1 files changed, 487 insertions, 0 deletions
diff --git a/security/tomoyo/realpath.c b/security/tomoyo/realpath.c
new file mode 100644
index 000000000000..5fd48d23a217
--- /dev/null
+++ b/security/tomoyo/realpath.c
@@ -0,0 +1,487 @@
+/*
+ * security/tomoyo/realpath.c
+ *
+ * Get the canonicalized absolute pathnames. The basis for TOMOYO.
+ *
+ * Copyright (C) 2005-2009  NTT DATA CORPORATION
+ *
+ * Version: 2.2.0-pre   2009/02/01
+ *
+ */
+
+#include <linux/types.h>
+#include <linux/mount.h>
+#include <linux/mnt_namespace.h>
+#include "common.h"
+#include "realpath.h"
+
+/**
+ * tomoyo_encode: Convert binary string to ascii string.
+ *
+ * @buffer:  Buffer for ASCII string.
+ * @buflen:  Size of @buffer.
+ * @str:     Binary string.
+ *
+ * Returns 0 on success, -ENOMEM otherwise.
+ */
+int tomoyo_encode(char *buffer, int buflen, const char *str)
+{
+	while (1) {
+		const unsigned char c = *(unsigned char *) str++;
+
+		if (tomoyo_is_valid(c)) {
+			if (--buflen <= 0)
+				break;
+			*buffer++ = (char) c;
+			if (c != '\\')
+				continue;
+			if (--buflen <= 0)
+				break;
+			*buffer++ = (char) c;
+			continue;
+		}
+		if (!c) {
+			if (--buflen <= 0)
+				break;
+			*buffer = '\0';
+			return 0;
+		}
+		buflen -= 4;
+		if (buflen <= 0)
+			break;
+		*buffer++ = '\\';
+		*buffer++ = (c >> 6) + '0';
+		*buffer++ = ((c >> 3) & 7) + '0';
+		*buffer++ = (c & 7) + '0';
+	}
+	return -ENOMEM;
+}
+
+/**
+ * tomoyo_realpath_from_path2 - Returns realpath(3) of the given dentry but ignores chroot'ed root.
+ *
+ * @path:        Pointer to "struct path".
+ * @newname:     Pointer to buffer to return value in.
+ * @newname_len: Size of @newname.
+ *
+ * Returns 0 on success, negative value otherwise.
+ *
+ * If dentry is a directory, trailing '/' is appended.
+ * Characters out of 0x20 < c < 0x7F range are converted to
+ * \ooo style octal string.
+ * Character \ is converted to \\ string.
+ */
+int tomoyo_realpath_from_path2(struct path *path, char *newname,
+			       int newname_len)
+{
+	int error = -ENOMEM;
+	struct dentry *dentry = path->dentry;
+	char *sp;
+
+	if (!dentry || !path->mnt || !newname || newname_len <= 2048)
+		return -EINVAL;
+	if (dentry->d_op && dentry->d_op->d_dname) {
+		/* For "socket:[\$]" and "pipe:[\$]". */
+		static const int offset = 1536;
+		sp = dentry->d_op->d_dname(dentry, newname + offset,
+					   newname_len - offset);
+	} else {
+		/* Taken from d_namespace_path(). */
+		struct path root;
+		struct path ns_root = { };
+		struct path tmp;
+
+		read_lock(&current->fs->lock);
+		root = current->fs->root;
+		path_get(&root);
+		read_unlock(&current->fs->lock);
+		spin_lock(&vfsmount_lock);
+		if (root.mnt && root.mnt->mnt_ns)
+			ns_root.mnt = mntget(root.mnt->mnt_ns->root);
+		if (ns_root.mnt)
+			ns_root.dentry = dget(ns_root.mnt->mnt_root);
+		spin_unlock(&vfsmount_lock);
+		spin_lock(&dcache_lock);
+		tmp = ns_root;
+		sp = __d_path(path, &tmp, newname, newname_len);
+		spin_unlock(&dcache_lock);
+		path_put(&root);
+		path_put(&ns_root);
+	}
+	if (IS_ERR(sp))
+		error = PTR_ERR(sp);
+	else
+		error = tomoyo_encode(newname, sp - newname, sp);
+	/* Append trailing '/' if dentry is a directory. */
+	if (!error && dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)
+	    && *newname) {
+		sp = newname + strlen(newname);
+		if (*(sp - 1) != '/') {
+			if (sp < newname + newname_len - 4) {
+				*sp++ = '/';
+				*sp = '\0';
+			} else {
+				error = -ENOMEM;
+			}
+		}
+	}
+	if (error)
+		printk(KERN_WARNING "tomoyo_realpath: Pathname too long.\n");
+	return error;
+}
+
+/**
+ * tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root.
+ *
+ * @path: Pointer to "struct path".
+ *
+ * Returns the realpath of the given @path on success, NULL otherwise.
+ *
+ * These functions use tomoyo_alloc(), so the caller must call tomoyo_free()
+ * if these functions didn't return NULL.
+ */
+char *tomoyo_realpath_from_path(struct path *path)
+{
+	char *buf = tomoyo_alloc(sizeof(struct tomoyo_page_buffer));
+
+	BUILD_BUG_ON(sizeof(struct tomoyo_page_buffer)
+		     <= TOMOYO_MAX_PATHNAME_LEN - 1);
+	if (!buf)
+		return NULL;
+	if (tomoyo_realpath_from_path2(path, buf,
+				       TOMOYO_MAX_PATHNAME_LEN - 1) == 0)
+		return buf;
+	tomoyo_free(buf);
+	return NULL;
+}
+
+/**
+ * tomoyo_realpath - Get realpath of a pathname.
+ *
+ * @pathname: The pathname to solve.
+ *
+ * Returns the realpath of @pathname on success, NULL otherwise.
+ */
+char *tomoyo_realpath(const char *pathname)
+{
+	struct nameidata nd;
+
+	if (pathname && path_lookup(pathname, LOOKUP_FOLLOW, &nd) == 0) {
+		char *buf = tomoyo_realpath_from_path(&nd.path);
+		path_put(&nd.path);
+		return buf;
+	}
+	return NULL;
+}
+
+/**
+ * tomoyo_realpath_nofollow - Get realpath of a pathname.
+ *
+ * @pathname: The pathname to solve.
+ *
+ * Returns the realpath of @pathname on success, NULL otherwise.
+ */
+char *tomoyo_realpath_nofollow(const char *pathname)
+{
+	struct nameidata nd;
+
+	if (pathname && path_lookup(pathname, 0, &nd) == 0) {
+		char *buf = tomoyo_realpath_from_path(&nd.path);
+		path_put(&nd.path);
+		return buf;
+	}
+	return NULL;
+}
+
+/* Memory allocated for non-string data. */
+static unsigned int tomoyo_allocated_memory_for_elements;
+/* Quota for holding non-string data. */
+static unsigned int tomoyo_quota_for_elements;
+
+/**
+ * tomoyo_alloc_element - Allocate permanent memory for structures.
+ *
+ * @size: Size in bytes.
+ *
+ * Returns pointer to allocated memory on success, NULL otherwise.
+ *
+ * Memory has to be zeroed.
+ * The RAM is chunked, so NEVER try to kfree() the returned pointer.
+ */
+void *tomoyo_alloc_element(const unsigned int size)
+{
+	static char *buf;
+	static DEFINE_MUTEX(lock);
+	static unsigned int buf_used_len = PATH_MAX;
+	char *ptr = NULL;
+	/*Assumes sizeof(void *) >= sizeof(long) is true. */
+	const unsigned int word_aligned_size
+		= roundup(size, max(sizeof(void *), sizeof(long)));
+	if (word_aligned_size > PATH_MAX)
+		return NULL;
+	/***** EXCLUSIVE SECTION START *****/
+	mutex_lock(&lock);
+	if (buf_used_len + word_aligned_size > PATH_MAX) {
+		if (!tomoyo_quota_for_elements ||
+		    tomoyo_allocated_memory_for_elements
+		    + PATH_MAX <= tomoyo_quota_for_elements)
+			ptr = kzalloc(PATH_MAX, GFP_KERNEL);
+		if (!ptr) {
+			printk(KERN_WARNING "ERROR: Out of memory "
+			       "for tomoyo_alloc_element().\n");
+			if (!tomoyo_policy_loaded)
+				panic("MAC Initialization failed.\n");
+		} else {
+			buf = ptr;
+			tomoyo_allocated_memory_for_elements += PATH_MAX;
+			buf_used_len = word_aligned_size;
+			ptr = buf;
+		}
+	} else if (word_aligned_size) {
+		int i;
+		ptr = buf + buf_used_len;
+		buf_used_len += word_aligned_size;
+		for (i = 0; i < word_aligned_size; i++) {
+			if (!ptr[i])
+				continue;
+			printk(KERN_ERR "WARNING: Reserved memory was tainted! "
+			       "The system might go wrong.\n");
+			ptr[i] = '\0';
+		}
+	}
+	mutex_unlock(&lock);
+	/***** EXCLUSIVE SECTION END *****/
+	return ptr;
+}
+
+/* Memory allocated for string data in bytes. */
+static unsigned int tomoyo_allocated_memory_for_savename;
+/* Quota for holding string data in bytes. */
+static unsigned int tomoyo_quota_for_savename;
+
+/*
+ * TOMOYO uses this hash only when appending a string into the string
+ * table. Frequency of appending strings is very low. So we don't need
+ * large (e.g. 64k) hash size. 256 will be sufficient.
+ */
+#define TOMOYO_MAX_HASH 256
+
+/* Structure for string data. */
+struct tomoyo_name_entry {
+	struct list_head list;
+	struct tomoyo_path_info entry;
+};
+
+/* Structure for available memory region. */
+struct tomoyo_free_memory_block_list {
+	struct list_head list;
+	char *ptr;             /* Pointer to a free area. */
+	int len;               /* Length of the area.     */
+};
+
+/*
+ * The list for "struct tomoyo_name_entry".
+ *
+ * This list is updated only inside tomoyo_save_name(), thus
+ * no global mutex exists.
+ */
+static struct list_head tomoyo_name_list[TOMOYO_MAX_HASH];
+
+/**
+ * tomoyo_save_name - Allocate permanent memory for string data.
+ *
+ * @name: The string to store into the permernent memory.
+ *
+ * Returns pointer to "struct tomoyo_path_info" on success, NULL otherwise.
+ *
+ * The RAM is shared, so NEVER try to modify or kfree() the returned name.
+ */
+const struct tomoyo_path_info *tomoyo_save_name(const char *name)
+{
+	static LIST_HEAD(fmb_list);
+	static DEFINE_MUTEX(lock);
+	struct tomoyo_name_entry *ptr;
+	unsigned int hash;
+	/* fmb contains available size in bytes.
+	   fmb is removed from the fmb_list when fmb->len becomes 0. */
+	struct tomoyo_free_memory_block_list *fmb;
+	int len;
+	char *cp;
+
+	if (!name)
+		return NULL;
+	len = strlen(name) + 1;
+	if (len > TOMOYO_MAX_PATHNAME_LEN) {
+		printk(KERN_WARNING "ERROR: Name too long "
+		       "for tomoyo_save_name().\n");
+		return NULL;
+	}
+	hash = full_name_hash((const unsigned char *) name, len - 1);
+	/***** EXCLUSIVE SECTION START *****/
+	mutex_lock(&lock);
+	list_for_each_entry(ptr, &tomoyo_name_list[hash % TOMOYO_MAX_HASH],
+			     list) {
+		if (hash == ptr->entry.hash && !strcmp(name, ptr->entry.name))
+			goto out;
+	}
+	list_for_each_entry(fmb, &fmb_list, list) {
+		if (len <= fmb->len)
+			goto ready;
+	}
+	if (!tomoyo_quota_for_savename ||
+	    tomoyo_allocated_memory_for_savename + PATH_MAX
+	    <= tomoyo_quota_for_savename)
+		cp = kzalloc(PATH_MAX, GFP_KERNEL);
+	else
+		cp = NULL;
+	fmb = kzalloc(sizeof(*fmb), GFP_KERNEL);
+	if (!cp || !fmb) {
+		kfree(cp);
+		kfree(fmb);
+		printk(KERN_WARNING "ERROR: Out of memory "
+		       "for tomoyo_save_name().\n");
+		if (!tomoyo_policy_loaded)
+			panic("MAC Initialization failed.\n");
+		ptr = NULL;
+		goto out;
+	}
+	tomoyo_allocated_memory_for_savename += PATH_MAX;
+	list_add(&fmb->list, &fmb_list);
+	fmb->ptr = cp;
+	fmb->len = PATH_MAX;
+ ready:
+	ptr = tomoyo_alloc_element(sizeof(*ptr));
+	if (!ptr)
+		goto out;
+	ptr->entry.name = fmb->ptr;
+	memmove(fmb->ptr, name, len);
+	tomoyo_fill_path_info(&ptr->entry);
+	fmb->ptr += len;
+	fmb->len -= len;
+	list_add_tail(&ptr->list, &tomoyo_name_list[hash % TOMOYO_MAX_HASH]);
+	if (fmb->len == 0) {
+		list_del(&fmb->list);
+		kfree(fmb);
+	}
+ out:
+	mutex_unlock(&lock);
+	/***** EXCLUSIVE SECTION END *****/
+	return ptr ? &ptr->entry : NULL;
+}
+
+/**
+ * tomoyo_realpath_init - Initialize realpath related code.
+ *
+ * Returns 0.
+ */
+static int __init tomoyo_realpath_init(void)
+{
+	int i;
+
+	BUILD_BUG_ON(TOMOYO_MAX_PATHNAME_LEN > PATH_MAX);
+	for (i = 0; i < TOMOYO_MAX_HASH; i++)
+		INIT_LIST_HEAD(&tomoyo_name_list[i]);
+	INIT_LIST_HEAD(&tomoyo_kernel_domain.acl_info_list);
+	tomoyo_kernel_domain.domainname = tomoyo_save_name(TOMOYO_ROOT_NAME);
+	list_add_tail(&tomoyo_kernel_domain.list, &tomoyo_domain_list);
+	down_read(&tomoyo_domain_list_lock);
+	if (tomoyo_find_domain(TOMOYO_ROOT_NAME) != &tomoyo_kernel_domain)
+		panic("Can't register tomoyo_kernel_domain");
+	up_read(&tomoyo_domain_list_lock);
+	return 0;
+}
+
+security_initcall(tomoyo_realpath_init);
+
+/* Memory allocated for temporary purpose. */
+static atomic_t tomoyo_dynamic_memory_size;
+
+/**
+ * tomoyo_alloc - Allocate memory for temporary purpose.
+ *
+ * @size: Size in bytes.
+ *
+ * Returns pointer to allocated memory on success, NULL otherwise.
+ */
+void *tomoyo_alloc(const size_t size)
+{
+	void *p = kzalloc(size, GFP_KERNEL);
+	if (p)
+		atomic_add(ksize(p), &tomoyo_dynamic_memory_size);
+	return p;
+}
+
+/**
+ * tomoyo_free - Release memory allocated by tomoyo_alloc().
+ *
+ * @p: Pointer returned by tomoyo_alloc(). May be NULL.
+ *
+ * Returns nothing.
+ */
+void tomoyo_free(const void *p)
+{
+	if (p) {
+		atomic_sub(ksize(p), &tomoyo_dynamic_memory_size);
+		kfree(p);
+	}
+}
+
+/**
+ * tomoyo_read_memory_counter - Check for memory usage in bytes.
+ *
+ * @head: Pointer to "struct tomoyo_io_buffer".
+ *
+ * Returns memory usage.
+ */
+int tomoyo_read_memory_counter(struct tomoyo_io_buffer *head)
+{
+	if (!head->read_eof) {
+		const unsigned int shared
+			= tomoyo_allocated_memory_for_savename;
+		const unsigned int private
+			= tomoyo_allocated_memory_for_elements;
+		const unsigned int dynamic
+			= atomic_read(&tomoyo_dynamic_memory_size);
+		char buffer[64];
+
+		memset(buffer, 0, sizeof(buffer));
+		if (tomoyo_quota_for_savename)
+			snprintf(buffer, sizeof(buffer) - 1,
+				 "   (Quota: %10u)",
+				 tomoyo_quota_for_savename);
+		else
+			buffer[0] = '\0';
+		tomoyo_io_printf(head, "Shared:  %10u%s\n", shared, buffer);
+		if (tomoyo_quota_for_elements)
+			snprintf(buffer, sizeof(buffer) - 1,
+				 "   (Quota: %10u)",
+				 tomoyo_quota_for_elements);
+		else
+			buffer[0] = '\0';
+		tomoyo_io_printf(head, "Private: %10u%s\n", private, buffer);
+		tomoyo_io_printf(head, "Dynamic: %10u\n", dynamic);
+		tomoyo_io_printf(head, "Total:   %10u\n",
+				 shared + private + dynamic);
+		head->read_eof = true;
+	}
+	return 0;
+}
+
+/**
+ * tomoyo_write_memory_quota - Set memory quota.
+ *
+ * @head: Pointer to "struct tomoyo_io_buffer".
+ *
+ * Returns 0.
+ */
+int tomoyo_write_memory_quota(struct tomoyo_io_buffer *head)
+{
+	char *data = head->write_buf;
+	unsigned int size;
+
+	if (sscanf(data, "Shared: %u", &size) == 1)
+		tomoyo_quota_for_savename = size;
+	else if (sscanf(data, "Private: %u", &size) == 1)
+		tomoyo_quota_for_elements = size;
+	return 0;
+}