1 /* General persistent per-UID keyrings register 2 * 3 * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved. 4 * Written by David Howells (dhowells@redhat.com) 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public Licence 8 * as published by the Free Software Foundation; either version 9 * 2 of the Licence, or (at your option) any later version. 10 */ 11 12 #include <linux/user_namespace.h> 13 #include <linux/cred.h> 14 15 #include "internal.h" 16 17 unsigned persistent_keyring_expiry = 3 * 24 * 3600; /* Expire after 3 days of non-use */ 18 19 /* 20 * Create the persistent keyring register for the current user namespace. 21 * 22 * Called with the namespace's sem locked for writing. 23 */ 24 static int key_create_persistent_register(struct user_namespace *ns) 25 { 26 struct key *reg = keyring_alloc(".persistent_register", 27 KUIDT_INIT(0), KGIDT_INIT(0), 28 current_cred(), 29 ((KEY_POS_ALL & ~KEY_POS_SETATTR) | 30 KEY_USR_VIEW | KEY_USR_READ), 31 KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL); 32 if (IS_ERR(reg)) 33 return PTR_ERR(reg); 34 35 ns->persistent_keyring_register = reg; 36 return 0; 37 } 38 39 /* 40 * Create the persistent keyring for the specified user. 41 * 42 * Called with the namespace's sem locked for writing. 43 */ 44 static key_ref_t key_create_persistent(struct user_namespace *ns, kuid_t uid, 45 struct keyring_index_key *index_key) 46 { 47 struct key *persistent; 48 key_ref_t reg_ref, persistent_ref; 49 50 if (!ns->persistent_keyring_register) { 51 long err = key_create_persistent_register(ns); 52 if (err < 0) 53 return ERR_PTR(err); 54 } else { 55 reg_ref = make_key_ref(ns->persistent_keyring_register, true); 56 persistent_ref = find_key_to_update(reg_ref, index_key); 57 if (persistent_ref) 58 return persistent_ref; 59 } 60 61 persistent = keyring_alloc(index_key->description, 62 uid, INVALID_GID, current_cred(), 63 ((KEY_POS_ALL & ~KEY_POS_SETATTR) | 64 KEY_USR_VIEW | KEY_USR_READ), 65 KEY_ALLOC_NOT_IN_QUOTA, NULL, 66 ns->persistent_keyring_register); 67 if (IS_ERR(persistent)) 68 return ERR_CAST(persistent); 69 70 return make_key_ref(persistent, true); 71 } 72 73 /* 74 * Get the persistent keyring for a specific UID and link it to the nominated 75 * keyring. 76 */ 77 static long key_get_persistent(struct user_namespace *ns, kuid_t uid, 78 key_ref_t dest_ref) 79 { 80 struct keyring_index_key index_key; 81 struct key *persistent; 82 key_ref_t reg_ref, persistent_ref; 83 char buf[32]; 84 long ret; 85 86 /* Look in the register if it exists */ 87 index_key.type = &key_type_keyring; 88 index_key.description = buf; 89 index_key.desc_len = sprintf(buf, "_persistent.%u", from_kuid(ns, uid)); 90 91 if (ns->persistent_keyring_register) { 92 reg_ref = make_key_ref(ns->persistent_keyring_register, true); 93 down_read(&ns->persistent_keyring_register_sem); 94 persistent_ref = find_key_to_update(reg_ref, &index_key); 95 up_read(&ns->persistent_keyring_register_sem); 96 97 if (persistent_ref) 98 goto found; 99 } 100 101 /* It wasn't in the register, so we'll need to create it. We might 102 * also need to create the register. 103 */ 104 down_write(&ns->persistent_keyring_register_sem); 105 persistent_ref = key_create_persistent(ns, uid, &index_key); 106 up_write(&ns->persistent_keyring_register_sem); 107 if (!IS_ERR(persistent_ref)) 108 goto found; 109 110 return PTR_ERR(persistent_ref); 111 112 found: 113 ret = key_task_permission(persistent_ref, current_cred(), KEY_NEED_LINK); 114 if (ret == 0) { 115 persistent = key_ref_to_ptr(persistent_ref); 116 ret = key_link(key_ref_to_ptr(dest_ref), persistent); 117 if (ret == 0) { 118 key_set_timeout(persistent, persistent_keyring_expiry); 119 ret = persistent->serial; 120 } 121 } 122 123 key_ref_put(persistent_ref); 124 return ret; 125 } 126 127 /* 128 * Get the persistent keyring for a specific UID and link it to the nominated 129 * keyring. 130 */ 131 long keyctl_get_persistent(uid_t _uid, key_serial_t destid) 132 { 133 struct user_namespace *ns = current_user_ns(); 134 key_ref_t dest_ref; 135 kuid_t uid; 136 long ret; 137 138 /* -1 indicates the current user */ 139 if (_uid == (uid_t)-1) { 140 uid = current_uid(); 141 } else { 142 uid = make_kuid(ns, _uid); 143 if (!uid_valid(uid)) 144 return -EINVAL; 145 146 /* You can only see your own persistent cache if you're not 147 * sufficiently privileged. 148 */ 149 if (!uid_eq(uid, current_uid()) && 150 !uid_eq(uid, current_euid()) && 151 !ns_capable(ns, CAP_SETUID)) 152 return -EPERM; 153 } 154 155 /* There must be a destination keyring */ 156 dest_ref = lookup_user_key(destid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE); 157 if (IS_ERR(dest_ref)) 158 return PTR_ERR(dest_ref); 159 if (key_ref_to_ptr(dest_ref)->type != &key_type_keyring) { 160 ret = -ENOTDIR; 161 goto out_put_dest; 162 } 163 164 ret = key_get_persistent(ns, uid, dest_ref); 165 166 out_put_dest: 167 key_ref_put(dest_ref); 168 return ret; 169 } 170