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 AA_SFS_FILE_BOOLEAN("extended", 1), 31 { } 32 }; 33 34 struct audit_cache { 35 const struct cred *ad_subj_cred; 36 /* Capabilities go from 0 to CAP_LAST_CAP */ 37 u64 ktime_ns_expiration[CAP_LAST_CAP+1]; 38 }; 39 40 static DEFINE_PER_CPU(struct audit_cache, audit_cache); 41 42 /** 43 * audit_cb - call back for capability components of audit struct 44 * @ab: audit buffer (NOT NULL) 45 * @va: audit struct to audit data from (NOT NULL) 46 */ 47 static void audit_cb(struct audit_buffer *ab, void *va) 48 { 49 struct common_audit_data *sa = va; 50 51 audit_log_format(ab, " capname="); 52 audit_log_untrustedstring(ab, capability_names[sa->u.cap]); 53 } 54 55 /** 56 * audit_caps - audit a capability 57 * @ad: audit data 58 * @profile: profile being tested for confinement (NOT NULL) 59 * @cap: capability tested 60 * @error: error code returned by test 61 * 62 * Do auditing of capability and handle, audit/complain/kill modes switching 63 * and duplicate message elimination. 64 * 65 * Returns: 0 or ad->error on success, error code on failure 66 */ 67 static int audit_caps(struct apparmor_audit_data *ad, struct aa_profile *profile, 68 int cap, int error) 69 { 70 const u64 AUDIT_CACHE_TIMEOUT_NS = 1000*1000*1000; /* 1 second */ 71 72 struct aa_ruleset *rules = profile->label.rules[0]; 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 = profile->label.rules[0]; 125 aa_state_t state; 126 int error; 127 128 state = RULE_MEDIATES(rules, ad->class); 129 if (state) { 130 struct aa_perms perms = { }; 131 u32 request; 132 133 /* caps broken into 256 x 32 bit permission chunks */ 134 state = aa_dfa_next(rules->policy->dfa, state, cap >> 5); 135 request = 1 << (cap & 0x1f); 136 perms = *aa_lookup_perms(rules->policy, state); 137 aa_apply_modes_to_perms(profile, &perms); 138 139 if (opts & CAP_OPT_NOAUDIT) { 140 if (perms.complain & request) 141 ad->info = "optional: no audit"; 142 else 143 ad = NULL; 144 } 145 return aa_check_perms(profile, &perms, request, ad, 146 audit_cb); 147 } 148 149 /* fallback to old caps mediation that doesn't support conditionals */ 150 if (cap_raised(rules->caps.allow, cap) && 151 !cap_raised(rules->caps.denied, cap)) 152 error = 0; 153 else 154 error = -EPERM; 155 156 if (opts & CAP_OPT_NOAUDIT) { 157 if (!COMPLAIN_MODE(profile)) 158 return error; 159 /* audit the cap request in complain mode but note that it 160 * should be optional. 161 */ 162 ad->info = "optional: no audit"; 163 } 164 165 return audit_caps(ad, profile, cap, error); 166 } 167 168 /** 169 * aa_capable - test permission to use capability 170 * @subj_cred: cred we are testing capability against 171 * @label: label being tested for capability (NOT NULL) 172 * @cap: capability to be tested 173 * @opts: CAP_OPT_NOAUDIT bit determines whether audit record is generated 174 * 175 * Look up capability in profile capability set. 176 * 177 * Returns: 0 on success, or else an error code. 178 */ 179 int aa_capable(const struct cred *subj_cred, struct aa_label *label, 180 int cap, unsigned int opts) 181 { 182 struct aa_profile *profile; 183 int error = 0; 184 DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_CAP, AA_CLASS_CAP, OP_CAPABLE); 185 186 ad.subj_cred = subj_cred; 187 ad.common.u.cap = cap; 188 error = fn_for_each_confined(label, profile, 189 profile_capable(profile, cap, opts, &ad)); 190 191 return error; 192 } 193 194 kernel_cap_t aa_profile_capget(struct aa_profile *profile) 195 { 196 struct aa_ruleset *rules = profile->label.rules[0]; 197 aa_state_t state; 198 199 state = RULE_MEDIATES(rules, AA_CLASS_CAP); 200 if (state) { 201 kernel_cap_t caps = CAP_EMPTY_SET; 202 int i; 203 204 /* caps broken into up to 256, 32 bit permission chunks */ 205 for (i = 0; i < (CAP_LAST_CAP >> 5); i++) { 206 struct aa_perms perms = { }; 207 aa_state_t tmp; 208 209 tmp = aa_dfa_next(rules->policy->dfa, state, i); 210 perms = *aa_lookup_perms(rules->policy, tmp); 211 aa_apply_modes_to_perms(profile, &perms); 212 caps.val |= ((u64)(perms.allow)) << (i * 5); 213 caps.val |= ((u64)(perms.complain)) << (i * 5); 214 } 215 return caps; 216 } 217 218 /* fallback to old caps */ 219 if (COMPLAIN_MODE(profile)) 220 return CAP_FULL_SET; 221 222 return rules->caps.allow; 223 } 224