Initial import

1 files changed, 835 insertions, 0 deletions

diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
new file mode 100644
index 000000000..78f005f37
--- /dev/null
+++ b/fs/binfmt_misc.c
@@ -0,0 +1,835 @@
+/*
+ * binfmt_misc.c
+ *
+ * Copyright (C) 1997 Richard Günther
+ *
+ * binfmt_misc detects binaries via a magic or filename extension and invokes
+ * a specified wrapper. See Documentation/binfmt_misc.txt for more details.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#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/string_helpers.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 <linux/uaccess.h>
+
+#ifdef DEBUG
+# define USE_DEBUG 1
+#else
+# define USE_DEBUG 0
+#endif
+
+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;
+
+/*
+ * Max length of the register string.  Determined by:
+ *  - 7 delimiters
+ *  - name:   ~50 bytes
+ *  - type:   1 byte
+ *  - offset: 3 bytes (has to be smaller than BINPRM_BUF_SIZE)
+ *  - magic:  128 bytes (512 in escaped form)
+ *  - mask:   128 bytes (512 in escaped form)
+ *  - interp: ~50 bytes
+ *  - flags:  5 bytes
+ * Round that up a bit, and then back off to hold the internal data
+ * (like struct Node).
+ */
+#define MAX_REGISTER_LENGTH 1920
+
+/*
+ * 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;
+
+	/* Walk all the registered handlers. */
+	list_for_each(l, &entries) {
+		Node *e = list_entry(l, Node, list);
+		char *s;
+		int j;
+
+		/* Make sure this one is currently enabled. */
+		if (!test_bit(Enabled, &e->flags))
+			continue;
+
+		/* Do matching based on extension if applicable. */
+		if (!test_bit(Magic, &e->flags)) {
+			if (p && !strcmp(e->magic, p + 1))
+				return e;
+			continue;
+		}
+
+		/* Do matching based on magic & mask. */
+		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;
+
+	/* Need to be able to load the file after exec */
+	if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE)
+		return -ENOENT;
+
+	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_flags(0);
+		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;
+		}
+	}
+	s[-1] ='\0';
+	return s;
+}
+
+static char *check_special_flags(char *sfs, Node *e)
+{
+	char *p = sfs;
+	int cont = 1;
+
+	/* special flags */
+	while (cont) {
+		switch (*p) {
+		case 'P':
+			pr_debug("register: flag: P (preserve argv0)\n");
+			p++;
+			e->flags |= MISC_FMT_PRESERVE_ARGV0;
+			break;
+		case 'O':
+			pr_debug("register: flag: O (open binary)\n");
+			p++;
+			e->flags |= MISC_FMT_OPEN_BINARY;
+			break;
+		case 'C':
+			pr_debug("register: flag: C (preserve creds)\n");
+			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;
+
+	pr_debug("register: received %zu bytes\n", count);
+
+	/* some sanity checks */
+	err = -EINVAL;
+	if ((count < 11) || (count > MAX_REGISTER_LENGTH))
+		goto out;
+
+	err = -ENOMEM;
+	memsize = sizeof(Node) + count + 8;
+	e = kmalloc(memsize, GFP_KERNEL);
+	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 */
+
+	pr_debug("register: delim: %#x {%c}\n", del, del);
+
+	/* Pad the buffer with the delim to simplify parsing below. */
+	memset(buf + count, del, 8);
+
+	/* Parse the 'name' field. */
+	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;
+
+	pr_debug("register: name: {%s}\n", e->name);
+
+	/* Parse the 'type' field. */
+	switch (*p++) {
+	case 'E':
+		pr_debug("register: type: E (extension)\n");
+		e->flags = 1 << Enabled;
+		break;
+	case 'M':
+		pr_debug("register: type: M (magic)\n");
+		e->flags = (1 << Enabled) | (1 << Magic);
+		break;
+	default:
+		goto einval;
+	}
+	if (*p++ != del)
+		goto einval;
+
+	if (test_bit(Magic, &e->flags)) {
+		/* Handle the 'M' (magic) format. */
+		char *s;
+
+		/* Parse the 'offset' field. */
+		s = strchr(p, del);
+		if (!s)
+			goto einval;
+		*s++ = '\0';
+		e->offset = simple_strtoul(p, &p, 10);
+		if (*p++)
+			goto einval;
+		pr_debug("register: offset: %#x\n", e->offset);
+
+		/* Parse the 'magic' field. */
+		e->magic = p;
+		p = scanarg(p, del);
+		if (!p)
+			goto einval;
+		if (!e->magic[0])
+			goto einval;
+		if (USE_DEBUG)
+			print_hex_dump_bytes(
+				KBUILD_MODNAME ": register: magic[raw]: ",
+				DUMP_PREFIX_NONE, e->magic, p - e->magic);
+
+		/* Parse the 'mask' field. */
+		e->mask = p;
+		p = scanarg(p, del);
+		if (!p)
+			goto einval;
+		if (!e->mask[0]) {
+			e->mask = NULL;
+			pr_debug("register:  mask[raw]: none\n");
+		} else if (USE_DEBUG)
+			print_hex_dump_bytes(
+				KBUILD_MODNAME ": register:  mask[raw]: ",
+				DUMP_PREFIX_NONE, e->mask, p - e->mask);
+
+		/*
+		 * Decode the magic & mask fields.
+		 * Note: while we might have accepted embedded NUL bytes from
+		 * above, the unescape helpers here will stop at the first one
+		 * it encounters.
+		 */
+		e->size = string_unescape_inplace(e->magic, UNESCAPE_HEX);
+		if (e->mask &&
+		    string_unescape_inplace(e->mask, UNESCAPE_HEX) != e->size)
+			goto einval;
+		if (e->size + e->offset > BINPRM_BUF_SIZE)
+			goto einval;
+		pr_debug("register: magic/mask length: %i\n", e->size);
+		if (USE_DEBUG) {
+			print_hex_dump_bytes(
+				KBUILD_MODNAME ": register: magic[decoded]: ",
+				DUMP_PREFIX_NONE, e->magic, e->size);
+
+			if (e->mask) {
+				int i;
+				char *masked = kmalloc(e->size, GFP_KERNEL);
+
+				print_hex_dump_bytes(
+					KBUILD_MODNAME ": register:  mask[decoded]: ",
+					DUMP_PREFIX_NONE, e->mask, e->size);
+
+				if (masked) {
+					for (i = 0; i < e->size; ++i)
+						masked[i] = e->magic[i] & e->mask[i];
+					print_hex_dump_bytes(
+						KBUILD_MODNAME ": register:  magic[masked]: ",
+						DUMP_PREFIX_NONE, masked, e->size);
+
+					kfree(masked);
+				}
+			}
+		}
+	} else {
+		/* Handle the 'E' (extension) format. */
+
+		/* Skip the 'offset' field. */
+		p = strchr(p, del);
+		if (!p)
+			goto einval;
+		*p++ = '\0';
+
+		/* Parse the 'magic' field. */
+		e->magic = p;
+		p = strchr(p, del);
+		if (!p)
+			goto einval;
+		*p++ = '\0';
+		if (!e->magic[0] || strchr(e->magic, '/'))
+			goto einval;
+		pr_debug("register: extension: {%s}\n", e->magic);
+
+		/* Skip the 'mask' field. */
+		p = strchr(p, del);
+		if (!p)
+			goto einval;
+		*p++ = '\0';
+	}
+
+	/* Parse the 'interpreter' field. */
+	e->interpreter = p;
+	p = strchr(p, del);
+	if (!p)
+		goto einval;
+	*p++ = '\0';
+	if (!e->interpreter[0])
+		goto einval;
+	pr_debug("register: interpreter: {%s}\n", e->interpreter);
+
+	/* Parse the 'flags' field. */
+	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 > 3)
+		return -EINVAL;
+	if (copy_from_user(s, buffer, count))
+		return -EFAULT;
+	if (!count)
+		return 0;
+	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 = page;
+	const char *status = "disabled";
+
+	if (test_bit(Enabled, &e->flags))
+		status = "enabled";
+
+	if (!VERBOSE_STATUS) {
+		sprintf(page, "%s\n", status);
+		return;
+	}
+
+	dp += sprintf(dp, "%s\ninterpreter %s\n", status, e->interpreter);
+
+	/* print the special flags */
+	dp += sprintf(dp, "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 {
+		dp += sprintf(dp, "offset %i\nmagic ", e->offset);
+		dp = bin2hex(dp, e->magic, e->size);
+		if (e->mask) {
+			dp += sprintf(dp, "\nmask ");
+			dp = bin2hex(dp, e->mask, e->size);
+		}
+		*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(d_inode(dentry));
+		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;
+
+	page = (char *) __get_free_page(GFP_KERNEL);
+	if (!page)
+		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:
+		/* Disable this handler. */
+		clear_bit(Enabled, &e->flags);
+		break;
+	case 2:
+		/* Enable this handler. */
+		set_bit(Enabled, &e->flags);
+		break;
+	case 3:
+		/* Delete this handler. */
+		root = dget(file->f_path.dentry->d_sb->s_root);
+		mutex_lock(&d_inode(root)->i_mutex);
+
+		kill_node(e);
+
+		mutex_unlock(&d_inode(root)->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(&d_inode(root)->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 (d_really_is_positive(dentry))
+		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(&d_inode(root)->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:
+		/* Disable all handlers. */
+		enabled = 0;
+		break;
+	case 2:
+		/* Enable all handlers. */
+		enabled = 1;
+		break;
+	case 3:
+		/* Delete all handlers. */
+		root = dget(file->f_path.dentry->d_sb->s_root);
+		mutex_lock(&d_inode(root)->i_mutex);
+
+		while (!list_empty(&entries))
+			kill_node(list_entry(entries.next, Node, list));
+
+		mutex_unlock(&d_inode(root)->i_mutex);
+		dput(root);
+		break;
+	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)
+{
+	int err;
+	static struct tree_descr bm_files[] = {
+		[2] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO},
+		[3] = {"register", &bm_register_operations, S_IWUSR},
+		/* last one */ {""}
+	};
+
+	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,
+};
+MODULE_ALIAS_FS("binfmt_misc");
+
+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");