ccs-patch/fs/sakura_pivot.c

/*
 * fs/sakura_pivot.c
 *
 * Implementation of the Domain-Free Mandatory Access Control.
 *
 * Copyright (C) 2005-2009  NTT DATA CORPORATION
 *
 * Version: 1.6.8   2009/05/28
 *
 * This file is applicable to both 2.4.30 and 2.6.11 and later.
 * See README.ccs for ChangeLog.
 *
 */

#include <linux/ccs_common.h>
#include <linux/sakura.h>
#include <linux/realpath.h>
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 5, 0)
#include <linux/namei.h>
#else
#include <linux/fs.h>
#endif

/* The list for "struct ccs_pivot_root_entry". */
LIST_HEAD(ccs_pivot_root_list);

/**
 * ccs_update_pivot_root_acl - Update "struct ccs_pivot_root_entry" list.
 *
 * @old_root:  The name of old root directory.
 * @new_root:  The name of new root directory.
 * @is_delete: True if it is a delete request.
 *
 * Returns 0 on success, negative value otherwise.
 */
static int ccs_update_pivot_root_acl(const char *old_root, const char *new_root,
                                     const bool is_delete)
{
        struct ccs_pivot_root_entry *entry = NULL;
        struct ccs_pivot_root_entry *ptr;
        const struct ccs_path_info *saved_old_root;
        const struct ccs_path_info *saved_new_root;
        int error = is_delete ? -ENOENT : -ENOMEM;
        if (!ccs_is_correct_path(old_root, 1, 0, 1) ||
            !ccs_is_correct_path(new_root, 1, 0, 1))
                return -EINVAL;
        saved_old_root = ccs_get_name(old_root);
        saved_new_root = ccs_get_name(new_root);
        if (!saved_old_root || !saved_new_root)
                goto out;
        if (!is_delete)
                entry = kzalloc(sizeof(*entry), GFP_KERNEL);
        mutex_lock(&ccs_policy_lock);
        list_for_each_entry_rcu(ptr, &ccs_pivot_root_list, list) {
                if (ptr->old_root != saved_old_root ||
                    ptr->new_root != saved_new_root)
                        continue;
                ptr->is_deleted = is_delete;
                error = 0;
                break;
        }
        if (!is_delete && error && ccs_memory_ok(entry)) {
                entry->old_root = saved_old_root;
                saved_old_root = NULL;
                entry->new_root = saved_new_root;
                saved_new_root = NULL;
                list_add_tail_rcu(&entry->list, &ccs_pivot_root_list);
                entry = NULL;
                error = 0;
        }
        mutex_unlock(&ccs_policy_lock);
        if (!is_delete && !error)
                printk(KERN_CONT "%sAllow pivot_root(%s, %s)\n", ccs_log_level,
                       new_root, old_root);
 out:
        ccs_put_name(saved_old_root);
        ccs_put_name(saved_new_root);
        kfree(entry);
        ccs_update_counter(CCS_UPDATES_COUNTER_SYSTEM_POLICY);
        return error;
}

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 27)
#define PATH_or_NAMEIDATA path
#else
#define PATH_or_NAMEIDATA nameidata
#endif
/**
 * ccs_check_pivot_root_permission - Check permission for pivot_root().
 *
 * @old_path: Pointer to "struct path" (for 2.6.27 and later).
 *            Pointer to "struct nameidata" (for 2.6.26 and earlier).
 * @new_path: Pointer to "struct path" (for 2.6.27 and later).
 *            Pointer to "struct nameidata" (for 2.6.26 and earlier).
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds srcu_read_lock(&ccs_ss).
 */
int ccs_check_pivot_root_permission(struct PATH_or_NAMEIDATA *old_path,
                                    struct PATH_or_NAMEIDATA *new_path)
{
        struct ccs_request_info r;
        int error;
        char *old_root;
        char *new_root;
        if (!ccs_can_sleep())
                return 0;
        ccs_init_request_info(&r, NULL, CCS_RESTRICT_PIVOT_ROOT);
        if (!r.mode) {
                error = 0;
                goto done;
        }
 retry:
        error = -EPERM;
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 25) && LINUX_VERSION_CODE <= KERNEL_VERSION(2, 6, 26)
        old_root = ccs_realpath_from_dentry(old_path->path.dentry,
                                            old_path->path.mnt);
        new_root = ccs_realpath_from_dentry(new_path->path.dentry,
                                            new_path->path.mnt);
#else
        old_root = ccs_realpath_from_dentry(old_path->dentry, old_path->mnt);
        new_root = ccs_realpath_from_dentry(new_path->dentry, new_path->mnt);
#endif
        if (old_root && new_root) {
                struct ccs_path_info old_root_dir;
                struct ccs_path_info new_root_dir;
                old_root_dir.name = old_root;
                ccs_fill_path_info(&old_root_dir);
                new_root_dir.name = new_root;
                ccs_fill_path_info(&new_root_dir);
                if (old_root_dir.is_dir && new_root_dir.is_dir) {
                        struct ccs_pivot_root_entry *ptr;
                        list_for_each_entry_rcu(ptr, &ccs_pivot_root_list,
                                                list) {
                                if (ptr->is_deleted)
                                        continue;
                                if (!ccs_path_matches_pattern(&old_root_dir,
                                                              ptr->old_root) ||
                                    !ccs_path_matches_pattern(&new_root_dir,
                                                              ptr->new_root))
                                        continue;
                                error = 0;
                                break;
                        }
                }
        }
        if (error) {
                const bool is_enforce = (r.mode == 3);
                const char *exename = ccs_get_exe();
                printk(KERN_WARNING "SAKURA-%s: pivot_root %s %s "
                       "(pid=%d:exe=%s): Permission denied.\n",
                       ccs_get_msg(is_enforce), new_root, old_root,
                       (pid_t) sys_getpid(), exename);
                if (is_enforce)
                        error = ccs_check_supervisor(&r, "# %s is requesting\n"
                                                     "pivot_root %s %s\n",
                                                     exename, new_root,
                                                     old_root);
                else
                        error = 0;
                if (exename)
                        ccs_free(exename);
                if (r.mode == 1 && old_root && new_root)
                        ccs_update_pivot_root_acl(old_root, new_root, false);
        }
        ccs_free(old_root);
        ccs_free(new_root);
        if (error == 1)
                goto retry;
 done:
        ccs_exit_request_info(&r);
        return error;
}

/**
 * ccs_write_pivot_root_policy - Write "struct ccs_pivot_root_entry" list.
 *
 * @data:      String to parse.
 * @is_delete: True if it is a delete request.
 *
 * Returns 0 on success, negative value otherwise.
 */
int ccs_write_pivot_root_policy(char *data, const bool is_delete)
{
        char *cp = strchr(data, ' ');
        if (!cp)
                return -EINVAL;
        *cp++ = '\0';
        return ccs_update_pivot_root_acl(cp, data, is_delete);
}

/**
 * ccs_read_pivot_root_policy - Read "struct ccs_pivot_root_entry" list.
 *
 * @head: Pointer to "struct ccs_io_buffer".
 *
 * Returns true on success, false otherwise.
 *
 * Caller holds srcu_read_lock(&ccs_ss).
 */
bool ccs_read_pivot_root_policy(struct ccs_io_buffer *head)
{
        struct list_head *pos;
        bool done = true;
        list_for_each_cookie(pos, head->read_var2, &ccs_pivot_root_list) {
                struct ccs_pivot_root_entry *ptr;
                ptr = list_entry(pos, struct ccs_pivot_root_entry, list);
                if (ptr->is_deleted)
                        continue;
                done = ccs_io_printf(head, KEYWORD_ALLOW_PIVOT_ROOT "%s %s\n",
                                     ptr->new_root->name, ptr->old_root->name);
                if (!done)
                        break;
        }
        return done;
}