1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * AppArmor security module 4 * 5 * This file contains AppArmor capability mediation functions 6 * 7 * Copyright (C) 1998-2008 Novell/SUSE 8 * Copyright 2009-2010 Canonical Ltd. 9 */ 10 11 #include <linux/capability.h> 12 #include <linux/errno.h> 13 #include <linux/gfp.h> 14 #include <linux/security.h> 15 #include <linux/timekeeping.h> 16 17 #include "include/apparmor.h" 18 #include "include/capability.h" 19 #include "include/cred.h" 20 #include "include/policy.h" 21 #include "include/audit.h" 22 23 /* 24 * Table of capability names: we generate it from capabilities.h. 25 */ 26 #include "capability_names.h" 27 28 struct aa_sfs_entry aa_sfs_entry_caps[] = { 29 AA_SFS_FILE_STRING("mask", AA_SFS_CAPS_MASK), 30 { } 31 }; 32 33 struct audit_cache { 34 const struct cred *ad_subj_cred; 35 /* Capabilities go from 0 to CAP_LAST_CAP */ 36 u64 ktime_ns_expiration[CAP_LAST_CAP+1]; 37 }; 38 39 static DEFINE_PER_CPU(struct audit_cache, audit_cache); 40 41 /** 42 * audit_cb - call back for capability components of audit struct 43 * @ab: audit buffer (NOT NULL) 44 * @va: audit struct to audit data from (NOT NULL) 45 */ 46 static void audit_cb(struct audit_buffer *ab, void *va) 47 { 48 struct common_audit_data *sa = va; 49 50 audit_log_format(ab, " capname="); 51 audit_log_untrustedstring(ab, capability_names[sa->u.cap]); 52 } 53 54 /** 55 * audit_caps - audit a capability 56 * @ad: audit data 57 * @profile: profile being tested for confinement (NOT NULL) 58 * @cap: capability tested 59 * @error: error code returned by test 60 * 61 * Do auditing of capability and handle, audit/complain/kill modes switching 62 * and duplicate message elimination. 63 * 64 * Returns: 0 or ad->error on success, error code on failure 65 */ 66 static int audit_caps(struct apparmor_audit_data *ad, struct aa_profile *profile, 67 int cap, int error) 68 { 69 const u64 AUDIT_CACHE_TIMEOUT_NS = 1000*1000*1000; /* 1 second */ 70 71 struct aa_ruleset *rules = list_first_entry(&profile->rules, 72 typeof(*rules), list); 73 struct audit_cache *ent; 74 int type = AUDIT_APPARMOR_AUTO; 75 76 ad->error = error; 77 78 if (likely(!error)) { 79 /* test if auditing is being forced */ 80 if (likely((AUDIT_MODE(profile) != AUDIT_ALL) && 81 !cap_raised(rules->caps.audit, cap))) 82 return 0; 83 type = AUDIT_APPARMOR_AUDIT; 84 } else if (KILL_MODE(profile) || 85 cap_raised(rules->caps.kill, cap)) { 86 type = AUDIT_APPARMOR_KILL; 87 } else if (cap_raised(rules->caps.quiet, cap) && 88 AUDIT_MODE(profile) != AUDIT_NOQUIET && 89 AUDIT_MODE(profile) != AUDIT_ALL) { 90 /* quiet auditing */ 91 return error; 92 } 93 94 /* Do simple duplicate message elimination */ 95 ent = &get_cpu_var(audit_cache); 96 /* If the capability was never raised the timestamp check would also catch that */ 97 if (ad->subj_cred == ent->ad_subj_cred && ktime_get_ns() <= ent->ktime_ns_expiration[cap]) { 98 put_cpu_var(audit_cache); 99 if (COMPLAIN_MODE(profile)) 100 return complain_error(error); 101 return error; 102 } else { 103 put_cred(ent->ad_subj_cred); 104 ent->ad_subj_cred = get_cred(ad->subj_cred); 105 ent->ktime_ns_expiration[cap] = ktime_get_ns() + AUDIT_CACHE_TIMEOUT_NS; 106 } 107 put_cpu_var(audit_cache); 108 109 return aa_audit(type, profile, ad, audit_cb); 110 } 111 112 /** 113 * profile_capable - test if profile allows use of capability @cap 114 * @profile: profile being enforced (NOT NULL, NOT unconfined) 115 * @cap: capability to test if allowed 116 * @opts: CAP_OPT_NOAUDIT bit determines whether audit record is generated 117 * @ad: audit data (NOT NULL) 118 * 119 * Returns: 0 if allowed else -EPERM 120 */ 121 static int profile_capable(struct aa_profile *profile, int cap, 122 unsigned int opts, struct apparmor_audit_data *ad) 123 { 124 struct aa_ruleset *rules = list_first_entry(&profile->rules, 125 typeof(*rules), list); 126 int error; 127 128 if (cap_raised(rules->caps.allow, cap) && 129 !cap_raised(rules->caps.denied, cap)) 130 error = 0; 131 else 132 error = -EPERM; 133 134 if (opts & CAP_OPT_NOAUDIT) { 135 if (!COMPLAIN_MODE(profile)) 136 return error; 137 /* audit the cap request in complain mode but note that it 138 * should be optional. 139 */ 140 ad->info = "optional: no audit"; 141 } 142 143 return audit_caps(ad, profile, cap, error); 144 } 145 146 /** 147 * aa_capable - test permission to use capability 148 * @subj_cred: cred we are testing capability against 149 * @label: label being tested for capability (NOT NULL) 150 * @cap: capability to be tested 151 * @opts: CAP_OPT_NOAUDIT bit determines whether audit record is generated 152 * 153 * Look up capability in profile capability set. 154 * 155 * Returns: 0 on success, or else an error code. 156 */ 157 int aa_capable(const struct cred *subj_cred, struct aa_label *label, 158 int cap, unsigned int opts) 159 { 160 struct aa_profile *profile; 161 int error = 0; 162 DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_CAP, AA_CLASS_CAP, OP_CAPABLE); 163 164 ad.subj_cred = subj_cred; 165 ad.common.u.cap = cap; 166 error = fn_for_each_confined(label, profile, 167 profile_capable(profile, cap, opts, &ad)); 168 169 return error; 170 } 171