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From: David Howells <dhowells@redhat.com>
To: keyrings@vger.kernel.org
Cc: dhowells@redhat.com, linux-afs@lists.infradead.org,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH 1/6] keys: Fix request_key() lack of Link perm check on found key
Date: Wed, 22 May 2019 23:46:10 +0100	[thread overview]
Message-ID: <155856517025.11737.11943384989202404333.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <155856516286.11737.11196637682919902718.stgit@warthog.procyon.org.uk>

The request_key() syscall allows a process to gain access to the 'possessor'
permits of any key that grants it Search permission by virtue of request_key()
not checking whether a key it finds grants Link permission to the caller.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 security/keys/request_key.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index e3653c6f85c6..d204d7c0152e 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -559,6 +559,16 @@ struct key *request_key_and_link(struct key_type *type,
 	key_ref = search_process_keyrings(&ctx);
 
 	if (!IS_ERR(key_ref)) {
+		if (dest_keyring) {
+			ret = key_task_permission(key_ref, current_cred(),
+						  KEY_NEED_LINK);
+			if (ret < 0) {
+				key_ref_put(key_ref);
+				key = ERR_PTR(ret);
+				goto error_free;
+			}
+		}
+
 		key = key_ref_to_ptr(key_ref);
 		if (dest_keyring) {
 			ret = key_link(dest_keyring, key);


  reply	other threads:[~2019-05-22 22:46 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-22 22:46 [PATCH 0/6] keys: request_key() improvements(vspace)s David Howells
2019-05-22 22:46 ` David Howells [this message]
2019-05-22 22:46 ` [PATCH 2/6] keys: Invalidate used request_key authentication keys David Howells
2019-05-22 22:46 ` [PATCH 3/6] keys: Move the RCU locks outwards from the keyring search functions David Howells
2019-05-22 22:46 ` [PATCH 4/6] keys: Cache result of request_key*() temporarily in task_struct David Howells
2019-05-22 22:46 ` [PATCH 5/6] afs: Provide an RCU-capable key lookup David Howells
2019-05-22 22:46 ` [PATCH 6/6] afs: Support RCU pathwalk David Howells

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