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From: mathew.j.martineau@linux.intel.com (Mat Martineau)
To: linux-security-module@vger.kernel.org
Subject: [PATCH v12 06/10] KEYS: Consistent ordering for __key_link_begin and restrict check
Date: Thu,  9 Mar 2017 12:23:11 -0800	[thread overview]
Message-ID: <20170309202315.15361-7-mathew.j.martineau@linux.intel.com> (raw)
In-Reply-To: <20170309202315.15361-1-mathew.j.martineau@linux.intel.com>

The keyring restrict callback was sometimes called before
__key_link_begin and sometimes after, which meant that the keyring
semaphores were not always held during the restrict callback.

If the semaphores are consistently acquired before checking link
restrictions, keyring contents cannot be changed after the restrict
check is complete but before the evaluated key is linked to the keyring.

Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 security/keys/key.c | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/security/keys/key.c b/security/keys/key.c
index 488adf2b6ad4..989ec35c1c48 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -500,21 +500,23 @@ int key_instantiate_and_link(struct key *key,
 	}
 
 	if (keyring) {
+		ret = __key_link_begin(keyring, &key->index_key, &edit);
+		if (ret < 0)
+			goto error;
+
 		if (keyring->restrict_link && keyring->restrict_link->check) {
 			struct key_restriction *keyres = keyring->restrict_link;
 
 			ret = keyres->check(keyring, key->type, &prep.payload,
 					    keyres->data);
 			if (ret < 0)
-				goto error;
+				goto error_link_end;
 		}
-		ret = __key_link_begin(keyring, &key->index_key, &edit);
-		if (ret < 0)
-			goto error;
 	}
 
 	ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
 
+error_link_end:
 	if (keyring)
 		__key_link_end(keyring, &key->index_key, edit);
 
@@ -855,21 +857,21 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref,
 	}
 	index_key.desc_len = strlen(index_key.description);
 
+	ret = __key_link_begin(keyring, &index_key, &edit);
+	if (ret < 0) {
+		key_ref = ERR_PTR(ret);
+		goto error_free_prep;
+	}
+
 	if (restrict_link && restrict_link->check) {
 		ret = restrict_link->check(keyring, index_key.type,
 					   &prep.payload, restrict_link->data);
 		if (ret < 0) {
 			key_ref = ERR_PTR(ret);
-			goto error_free_prep;
+			goto error_link_end;
 		}
 	}
 
-	ret = __key_link_begin(keyring, &index_key, &edit);
-	if (ret < 0) {
-		key_ref = ERR_PTR(ret);
-		goto error_free_prep;
-	}
-
 	/* if we're going to allocate a new key, we're going to have
 	 * to modify the keyring */
 	ret = key_permission(keyring_ref, KEY_NEED_WRITE);
-- 
2.12.0

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  parent reply	other threads:[~2017-03-09 20:23 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-09 20:23 [PATCH v12 00/10] Make keyring link restrictions accessible from userspace Mat Martineau
2017-03-09 20:23 ` [PATCH v12 01/10] KEYS: Use a typedef for restrict_link function pointers Mat Martineau
2017-03-09 20:23 ` [PATCH v12 02/10] KEYS: Split role of the keyring pointer for keyring restrict functions Mat Martineau
2017-03-09 20:23 ` [PATCH v12 03/10] KEYS: Add a key restriction struct Mat Martineau
2017-03-09 20:23 ` [PATCH v12 04/10] KEYS: Use structure to capture key restriction function and data Mat Martineau
2017-03-09 20:23 ` [PATCH v12 05/10] KEYS: Add an optional lookup_restriction hook to key_type Mat Martineau
2017-03-09 20:23 ` Mat Martineau [this message]
2017-03-09 20:23 ` [PATCH v12 07/10] KEYS: Add KEYCTL_RESTRICT_KEYRING Mat Martineau
2017-03-09 20:23 ` [PATCH v12 08/10] KEYS: Add a lookup_restriction function for the asymmetric key type Mat Martineau
2017-03-09 20:23 ` [PATCH v12 09/10] KEYS: Restrict asymmetric key linkage using a specific keychain Mat Martineau
2017-03-09 20:23 ` [PATCH v12 10/10] KEYS: Keyring asymmetric key restrict method with chaining Mat Martineau
2017-03-16 10:00 ` [PATCH v12 02/10] KEYS: Split role of the keyring pointer for keyring restrict functions David Howells
2017-03-16 10:09 ` [PATCH v12 05/10] KEYS: Add an optional lookup_restriction hook to key_type David Howells
2017-03-16 23:02   ` Mat Martineau
2017-03-16 10:17 ` [PATCH v12 06/10] KEYS: Consistent ordering for __key_link_begin and restrict check David Howells
2017-03-17  0:47   ` Mat Martineau
2017-03-17  7:43   ` David Howells
2017-03-17 22:35     ` Mat Martineau
2017-03-18  8:10     ` David Howells

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