1 files changed, 743 insertions, 0 deletions

diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
new file mode 100644
index 00000000..613aa061
--- /dev/null
+++ b/fs/binfmt_misc.c
@@ -0,0 +1,743 @@
+/*
+ *  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, struct pt_regs *regs)
+{
+	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;
+
+	retval = -ENOEXEC;
+	if (bprm->recursion_depth > BINPRM_MAX_RECURSION)
+		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 ++;
+
+	bprm->interp = iname;	/* for binfmt_script */
+
+	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;
+
+	bprm->recursion_depth++;
+
+	retval = search_binary_handler (bprm, regs);
+	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)
+{
+	end_writeback(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->f_path.dentry->d_inode->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->f_path.dentry->d_inode->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");