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167 lines
4.3 KiB
167 lines
4.3 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* General persistent per-UID keyrings register |
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* |
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* Copyright (C) 2013 Red Hat, Inc. All Rights Reserved. |
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* Written by David Howells ([email protected]) |
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*/ |
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#include <linux/user_namespace.h> |
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#include <linux/cred.h> |
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#include "internal.h" |
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unsigned persistent_keyring_expiry = 3 * 24 * 3600; /* Expire after 3 days of non-use */ |
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/* |
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* Create the persistent keyring register for the current user namespace. |
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* |
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* Called with the namespace's sem locked for writing. |
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*/ |
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static int key_create_persistent_register(struct user_namespace *ns) |
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{ |
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struct key *reg = keyring_alloc(".persistent_register", |
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KUIDT_INIT(0), KGIDT_INIT(0), |
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current_cred(), |
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((KEY_POS_ALL & ~KEY_POS_SETATTR) | |
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KEY_USR_VIEW | KEY_USR_READ), |
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KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL); |
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if (IS_ERR(reg)) |
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return PTR_ERR(reg); |
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ns->persistent_keyring_register = reg; |
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return 0; |
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} |
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/* |
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* Create the persistent keyring for the specified user. |
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* |
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* Called with the namespace's sem locked for writing. |
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*/ |
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static key_ref_t key_create_persistent(struct user_namespace *ns, kuid_t uid, |
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struct keyring_index_key *index_key) |
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{ |
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struct key *persistent; |
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key_ref_t reg_ref, persistent_ref; |
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if (!ns->persistent_keyring_register) { |
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long err = key_create_persistent_register(ns); |
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if (err < 0) |
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return ERR_PTR(err); |
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} else { |
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reg_ref = make_key_ref(ns->persistent_keyring_register, true); |
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persistent_ref = find_key_to_update(reg_ref, index_key); |
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if (persistent_ref) |
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return persistent_ref; |
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} |
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persistent = keyring_alloc(index_key->description, |
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uid, INVALID_GID, current_cred(), |
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((KEY_POS_ALL & ~KEY_POS_SETATTR) | |
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KEY_USR_VIEW | KEY_USR_READ), |
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KEY_ALLOC_NOT_IN_QUOTA, NULL, |
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ns->persistent_keyring_register); |
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if (IS_ERR(persistent)) |
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return ERR_CAST(persistent); |
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return make_key_ref(persistent, true); |
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} |
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/* |
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* Get the persistent keyring for a specific UID and link it to the nominated |
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* keyring. |
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*/ |
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static long key_get_persistent(struct user_namespace *ns, kuid_t uid, |
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key_ref_t dest_ref) |
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{ |
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struct keyring_index_key index_key; |
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struct key *persistent; |
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key_ref_t reg_ref, persistent_ref; |
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char buf[32]; |
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long ret; |
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/* Look in the register if it exists */ |
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memset(&index_key, 0, sizeof(index_key)); |
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index_key.type = &key_type_keyring; |
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index_key.description = buf; |
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index_key.desc_len = sprintf(buf, "_persistent.%u", from_kuid(ns, uid)); |
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key_set_index_key(&index_key); |
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if (ns->persistent_keyring_register) { |
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reg_ref = make_key_ref(ns->persistent_keyring_register, true); |
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down_read(&ns->keyring_sem); |
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persistent_ref = find_key_to_update(reg_ref, &index_key); |
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up_read(&ns->keyring_sem); |
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if (persistent_ref) |
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goto found; |
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} |
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/* It wasn't in the register, so we'll need to create it. We might |
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* also need to create the register. |
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*/ |
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down_write(&ns->keyring_sem); |
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persistent_ref = key_create_persistent(ns, uid, &index_key); |
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up_write(&ns->keyring_sem); |
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if (!IS_ERR(persistent_ref)) |
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goto found; |
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return PTR_ERR(persistent_ref); |
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found: |
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ret = key_task_permission(persistent_ref, current_cred(), KEY_NEED_LINK); |
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if (ret == 0) { |
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persistent = key_ref_to_ptr(persistent_ref); |
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ret = key_link(key_ref_to_ptr(dest_ref), persistent); |
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if (ret == 0) { |
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key_set_timeout(persistent, persistent_keyring_expiry); |
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ret = persistent->serial; |
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} |
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} |
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key_ref_put(persistent_ref); |
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return ret; |
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} |
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/* |
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* Get the persistent keyring for a specific UID and link it to the nominated |
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* keyring. |
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*/ |
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long keyctl_get_persistent(uid_t _uid, key_serial_t destid) |
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{ |
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struct user_namespace *ns = current_user_ns(); |
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key_ref_t dest_ref; |
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kuid_t uid; |
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long ret; |
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/* -1 indicates the current user */ |
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if (_uid == (uid_t)-1) { |
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uid = current_uid(); |
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} else { |
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uid = make_kuid(ns, _uid); |
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if (!uid_valid(uid)) |
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return -EINVAL; |
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/* You can only see your own persistent cache if you're not |
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* sufficiently privileged. |
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*/ |
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if (!uid_eq(uid, current_uid()) && |
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!uid_eq(uid, current_euid()) && |
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!ns_capable(ns, CAP_SETUID)) |
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return -EPERM; |
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} |
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/* There must be a destination keyring */ |
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dest_ref = lookup_user_key(destid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE); |
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if (IS_ERR(dest_ref)) |
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return PTR_ERR(dest_ref); |
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if (key_ref_to_ptr(dest_ref)->type != &key_type_keyring) { |
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ret = -ENOTDIR; |
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goto out_put_dest; |
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} |
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ret = key_get_persistent(ns, uid, dest_ref); |
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out_put_dest: |
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key_ref_put(dest_ref); |
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return ret; |
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}
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