[GitHub/mt8127/android_kernel_alcatel_ttab.git] / fs / binfmt_misc.c

/*
 *  binfmt_misc.c
 *
 *  Copyright (C) 1997 Richard Günther
 *
 *  binfmt_misc detects binaries via a magic or filename extension and invokes
 *  a specified wrapper. This should obsolete binfmt_java, binfmt_em86 and
 *  binfmt_mz.
 *
 *  1997-04-25 first version
 *  [...]
 *  1997-05-19 cleanup
 *  1997-06-26 hpa: pass the real filename rather than argv[0]
 *  1997-06-30 minor cleanup
 *  1997-08-09 removed extension stripping, locking cleanup
 *  2001-02-28 AV: rewritten into something that resembles C. Original didn't.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/magic.h>
#include <linux/binfmts.h>
#include <linux/slab.h>
#include <linux/ctype.h>
#include <linux/file.h>
#include <linux/pagemap.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/syscalls.h>
#include <linux/fs.h>

#include <asm/uaccess.h>

enum {
	VERBOSE_STATUS = 1 /* make it zero to save 400 bytes kernel memory */
};

static LIST_HEAD(entries);
static int enabled = 1;

enum {Enabled, Magic};
#define MISC_FMT_PRESERVE_ARGV0 (1<<31)
#define MISC_FMT_OPEN_BINARY (1<<30)
#define MISC_FMT_CREDENTIALS (1<<29)

typedef struct {
	struct list_head list;
	unsigned long flags;		/* type, status, etc. */
	int offset;			/* offset of magic */
	int size;			/* size of magic/mask */
	char *magic;			/* magic or filename extension */
	char *mask;			/* mask, NULL for exact match */
	char *interpreter;		/* filename of interpreter */
	char *name;
	struct dentry *dentry;
} Node;

static DEFINE_RWLOCK(entries_lock);
static struct file_system_type bm_fs_type;
static struct vfsmount *bm_mnt;
static int entry_count;

/* 
 * Check if we support the binfmt
 * if we do, return the node, else NULL
 * locking is done in load_misc_binary
 */
static Node *check_file(struct linux_binprm *bprm)
{
	char *p = strrchr(bprm->interp, '.');
	struct list_head *l;

	list_for_each(l, &entries) {
		Node *e = list_entry(l, Node, list);
		char *s;
		int j;

		if (!test_bit(Enabled, &e->flags))
			continue;

		if (!test_bit(Magic, &e->flags)) {
			if (p && !strcmp(e->magic, p + 1))
				return e;
			continue;
		}

		s = bprm->buf + e->offset;
		if (e->mask) {
			for (j = 0; j < e->size; j++)
				if ((*s++ ^ e->magic[j]) & e->mask[j])
					break;
		} else {
			for (j = 0; j < e->size; j++)
				if ((*s++ ^ e->magic[j]))
					break;
		}
		if (j == e->size)
			return e;
	}
	return NULL;
}

/*
 * the loader itself
 */
static int load_misc_binary(struct linux_binprm *bprm)
{
	Node *fmt;
	struct file * interp_file = NULL;
	char iname[BINPRM_BUF_SIZE];
	const char *iname_addr = iname;
	int retval;
	int fd_binary = -1;

	retval = -ENOEXEC;
	if (!enabled)
		goto _ret;

	/* to keep locking time low, we copy the interpreter string */
	read_lock(&entries_lock);
	fmt = check_file(bprm);
	if (fmt)
		strlcpy(iname, fmt->interpreter, BINPRM_BUF_SIZE);
	read_unlock(&entries_lock);
	if (!fmt)
		goto _ret;

	if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) {
		retval = remove_arg_zero(bprm);
		if (retval)
			goto _ret;
	}

	if (fmt->flags & MISC_FMT_OPEN_BINARY) {

		/* if the binary should be opened on behalf of the
		 * interpreter than keep it open and assign descriptor
		 * to it */
 		fd_binary = get_unused_fd();
 		if (fd_binary < 0) {
 			retval = fd_binary;
 			goto _ret;
 		}
 		fd_install(fd_binary, bprm->file);

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

		allow_write_access(bprm->file);
		bprm->file = NULL;

		/* mark the bprm that fd should be passed to interp */
		bprm->interp_flags |= BINPRM_FLAGS_EXECFD;
		bprm->interp_data = fd_binary;

 	} else {
 		allow_write_access(bprm->file);
 		fput(bprm->file);
 		bprm->file = NULL;
 	}
	/* make argv[1] be the path to the binary */
	retval = copy_strings_kernel (1, &bprm->interp, bprm);
	if (retval < 0)
		goto _error;
	bprm->argc++;

	/* add the interp as argv[0] */
	retval = copy_strings_kernel (1, &iname_addr, bprm);
	if (retval < 0)
		goto _error;
	bprm->argc ++;

	/* Update interp in case binfmt_script needs it. */
	retval = bprm_change_interp(iname, bprm);
	if (retval < 0)
		goto _error;

	interp_file = open_exec (iname);
	retval = PTR_ERR (interp_file);
	if (IS_ERR (interp_file))
		goto _error;

	bprm->file = interp_file;
	if (fmt->flags & MISC_FMT_CREDENTIALS) {
		/*
		 * No need to call prepare_binprm(), it's already been
		 * done.  bprm->buf is stale, update from interp_file.
		 */
		memset(bprm->buf, 0, BINPRM_BUF_SIZE);
		retval = kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
	} else
		retval = prepare_binprm (bprm);

	if (retval < 0)
		goto _error;

	retval = search_binary_handler(bprm);
	if (retval < 0)
		goto _error;

_ret:
	return retval;
_error:
	if (fd_binary > 0)
		sys_close(fd_binary);
	bprm->interp_flags = 0;
	bprm->interp_data = 0;
	goto _ret;
}

/* Command parsers */

/*
 * parses and copies one argument enclosed in del from *sp to *dp,
 * recognising the \x special.
 * returns pointer to the copied argument or NULL in case of an
 * error (and sets err) or null argument length.
 */
static char *scanarg(char *s, char del)
{
	char c;

	while ((c = *s++) != del) {
		if (c == '\\' && *s == 'x') {
			s++;
			if (!isxdigit(*s++))
				return NULL;
			if (!isxdigit(*s++))
				return NULL;
		}
	}
	return s;
}

static int unquote(char *from)
{
	char c = 0, *s = from, *p = from;

	while ((c = *s++) != '\0') {
		if (c == '\\' && *s == 'x') {
			s++;
			c = toupper(*s++);
			*p = (c - (isdigit(c) ? '0' : 'A' - 10)) << 4;
			c = toupper(*s++);
			*p++ |= c - (isdigit(c) ? '0' : 'A' - 10);
			continue;
		}
		*p++ = c;
	}
	return p - from;
}

static char * check_special_flags (char * sfs, Node * e)
{
	char * p = sfs;
	int cont = 1;

	/* special flags */
	while (cont) {
		switch (*p) {
			case 'P':
				p++;
				e->flags |= MISC_FMT_PRESERVE_ARGV0;
				break;
			case 'O':
				p++;
				e->flags |= MISC_FMT_OPEN_BINARY;
				break;
			case 'C':
				p++;
				/* this flags also implies the
				   open-binary flag */
				e->flags |= (MISC_FMT_CREDENTIALS |
						MISC_FMT_OPEN_BINARY);
				break;
			default:
				cont = 0;
		}
	}

	return p;
}
/*
 * This registers a new binary format, it recognises the syntax
 * ':name:type:offset:magic:mask:interpreter:flags'
 * where the ':' is the IFS, that can be chosen with the first char
 */
static Node *create_entry(const char __user *buffer, size_t count)
{
	Node *e;
	int memsize, err;
	char *buf, *p;
	char del;

	/* some sanity checks */
	err = -EINVAL;
	if ((count < 11) || (count > 256))
		goto out;

	err = -ENOMEM;
	memsize = sizeof(Node) + count + 8;
	e = kmalloc(memsize, GFP_USER);
	if (!e)
		goto out;

	p = buf = (char *)e + sizeof(Node);

	memset(e, 0, sizeof(Node));
	if (copy_from_user(buf, buffer, count))
		goto Efault;

	del = *p++;	/* delimeter */

	memset(buf+count, del, 8);

	e->name = p;
	p = strchr(p, del);
	if (!p)
		goto Einval;
	*p++ = '\0';
	if (!e->name[0] ||
	    !strcmp(e->name, ".") ||
	    !strcmp(e->name, "..") ||
	    strchr(e->name, '/'))
		goto Einval;
	switch (*p++) {
		case 'E': e->flags = 1<<Enabled; break;
		case 'M': e->flags = (1<<Enabled) | (1<<Magic); break;
		default: goto Einval;
	}
	if (*p++ != del)
		goto Einval;
	if (test_bit(Magic, &e->flags)) {
		char *s = strchr(p, del);
		if (!s)
			goto Einval;
		*s++ = '\0';
		e->offset = simple_strtoul(p, &p, 10);
		if (*p++)
			goto Einval;
		e->magic = p;
		p = scanarg(p, del);
		if (!p)
			goto Einval;
		p[-1] = '\0';
		if (!e->magic[0])
			goto Einval;
		e->mask = p;
		p = scanarg(p, del);
		if (!p)
			goto Einval;
		p[-1] = '\0';
		if (!e->mask[0])
			e->mask = NULL;
		e->size = unquote(e->magic);
		if (e->mask && unquote(e->mask) != e->size)
			goto Einval;
		if (e->size + e->offset > BINPRM_BUF_SIZE)
			goto Einval;
	} else {
		p = strchr(p, del);
		if (!p)
			goto Einval;
		*p++ = '\0';
		e->magic = p;
		p = strchr(p, del);
		if (!p)
			goto Einval;
		*p++ = '\0';
		if (!e->magic[0] || strchr(e->magic, '/'))
			goto Einval;
		p = strchr(p, del);
		if (!p)
			goto Einval;
		*p++ = '\0';
	}
	e->interpreter = p;
	p = strchr(p, del);
	if (!p)
		goto Einval;
	*p++ = '\0';
	if (!e->interpreter[0])
		goto Einval;


	p = check_special_flags (p, e);

	if (*p == '\n')
		p++;
	if (p != buf + count)
		goto Einval;
	return e;

out:
	return ERR_PTR(err);

Efault:
	kfree(e);
	return ERR_PTR(-EFAULT);
Einval:
	kfree(e);
	return ERR_PTR(-EINVAL);
}

/*
 * Set status of entry/binfmt_misc:
 * '1' enables, '0' disables and '-1' clears entry/binfmt_misc
 */
static int parse_command(const char __user *buffer, size_t count)
{
	char s[4];

	if (!count)
		return 0;
	if (count > 3)
		return -EINVAL;
	if (copy_from_user(s, buffer, count))
		return -EFAULT;
	if (s[count-1] == '\n')
		count--;
	if (count == 1 && s[0] == '0')
		return 1;
	if (count == 1 && s[0] == '1')
		return 2;
	if (count == 2 && s[0] == '-' && s[1] == '1')
		return 3;
	return -EINVAL;
}

/* generic stuff */

static void entry_status(Node *e, char *page)
{
	char *dp;
	char *status = "disabled";
	const char * flags = "flags: ";

	if (test_bit(Enabled, &e->flags))
		status = "enabled";

	if (!VERBOSE_STATUS) {
		sprintf(page, "%s\n", status);
		return;
	}

	sprintf(page, "%s\ninterpreter %s\n", status, e->interpreter);
	dp = page + strlen(page);

	/* print the special flags */
	sprintf (dp, "%s", flags);
	dp += strlen (flags);
	if (e->flags & MISC_FMT_PRESERVE_ARGV0) {
		*dp ++ = 'P';
	}
	if (e->flags & MISC_FMT_OPEN_BINARY) {
		*dp ++ = 'O';
	}
	if (e->flags & MISC_FMT_CREDENTIALS) {
		*dp ++ = 'C';
	}
	*dp ++ = '\n';


	if (!test_bit(Magic, &e->flags)) {
		sprintf(dp, "extension .%s\n", e->magic);
	} else {
		int i;

		sprintf(dp, "offset %i\nmagic ", e->offset);
		dp = page + strlen(page);
		for (i = 0; i < e->size; i++) {
			sprintf(dp, "%02x", 0xff & (int) (e->magic[i]));
			dp += 2;
		}
		if (e->mask) {
			sprintf(dp, "\nmask ");
			dp += 6;
			for (i = 0; i < e->size; i++) {
				sprintf(dp, "%02x", 0xff & (int) (e->mask[i]));
				dp += 2;
			}
		}
		*dp++ = '\n';
		*dp = '\0';
	}
}

static struct inode *bm_get_inode(struct super_block *sb, int mode)
{
	struct inode * inode = new_inode(sb);

	if (inode) {
		inode->i_ino = get_next_ino();
		inode->i_mode = mode;
		inode->i_atime = inode->i_mtime = inode->i_ctime =
			current_fs_time(inode->i_sb);
	}
	return inode;
}

static void bm_evict_inode(struct inode *inode)
{
	clear_inode(inode);
	kfree(inode->i_private);
}

static void kill_node(Node *e)
{
	struct dentry *dentry;

	write_lock(&entries_lock);
	dentry = e->dentry;
	if (dentry) {
		list_del_init(&e->list);
		e->dentry = NULL;
	}
	write_unlock(&entries_lock);

	if (dentry) {
		drop_nlink(dentry->d_inode);
		d_drop(dentry);
		dput(dentry);
		simple_release_fs(&bm_mnt, &entry_count);
	}
}

/* /<entry> */

static ssize_t
bm_entry_read(struct file * file, char __user * buf, size_t nbytes, loff_t *ppos)
{
	Node *e = file_inode(file)->i_private;
	ssize_t res;
	char *page;

	if (!(page = (char*) __get_free_page(GFP_KERNEL)))
		return -ENOMEM;

	entry_status(e, page);

	res = simple_read_from_buffer(buf, nbytes, ppos, page, strlen(page));

	free_page((unsigned long) page);
	return res;
}

static ssize_t bm_entry_write(struct file *file, const char __user *buffer,
				size_t count, loff_t *ppos)
{
	struct dentry *root;
	Node *e = file_inode(file)->i_private;
	int res = parse_command(buffer, count);

	switch (res) {
		case 1: clear_bit(Enabled, &e->flags);
			break;
		case 2: set_bit(Enabled, &e->flags);
			break;
		case 3: root = dget(file->f_path.dentry->d_sb->s_root);
			mutex_lock(&root->d_inode->i_mutex);

			kill_node(e);

			mutex_unlock(&root->d_inode->i_mutex);
			dput(root);
			break;
		default: return res;
	}
	return count;
}

static const struct file_operations bm_entry_operations = {
	.read		= bm_entry_read,
	.write		= bm_entry_write,
	.llseek		= default_llseek,
};

/* /register */

static ssize_t bm_register_write(struct file *file, const char __user *buffer,
			       size_t count, loff_t *ppos)
{
	Node *e;
	struct inode *inode;
	struct dentry *root, *dentry;
	struct super_block *sb = file->f_path.dentry->d_sb;
	int err = 0;

	e = create_entry(buffer, count);

	if (IS_ERR(e))
		return PTR_ERR(e);

	root = dget(sb->s_root);
	mutex_lock(&root->d_inode->i_mutex);
	dentry = lookup_one_len(e->name, root, strlen(e->name));
	err = PTR_ERR(dentry);
	if (IS_ERR(dentry))
		goto out;

	err = -EEXIST;
	if (dentry->d_inode)
		goto out2;

	inode = bm_get_inode(sb, S_IFREG | 0644);

	err = -ENOMEM;
	if (!inode)
		goto out2;

	err = simple_pin_fs(&bm_fs_type, &bm_mnt, &entry_count);
	if (err) {
		iput(inode);
		inode = NULL;
		goto out2;
	}

	e->dentry = dget(dentry);
	inode->i_private = e;
	inode->i_fop = &bm_entry_operations;

	d_instantiate(dentry, inode);
	write_lock(&entries_lock);
	list_add(&e->list, &entries);
	write_unlock(&entries_lock);

	err = 0;
out2:
	dput(dentry);
out:
	mutex_unlock(&root->d_inode->i_mutex);
	dput(root);

	if (err) {
		kfree(e);
		return -EINVAL;
	}
	return count;
}

static const struct file_operations bm_register_operations = {
	.write		= bm_register_write,
	.llseek		= noop_llseek,
};

/* /status */

static ssize_t
bm_status_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
{
	char *s = enabled ? "enabled\n" : "disabled\n";

	return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s));
}

static ssize_t bm_status_write(struct file * file, const char __user * buffer,
		size_t count, loff_t *ppos)
{
	int res = parse_command(buffer, count);
	struct dentry *root;

	switch (res) {
		case 1: enabled = 0; break;
		case 2: enabled = 1; break;
		case 3: root = dget(file->f_path.dentry->d_sb->s_root);
			mutex_lock(&root->d_inode->i_mutex);

			while (!list_empty(&entries))
				kill_node(list_entry(entries.next, Node, list));

			mutex_unlock(&root->d_inode->i_mutex);
			dput(root);
		default: return res;
	}
	return count;
}

static const struct file_operations bm_status_operations = {
	.read		= bm_status_read,
	.write		= bm_status_write,
	.llseek		= default_llseek,
};

/* Superblock handling */

static const struct super_operations s_ops = {
	.statfs		= simple_statfs,
	.evict_inode	= bm_evict_inode,
};

static int bm_fill_super(struct super_block * sb, void * data, int silent)
{
	static struct tree_descr bm_files[] = {
		[2] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO},
		[3] = {"register", &bm_register_operations, S_IWUSR},
		/* last one */ {""}
	};
	int err = simple_fill_super(sb, BINFMTFS_MAGIC, bm_files);
	if (!err)
		sb->s_op = &s_ops;
	return err;
}

static struct dentry *bm_mount(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data)
{
	return mount_single(fs_type, flags, data, bm_fill_super);
}

static struct linux_binfmt misc_format = {
	.module = THIS_MODULE,
	.load_binary = load_misc_binary,
};

static struct file_system_type bm_fs_type = {
	.owner		= THIS_MODULE,
	.name		= "binfmt_misc",
	.mount		= bm_mount,
	.kill_sb	= kill_litter_super,
};

static int __init init_misc_binfmt(void)
{
	int err = register_filesystem(&bm_fs_type);
	if (!err)
		insert_binfmt(&misc_format);
	return err;
}

static void __exit exit_misc_binfmt(void)
{
	unregister_binfmt(&misc_format);
	unregister_filesystem(&bm_fs_type);
}

core_initcall(init_misc_binfmt);
module_exit(exit_misc_binfmt);
MODULE_LICENSE("GPL");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* binfmt_misc.c
	3	*
96de0e25	4	* Copyright (C) 1997 Richard Günther
1da177e4 LT	5	*
	6	* binfmt_misc detects binaries via a magic or filename extension and invokes
	7	* a specified wrapper. This should obsolete binfmt_java, binfmt_em86 and
	8	* binfmt_mz.
	9	*
	10	* 1997-04-25 first version
	11	* [...]
	12	* 1997-05-19 cleanup
	13	* 1997-06-26 hpa: pass the real filename rather than argv[0]
	14	* 1997-06-30 minor cleanup
	15	* 1997-08-09 removed extension stripping, locking cleanup
	16	* 2001-02-28 AV: rewritten into something that resembles C. Original didn't.
	17	*/
	18
	19	#include <linux/module.h>
	20	#include <linux/init.h>
e8edc6e0	21	#include <linux/sched.h>
b502bd11	22	#include <linux/magic.h>
1da177e4 LT	23	#include <linux/binfmts.h>
	24	#include <linux/slab.h>
	25	#include <linux/ctype.h>
	26	#include <linux/file.h>
	27	#include <linux/pagemap.h>
	28	#include <linux/namei.h>
	29	#include <linux/mount.h>
	30	#include <linux/syscalls.h>
6e2c10a1	31	#include <linux/fs.h>
1da177e4 LT	32
	33	#include <asm/uaccess.h>
	34
	35	enum {
	36	VERBOSE_STATUS = 1 /* make it zero to save 400 bytes kernel memory */
	37	};
	38
	39	static LIST_HEAD(entries);
	40	static int enabled = 1;
	41
	42	enum {Enabled, Magic};
	43	#define MISC_FMT_PRESERVE_ARGV0 (1<<31)
	44	#define MISC_FMT_OPEN_BINARY (1<<30)
	45	#define MISC_FMT_CREDENTIALS (1<<29)
	46
	47	typedef struct {
	48	struct list_head list;
	49	unsigned long flags; /* type, status, etc. */
	50	int offset; /* offset of magic */
	51	int size; /* size of magic/mask */
	52	char magic; / magic or filename extension */
	53	char mask; / mask, NULL for exact match */
	54	char interpreter; / filename of interpreter */
	55	char *name;
	56	struct dentry *dentry;
	57	} Node;
	58
	59	static DEFINE_RWLOCK(entries_lock);
1f5ce9e9	60	static struct file_system_type bm_fs_type;
1da177e4 LT	61	static struct vfsmount *bm_mnt;
	62	static int entry_count;
	63
	64	/*
	65	* Check if we support the binfmt
	66	* if we do, return the node, else NULL
	67	* locking is done in load_misc_binary
	68	*/
	69	static Node check_file(struct linux_binprm bprm)
	70	{
	71	char *p = strrchr(bprm->interp, '.');
	72	struct list_head *l;
	73
	74	list_for_each(l, &entries) {
	75	Node *e = list_entry(l, Node, list);
	76	char *s;
	77	int j;
	78
	79	if (!test_bit(Enabled, &e->flags))
	80	continue;
	81
	82	if (!test_bit(Magic, &e->flags)) {
	83	if (p && !strcmp(e->magic, p + 1))
	84	return e;
	85	continue;
	86	}
	87
	88	s = bprm->buf + e->offset;
	89	if (e->mask) {
	90	for (j = 0; j < e->size; j++)
	91	if ((*s++ ^ e->magic[j]) & e->mask[j])
	92	break;
	93	} else {
	94	for (j = 0; j < e->size; j++)
	95	if ((*s++ ^ e->magic[j]))
	96	break;
	97	}
	98	if (j == e->size)
	99	return e;
	100	}
	101	return NULL;
	102	}
	103
	104	/*
	105	* the loader itself
	106	*/
71613c3b	107	static int load_misc_binary(struct linux_binprm *bprm)
1da177e4 LT	108	{
	109	Node *fmt;
	110	struct file * interp_file = NULL;
	111	char iname[BINPRM_BUF_SIZE];
d7627467	112	const char *iname_addr = iname;
1da177e4 LT	113	int retval;
1da177e4 LT	114	int fd_binary = -1;
1da177e4 LT	115
	116	retval = -ENOEXEC;
	117	if (!enabled)
	118	goto _ret;
	119
	120	/* to keep locking time low, we copy the interpreter string */
	121	read_lock(&entries_lock);
	122	fmt = check_file(bprm);
	123	if (fmt)
	124	strlcpy(iname, fmt->interpreter, BINPRM_BUF_SIZE);
	125	read_unlock(&entries_lock);
	126	if (!fmt)
	127	goto _ret;
	128
	129	if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) {
b6a2fea3 OW	130	retval = remove_arg_zero(bprm);
	131	if (retval)
	132	goto _ret;
1da177e4 LT	133	}
	134
	135	if (fmt->flags & MISC_FMT_OPEN_BINARY) {
	136
1da177e4 LT	137	/* if the binary should be opened on behalf of the
	138	* interpreter than keep it open and assign descriptor
	139	* to it */
	140	fd_binary = get_unused_fd();
	141	if (fd_binary < 0) {
	142	retval = fd_binary;
fd8328be	143	goto _ret;
1da177e4 LT	144	}
	145	fd_install(fd_binary, bprm->file);
	146
	147	/* if the binary is not readable than enforce mm->dumpable=0
	148	regardless of the interpreter's permissions */
1b5d783c	149	would_dump(bprm, bprm->file);
1da177e4 LT	150
	151	allow_write_access(bprm->file);
	152	bprm->file = NULL;
	153
	154	/* mark the bprm that fd should be passed to interp */
	155	bprm->interp_flags \|= BINPRM_FLAGS_EXECFD;
	156	bprm->interp_data = fd_binary;
	157
	158	} else {
	159	allow_write_access(bprm->file);
	160	fput(bprm->file);
	161	bprm->file = NULL;
	162	}
	163	/* make argv[1] be the path to the binary */
	164	retval = copy_strings_kernel (1, &bprm->interp, bprm);
	165	if (retval < 0)
	166	goto _error;
	167	bprm->argc++;
	168
	169	/* add the interp as argv[0] */
	170	retval = copy_strings_kernel (1, &iname_addr, bprm);
	171	if (retval < 0)
	172	goto _error;
	173	bprm->argc ++;
	174
b66c5984 KC	175	/* Update interp in case binfmt_script needs it. */
	176	retval = bprm_change_interp(iname, bprm);
	177	if (retval < 0)
	178	goto _error;
1da177e4 LT	179
	180	interp_file = open_exec (iname);
	181	retval = PTR_ERR (interp_file);
	182	if (IS_ERR (interp_file))
	183	goto _error;
	184
	185	bprm->file = interp_file;
	186	if (fmt->flags & MISC_FMT_CREDENTIALS) {
	187	/*
	188	* No need to call prepare_binprm(), it's already been
	189	* done. bprm->buf is stale, update from interp_file.
	190	*/
	191	memset(bprm->buf, 0, BINPRM_BUF_SIZE);
	192	retval = kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
	193	} else
	194	retval = prepare_binprm (bprm);
	195
	196	if (retval < 0)
	197	goto _error;
	198
3c456bfc	199	retval = search_binary_handler(bprm);
1da177e4 LT	200	if (retval < 0)
	201	goto _error;
	202
1da177e4 LT	203	_ret:
	204	return retval;
	205	_error:
	206	if (fd_binary > 0)
	207	sys_close(fd_binary);
	208	bprm->interp_flags = 0;
	209	bprm->interp_data = 0;
1da177e4 LT	210	goto _ret;
	211	}
	212
	213	/* Command parsers */
	214
	215	/*
	216	* parses and copies one argument enclosed in del from sp to dp,
	217	* recognising the \x special.
	218	* returns pointer to the copied argument or NULL in case of an
	219	* error (and sets err) or null argument length.
	220	*/
	221	static char scanarg(char s, char del)
	222	{
	223	char c;
	224
	225	while ((c = *s++) != del) {
	226	if (c == '\\' && *s == 'x') {
	227	s++;
	228	if (!isxdigit(*s++))
	229	return NULL;
	230	if (!isxdigit(*s++))
	231	return NULL;
	232	}
	233	}
	234	return s;
	235	}
	236
	237	static int unquote(char *from)
	238	{
	239	char c = 0, s = from, p = from;
	240
	241	while ((c = *s++) != '\0') {
	242	if (c == '\\' && *s == 'x') {
	243	s++;
	244	c = toupper(*s++);
	245	*p = (c - (isdigit(c) ? '0' : 'A' - 10)) << 4;
	246	c = toupper(*s++);
	247	*p++ \|= c - (isdigit(c) ? '0' : 'A' - 10);
	248	continue;
	249	}
	250	*p++ = c;
	251	}
	252	return p - from;
	253	}
	254
858119e1	255	static char * check_special_flags (char * sfs, Node * e)
1da177e4 LT	256	{
	257	char * p = sfs;
	258	int cont = 1;
	259
	260	/* special flags */
	261	while (cont) {
	262	switch (*p) {
	263	case 'P':
	264	p++;
	265	e->flags \|= MISC_FMT_PRESERVE_ARGV0;
	266	break;
	267	case 'O':
	268	p++;
	269	e->flags \|= MISC_FMT_OPEN_BINARY;
	270	break;
	271	case 'C':
	272	p++;
	273	/* this flags also implies the
	274	open-binary flag */
	275	e->flags \|= (MISC_FMT_CREDENTIALS \|
	276	MISC_FMT_OPEN_BINARY);
	277	break;
	278	default:
	279	cont = 0;
	280	}
	281	}
	282
	283	return p;
	284	}
	285	/*
	286	* This registers a new binary format, it recognises the syntax
	287	* ':name:type:offset:magic:mask:interpreter:flags'
	288	* where the ':' is the IFS, that can be chosen with the first char
	289	*/
	290	static Node create_entry(const char __user buffer, size_t count)
	291	{
	292	Node *e;
	293	int memsize, err;
	294	char buf, p;
	295	char del;
	296
	297	/* some sanity checks */
	298	err = -EINVAL;
	299	if ((count < 11) \|\| (count > 256))
	300	goto out;
	301
	302	err = -ENOMEM;
	303	memsize = sizeof(Node) + count + 8;
5cbded58	304	e = kmalloc(memsize, GFP_USER);
1da177e4 LT	305	if (!e)
	306	goto out;
	307
	308	p = buf = (char *)e + sizeof(Node);
	309
	310	memset(e, 0, sizeof(Node));
	311	if (copy_from_user(buf, buffer, count))
	312	goto Efault;
	313
	314	del = p++; / delimeter */
	315
	316	memset(buf+count, del, 8);
	317
	318	e->name = p;
	319	p = strchr(p, del);
	320	if (!p)
	321	goto Einval;
	322	*p++ = '\0';
	323	if (!e->name[0] \|\|
	324	!strcmp(e->name, ".") \|\|
	325	!strcmp(e->name, "..") \|\|
	326	strchr(e->name, '/'))
	327	goto Einval;
	328	switch (*p++) {
	329	case 'E': e->flags = 1<<Enabled; break;
	330	case 'M': e->flags = (1<<Enabled) \| (1<<Magic); break;
	331	default: goto Einval;
	332	}
	333	if (*p++ != del)
	334	goto Einval;
	335	if (test_bit(Magic, &e->flags)) {
	336	char *s = strchr(p, del);
	337	if (!s)
	338	goto Einval;
	339	*s++ = '\0';
	340	e->offset = simple_strtoul(p, &p, 10);
	341	if (*p++)
	342	goto Einval;
	343	e->magic = p;
	344	p = scanarg(p, del);
	345	if (!p)
	346	goto Einval;
	347	p[-1] = '\0';
	348	if (!e->magic[0])
	349	goto Einval;
	350	e->mask = p;
	351	p = scanarg(p, del);
	352	if (!p)
	353	goto Einval;
	354	p[-1] = '\0';
	355	if (!e->mask[0])
	356	e->mask = NULL;
	357	e->size = unquote(e->magic);
	358	if (e->mask && unquote(e->mask) != e->size)
	359	goto Einval;
	360	if (e->size + e->offset > BINPRM_BUF_SIZE)
	361	goto Einval;
	362	} else {
	363	p = strchr(p, del);
	364	if (!p)
	365	goto Einval;
	366	*p++ = '\0';
	367	e->magic = p;
	368	p = strchr(p, del);
369	if (!p)
370	goto Einval;
371	*p++ = '\0';
372	if (!e->magic[0] \|\| strchr(e->magic, '/'))
373	goto Einval;
374	p = strchr(p, del);
375	if (!p)
376	goto Einval;
377	*p++ = '\0';
378	}
379	e->interpreter = p;
380	p = strchr(p, del);
381	if (!p)
382	goto Einval;
383	*p++ = '\0';
384	if (!e->interpreter[0])
385	goto Einval;
386
387
388	p = check_special_flags (p, e);
389
390	if (*p == '\n')
391	p++;
392	if (p != buf + count)
393	goto Einval;
394	return e;
395
396	out:
397	return ERR_PTR(err);
398
399	Efault:
400	kfree(e);
401	return ERR_PTR(-EFAULT);
402	Einval:
403	kfree(e);
404	return ERR_PTR(-EINVAL);
405	}
406
407	/*
408	* Set status of entry/binfmt_misc:
409	* '1' enables, '0' disables and '-1' clears entry/binfmt_misc
410	*/
411	static int parse_command(const char __user *buffer, size_t count)
412	{
413	char s[4];
414
415	if (!count)
416	return 0;
417	if (count > 3)
418	return -EINVAL;
419	if (copy_from_user(s, buffer, count))
420	return -EFAULT;
421	if (s[count-1] == '\n')
422	count--;
423	if (count == 1 && s[0] == '0')
424	return 1;
425	if (count == 1 && s[0] == '1')
426	return 2;
427	if (count == 2 && s[0] == '-' && s[1] == '1')
428	return 3;
429	return -EINVAL;
430	}
431
432	/* generic stuff */
433
434	static void entry_status(Node e, char page)
435	{
436	char *dp;
437	char *status = "disabled";
438	const char * flags = "flags: ";
439
440	if (test_bit(Enabled, &e->flags))
441	status = "enabled";
442
443	if (!VERBOSE_STATUS) {
444	sprintf(page, "%s\n", status);
445	return;
446	}
447
448	sprintf(page, "%s\ninterpreter %s\n", status, e->interpreter);
449	dp = page + strlen(page);
450
451	/* print the special flags */
452	sprintf (dp, "%s", flags);
453	dp += strlen (flags);
454	if (e->flags & MISC_FMT_PRESERVE_ARGV0) {
455	*dp ++ = 'P';
456	}
457	if (e->flags & MISC_FMT_OPEN_BINARY) {
458	*dp ++ = 'O';
459	}
460	if (e->flags & MISC_FMT_CREDENTIALS) {
461	*dp ++ = 'C';
462	}
463	*dp ++ = '\n';
464
465
466	if (!test_bit(Magic, &e->flags)) {
467	sprintf(dp, "extension .%s\n", e->magic);
468	} else {
469	int i;
470
471	sprintf(dp, "offset %i\nmagic ", e->offset);
472	dp = page + strlen(page);
473	for (i = 0; i < e->size; i++) {
474	sprintf(dp, "%02x", 0xff & (int) (e->magic[i]));
475	dp += 2;
476	}
477	if (e->mask) {
478	sprintf(dp, "\nmask ");
479	dp += 6;
480	for (i = 0; i < e->size; i++) {
481	sprintf(dp, "%02x", 0xff & (int) (e->mask[i]));
482	dp += 2;
483	}
484	}
485	*dp++ = '\n';
486	*dp = '\0';
487	}
488	}
489
490	static struct inode bm_get_inode(struct super_block sb, int mode)
491	{
492	struct inode * inode = new_inode(sb);
493
494	if (inode) {
85fe4025	495	inode->i_ino = get_next_ino();
1da177e4	496	inode->i_mode = mode;
1da177e4 LT	497	inode->i_atime = inode->i_mtime = inode->i_ctime =
	498	current_fs_time(inode->i_sb);
	499	}
	500	return inode;
	501	}
	502
b57922d9	503	static void bm_evict_inode(struct inode *inode)
1da177e4	504	{
dbd5768f	505	clear_inode(inode);
8e18e294	506	kfree(inode->i_private);
1da177e4 LT	507	}
	508
	509	static void kill_node(Node *e)
	510	{
	511	struct dentry *dentry;
	512
	513	write_lock(&entries_lock);
	514	dentry = e->dentry;
	515	if (dentry) {
	516	list_del_init(&e->list);
	517	e->dentry = NULL;
	518	}
	519	write_unlock(&entries_lock);
	520
	521	if (dentry) {
6d6b77f1	522	drop_nlink(dentry->d_inode);
1da177e4 LT	523	d_drop(dentry);
	524	dput(dentry);
	525	simple_release_fs(&bm_mnt, &entry_count);
	526	}
	527	}
	528
	529	/* /<entry> */
	530
	531	static ssize_t
	532	bm_entry_read(struct file * file, char __user * buf, size_t nbytes, loff_t *ppos)
	533	{
496ad9aa	534	Node *e = file_inode(file)->i_private;
1da177e4 LT	535	ssize_t res;
1da177e4 LT	536	char *page;
1da177e4 LT	537
	538	if (!(page = (char*) __get_free_page(GFP_KERNEL)))
	539	return -ENOMEM;
	540
	541	entry_status(e, page);
1da177e4	542
6e2c10a1 AM	543	res = simple_read_from_buffer(buf, nbytes, ppos, page, strlen(page));
6e2c10a1 AM	544
1da177e4 LT	545	free_page((unsigned long) page);
	546	return res;
	547	}
	548
	549	static ssize_t bm_entry_write(struct file file, const char __user buffer,
	550	size_t count, loff_t *ppos)
	551	{
	552	struct dentry *root;
496ad9aa	553	Node *e = file_inode(file)->i_private;
1da177e4 LT	554	int res = parse_command(buffer, count);
	555
	556	switch (res) {
	557	case 1: clear_bit(Enabled, &e->flags);
	558	break;
	559	case 2: set_bit(Enabled, &e->flags);
	560	break;
d8c9584e	561	case 3: root = dget(file->f_path.dentry->d_sb->s_root);
1b1dcc1b	562	mutex_lock(&root->d_inode->i_mutex);
1da177e4 LT	563
	564	kill_node(e);
	565
1b1dcc1b	566	mutex_unlock(&root->d_inode->i_mutex);
1da177e4 LT	567	dput(root);
	568	break;
	569	default: return res;
	570	}
	571	return count;
	572	}
	573
4b6f5d20	574	static const struct file_operations bm_entry_operations = {
1da177e4 LT	575	.read = bm_entry_read,
1da177e4 LT	576	.write = bm_entry_write,
6038f373	577	.llseek = default_llseek,
1da177e4 LT	578	};
	579
	580	/* /register */
	581
	582	static ssize_t bm_register_write(struct file file, const char __user buffer,
	583	size_t count, loff_t *ppos)
	584	{
	585	Node *e;
	586	struct inode *inode;
	587	struct dentry root, dentry;
d8c9584e	588	struct super_block *sb = file->f_path.dentry->d_sb;
1da177e4 LT	589	int err = 0;
	590
	591	e = create_entry(buffer, count);
	592
	593	if (IS_ERR(e))
	594	return PTR_ERR(e);
	595
	596	root = dget(sb->s_root);
1b1dcc1b	597	mutex_lock(&root->d_inode->i_mutex);
1da177e4 LT	598	dentry = lookup_one_len(e->name, root, strlen(e->name));
	599	err = PTR_ERR(dentry);
	600	if (IS_ERR(dentry))
	601	goto out;
	602
	603	err = -EEXIST;
	604	if (dentry->d_inode)
	605	goto out2;
	606
	607	inode = bm_get_inode(sb, S_IFREG \| 0644);
	608
	609	err = -ENOMEM;
	610	if (!inode)
	611	goto out2;
	612
1f5ce9e9	613	err = simple_pin_fs(&bm_fs_type, &bm_mnt, &entry_count);
1da177e4 LT	614	if (err) {
	615	iput(inode);
	616	inode = NULL;
	617	goto out2;
	618	}
	619
	620	e->dentry = dget(dentry);
8e18e294	621	inode->i_private = e;
1da177e4 LT	622	inode->i_fop = &bm_entry_operations;
	623
	624	d_instantiate(dentry, inode);
	625	write_lock(&entries_lock);
	626	list_add(&e->list, &entries);
	627	write_unlock(&entries_lock);
	628
	629	err = 0;
	630	out2:
	631	dput(dentry);
	632	out:
1b1dcc1b	633	mutex_unlock(&root->d_inode->i_mutex);
1da177e4 LT	634	dput(root);
	635
	636	if (err) {
	637	kfree(e);
	638	return -EINVAL;
	639	}
	640	return count;
	641	}
	642
4b6f5d20	643	static const struct file_operations bm_register_operations = {
1da177e4	644	.write = bm_register_write,
6038f373	645	.llseek = noop_llseek,
1da177e4 LT	646	};
	647
	648	/* /status */
	649
	650	static ssize_t
	651	bm_status_read(struct file file, char __user buf, size_t nbytes, loff_t *ppos)
	652	{
87113e80	653	char *s = enabled ? "enabled\n" : "disabled\n";
1da177e4	654
92f4c701	655	return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s));
1da177e4 LT	656	}
	657
	658	static ssize_t bm_status_write(struct file * file, const char __user * buffer,
	659	size_t count, loff_t *ppos)
	660	{
	661	int res = parse_command(buffer, count);
	662	struct dentry *root;
	663
	664	switch (res) {
	665	case 1: enabled = 0; break;
	666	case 2: enabled = 1; break;
d8c9584e	667	case 3: root = dget(file->f_path.dentry->d_sb->s_root);
1b1dcc1b	668	mutex_lock(&root->d_inode->i_mutex);
1da177e4 LT	669
	670	while (!list_empty(&entries))
	671	kill_node(list_entry(entries.next, Node, list));
	672
1b1dcc1b	673	mutex_unlock(&root->d_inode->i_mutex);
1da177e4 LT	674	dput(root);
	675	default: return res;
	676	}
	677	return count;
	678	}
	679
4b6f5d20	680	static const struct file_operations bm_status_operations = {
1da177e4 LT	681	.read = bm_status_read,
1da177e4 LT	682	.write = bm_status_write,
6038f373	683	.llseek = default_llseek,
1da177e4 LT	684	};
	685
	686	/* Superblock handling */
	687
ee9b6d61	688	static const struct super_operations s_ops = {
1da177e4	689	.statfs = simple_statfs,
b57922d9	690	.evict_inode = bm_evict_inode,
1da177e4 LT	691	};
	692
	693	static int bm_fill_super(struct super_block * sb, void * data, int silent)
	694	{
	695	static struct tree_descr bm_files[] = {
1a1c9bb4 JL	696	[2] = {"status", &bm_status_operations, S_IWUSR\|S_IRUGO},
1a1c9bb4 JL	697	[3] = {"register", &bm_register_operations, S_IWUSR},
1da177e4 LT	698	/* last one */ {""}
1da177e4 LT	699	};
b502bd11	700	int err = simple_fill_super(sb, BINFMTFS_MAGIC, bm_files);
1da177e4 LT	701	if (!err)
	702	sb->s_op = &s_ops;
	703	return err;
	704	}
	705
fc14f2fe AV	706	static struct dentry bm_mount(struct file_system_type fs_type,
fc14f2fe AV	707	int flags, const char dev_name, void data)
1da177e4	708	{
fc14f2fe	709	return mount_single(fs_type, flags, data, bm_fill_super);
1da177e4 LT	710	}
	711
	712	static struct linux_binfmt misc_format = {
	713	.module = THIS_MODULE,
	714	.load_binary = load_misc_binary,
	715	};
	716
	717	static struct file_system_type bm_fs_type = {
	718	.owner = THIS_MODULE,
	719	.name = "binfmt_misc",
fc14f2fe	720	.mount = bm_mount,
1da177e4 LT	721	.kill_sb = kill_litter_super,
	722	};
	723
	724	static int __init init_misc_binfmt(void)
	725	{
	726	int err = register_filesystem(&bm_fs_type);
8fc3dc5a AV	727	if (!err)
8fc3dc5a AV	728	insert_binfmt(&misc_format);
1da177e4 LT	729	return err;
	730	}
	731
	732	static void __exit exit_misc_binfmt(void)
	733	{
	734	unregister_binfmt(&misc_format);
	735	unregister_filesystem(&bm_fs_type);
	736	}
	737
	738	core_initcall(init_misc_binfmt);
	739	module_exit(exit_misc_binfmt);
	740	MODULE_LICENSE("GPL");