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![David Howells](/assets/img/avatar_default.png)
If a key has an expiration time, then when that time passes, the key is
left around for a certain amount of time before being collected (5 mins by
default) so that EKEYEXPIRED can be returned instead of ENOKEY. This is a
problem for DNS keys because we want to redo the DNS lookup immediately at
that point.
Fix this by allowing key types to be marked such that keys of that type
don't have this extra period, but are reclaimed as soon as they expire and
turn this on for dns_resolver-type keys. To make this easier to handle,
key->expiry is changed to be permanent if TIME64_MAX rather than 0.
Furthermore, give such new-style negative DNS results a 1s default expiry
if no other expiry time is set rather than allowing it to stick around
indefinitely. This shouldn't be zero as ls will follow a failing stat call
immediately with a second with AT_SYMLINK_NOFOLLOW added.
Fixes: 1a4240f476
("DNS: Separate out CIFS DNS Resolver code")
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Markus Suvanto <markus.suvanto@gmail.com>
cc: Wang Lei <wang840925@gmail.com>
cc: Jeff Layton <jlayton@redhat.com>
cc: Steve French <smfrench@gmail.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Jarkko Sakkinen <jarkko@kernel.org>
cc: "David S. Miller" <davem@davemloft.net>
cc: Eric Dumazet <edumazet@google.com>
cc: Jakub Kicinski <kuba@kernel.org>
cc: Paolo Abeni <pabeni@redhat.com>
cc: linux-afs@lists.infradead.org
cc: linux-cifs@vger.kernel.org
cc: linux-nfs@vger.kernel.org
cc: ceph-devel@vger.kernel.org
cc: keyrings@vger.kernel.org
cc: netdev@vger.kernel.org
324 lines
7.8 KiB
C
324 lines
7.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* procfs files for key database enumeration
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*
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* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/fs.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include <asm/errno.h>
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#include "internal.h"
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static void *proc_keys_start(struct seq_file *p, loff_t *_pos);
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static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos);
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static void proc_keys_stop(struct seq_file *p, void *v);
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static int proc_keys_show(struct seq_file *m, void *v);
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static const struct seq_operations proc_keys_ops = {
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.start = proc_keys_start,
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.next = proc_keys_next,
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.stop = proc_keys_stop,
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.show = proc_keys_show,
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};
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static void *proc_key_users_start(struct seq_file *p, loff_t *_pos);
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static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos);
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static void proc_key_users_stop(struct seq_file *p, void *v);
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static int proc_key_users_show(struct seq_file *m, void *v);
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static const struct seq_operations proc_key_users_ops = {
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.start = proc_key_users_start,
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.next = proc_key_users_next,
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.stop = proc_key_users_stop,
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.show = proc_key_users_show,
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};
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/*
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* Declare the /proc files.
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*/
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static int __init key_proc_init(void)
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{
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struct proc_dir_entry *p;
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p = proc_create_seq("keys", 0, NULL, &proc_keys_ops);
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if (!p)
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panic("Cannot create /proc/keys\n");
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p = proc_create_seq("key-users", 0, NULL, &proc_key_users_ops);
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if (!p)
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panic("Cannot create /proc/key-users\n");
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return 0;
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}
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__initcall(key_proc_init);
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/*
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* Implement "/proc/keys" to provide a list of the keys on the system that
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* grant View permission to the caller.
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*/
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static struct rb_node *key_serial_next(struct seq_file *p, struct rb_node *n)
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{
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struct user_namespace *user_ns = seq_user_ns(p);
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n = rb_next(n);
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while (n) {
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struct key *key = rb_entry(n, struct key, serial_node);
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if (kuid_has_mapping(user_ns, key->user->uid))
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break;
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n = rb_next(n);
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}
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return n;
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}
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static struct key *find_ge_key(struct seq_file *p, key_serial_t id)
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{
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struct user_namespace *user_ns = seq_user_ns(p);
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struct rb_node *n = key_serial_tree.rb_node;
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struct key *minkey = NULL;
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while (n) {
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struct key *key = rb_entry(n, struct key, serial_node);
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if (id < key->serial) {
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if (!minkey || minkey->serial > key->serial)
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minkey = key;
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n = n->rb_left;
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} else if (id > key->serial) {
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n = n->rb_right;
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} else {
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minkey = key;
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break;
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}
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key = NULL;
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}
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if (!minkey)
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return NULL;
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for (;;) {
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if (kuid_has_mapping(user_ns, minkey->user->uid))
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return minkey;
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n = rb_next(&minkey->serial_node);
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if (!n)
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return NULL;
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minkey = rb_entry(n, struct key, serial_node);
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}
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}
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static void *proc_keys_start(struct seq_file *p, loff_t *_pos)
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__acquires(key_serial_lock)
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{
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key_serial_t pos = *_pos;
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struct key *key;
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spin_lock(&key_serial_lock);
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if (*_pos > INT_MAX)
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return NULL;
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key = find_ge_key(p, pos);
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if (!key)
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return NULL;
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*_pos = key->serial;
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return &key->serial_node;
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}
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static inline key_serial_t key_node_serial(struct rb_node *n)
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{
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struct key *key = rb_entry(n, struct key, serial_node);
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return key->serial;
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}
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static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos)
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{
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struct rb_node *n;
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n = key_serial_next(p, v);
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if (n)
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*_pos = key_node_serial(n);
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else
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(*_pos)++;
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return n;
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}
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static void proc_keys_stop(struct seq_file *p, void *v)
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__releases(key_serial_lock)
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{
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spin_unlock(&key_serial_lock);
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}
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static int proc_keys_show(struct seq_file *m, void *v)
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{
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struct rb_node *_p = v;
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struct key *key = rb_entry(_p, struct key, serial_node);
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unsigned long flags;
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key_ref_t key_ref, skey_ref;
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time64_t now, expiry;
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char xbuf[16];
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short state;
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u64 timo;
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int rc;
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struct keyring_search_context ctx = {
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.index_key = key->index_key,
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.cred = m->file->f_cred,
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.match_data.cmp = lookup_user_key_possessed,
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.match_data.raw_data = key,
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.match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
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.flags = (KEYRING_SEARCH_NO_STATE_CHECK |
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KEYRING_SEARCH_RECURSE),
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};
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key_ref = make_key_ref(key, 0);
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/* determine if the key is possessed by this process (a test we can
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* skip if the key does not indicate the possessor can view it
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*/
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if (key->perm & KEY_POS_VIEW) {
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rcu_read_lock();
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skey_ref = search_cred_keyrings_rcu(&ctx);
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rcu_read_unlock();
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if (!IS_ERR(skey_ref)) {
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key_ref_put(skey_ref);
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key_ref = make_key_ref(key, 1);
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}
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}
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/* check whether the current task is allowed to view the key */
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rc = key_task_permission(key_ref, ctx.cred, KEY_NEED_VIEW);
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if (rc < 0)
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return 0;
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now = ktime_get_real_seconds();
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rcu_read_lock();
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/* come up with a suitable timeout value */
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expiry = READ_ONCE(key->expiry);
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if (expiry == TIME64_MAX) {
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memcpy(xbuf, "perm", 5);
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} else if (now >= expiry) {
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memcpy(xbuf, "expd", 5);
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} else {
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timo = expiry - now;
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if (timo < 60)
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sprintf(xbuf, "%llus", timo);
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else if (timo < 60*60)
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sprintf(xbuf, "%llum", div_u64(timo, 60));
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else if (timo < 60*60*24)
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sprintf(xbuf, "%lluh", div_u64(timo, 60 * 60));
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else if (timo < 60*60*24*7)
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sprintf(xbuf, "%llud", div_u64(timo, 60 * 60 * 24));
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else
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sprintf(xbuf, "%lluw", div_u64(timo, 60 * 60 * 24 * 7));
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}
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state = key_read_state(key);
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#define showflag(FLAGS, LETTER, FLAG) \
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((FLAGS & (1 << FLAG)) ? LETTER : '-')
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flags = READ_ONCE(key->flags);
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seq_printf(m, "%08x %c%c%c%c%c%c%c %5d %4s %08x %5d %5d %-9.9s ",
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key->serial,
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state != KEY_IS_UNINSTANTIATED ? 'I' : '-',
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showflag(flags, 'R', KEY_FLAG_REVOKED),
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showflag(flags, 'D', KEY_FLAG_DEAD),
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showflag(flags, 'Q', KEY_FLAG_IN_QUOTA),
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showflag(flags, 'U', KEY_FLAG_USER_CONSTRUCT),
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state < 0 ? 'N' : '-',
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showflag(flags, 'i', KEY_FLAG_INVALIDATED),
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refcount_read(&key->usage),
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xbuf,
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key->perm,
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from_kuid_munged(seq_user_ns(m), key->uid),
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from_kgid_munged(seq_user_ns(m), key->gid),
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key->type->name);
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#undef showflag
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if (key->type->describe)
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key->type->describe(key, m);
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seq_putc(m, '\n');
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rcu_read_unlock();
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return 0;
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}
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static struct rb_node *__key_user_next(struct user_namespace *user_ns, struct rb_node *n)
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{
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while (n) {
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struct key_user *user = rb_entry(n, struct key_user, node);
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if (kuid_has_mapping(user_ns, user->uid))
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break;
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n = rb_next(n);
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}
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return n;
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}
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static struct rb_node *key_user_next(struct user_namespace *user_ns, struct rb_node *n)
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{
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return __key_user_next(user_ns, rb_next(n));
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}
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static struct rb_node *key_user_first(struct user_namespace *user_ns, struct rb_root *r)
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{
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struct rb_node *n = rb_first(r);
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return __key_user_next(user_ns, n);
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}
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static void *proc_key_users_start(struct seq_file *p, loff_t *_pos)
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__acquires(key_user_lock)
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{
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struct rb_node *_p;
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loff_t pos = *_pos;
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spin_lock(&key_user_lock);
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_p = key_user_first(seq_user_ns(p), &key_user_tree);
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while (pos > 0 && _p) {
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pos--;
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_p = key_user_next(seq_user_ns(p), _p);
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}
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return _p;
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}
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static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos)
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{
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(*_pos)++;
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return key_user_next(seq_user_ns(p), (struct rb_node *)v);
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}
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static void proc_key_users_stop(struct seq_file *p, void *v)
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__releases(key_user_lock)
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{
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spin_unlock(&key_user_lock);
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}
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static int proc_key_users_show(struct seq_file *m, void *v)
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{
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struct rb_node *_p = v;
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struct key_user *user = rb_entry(_p, struct key_user, node);
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unsigned maxkeys = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
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key_quota_root_maxkeys : key_quota_maxkeys;
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unsigned maxbytes = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
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key_quota_root_maxbytes : key_quota_maxbytes;
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seq_printf(m, "%5u: %5d %d/%d %d/%d %d/%d\n",
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from_kuid_munged(seq_user_ns(m), user->uid),
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refcount_read(&user->usage),
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atomic_read(&user->nkeys),
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atomic_read(&user->nikeys),
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user->qnkeys,
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maxkeys,
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user->qnbytes,
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maxbytes);
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return 0;
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}
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