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 33F0533CE8A; Thu, 28 May 2026 20:14:40 +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=1779999281; cv=none; b=ZEAElV/sujKL6PG77/HKPKk4ELRxOvnBp+mGy+YKhWTNQTEPVfWPgVepxVeHDXS/AlIyCybJf7TCTL5Wy8d8QyRGMr0EnMquT8FU4qUKdJ1KijdmLKjKflYzs00JXiXvt8bPeOldnUK2Z1eUQ5R7ilsBpDvE84dJThn6ZVfvkIo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779999281; c=relaxed/simple; bh=cjnDDRXY9RLjaliqdF4L64WbP7xzVeoEBMCb6YLQwuo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VdMzNhfke2ef1bwQREoR2hzkQ9+LYOoppBIOYEJHBLZ8ATIwFqfHJ7tnVlBtxPVA/NJy7m1Rzv6EEWsWByOm/QW+F6npbzMP3if82sM0Hrt07jWjhb0gJbCAuJYRDKxlhak7mULN0ygWdhQCM3Bc1JiD9H9sD9TJcB8NTbjwHCE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=SNgCXhfD; 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="SNgCXhfD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8A5331F000E9; Thu, 28 May 2026 20:14:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1779999280; bh=D+mQO/ZeKASSEr9FS8PBz6qJ0AVaTdLcd+IpVJ+aL5Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=SNgCXhfDKbb36j+GhDh1ljIzLrhwrf1DrGK5U1wzLC/LCkwD67o8zaJgOsR3WrwH/ wnjsBHSQuPY1nxJrgXhWSW9mcxemrinO/wYZRpYYpg6gfmjIauGgBFRdFVvhD9pitJ ateTdsB2jW3nLOIHeKMApwr1Nmewk+UaipJEPAtI= 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 6.18 011/377] smb: client: reject userspace cifs.spnego descriptions Date: Thu, 28 May 2026 21:44:09 +0200 Message-ID: <20260528194638.715343147@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260528194638.371537336@linuxfoundation.org> References: <20260528194638.371537336@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-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 @@ -40,12 +41,27 @@ 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,