security/apparmor/resource.c

   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
  26 struct 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 */
  32 static 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  */
  49 static 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  */
  74 int 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  */
  90 int 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  */
 112 void __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 }