From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-174.mta0.migadu.com (out-174.mta0.migadu.com [91.218.175.174]) (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 2E94A1119B for ; Thu, 25 Jan 2024 22:35:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706222104; cv=none; b=lmwTDGTDHWzcNFcXJSdJQxXza2z4xxFnd51pRfQnVP1fxPP9OmCG860sY9EPGFQjkEYsFTHjv01zdc9IoHS1Y1uoxB/wih8xW4GzhB9tSl8IzY88ZF70U5vz3b84Zsfy/f7IhtCdLBY9009+pU2QvXqeWDKpkUQwDaLFmsSre2I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706222104; c=relaxed/simple; bh=QjRL4Lk5HuY4dVTiSx8FBdwbiQ0YMbtGB8QHYiNAY2I=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Ciq68L0B98EzsWyB3LGTewYFFOz0SkdDL2any+oQe4eAkd90ElgIsGFILSTkoTctm25eu2wXD93uRNANWUtOHXmvWQ3c4D1bDGIGMeKfns7gpq9NF3Zhp2ch83FE58F14sDqyz+dJcLAXiLIywj39u2HnyNc+FaNDWQIJcxZ5Ac= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=wtzgWT5L; arc=none smtp.client-ip=91.218.175.174 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="wtzgWT5L" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1706222099; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=3VzS1vt3EtrBAK2HSrfT6Y50voBH4lEx0F/Lw8xZM2M=; b=wtzgWT5LTkRp2WrBIhRy7sO7hmnbBZqcOjMT8tTrhe71/FP+70vIqM4XKn27NrqSYdKoM3 E6F/jTVuouhXLpdawNbgUQVPLQv4K1u7ZMpZ4qsgn5ulBZV75N0guGW62B5W/gz8/1P3Pv EGVjC+iRhS/rPAQEHvUFwOoNC/WHDSQ= Date: Thu, 25 Jan 2024 14:34:49 -0800 Precedence: bulk X-Mailing-List: linux-crypto@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf-next v8 1/3] bpf: make common crypto API for TC/XDP programs Content-Language: en-US To: Vadim Fedorenko , Vadim Fedorenko Cc: netdev@vger.kernel.org, linux-crypto@vger.kernel.org, bpf@vger.kernel.org, Victor Stewart , Jakub Kicinski , Andrii Nakryiko , Alexei Starovoitov , Mykola Lysenko , Herbert Xu References: <20240115220803.1973440-1-vadfed@meta.com> <3d2d5f4e-c554-4648-bcec-839d83585123@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Martin KaFai Lau In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 1/25/24 3:19 AM, Vadim Fedorenko wrote: > On 25/01/2024 01:10, Martin KaFai Lau wrote: >> On 1/15/24 2:08 PM, Vadim Fedorenko wrote: >>> +static int bpf_crypto_crypt(const struct bpf_crypto_ctx *ctx, >>> +                const struct bpf_dynptr_kern *src, >>> +                struct bpf_dynptr_kern *dst, >>> +                const struct bpf_dynptr_kern *siv, >>> +                bool decrypt) >>> +{ >>> +    u32 src_len, dst_len, siv_len; >>> +    const u8 *psrc; >>> +    u8 *pdst, *piv; >>> +    int err; >>> + >>> +    if (ctx->type->get_flags(ctx->tfm) & CRYPTO_TFM_NEED_KEY) >> >> nit. Does the indirect call get_flags() return different values? >> Should it be rejected earlier, e.g. in bpf_crypto_ctx_create()? > > Well, that is the common pattern in crypto subsys to check flags. > But after looking at it second time, I think I have to refactor this > part. CRYPTO_TFM_NEED_KEY is set during tfm creation if algo requires > the key. And it's freed when the key setup is successful. As there is no > way bpf programs can modify tfm directly we can move this check to > bpf_crypto_ctx_create() to key setup part and avoid indirect call in this place. >> >>> +        return -EINVAL; >>> + >>> +    if (__bpf_dynptr_is_rdonly(dst)) >>> +        return -EINVAL; >>> + >>> +    siv_len = __bpf_dynptr_size(siv); >>> +    src_len = __bpf_dynptr_size(src); >>> +    dst_len = __bpf_dynptr_size(dst); >>> +    if (!src_len || !dst_len) >>> +        return -EINVAL; >>> + >>> +    if (siv_len != (ctx->type->ivsize(ctx->tfm) + >>> ctx->type->statesize(ctx->tfm))) >> >> Same here, two indirect calls per en/decrypt kfunc call. Does the return value >> change? > > I have to check the size of IV provided by the caller, and then to avoid > indirect calls I have to store these values somewhere in ctx. It gives a > direct access to these values to bpf programs, which can potentially > abuse them. Not sure if it's good to open such opportunity. I don't think it makes any difference considering tfm has already been accessible in ctx->tfm. A noob question, what secret is in the siv len? btw, unrelated, based on the selftest in patch 3, is it supporting any siv_len > 0 for now? > >> >>> +        return -EINVAL; >>> + >>> +    psrc = __bpf_dynptr_data(src, src_len); >>> +    if (!psrc) >>> +        return -EINVAL; >>> +    pdst = __bpf_dynptr_data_rw(dst, dst_len); >>> +    if (!pdst) >>> +        return -EINVAL; >>> + >>> +    piv = siv_len ? __bpf_dynptr_data_rw(siv, siv_len) : NULL; >>> +    if (siv_len && !piv) >>> +        return -EINVAL; >>> + >>> +    err = decrypt ? ctx->type->decrypt(ctx->tfm, psrc, pdst, src_len, piv) >>> +              : ctx->type->encrypt(ctx->tfm, psrc, pdst, src_len, piv); >>> + >>> +    return err; >>> +} >> >