_op->default_file_ops)
		goto end_coredump;
	if (get_write_access(inode))
		goto end_coredump;
	file.f_mode = 3;
	file.f_flags = 0;
	file.f_count = 1;
	file.f_inode = inode;
	file.f_pos = 0;
	file.f_reada = 0;
	file.f_op = inode->i_op->default_file_ops;
	if (file.f_op->open)
		if (file.f_op->open(inode,&file))
			goto done_coredump;
	if (!file.f_op->write)
		goto close_coredump;
	has_dumped = 1;
	current->flags |= PF_DUMPCORE;
       	strncpy(dump.u_comm, current->comm, sizeof(current->comm));
	dump.u_ar0 = (void *)(((unsigned long)(&dump.regs)) - ((unsigned long)(&dump)));
	dump.signal = signr;
	dump_thread(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 >
	    current->rlim[RLIMIT_CORE].rlim_cur)
		dump.u_dsize = 0;

/* Make sure we have enough room to write the stack and data areas. */
	if ((dump.u_ssize+1) * PAGE_SIZE >
	    current->rlim[RLIMIT_CORE].rlim_cur)
		dump.u_ssize = 0;

/* make sure we actually have a data and stack area to dump */
	set_fs(USER_DS);
	if (verify_area(VERIFY_READ, (void *) START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
		dump.u_dsize = 0;
	if (verify_area(VERIFY_READ, (void *) dump.start_stack, dump.u_ssize << PAGE_SHIFT))
		dump.u_ssize = 0;

	set_fs(KERNEL_DS);
/* struct user */
	DUMP_WRITE(&dump,sizeof(dump));
/* Now dump all of the user data.  Include malloced stuff as well */
	DUMP_SEEK(PAGE_SIZE);
/* 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;
		DUMP_WRITE(dump_start,dump_size);
	}
/* Now prepare to dump the stack area */
	if (dump.u_ssize != 0) {
		dump_start = dump.start_stack;
		dump_size = dump.u_ssize << PAGE_SHIFT;
		DUMP_WRITE(dump_start,dump_size);
	}
/* Finally dump the task struct.  Not be used by gdb, but could be useful */
	set_fs(KERNEL_DS);
	DUMP_WRITE(current,sizeof(*current));
close_coredump:
	if (file.f_op->release)
		file.f_op->release(inode,&file);
done_coredump:
	put_write_access(inode);
end_coredump:
	set_fs(fs);
	iput(inode);
	return has_dumped;
}

static int
aout_core_dump(long signr, struct pt_regs * regs)
{
	int retval;

	MOD_INC_USE_COUNT;
	retval = do_aout_core_dump(signr, regs);
	MOD_DEC_USE_COUNT;
	return retval;
}

/*
 * 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 * create_aout_tables(char * p, struct linux_binprm * bprm)
{
	unsigned long *argv,*envp;
	unsigned long * sp;
	int argc = bprm->argc;
	int envc = bprm->envc;

	sp = (unsigned long *) ((-(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(0x3eb, --sp);
		put_user(bprm->loader, --sp);
		put_user(0x3ea, --sp);
	}
	put_user(bprm->exec, --sp);
	put_user(0x3e9, --sp);
#endif
	sp -= envc+1;
	envp = sp;
	sp -= argc+1;
	argv = sp;
#if defined(__i386__) || defined(__mc68000__)
	put_user(envp,--sp);
	put_user(argv,--sp);
#endif
	put_user(argc,--sp);
	current->mm->arg_start = (unsigned long) p;
	while (argc-->0) {
		put_user(p,argv++);
		while (get_user(p++)) /* nothing */ ;
	}
	put_user(NULL,argv);
	current->mm->arg_end = current->mm->env_start = (unsigned long) p;
	while (envc-->0) {
		put_user(p,envp++);
		while (get_user(p++)) /* nothing */ ;
	}
	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 inline int
do_load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
{
	struct exec ex;
	struct file * file;
	int fd;
	unsigned long error;
	unsigned long p = bprm->p;
	unsigned long fd_offset;
	unsigned long rlim;

	ex = *((struct exec *) bprm->buf);		/* exec-header */
	if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC && 
	     N_MAGIC(ex) != QMAGIC) ||
	    N_TRSIZE(ex) || N_DRSIZE(ex) ||
	    bprm->inode->i_size < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
		return -ENOEXEC;
	}

	current->personality = PER_LINUX;
	fd_offset = N_TXTOFF(ex);

#ifdef __i386__
	if (N_MAGIC(ex) == ZMAGIC && fd_offset != BLOCK_SIZE) {
		printk(KERN_NOTICE "N_TXTOFF != BLOCK_SIZE. See a.out.h.\n");
		return -ENOEXEC;
	}

	if (N_MAGIC(ex) == ZMAGIC && ex.a_text &&
	    (fd_offset < bprm->inode->i_sb->s_blocksize)) {
		printk(KERN_NOTICE "N_TXTOFF < BLOCK_SIZE. Please convert binary.\n");
		return -ENOEXEC;
	}
#endif

	/* 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 = current->rlim[RLIMIT_DATA].rlim_cur;
	if (rlim >= RLIM_INFINITY)
		rlim = ~0;
	if (ex.a_data + ex.a_bss > rlim)
		return -ENOMEM;

	if (flush_old_exec(bprm))
		return -ENOMEM;

	/* OK, This is the point of no return */

	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));

	current->mm->rss = 0;
	current->mm->mmap = NULL;
	current->suid = current->euid = current->fsuid = bprm->e_uid;
	current->sgid = current->egid = current->fsgid = bprm->e_gid;
 	current->flags &= ~PF_FORKNOEXEC;
	if (N_MAGIC(ex) == OMAGIC) {
#ifdef __alpha__
		do_mmap(NULL, N_TXTADDR(ex) & PAGE_MASK,
			ex.a_text+ex.a_data + PAGE_SIZE - 1,
			PROT_READ|PROT_WRITE|PROT_EXEC,
			MAP_FIXED|MAP_PRIVATE, 0);
		read_exec(bprm->inode, fd_offset, (char *) N_TXTADDR(ex),
			  ex.a_text+ex.a_data, 0);
#else
		do_mmap(NULL, 0, ex.a_text+ex.a_data,
			PROT_READ|PROT_WRITE|PROT_EXEC,
			MAP_FIXED|MAP_PRIVATE, 0);
		read_exec(bprm->inode, 32, (char *) 0, ex.a_text+ex.a_data, 0);
#endif
	} else {
		if (ex.a_text & 0xfff || ex.a_data & 0xfff)
			printk(KERN_NOTICE "executable not page aligned\n");
		
		fd = open_inode(bprm->inode, O_RDONLY);
		
		if (fd < 0)
			return fd;
		file = current->files->fd[fd];
		if (!file->f_op || !file->f_op->mmap) {
			sys_close(fd);
			do_mmap(NULL, 0, ex.a_text+ex.a_data,
				PROT_READ|PROT_WRITE|PROT_EXEC,
				MAP_FIXED|MAP_PRIVATE, 0);
			read_exec(bprm->inode, fd_offset,
				  (char *) N_TXTADDR(ex), ex.a_text+ex.a_data, 0);
			goto beyond_if;
		}

		error = do_mmap(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)) {
			sys_close(fd);
			send_sig(SIGKILL, current, 0);
			return error;
		}
		
 		error = do_mmap(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);
		sys_close(fd);
		if (error != N_DATADDR(ex)) {
			send_sig(SIGKILL, current, 0);
			return error;
		}
	}
beyond_if:
	if (current->exec_domain && current->exec_domain->use_count)
		(*current->exec_domain->use_count)--;
	if (current->binfmt && current->binfmt->use_count)
		(*current->binfmt->use_count)--;
	current->exec_domain = lookup_exec_domain(current->personality);
	current->binfmt = &aout_format;
	if (current->exec_domain && current->exec_domain->use_count)
		(*current->exec_domain->use_count)++;
	if (current->binfmt && current->binfmt->use_count)
		(*current->binfmt->use_count)++;

	set_brk(current->mm->start_brk, current->mm->brk);

	p = setup_arg_pages(p, bprm);
	
	p = (unsigned long) create_aout_tables((char *)p, bprm);
	current->mm->start_stack = p;
#ifdef __alpha__
	regs->gp = ex.a_gpvalue;
#endif
	start_thread(regs, ex.a_entry, p);
	if (current->flags & PF_PTRACED)
		send_sig(SIGTRAP, current, 0);
	return 0;
}

static int
load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
{
	int retval;

	MOD_INC_USE_COUNT;
	retval = do_load_aout_binary(bprm, regs);
	MOD_DEC_USE_COUNT;
	return retval;
}

static inline int
do_load_aout_library(int fd)
{
        struct file * file;
	struct exec ex;
	struct  inode * inode;
	unsigned int len;
	unsigned int bss;
	unsigned int start_addr;
	unsigned long error;
	
	file = current->files->fd[fd];
	inode = file->f_inode;
	
	if (!file || !file->f_op)
		return -EACCES;

	/* Seek into the file */
	if (file->f_op->lseek) {
		if ((error = file->f_op->lseek(inode, file, 0, 0)) != 0)
			return -ENOEXEC;
	} else
		file->f_pos = 0;

	set_fs(KERNEL_DS);
	error = file->f_op->read(inode, file, (char *) &ex, sizeof(ex));
	set_fs(USER_DS);
	if (error != sizeof(ex))
		return -ENOEXEC;

	/* 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) ||
	    inode->i_size < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
		return -ENOEXEC;
	}
	if (N_MAGIC(ex) == ZMAGIC && N_TXTOFF(ex) && 
	    (N_TXTOFF(ex) < inode->i_sb->s_blocksize)) {
		printk("N_TXTOFF < BLOCK_SIZE. Please convert library\n");
		return -ENOEXEC;
	}
	
	if (N_FLAGS(ex)) return -ENOEXEC;

	/* 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;

	/* Now use mmap to map the library into memory. */
	error = do_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));
	if (error != start_addr)
		return error;
	len = PAGE_ALIGN(ex.a_text + ex.a_data);
	bss = ex.a_text + ex.a_data + ex.a_bss;
	if (bss > len) {
		error = do_mmap(NULL, start_addr + len, bss-len,
				PROT_READ|PROT_WRITE|PROT_EXEC,
				MAP_PRIVATE|MAP_FIXED, 0);
		if (error != start_addr + len)
			return error;
	}
	return 0;
}

static int
load_aout_library(int fd)
{
	int retval;

	MOD_INC_USE_COUNT;
	retval = do_load_aout_library(fd);
	MOD_DEC_USE_COUNT;
	return retval;
}


int init_aout_binfmt(void) {
	return register_binfmt(&aout_format);
}

#ifdef MODULE
int init_module(void) {
	return init_aout_binfmt();
}

void cleanup_module( void) {
	unregister_binfmt(&aout_format);
}
#endif