security/apparmor/resource.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * AppArmor security module
   4  *
   5  * This file contains AppArmor resource mediation and attachment
   6  *
   7  * Copyright (C) 1998-2008 Novell/SUSE
   8  * Copyright 2009-2010 Canonical Ltd.
   9  */
  10
  11 #include <linux/audit.h>
  12 #include <linux/security.h>
  13
  14 #include "include/audit.h"
  15 #include "include/cred.h"
  16 #include "include/resource.h"
  17 #include "include/policy.h"
  18
  19 /*
  20  * Table of rlimit names: we generate it from resource.h.
  21  */
  22 #include "rlim_names.h"
  23
  24 struct aa_sfs_entry aa_sfs_entry_rlimit[] = {
  25         AA_SFS_FILE_STRING("mask", AA_SFS_RLIMIT_MASK),
  26         { }
  27 };
  28
  29 /* audit callback for resource specific fields */
  30 static void audit_cb(struct audit_buffer *ab, void *va)
  31 {
  32         struct common_audit_data *sa = va;
  33         struct apparmor_audit_data *ad = aad(sa);
  34
  35         audit_log_format(ab, " rlimit=%s value=%lu",
  36                          rlim_names[ad->rlim.rlim], ad->rlim.max);
  37         if (ad->peer) {
  38                 audit_log_format(ab, " peer=");
  39                 aa_label_xaudit(ab, labels_ns(ad->subj_label), ad->peer,
  40                                 FLAGS_NONE, GFP_ATOMIC);
  41         }
  42 }
  43
  44 /**
  45  * audit_resource - audit setting resource limit
  46  * @subj_cred: cred setting the resource
  47  * @profile: profile being enforced  (NOT NULL)
  48  * @resource: rlimit being auditing
  49  * @value: value being set
  50  * @peer: aa_albel of the task being set
  51  * @info: info being auditing
  52  * @error: error value
  53  *
  54  * Returns: 0 or ad->error else other error code on failure
  55  */
  56 static int audit_resource(const struct cred *subj_cred,
  57                           struct aa_profile *profile, unsigned int resource,
  58                           unsigned long value, struct aa_label *peer,
  59                           const char *info, int error)
  60 {
  61         DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_NONE, AA_CLASS_RLIMITS,
  62                           OP_SETRLIMIT);
  63
  64         ad.subj_cred = subj_cred;
  65         ad.rlim.rlim = resource;
  66         ad.rlim.max = value;
  67         ad.peer = peer;
  68         ad.info = info;
  69         ad.error = error;
  70
  71         return aa_audit(AUDIT_APPARMOR_AUTO, profile, &ad, audit_cb);
  72 }
  73
  74 /**
  75  * aa_map_resource - map compiled policy resource to internal #
  76  * @resource: flattened policy resource number
  77  *
  78  * Returns: resource # for the current architecture.
  79  *
  80  * rlimit resource can vary based on architecture, map the compiled policy
  81  * resource # to the internal representation for the architecture.
  82  */
  83 int aa_map_resource(int resource)
  84 {
  85         return rlim_map[resource];
  86 }
  87
  88 static int profile_setrlimit(const struct cred *subj_cred,
  89                              struct aa_profile *profile, unsigned int resource,
  90                              struct rlimit *new_rlim)
  91 {
  92         struct aa_ruleset *rules = list_first_entry(&profile->rules,
  93                                                     typeof(*rules), list);
  94         int e = 0;
  95
  96         if (rules->rlimits.mask & (1 << resource) && new_rlim->rlim_max >
  97             rules->rlimits.limits[resource].rlim_max)
  98                 e = -EACCES;
  99         return audit_resource(subj_cred, profile, resource, new_rlim->rlim_max,
 100                               NULL, NULL, e);
 101 }
 102
 103 /**
 104  * aa_task_setrlimit - test permission to set an rlimit
 105  * @subj_cred: cred setting the limit
 106  * @label: label confining the task  (NOT NULL)
 107  * @task: task the resource is being set on
 108  * @resource: the resource being set
 109  * @new_rlim: the new resource limit  (NOT NULL)
 110  *
 111  * Control raising the processes hard limit.
 112  *
 113  * Returns: 0 or error code if setting resource failed
 114  */
 115 int aa_task_setrlimit(const struct cred *subj_cred, struct aa_label *label,
 116                       struct task_struct *task,
 117                       unsigned int resource, struct rlimit *new_rlim)
 118 {
 119         struct aa_profile *profile;
 120         struct aa_label *peer;
 121         int error = 0;
 122
 123         rcu_read_lock();
 124         peer = aa_get_newest_cred_label(__task_cred(task));
 125         rcu_read_unlock();
 126
 127         /* TODO: extend resource control to handle other (non current)
 128          * profiles.  AppArmor rules currently have the implicit assumption
 129          * that the task is setting the resource of a task confined with
 130          * the same profile or that the task setting the resource of another
 131          * task has CAP_SYS_RESOURCE.
 132          */
 133
 134         if (label != peer &&
 135             aa_capable(subj_cred, label, CAP_SYS_RESOURCE, CAP_OPT_NOAUDIT) != 0)
 136                 error = fn_for_each(label, profile,
 137                                 audit_resource(subj_cred, profile, resource,
 138                                                new_rlim->rlim_max, peer,
 139                                                "cap_sys_resource", -EACCES));
 140         else
 141                 error = fn_for_each_confined(label, profile,
 142                                 profile_setrlimit(subj_cred, profile, resource,
 143                                                   new_rlim));
 144         aa_put_label(peer);
 145
 146         return error;
 147 }
 148
 149 /**
 150  * __aa_transition_rlimits - apply new profile rlimits
 151  * @old_l: old label on task  (NOT NULL)
 152  * @new_l: new label with rlimits to apply  (NOT NULL)
 153  */
 154 void __aa_transition_rlimits(struct aa_label *old_l, struct aa_label *new_l)
 155 {
 156         unsigned int mask = 0;
 157         struct rlimit *rlim, *initrlim;
 158         struct aa_profile *old, *new;
 159         struct label_it i;
 160
 161         old = labels_profile(old_l);
 162         new = labels_profile(new_l);
 163
 164         /* for any rlimits the profile controlled, reset the soft limit
 165          * to the lesser of the tasks hard limit and the init tasks soft limit
 166          */
 167         label_for_each_confined(i, old_l, old) {
 168                 struct aa_ruleset *rules = list_first_entry(&old->rules,
 169                                                             typeof(*rules),
 170                                                             list);
 171                 if (rules->rlimits.mask) {
 172                         int j;
 173
 174                         for (j = 0, mask = 1; j < RLIM_NLIMITS; j++,
 175                                      mask <<= 1) {
 176                                 if (rules->rlimits.mask & mask) {
 177                                         rlim = current->signal->rlim + j;
 178                                         initrlim = init_task.signal->rlim + j;
 179                                         rlim->rlim_cur = min(rlim->rlim_max,
 180                                                             initrlim->rlim_cur);
 181                                 }
 182                         }
 183                 }
 184         }
 185
 186         /* set any new hard limits as dictated by the new profile */
 187         label_for_each_confined(i, new_l, new) {
 188                 struct aa_ruleset *rules = list_first_entry(&new->rules,
 189                                                             typeof(*rules),
 190                                                             list);
 191                 int j;
 192
 193                 if (!rules->rlimits.mask)
 194                         continue;
 195                 for (j = 0, mask = 1; j < RLIM_NLIMITS; j++, mask <<= 1) {
 196                         if (!(rules->rlimits.mask & mask))
 197                                 continue;
 198
 199                         rlim = current->signal->rlim + j;
 200                         rlim->rlim_max = min(rlim->rlim_max,
 201                                              rules->rlimits.limits[j].rlim_max);
 202                         /* soft limit should not exceed hard limit */
 203                         rlim->rlim_cur = min(rlim->rlim_cur, rlim->rlim_max);
 204                 }
 205         }
 206 }