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 /* audit callback for resource specific fields */
  27 static void audit_cb(struct audit_buffer *ab, void *va)
  28 {
  29         struct common_audit_data *sa = va;
  30
  31         audit_log_format(ab, " rlimit=%s value=%lu",
  32                          rlim_names[sa->aad.rlim.rlim], sa->aad.rlim.max);
  33 }
  34
  35 /**
  36  * audit_resource - audit setting resource limit
  37  * @profile: profile being enforced  (NOT NULL)
  38  * @resoure: rlimit being auditing
  39  * @value: value being set
  40  * @error: error value
  41  *
  42  * Returns: 0 or sa->error else other error code on failure
  43  */
  44 static int audit_resource(struct aa_profile *profile, unsigned int resource,
  45                           unsigned long value, int error)
  46 {
  47         struct common_audit_data sa;
  48
  49         COMMON_AUDIT_DATA_INIT(&sa, NONE);
  50         sa.aad.op = OP_SETRLIMIT,
  51         sa.aad.rlim.rlim = resource;
  52         sa.aad.rlim.max = value;
  53         sa.aad.error = error;
  54         return aa_audit(AUDIT_APPARMOR_AUTO, profile, GFP_KERNEL, &sa,
  55                         audit_cb);
  56 }
  57
  58 /**
  59  * aa_map_resouce - map compiled policy resource to internal #
  60  * @resource: flattened policy resource number
  61  *
  62  * Returns: resource # for the current architecture.
  63  *
  64  * rlimit resource can vary based on architecture, map the compiled policy
  65  * resource # to the internal representation for the architecture.
  66  */
  67 int aa_map_resource(int resource)
  68 {
  69         return rlim_map[resource];
  70 }
  71
  72 /**
  73  * aa_task_setrlimit - test permission to set an rlimit
  74  * @profile - profile confining the task  (NOT NULL)
  75  * @task - task the resource is being set on
  76  * @resource - the resource being set
  77  * @new_rlim - the new resource limit  (NOT NULL)
  78  *
  79  * Control raising the processes hard limit.
  80  *
  81  * Returns: 0 or error code if setting resource failed
  82  */
  83 int aa_task_setrlimit(struct aa_profile *profile, struct task_struct *task,
  84                       unsigned int resource, struct rlimit *new_rlim)
  85 {
  86         int error = 0;
  87
  88         /* TODO: extend resource control to handle other (non current)
  89          * processes.  AppArmor rules currently have the implicit assumption
  90          * that the task is setting the resource of the current process
  91          */
  92         if ((task != current->group_leader) ||
  93             (profile->rlimits.mask & (1 << resource) &&
  94              new_rlim->rlim_max > profile->rlimits.limits[resource].rlim_max))
  95                 error = -EACCES;
  96
  97         return audit_resource(profile, resource, new_rlim->rlim_max, error);
  98 }
  99
 100 /**
 101  * __aa_transition_rlimits - apply new profile rlimits
 102  * @old: old profile on task  (NOT NULL)
 103  * @new: new profile with rlimits to apply  (NOT NULL)
 104  */
 105 void __aa_transition_rlimits(struct aa_profile *old, struct aa_profile *new)
 106 {
 107         unsigned int mask = 0;
 108         struct rlimit *rlim, *initrlim;
 109         int i;
 110
 111         /* for any rlimits the profile controlled reset the soft limit
 112          * to the less of the tasks hard limit and the init tasks soft limit
 113          */
 114         if (old->rlimits.mask) {
 115                 for (i = 0, mask = 1; i < RLIM_NLIMITS; i++, mask <<= 1) {
 116                         if (old->rlimits.mask & mask) {
 117                                 rlim = current->signal->rlim + i;
 118                                 initrlim = init_task.signal->rlim + i;
 119                                 rlim->rlim_cur = min(rlim->rlim_max,
 120                                                      initrlim->rlim_cur);
 121                         }
 122                 }
 123         }
 124
 125         /* set any new hard limits as dictated by the new profile */
 126         if (!new->rlimits.mask)
 127                 return;
 128         for (i = 0, mask = 1; i < RLIM_NLIMITS; i++, mask <<= 1) {
 129                 if (!(new->rlimits.mask & mask))
 130                         continue;
 131
 132                 rlim = current->signal->rlim + i;
 133                 rlim->rlim_max = min(rlim->rlim_max,
 134                                      new->rlimits.limits[i].rlim_max);
 135                 /* soft limit should not exceed hard limit */
 136                 rlim->rlim_cur = min(rlim->rlim_cur, rlim->rlim_max);
 137         }
 138 }