From patchwork Tue Dec 12 14:46:11 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 13489353 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ik0mN7sY" Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4B6321BE4 for ; Tue, 12 Dec 2023 06:46:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1702392388; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=y8Ls3k4OLqAXdAO2oDj775VG4CjskNZZKzFBZns4rfY=; b=ik0mN7sYkIhInt/gfNavqLT+Xak8cO6Lt4WN8aBWQcPi0DAoe5sdz4MbrxBnbir000wB4W rTPnlyEHC4R0GNcLFyjneh0O9488SfcKxP1DWDB1c+/TTyGlaJs6aNqTZT3xTGnouiqRsn 9Z+0VgU6UP9e9mEVQtcTizXD7nzslBk= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-10-x3bcL5NYNR6aT9ys9ue44w-1; Tue, 12 Dec 2023 09:46:24 -0500 X-MC-Unique: x3bcL5NYNR6aT9ys9ue44w-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 361261E441D3; Tue, 12 Dec 2023 14:46:22 +0000 (UTC) Received: from warthog.procyon.org.com (unknown [10.42.28.2]) by smtp.corp.redhat.com (Postfix) with ESMTP id AFA6840C6EB9; Tue, 12 Dec 2023 14:46:19 +0000 (UTC) From: David Howells To: Markus Suvanto , Marc Dionne Cc: David Howells , linux-afs@lists.infradead.org, keyrings@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Wang Lei , Jeff Layton , Steve French , Jarkko Sakkinen , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH v3 3/3] keys, dns: Allow key types (eg. DNS) to be reclaimed immediately on expiry Date: Tue, 12 Dec 2023 14:46:11 +0000 Message-ID: <20231212144611.3100234-4-dhowells@redhat.com> In-Reply-To: <20231212144611.3100234-1-dhowells@redhat.com> References: <20231212144611.3100234-1-dhowells@redhat.com> Precedence: bulk X-Mailing-List: linux-cifs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.2 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 10s 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: 1a4240f4764a ("DNS: Separate out CIFS DNS Resolver code") Signed-off-by: David Howells cc: Wang Lei cc: Jeff Layton cc: Steve French cc: Marc Dionne cc: Jarkko Sakkinen cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni 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 Reviewed-by: Jeffrey Altman --- Notes: Changes ======= ver #3) - Don't add to TIME64_MAX (ie. permanent) when checking expiry time. include/linux/key-type.h | 1 + net/dns_resolver/dns_key.c | 10 +++++++++- security/keys/gc.c | 31 +++++++++++++++++++++---------- security/keys/internal.h | 11 ++++++++++- security/keys/key.c | 15 +++++---------- security/keys/proc.c | 2 +- 6 files changed, 47 insertions(+), 23 deletions(-) diff --git a/include/linux/key-type.h b/include/linux/key-type.h index 7d985a1dfe4a..5caf3ce82373 100644 --- a/include/linux/key-type.h +++ b/include/linux/key-type.h @@ -73,6 +73,7 @@ struct key_type { unsigned int flags; #define KEY_TYPE_NET_DOMAIN 0x00000001 /* Keys of this type have a net namespace domain */ +#define KEY_TYPE_INSTANT_REAP 0x00000002 /* Keys of this type don't have a delay after expiring */ /* vet a description */ int (*vet_description)(const char *description); diff --git a/net/dns_resolver/dns_key.c b/net/dns_resolver/dns_key.c index 01e54b46ae0b..3233f4f25fed 100644 --- a/net/dns_resolver/dns_key.c +++ b/net/dns_resolver/dns_key.c @@ -91,6 +91,7 @@ const struct cred *dns_resolver_cache; static int dns_resolver_preparse(struct key_preparsed_payload *prep) { + const struct dns_server_list_v1_header *v1; const struct dns_payload_header *bin; struct user_key_payload *upayload; unsigned long derrno; @@ -122,6 +123,13 @@ dns_resolver_preparse(struct key_preparsed_payload *prep) return -EINVAL; } + v1 = (const struct dns_server_list_v1_header *)bin; + if ((v1->status != DNS_LOOKUP_GOOD && + v1->status != DNS_LOOKUP_GOOD_WITH_BAD)) { + if (prep->expiry == TIME64_MAX) + prep->expiry = ktime_get_real_seconds() + 10; + } + result_len = datalen; goto store_result; } @@ -314,7 +322,7 @@ static long dns_resolver_read(const struct key *key, struct key_type key_type_dns_resolver = { .name = "dns_resolver", - .flags = KEY_TYPE_NET_DOMAIN, + .flags = KEY_TYPE_NET_DOMAIN | KEY_TYPE_INSTANT_REAP, .preparse = dns_resolver_preparse, .free_preparse = dns_resolver_free_preparse, .instantiate = generic_key_instantiate, diff --git a/security/keys/gc.c b/security/keys/gc.c index 3c90807476eb..eaddaceda14e 100644 --- a/security/keys/gc.c +++ b/security/keys/gc.c @@ -66,6 +66,19 @@ void key_schedule_gc(time64_t gc_at) } } +/* + * Set the expiration time on a key. + */ +void key_set_expiry(struct key *key, time64_t expiry) +{ + key->expiry = expiry; + if (expiry != TIME64_MAX) { + if (!(key->type->flags & KEY_TYPE_INSTANT_REAP)) + expiry += key_gc_delay; + key_schedule_gc(expiry); + } +} + /* * Schedule a dead links collection run. */ @@ -176,7 +189,6 @@ static void key_garbage_collector(struct work_struct *work) static u8 gc_state; /* Internal persistent state */ #define KEY_GC_REAP_AGAIN 0x01 /* - Need another cycle */ #define KEY_GC_REAPING_LINKS 0x02 /* - We need to reap links */ -#define KEY_GC_SET_TIMER 0x04 /* - We need to restart the timer */ #define KEY_GC_REAPING_DEAD_1 0x10 /* - We need to mark dead keys */ #define KEY_GC_REAPING_DEAD_2 0x20 /* - We need to reap dead key links */ #define KEY_GC_REAPING_DEAD_3 0x40 /* - We need to reap dead keys */ @@ -184,21 +196,17 @@ static void key_garbage_collector(struct work_struct *work) struct rb_node *cursor; struct key *key; - time64_t new_timer, limit; + time64_t new_timer, limit, expiry; kenter("[%lx,%x]", key_gc_flags, gc_state); limit = ktime_get_real_seconds(); - if (limit > key_gc_delay) - limit -= key_gc_delay; - else - limit = key_gc_delay; /* Work out what we're going to be doing in this pass */ gc_state &= KEY_GC_REAPING_DEAD_1 | KEY_GC_REAPING_DEAD_2; gc_state <<= 1; if (test_and_clear_bit(KEY_GC_KEY_EXPIRED, &key_gc_flags)) - gc_state |= KEY_GC_REAPING_LINKS | KEY_GC_SET_TIMER; + gc_state |= KEY_GC_REAPING_LINKS; if (test_and_clear_bit(KEY_GC_REAP_KEYTYPE, &key_gc_flags)) gc_state |= KEY_GC_REAPING_DEAD_1; @@ -233,8 +241,11 @@ static void key_garbage_collector(struct work_struct *work) } } - if (gc_state & KEY_GC_SET_TIMER) { - if (key->expiry > limit && key->expiry < new_timer) { + expiry = key->expiry; + if (expiry != TIME64_MAX) { + if (!(key->type->flags & KEY_TYPE_INSTANT_REAP)) + expiry += key_gc_delay; + if (expiry > limit && expiry < new_timer) { kdebug("will expire %x in %lld", key_serial(key), key->expiry - limit); new_timer = key->expiry; @@ -276,7 +287,7 @@ static void key_garbage_collector(struct work_struct *work) */ kdebug("pass complete"); - if (gc_state & KEY_GC_SET_TIMER && new_timer != (time64_t)TIME64_MAX) { + if (new_timer != TIME64_MAX) { new_timer += key_gc_delay; key_schedule_gc(new_timer); } diff --git a/security/keys/internal.h b/security/keys/internal.h index 471cf36dedc0..2cffa6dc8255 100644 --- a/security/keys/internal.h +++ b/security/keys/internal.h @@ -167,6 +167,7 @@ extern unsigned key_gc_delay; extern void keyring_gc(struct key *keyring, time64_t limit); extern void keyring_restriction_gc(struct key *keyring, struct key_type *dead_type); +void key_set_expiry(struct key *key, time64_t expiry); extern void key_schedule_gc(time64_t gc_at); extern void key_schedule_gc_links(void); extern void key_gc_keytype(struct key_type *ktype); @@ -215,10 +216,18 @@ extern struct key *key_get_instantiation_authkey(key_serial_t target_id); */ static inline bool key_is_dead(const struct key *key, time64_t limit) { + time64_t expiry = key->expiry; + + if (expiry != TIME64_MAX) { + if (!(key->type->flags & KEY_TYPE_INSTANT_REAP)) + expiry += key_gc_delay; + if (expiry <= limit) + return true; + } + return key->flags & ((1 << KEY_FLAG_DEAD) | (1 << KEY_FLAG_INVALIDATED)) || - (key->expiry > 0 && key->expiry <= limit) || key->domain_tag->removed; } diff --git a/security/keys/key.c b/security/keys/key.c index 0260a1902922..5b10641debd5 100644 --- a/security/keys/key.c +++ b/security/keys/key.c @@ -294,6 +294,7 @@ struct key *key_alloc(struct key_type *type, const char *desc, key->uid = uid; key->gid = gid; key->perm = perm; + key->expiry = TIME64_MAX; key->restrict_link = restrict_link; key->last_used_at = ktime_get_real_seconds(); @@ -463,10 +464,7 @@ static int __key_instantiate_and_link(struct key *key, if (authkey) key_invalidate(authkey); - if (prep->expiry != TIME64_MAX) { - key->expiry = prep->expiry; - key_schedule_gc(prep->expiry + key_gc_delay); - } + key_set_expiry(key, prep->expiry); } } @@ -606,8 +604,7 @@ int key_reject_and_link(struct key *key, atomic_inc(&key->user->nikeys); mark_key_instantiated(key, -error); notify_key(key, NOTIFY_KEY_INSTANTIATED, -error); - key->expiry = ktime_get_real_seconds() + timeout; - key_schedule_gc(key->expiry + key_gc_delay); + key_set_expiry(key, ktime_get_real_seconds() + timeout); if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) awaken = 1; @@ -723,16 +720,14 @@ struct key_type *key_type_lookup(const char *type) void key_set_timeout(struct key *key, unsigned timeout) { - time64_t expiry = 0; + time64_t expiry = TIME64_MAX; /* make the changes with the locks held to prevent races */ down_write(&key->sem); if (timeout > 0) expiry = ktime_get_real_seconds() + timeout; - - key->expiry = expiry; - key_schedule_gc(key->expiry + key_gc_delay); + key_set_expiry(key, expiry); up_write(&key->sem); } diff --git a/security/keys/proc.c b/security/keys/proc.c index d0cde6685627..4f4e2c1824f1 100644 --- a/security/keys/proc.c +++ b/security/keys/proc.c @@ -198,7 +198,7 @@ static int proc_keys_show(struct seq_file *m, void *v) /* come up with a suitable timeout value */ expiry = READ_ONCE(key->expiry); - if (expiry == 0) { + if (expiry == TIME64_MAX) { memcpy(xbuf, "perm", 5); } else if (now >= expiry) { memcpy(xbuf, "expd", 5);