From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793207349; b=iO2gzB2J0jn1OLMeJ6S19t7P/AHu6nNYkS8KbVF3H6h1X8fOs3PiiIBx4lT1ebskaHOJ wCaxfW+lgVEevfDJVijCJIY/ta/nVn3REl/RAZvtZv1EKSPKZZT6wiowT4qt1GzX2FOzK B7xBTDvcjwV+nSZfeYWGybOltPgX/1QbxtvVdkqhnYf5t+NevVd64ODYJQ0olmy8VWiOw pCnMU6a67EMrl2E6d3dm0IRl/cG7C+X+JN/dDasL2kIuwxkUaB06h8r3JuTGn6wGuLWLw gZ7YHPBUGYFSR7VQv/U2SEyue+sFg4Wr0Rh6x6a8W5oQZr9GX2Ja4T3sQt175+zb0mA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793207349; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=jxsC0r4D3qpyDpkIH+Mo+/w22zyfKoyourhWSKgwvS0=; b=SJERs+EM/3GSuZ4arCh3SEg0nKdRj8oJq5NeW7V9Z3pIzpOIIiun1d1od3pay+4dQs1a Cy+Y7PBHW+tCaRIOh//EaxB3xPWAH99tgIinDC1PWpCosC35ENoOGYNtTAN4PjA/Uyvc1 BHb18t49M0d3wdOZJopbG71N1Hi/uyhGnqYVQ2NXS6cjxbeo8qdWhRfgFZ0DzSZ9tPl4l YiRevgjFdip4VZH+672TW37etsiZaOu6pq/m8DgLxX5d2f8sOAf41dcDJOKRZzw+x+gl0 sc7aYZp3/LP8mjEKICRZs2HbLIMv9402zjpQVr3eZaA+7Gk+tiZm5/DCpKHT4T1HzJQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b="SQMS/TcY"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 122DC606A320; Wed, 28 Oct 2026 17:09:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=SQMS/TcY Received: by smtp.kernel.org (Postfix) with ESMTPSA id 633701F031E6; Wed, 28 Oct 2026 17:09:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793207348; bh=jxsC0r4D3qpyDpkIH+Mo+/w22zyfKoyourhWSKgwvS0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=SQMS/TcYgK1isfULoyqALb1IDoCK1y+x9Td7GG7jK0/zjJZdQxTtRmDggO4vhzeQo 9fCydJfK+q36mYUs70QLKGe+TNzdeyJqlpLLvKX1OLWbDxSfgJ1a3x2LhxZ8brQEgS DBegJPn9jSmbQyIep5AVtxsw4cMPWUzpkB9os0Bc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jarkko Sakkinen , Adrian Martinez Subject: [PATCH 7.2 75/88] KEYS: Fix key_reject_and_link() race with keyring restriction Date: Wed, 28 Oct 2026 18:00:23 +0100 Message-ID: <20261028165943.881612698@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028165942.107695352@linuxfoundation.org> References: <20261028165942.107695352@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Adrian Martinez commit 0b157166e612b70f98a332b6c7be7eac6f8e9593 upstream. The restrict_link check in key_reject_and_link() is done before taking the keyring semaphore, racing with a concurrent keyring_restrict() that installs the restriction while holding the semaphore in write mode. Move the check to after __key_link_lock(), so it is done under the semaphore, matching the pattern used in __key_create_or_update(). Cc: stable@vger.kernel.org Fixes: 5ac7eace2d00 ("KEYS: Add a facility to restrict new links into a keyring") Reviewed-by: Jarkko Sakkinen Signed-off-by: Adrian Martinez Link: https://lore.kernel.org/r/CACO1+RT+m==BY+ZPkE+fo536D0qu3wog4xE1dfuXQ56g+=Qv=A@mail.gmail.com Signed-off-by: Jarkko Sakkinen Signed-off-by: Greg Kroah-Hartman --- security/keys/key.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) --- a/security/keys/key.c +++ b/security/keys/key.c @@ -588,11 +588,18 @@ int key_reject_and_link(struct key *key, ret = -EBUSY; if (keyring) { - if (keyring->restrict_link) - return -EPERM; - link_ret = __key_link_lock(keyring, &key->index_key); if (link_ret == 0) { + /* + * Check the restriction under the keyring semaphore. + * keyring_restrict() installs it while holding the + * semaphore, so testing it beforehand races with a + * concurrent restriction install. + */ + if (keyring->restrict_link) { + __key_link_end(keyring, &key->index_key, edit); + return -EPERM; + } link_ret = __key_link_begin(keyring, &key->index_key, &edit); if (link_ret < 0) __key_link_end(keyring, &key->index_key, edit);