linux/security/apparmor/resource.c
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   1/*
   2 * AppArmor security module
   3 *
   4 * This file contains AppArmor resource mediation and attachment
   5 *
   6 * Copyright (C) 1998-2008 Novell/SUSE
   7 * Copyright 2009-2010 Canonical Ltd.
   8 *
   9 * This program is free software; you can redistribute it and/or
  10 * modify it under the terms of the GNU General Public License as
  11 * published by the Free Software Foundation, version 2 of the
  12 * License.
  13 */
  14
  15#include <linux/audit.h>
  16
  17#include "include/audit.h"
  18#include "include/resource.h"
  19#include "include/policy.h"
  20
  21/*
  22 * Table of rlimit names: we generate it from resource.h.
  23 */
  24#include "rlim_names.h"
  25
  26struct aa_fs_entry aa_fs_entry_rlimit[] = {
  27        AA_FS_FILE_STRING("mask", AA_FS_RLIMIT_MASK),
  28        { }
  29};
  30
  31/* audit callback for resource specific fields */
  32static void audit_cb(struct audit_buffer *ab, void *va)
  33{
  34        struct common_audit_data *sa = va;
  35
  36        audit_log_format(ab, " rlimit=%s value=%lu",
  37                         rlim_names[sa->aad->rlim.rlim], sa->aad->rlim.max);
  38}
  39
  40/**
  41 * audit_resource - audit setting resource limit
  42 * @profile: profile being enforced  (NOT NULL)
  43 * @resoure: rlimit being auditing
  44 * @value: value being set
  45 * @error: error value
  46 *
  47 * Returns: 0 or sa->error else other error code on failure
  48 */
  49static int audit_resource(struct aa_profile *profile, unsigned int resource,
  50                          unsigned long value, int error)
  51{
  52        struct common_audit_data sa;
  53        struct apparmor_audit_data aad = {0,};
  54
  55        sa.type = LSM_AUDIT_DATA_NONE;
  56        sa.aad = &aad;
  57        aad.op = OP_SETRLIMIT,
  58        aad.rlim.rlim = resource;
  59        aad.rlim.max = value;
  60        aad.error = error;
  61        return aa_audit(AUDIT_APPARMOR_AUTO, profile, GFP_KERNEL, &sa,
  62                        audit_cb);
  63}
  64
  65/**
  66 * aa_map_resouce - map compiled policy resource to internal #
  67 * @resource: flattened policy resource number
  68 *
  69 * Returns: resource # for the current architecture.
  70 *
  71 * rlimit resource can vary based on architecture, map the compiled policy
  72 * resource # to the internal representation for the architecture.
  73 */
  74int aa_map_resource(int resource)
  75{
  76        return rlim_map[resource];
  77}
  78
  79/**
  80 * aa_task_setrlimit - test permission to set an rlimit
  81 * @profile - profile confining the task  (NOT NULL)
  82 * @task - task the resource is being set on
  83 * @resource - the resource being set
  84 * @new_rlim - the new resource limit  (NOT NULL)
  85 *
  86 * Control raising the processes hard limit.
  87 *
  88 * Returns: 0 or error code if setting resource failed
  89 */
  90int aa_task_setrlimit(struct aa_profile *profile, struct task_struct *task,
  91                      unsigned int resource, struct rlimit *new_rlim)
  92{
  93        int error = 0;
  94
  95        /* TODO: extend resource control to handle other (non current)
  96         * processes.  AppArmor rules currently have the implicit assumption
  97         * that the task is setting the resource of the current process
  98         */
  99        if ((task != current->group_leader) ||
 100            (profile->rlimits.mask & (1 << resource) &&
 101             new_rlim->rlim_max > profile->rlimits.limits[resource].rlim_max))
 102                error = -EACCES;
 103
 104        return audit_resource(profile, resource, new_rlim->rlim_max, error);
 105}
 106
 107/**
 108 * __aa_transition_rlimits - apply new profile rlimits
 109 * @old: old profile on task  (NOT NULL)
 110 * @new: new profile with rlimits to apply  (NOT NULL)
 111 */
 112void __aa_transition_rlimits(struct aa_profile *old, struct aa_profile *new)
 113{
 114        unsigned int mask = 0;
 115        struct rlimit *rlim, *initrlim;
 116        int i;
 117
 118        /* for any rlimits the profile controlled reset the soft limit
 119         * to the less of the tasks hard limit and the init tasks soft limit
 120         */
 121        if (old->rlimits.mask) {
 122                for (i = 0, mask = 1; i < RLIM_NLIMITS; i++, mask <<= 1) {
 123                        if (old->rlimits.mask & mask) {
 124                                rlim = current->signal->rlim + i;
 125                                initrlim = init_task.signal->rlim + i;
 126                                rlim->rlim_cur = min(rlim->rlim_max,
 127                                                     initrlim->rlim_cur);
 128                        }
 129                }
 130        }
 131
 132        /* set any new hard limits as dictated by the new profile */
 133        if (!new->rlimits.mask)
 134                return;
 135        for (i = 0, mask = 1; i < RLIM_NLIMITS; i++, mask <<= 1) {
 136                if (!(new->rlimits.mask & mask))
 137                        continue;
 138
 139                rlim = current->signal->rlim + i;
 140                rlim->rlim_max = min(rlim->rlim_max,
 141                                     new->rlimits.limits[i].rlim_max);
 142                /* soft limit should not exceed hard limit */
 143                rlim->rlim_cur = min(rlim->rlim_cur, rlim->rlim_max);
 144        }
 145}
 146
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