TOMOYO: Add mount restriction.

mount(2) has three string and one numeric parameters.
Split mount restriction code from security/tomoyo/file.c .

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 366 insertions, 0 deletions

diff --git a/security/tomoyo/mount.c b/security/tomoyo/mount.c
new file mode 100644
index 000000000000..507be09e93a9
--- /dev/null
+++ b/security/tomoyo/mount.c
@@ -0,0 +1,366 @@
+/*
+ * security/tomoyo/mount.c
+ *
+ * Copyright (C) 2005-2010  NTT DATA CORPORATION
+ */
+
+#include <linux/slab.h>
+#include "common.h"
+
+/* Keywords for mount restrictions. */
+
+/* Allow to call 'mount --bind /source_dir /dest_dir' */
+#define TOMOYO_MOUNT_BIND_KEYWORD                        "--bind"
+/* Allow to call 'mount --move /old_dir    /new_dir ' */
+#define TOMOYO_MOUNT_MOVE_KEYWORD                        "--move"
+/* Allow to call 'mount -o remount /dir             ' */
+#define TOMOYO_MOUNT_REMOUNT_KEYWORD                     "--remount"
+/* Allow to call 'mount --make-unbindable /dir'       */
+#define TOMOYO_MOUNT_MAKE_UNBINDABLE_KEYWORD             "--make-unbindable"
+/* Allow to call 'mount --make-private /dir'          */
+#define TOMOYO_MOUNT_MAKE_PRIVATE_KEYWORD                "--make-private"
+/* Allow to call 'mount --make-slave /dir'            */
+#define TOMOYO_MOUNT_MAKE_SLAVE_KEYWORD                  "--make-slave"
+/* Allow to call 'mount --make-shared /dir'           */
+#define TOMOYO_MOUNT_MAKE_SHARED_KEYWORD                 "--make-shared"
+
+/**
+ * tomoyo_encode2: Encode binary string to ascii string.
+ *
+ * @str: String in binary format.
+ *
+ * Returns pointer to @str in ascii format on success, NULL otherwise.
+ *
+ * This function uses kzalloc(), so caller must kfree() if this function
+ * didn't return NULL.
+ */
+static char *tomoyo_encode2(const char *str)
+{
+        int len = 0;
+        const char *p = str;
+        char *cp;
+        char *cp0;
+        if (!p)
+                return NULL;
+        while (*p) {
+                const unsigned char c = *p++;
+                if (c == '\\')
+                        len += 2;
+                else if (c > ' ' && c < 127)
+                        len++;
+                else
+                        len += 4;
+        }
+        len++;
+        /* Reserve space for appending "/". */
+        cp = kzalloc(len + 10, GFP_NOFS);
+        if (!cp)
+                return NULL;
+        cp0 = cp;
+        p = str;
+        while (*p) {
+                const unsigned char c = *p++;
+                if (c == '\\') {
+                        *cp++ = '\\';
+                        *cp++ = '\\';
+                } else if (c > ' ' && c < 127) {
+                        *cp++ = c;
+                } else {
+                        *cp++ = '\\';
+                        *cp++ = (c >> 6) + '0';
+                        *cp++ = ((c >> 3) & 7) + '0';
+                        *cp++ = (c & 7) + '0';
+                }
+        }
+        return cp0;
+}
+
+/**
+ * tomoyo_mount_acl2 - Check permission for mount() operation.
+ *
+ * @r:        Pointer to "struct tomoyo_request_info".
+ * @dev_name: Name of device file.
+ * @dir:      Pointer to "struct path".
+ * @type:     Name of filesystem type.
+ * @flags:    Mount options.
+ *
+ * Returns 0 on success, negative value otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+static int tomoyo_mount_acl2(struct tomoyo_request_info *r, char *dev_name,
+                             struct path *dir, char *type, unsigned long flags)
+{
+        struct path path;
+        struct tomoyo_acl_info *ptr;
+        struct file_system_type *fstype = NULL;
+        const char *requested_type = NULL;
+        const char *requested_dir_name = NULL;
+        const char *requested_dev_name = NULL;
+        struct tomoyo_path_info rtype;
+        struct tomoyo_path_info rdev;
+        struct tomoyo_path_info rdir;
+        int need_dev = 0;
+        int error = -ENOMEM;
+
+        /* Get fstype. */
+        requested_type = tomoyo_encode2(type);
+        if (!requested_type)
+                goto out;
+        rtype.name = requested_type;
+        tomoyo_fill_path_info(&rtype);
+
+        /* Get mount point. */
+        requested_dir_name = tomoyo_realpath_from_path(dir);
+        if (!requested_dir_name) {
+                error = -ENOMEM;
+                goto out;
+        }
+        rdir.name = requested_dir_name;
+        tomoyo_fill_path_info(&rdir);
+
+        /* Compare fs name. */
+        if (!strcmp(type, TOMOYO_MOUNT_REMOUNT_KEYWORD)) {
+                /* dev_name is ignored. */
+        } else if (!strcmp(type, TOMOYO_MOUNT_MAKE_UNBINDABLE_KEYWORD) ||
+                   !strcmp(type, TOMOYO_MOUNT_MAKE_PRIVATE_KEYWORD) ||
+                   !strcmp(type, TOMOYO_MOUNT_MAKE_SLAVE_KEYWORD) ||
+                   !strcmp(type, TOMOYO_MOUNT_MAKE_SHARED_KEYWORD)) {
+                /* dev_name is ignored. */
+        } else if (!strcmp(type, TOMOYO_MOUNT_BIND_KEYWORD) ||
+                   !strcmp(type, TOMOYO_MOUNT_MOVE_KEYWORD)) {
+                need_dev = -1; /* dev_name is a directory */
+        } else {
+                fstype = get_fs_type(type);
+                if (!fstype) {
+                        error = -ENODEV;
+                        goto out;
+                }
+                if (fstype->fs_flags & FS_REQUIRES_DEV)
+                        /* dev_name is a block device file. */
+                        need_dev = 1;
+        }
+        if (need_dev) {
+                /* Get mount point or device file. */
+                if (kern_path(dev_name, LOOKUP_FOLLOW, &path)) {
+                        error = -ENOENT;
+                        goto out;
+                }
+                requested_dev_name = tomoyo_realpath_from_path(&path);
+                if (!requested_dev_name) {
+                        error = -ENOENT;
+                        goto out;
+                }
+        } else {
+                /* Map dev_name to "<NULL>" if no dev_name given. */
+                if (!dev_name)
+                        dev_name = "<NULL>";
+                requested_dev_name = tomoyo_encode2(dev_name);
+                if (!requested_dev_name) {
+                        error = -ENOMEM;
+                        goto out;
+                }
+        }
+        rdev.name = requested_dev_name;
+        tomoyo_fill_path_info(&rdev);
+        list_for_each_entry_rcu(ptr, &r->domain->acl_info_list, list) {
+                struct tomoyo_mount_acl *acl;
+                if (ptr->type != TOMOYO_TYPE_MOUNT_ACL)
+                        continue;
+                acl = container_of(ptr, struct tomoyo_mount_acl, head);
+                if (acl->is_deleted ||
+                    !tomoyo_compare_number_union(flags, &acl->flags) ||
+                    !tomoyo_compare_name_union(&rtype, &acl->fs_type) ||
+                    !tomoyo_compare_name_union(&rdir, &acl->dir_name) ||
+                    (need_dev &&
+                     !tomoyo_compare_name_union(&rdev, &acl->dev_name)))
+                        continue;
+                error = 0;
+                break;
+        }
+        if (error) {
+                const char *dev = tomoyo_get_file_pattern(&rdev)->name;
+                const char *dir = tomoyo_get_file_pattern(&rdir)->name;
+                int len = strlen(dev) + strlen(dir) + strlen(requested_type)
+                        + 64;
+                char *buf = kzalloc(len, GFP_NOFS);
+                if (buf) {
+                        snprintf(buf, len - 1, "%s %s %s 0x%lX",
+                                 dev, dir, requested_type, flags);
+                        tomoyo_write_mount_policy(buf, r->domain, false);
+                        kfree(buf);
+                }
+        }
+ out:
+        kfree(requested_dev_name);
+        kfree(requested_dir_name);
+        if (fstype)
+                put_filesystem(fstype);
+        kfree(requested_type);
+        return error;
+}
+
+/**
+ * tomoyo_mount_acl - Check permission for mount() operation.
+ *
+ * @r:        Pointer to "struct tomoyo_request_info".
+ * @dev_name: Name of device file.
+ * @dir:      Pointer to "struct path".
+ * @type:     Name of filesystem type.
+ * @flags:    Mount options.
+ *
+ * Returns 0 on success, negative value otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+static int tomoyo_mount_acl(struct tomoyo_request_info *r, char *dev_name,
+                            struct path *dir, char *type, unsigned long flags)
+{
+        int error;
+        error = -EPERM;
+        if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
+                flags &= ~MS_MGC_MSK;
+        switch (flags & (MS_REMOUNT | MS_MOVE | MS_BIND)) {
+        case MS_REMOUNT:
+        case MS_MOVE:
+        case MS_BIND:
+        case 0:
+                break;
+        default:
+                printk(KERN_WARNING "ERROR: "
+                       "%s%s%sare given for single mount operation.\n",
+                       flags & MS_REMOUNT ? "'remount' " : "",
+                       flags & MS_MOVE    ? "'move' " : "",
+                       flags & MS_BIND    ? "'bind' " : "");
+                return -EINVAL;
+        }
+        switch (flags & (MS_UNBINDABLE | MS_PRIVATE | MS_SLAVE | MS_SHARED)) {
+        case MS_UNBINDABLE:
+        case MS_PRIVATE:
+        case MS_SLAVE:
+        case MS_SHARED:
+        case 0:
+                break;
+        default:
+                printk(KERN_WARNING "ERROR: "
+                       "%s%s%s%sare given for single mount operation.\n",
+                       flags & MS_UNBINDABLE ? "'unbindable' " : "",
+                       flags & MS_PRIVATE    ? "'private' " : "",
+                       flags & MS_SLAVE      ? "'slave' " : "",
+                       flags & MS_SHARED     ? "'shared' " : "");
+                return -EINVAL;
+        }
+        if (flags & MS_REMOUNT)
+                error = tomoyo_mount_acl(r, dev_name, dir,
+                                      TOMOYO_MOUNT_REMOUNT_KEYWORD,
+                                      flags & ~MS_REMOUNT);
+        else if (flags & MS_MOVE)
+                error = tomoyo_mount_acl(r, dev_name, dir,
+                                      TOMOYO_MOUNT_MOVE_KEYWORD,
+                                      flags & ~MS_MOVE);
+        else if (flags & MS_BIND)
+                error = tomoyo_mount_acl(r, dev_name, dir,
+                                      TOMOYO_MOUNT_BIND_KEYWORD,
+                                      flags & ~MS_BIND);
+        else if (flags & MS_UNBINDABLE)
+                error = tomoyo_mount_acl(r, dev_name, dir,
+                                      TOMOYO_MOUNT_MAKE_UNBINDABLE_KEYWORD,
+                                      flags & ~MS_UNBINDABLE);
+        else if (flags & MS_PRIVATE)
+                error = tomoyo_mount_acl(r, dev_name, dir,
+                                      TOMOYO_MOUNT_MAKE_PRIVATE_KEYWORD,
+                                      flags & ~MS_PRIVATE);
+        else if (flags & MS_SLAVE)
+                error = tomoyo_mount_acl(r, dev_name, dir,
+                                      TOMOYO_MOUNT_MAKE_SLAVE_KEYWORD,
+                                      flags & ~MS_SLAVE);
+        else if (flags & MS_SHARED)
+                error = tomoyo_mount_acl(r, dev_name, dir,
+                                      TOMOYO_MOUNT_MAKE_SHARED_KEYWORD,
+                                      flags & ~MS_SHARED);
+        else
+                error = tomoyo_mount_acl2(r, dev_name, dir, type, flags);
+        if (r->mode != TOMOYO_CONFIG_ENFORCING)
+                error = 0;
+        return error;
+}
+
+/**
+ * tomoyo_mount_permission - Check permission for mount() operation.
+ *
+ * @dev_name:  Name of device file.
+ * @path:      Pointer to "struct path".
+ * @type:      Name of filesystem type. May be NULL.
+ * @flags:     Mount options.
+ * @data_page: Optional data. May be NULL.
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+int tomoyo_mount_permission(char *dev_name, struct path *path, char *type,
+                            unsigned long flags, void *data_page)
+{
+        struct tomoyo_request_info r;
+        int error;
+        int idx;
+
+        if (tomoyo_init_request_info(&r, NULL) == TOMOYO_CONFIG_DISABLED)
+                return 0;
+        if (!type)
+                type = "<NULL>";
+        idx = tomoyo_read_lock();
+        error = tomoyo_mount_acl(&r, dev_name, path, type, flags);
+        tomoyo_read_unlock(idx);
+        return error;
+}
+
+/**
+ * tomoyo_write_mount_policy - Write "struct tomoyo_mount_acl" list.
+ *
+ * @data:      String to parse.
+ * @domain:    Pointer to "struct tomoyo_domain_info".
+ * @is_delete: True if it is a delete request.
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+int tomoyo_write_mount_policy(char *data, struct tomoyo_domain_info *domain,
+                              const bool is_delete)
+{
+        struct tomoyo_acl_info *ptr;
+        struct tomoyo_mount_acl e = { .head.type = TOMOYO_TYPE_MOUNT_ACL };
+        int error = is_delete ? -ENOENT : -ENOMEM;
+        char *w[4];
+        if (!tomoyo_tokenize(data, w, sizeof(w)) || !w[3][0])
+                return -EINVAL;
+        if (!tomoyo_parse_name_union(w[0], &e.dev_name) ||
+            !tomoyo_parse_name_union(w[1], &e.dir_name) ||
+            !tomoyo_parse_name_union(w[2], &e.fs_type) ||
+            !tomoyo_parse_number_union(w[3], &e.flags))
+                goto out;
+        if (mutex_lock_interruptible(&tomoyo_policy_lock))
+                goto out;
+        list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) {
+                struct tomoyo_mount_acl *acl =
+                        container_of(ptr, struct tomoyo_mount_acl, head);
+                if (!tomoyo_is_same_mount_acl(acl, &e))
+                        continue;
+                acl->is_deleted = is_delete;
+                error = 0;
+                break;
+        }
+        if (!is_delete && error) {
+                struct tomoyo_mount_acl *entry =
+                        tomoyo_commit_ok(&e, sizeof(e));
+                if (entry) {
+                        list_add_tail_rcu(&entry->head.list,
+                                          &domain->acl_info_list);
+                        error = 0;
+                }
+        }
+        mutex_unlock(&tomoyo_policy_lock);
+ out:
+        tomoyo_put_name_union(&e.dev_name);
+        tomoyo_put_name_union(&e.dir_name);
+        tomoyo_put_name_union(&e.fs_type);
+        tomoyo_put_number_union(&e.flags);
+        return error;
+}