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/context.h"
  19 #include "include/resource.h"
  20 #include "include/policy.h"
  21
  22 /*
  23  * Table of rlimit names: we generate it from resource.h.
  24  */
  25 #include "rlim_names.h"
  26
  27 struct aa_fs_entry aa_fs_entry_rlimit[] = {
  28         AA_FS_FILE_STRING("mask", AA_FS_RLIMIT_MASK),
  29         { }
  30 };
  31
  32 /* audit callback for resource specific fields */
  33 static void audit_cb(struct audit_buffer *ab, void *va)
  34 {
  35         struct common_audit_data *sa = va;
  36
  37         audit_log_format(ab, " rlimit=%s value=%lu",
  38                          rlim_names[aad(sa)->rlim.rlim], aad(sa)->rlim.max);
  39 }
  40
  41 /**
  42  * audit_resource - audit setting resource limit
  43  * @profile: profile being enforced  (NOT NULL)
  44  * @resoure: rlimit being auditing
  45  * @value: value being set
  46  * @error: error value
  47  *
  48  * Returns: 0 or sa->error else other error code on failure
  49  */
  50 static int audit_resource(struct aa_profile *profile, unsigned int resource,
  51                           unsigned long value, int error)
  52 {
  53         DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_SETRLIMIT);
  54
  55         aad(&sa)->rlim.rlim = resource;
  56         aad(&sa)->rlim.max = value;
  57         aad(&sa)->error = error;
  58         return aa_audit(AUDIT_APPARMOR_AUTO, profile, &sa, audit_cb);
  59 }
  60
  61 /**
  62  * aa_map_resouce - map compiled policy resource to internal #
  63  * @resource: flattened policy resource number
  64  *
  65  * Returns: resource # for the current architecture.
  66  *
  67  * rlimit resource can vary based on architecture, map the compiled policy
  68  * resource # to the internal representation for the architecture.
  69  */
  70 int aa_map_resource(int resource)
  71 {
  72         return rlim_map[resource];
  73 }
  74
  75 /**
  76  * aa_task_setrlimit - test permission to set an rlimit
  77  * @profile - profile confining the task  (NOT NULL)
  78  * @task - task the resource is being set on
  79  * @resource - the resource being set
  80  * @new_rlim - the new resource limit  (NOT NULL)
  81  *
  82  * Control raising the processes hard limit.
  83  *
  84  * Returns: 0 or error code if setting resource failed
  85  */
  86 int aa_task_setrlimit(struct aa_profile *profile, struct task_struct *task,
  87                       unsigned int resource, struct rlimit *new_rlim)
  88 {
  89         struct aa_profile *task_profile;
  90         int error = 0;
  91
  92         rcu_read_lock();
  93         task_profile = aa_get_profile(aa_cred_profile(__task_cred(task)));
  94         rcu_read_unlock();
  95
  96         /* TODO: extend resource control to handle other (non current)
  97          * profiles.  AppArmor rules currently have the implicit assumption
  98          * that the task is setting the resource of a task confined with
  99          * the same profile or that the task setting the resource of another
 100          * task has CAP_SYS_RESOURCE.
 101          */
 102         if ((profile != task_profile &&
 103              aa_capable(profile, CAP_SYS_RESOURCE, 1)) ||
 104             (profile->rlimits.mask & (1 << resource) &&
 105              new_rlim->rlim_max > profile->rlimits.limits[resource].rlim_max))
 106                 error = -EACCES;
 107
 108         aa_put_profile(task_profile);
 109
 110         return audit_resource(profile, resource, new_rlim->rlim_max, error);
 111 }
 112
 113 /**
 114  * __aa_transition_rlimits - apply new profile rlimits
 115  * @old: old profile on task  (NOT NULL)
 116  * @new: new profile with rlimits to apply  (NOT NULL)
 117  */
 118 void __aa_transition_rlimits(struct aa_profile *old, struct aa_profile *new)
 119 {
 120         unsigned int mask = 0;
 121         struct rlimit *rlim, *initrlim;
 122         int i;
 123
 124         /* for any rlimits the profile controlled reset the soft limit
 125          * to the less of the tasks hard limit and the init tasks soft limit
 126          */
 127         if (old->rlimits.mask) {
 128                 for (i = 0, mask = 1; i < RLIM_NLIMITS; i++, mask <<= 1) {
 129                         if (old->rlimits.mask & mask) {
 130                                 rlim = current->signal->rlim + i;
 131                                 initrlim = init_task.signal->rlim + i;
 132                                 rlim->rlim_cur = min(rlim->rlim_max,
 133                                                      initrlim->rlim_cur);
 134                         }
 135                 }
 136         }
 137
 138         /* set any new hard limits as dictated by the new profile */
 139         if (!new->rlimits.mask)
 140                 return;
 141         for (i = 0, mask = 1; i < RLIM_NLIMITS; i++, mask <<= 1) {
 142                 if (!(new->rlimits.mask & mask))
 143                         continue;
 144
 145                 rlim = current->signal->rlim + i;
 146                 rlim->rlim_max = min(rlim->rlim_max,
 147                                      new->rlimits.limits[i].rlim_max);
 148                 /* soft limit should not exceed hard limit */
 149                 rlim->rlim_cur = min(rlim->rlim_cur, rlim->rlim_max);
 150         }
 151 }