security/ccsecurity/chroot.c

/*
 * security/ccsecurity/chroot.c
 *
 * Copyright (C) 2005-2009  NTT DATA CORPORATION
 *
 * Version: 1.7.0-rc   2009/09/01
 *
 * This file is applicable to both 2.4.30 and 2.6.11 and later.
 * See README.ccs for ChangeLog.
 *
 */

#include <linux/version.h>
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 5, 0)
#include <linux/dcache.h>
#include <linux/namei.h>
#else
#include <linux/fs.h>
#endif
#include "internal.h"

/**
 * ccs_audit_chroot_log - Audit chroot log.
 *
 * @r:          Pointer to "struct ccs_request_info".
 * @root:       New root directory.
 * @is_granted: True if this is a granted log.
 *
 * Returns 0 on success, negative value otherwise.
 */
static int ccs_audit_chroot_log(struct ccs_request_info *r,
                                const char *root, const bool is_granted)
{
        if (!is_granted)
                ccs_warn_log(r, "chroot %s", root);
        return ccs_write_audit_log(is_granted, r, CCS_KEYWORD_ALLOW_CHROOT
                                   "%s\n", root);
}

/**
 * ccs_chroot_acl - Check permission for chroot().
 *
 * @path: Pointer to "struct path".
 *
 * Returns 0 on success, negative value otherwise.
 *
 * Caller holds ccs_read_lock().
 */
static int ccs_chroot_acl(struct path *path)
{
        struct ccs_request_info r;
        int error;
        struct ccs_path_info dir;
        char *root_name;
        struct ccs_obj_info obj = {
                .path1 = *path
        };
        if (ccs_init_request_info(&r, NULL, CCS_MAC_FILE_CHROOT)
            == CCS_CONFIG_DISABLED)
                return 0;
        r.obj = &obj;
        error = -ENOMEM;
        root_name = ccs_realpath_from_path(path);
        if (!root_name)
                goto out;
        dir.name = root_name;
        ccs_fill_path_info(&dir);
        if (!dir.is_dir)
                goto out;
        do {
                struct ccs_acl_info *ptr;
                error = -EPERM;
                list_for_each_entry_rcu(ptr, &r.domain->acl_info_list, list) {
                        struct ccs_chroot_acl *acl;
                        if (ptr->is_deleted ||
                            ptr->type != CCS_TYPE_CHROOT_ACL)
                                continue;
                        acl = container_of(ptr, struct ccs_chroot_acl,
                                           head);
                        if (!ccs_compare_name_union(&dir, &acl->dir) ||
                            !ccs_condition(&r, ptr))
                                continue;
                        r.cond = ptr->cond;
                        error = 0;
                        break;
                }
                ccs_audit_chroot_log(&r, root_name, !error);
                if (!error)
                        break;
                error = ccs_supervisor(&r, CCS_KEYWORD_ALLOW_CHROOT
                                       "%s\n", ccs_file_pattern(&dir));
        } while (error == 1);
 out:
        kfree(root_name);
        if (r.mode != CCS_CONFIG_ENFORCING)
                error = 0;
        return error;
}

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 27)
#define PATH_or_NAMEIDATA path
#else
#define PATH_or_NAMEIDATA nameidata
#endif

/**
 * ccs_chroot_permission - Check permission for chroot().
 *
 * @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.
 */
int ccs_chroot_permission(struct PATH_or_NAMEIDATA *path)
{
#if LINUX_VERSION_CODE == KERNEL_VERSION(2, 6, 25) || LINUX_VERSION_CODE == KERNEL_VERSION(2, 6, 26)
        struct path tmp_path = { path->path.mnt, path->path.dentry };
#else
        struct path tmp_path = { path->mnt, path->dentry };
#endif
        const int idx = ccs_read_lock();
        const int error = ccs_chroot_acl(&tmp_path);
        ccs_read_unlock(idx);
        return error;
}

/**
 * ccs_write_chroot_policy - Write "struct ccs_chroot_acl" list.
 *
 * @data:      String to parse.
 * @domain:    Pointer to "struct ccs_domain_info".
 * @condition: Pointer to "struct ccs_condition". May be NULL.
 * @is_delete: True if it is a delete request.
 *
 * Returns 0 on success, negative value otherwise.
 */
int ccs_write_chroot_policy(char *data, struct ccs_domain_info *domain,
                            struct ccs_condition *condition,
                            const bool is_delete)
{
        struct ccs_chroot_acl *entry = NULL;
        struct ccs_acl_info *ptr;
        struct ccs_chroot_acl e = {
                .head.type = CCS_TYPE_CHROOT_ACL,
                .head.cond = condition
        };
        int error = is_delete ? -ENOENT : -ENOMEM;
        if (data[0] != '@' && !ccs_is_correct_path(data, 1, 0, 1))
                return -EINVAL;
        if (!ccs_parse_name_union(data, &e.dir))
                return error;
        if (!is_delete)
                entry = kmalloc(sizeof(e), GFP_KERNEL);
        mutex_lock(&ccs_policy_lock);
        list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) {
                struct ccs_chroot_acl *acl =
                        container_of(ptr, struct ccs_chroot_acl, head);
                if (ptr->type != CCS_TYPE_CHROOT_ACL || ptr->cond != condition
                    || memcmp(&acl->dir, &e.dir, sizeof(e.dir)))
                        continue;
                ptr->is_deleted = is_delete;
                error = 0;
                break;
        }
        if (!is_delete && error && ccs_commit_ok(entry, &e, sizeof(e))) {
                ccs_add_domain_acl(domain, &entry->head);
                entry = NULL;
                error = 0;
        }
        mutex_unlock(&ccs_policy_lock);
        ccs_put_name_union(&e.dir);
        kfree(entry);
        return error;
}