From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 22983333730; Thu, 28 May 2026 20:45:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780001124; cv=none; b=NZ0lfn02S2LIgBArGBiveE1aPk9BbjTFzbi1GmqMRpG4d5tuzk+wpSSpccgncTLkJ5RpCsTq4G8kflCTcySkMmYVYXjD8bJ8Nl1vNa+rWGoVDdzfxNh/7qtgsikF5ewQymxf6Hj7nTqun49LqAhp94jlxqImArfqzsWcbN9U2dM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780001124; c=relaxed/simple; bh=yBU98Tkw9CizCE6SiIIzi64uC5xeLIQAh+1Ezj0vNZ0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MUDO+Q9iD9lJ/JGfMf/T6FC4vCsX6E6w1XFpea4ICCV1KETfVEuG/ZcV2a1FP7c+S/X/r5LzYGyZPv3TsYMHpUwJKdXiZCCUAyl6xkbIoAAz4eztLGHkedazgcCHOCkXFy4eKjBsSRPgYeKqo6G7onZ8DkcU5EF5+JjqK2f5Eec= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=AV7PmYxS; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="AV7PmYxS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 77DFB1F000E9; Thu, 28 May 2026 20:45:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1780001123; bh=F4kUcw8ieCHiGh5zMN0qCXH6eDiT+HNHxAlrxmk++bo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=AV7PmYxSRgHM89q+fiCMzIzoqIzpN87OEXgqdeqAITufywcMwUmjr8m/7OgXesWKt RSh/j2s9pxj1b2zWIiKo2hejzQj+y5qmsFBtA7mM2IfouKzruQpQf3ET0uSHzgDReY 2No3xsKXnfm5mMuw0guW8zncXBI3Q/p2JMsRN7IU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, David Howells , Asim Viladi Oglu Manizada , Steve French Subject: [PATCH 6.6 016/186] smb: client: reject userspace cifs.spnego descriptions Date: Thu, 28 May 2026 21:48:16 +0200 Message-ID: <20260528194929.394180968@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260528194928.941004471@linuxfoundation.org> References: <20260528194928.941004471@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Asim Viladi Oglu Manizada commit 3da1fdf4efbc490041eb4f836bf596201203f8f2 upstream. cifs.spnego key descriptions contain authority-bearing fields such as pid, uid, creduid, and upcall_target that cifs.upcall treats as kernel-originating inputs. However, userspace can also create keys of this type through request_key(2) or add_key(2), allowing those fields to be supplied without CIFS origin. Only accept cifs.spnego descriptions while CIFS is using its private spnego_cred to request the key. Fixes: f1d662a7d5e5 ("[CIFS] Add upcall files for cifs to use spnego/kerberos") Assisted-by: avom-custom-harness:gpt-5.5-qwen3.6-mod-mix Reviewed-by: David Howells Signed-off-by: Asim Viladi Oglu Manizada Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/smb/client/cifs_spnego.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) --- a/fs/smb/client/cifs_spnego.c +++ b/fs/smb/client/cifs_spnego.c @@ -8,6 +8,7 @@ */ #include +#include #include #include #include @@ -46,12 +47,27 @@ cifs_spnego_key_destroy(struct key *key) kfree(key->payload.data[0]); } +static int +cifs_spnego_key_vet_description(const char *description) +{ + /* + * cifs.spnego descriptions are authority-bearing inputs to cifs.upcall. + * They are only valid when produced by CIFS while using the private + * spnego_cred installed below. Do not let userspace create this type + * of key through request_key(2)/add_key(2), since the helper treats + * pid/uid/creduid/upcall_target as kernel-originating fields. + */ + if (current_cred() != spnego_cred) + return -EPERM; + return 0; +} /* * keytype for CIFS spnego keys */ struct key_type cifs_spnego_key_type = { .name = "cifs.spnego", + .vet_description = cifs_spnego_key_vet_description, .instantiate = cifs_spnego_key_instantiate, .destroy = cifs_spnego_key_destroy, .describe = user_describe,