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;
+}