From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-189.mta1.migadu.com (out-189.mta1.migadu.com [95.215.58.189]) (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 E7C8316FF4C for ; Fri, 5 Apr 2024 15:53:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.189 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712332402; cv=none; b=ZJr7HCGGq2uNgTBCljjt1kn1hhfe4WM+z0IYmh3NJh00tEy1YuiRwGspYAwgEJ6rS0/y9huOSVMjivNf0INFUGOz5llBNVy3C/pRWqpHtbUOFuraQKj13i4uJlYHgFqKLaQyv+yQq6XAGiPVu96fu0zD82Q6MzDxNgEZTCfg4cE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712332402; c=relaxed/simple; bh=cgFgLDvXzVVBZx90EIohepeVJaMj4xdg03IMlJj/h5o=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=qA+SKGAo8A2LZM6gPz7WqUpicIVwSLgsaNvZkcG7UQ3MDWFtoTiwadjoyhjj2NSo1M3Esto5K+nTUUAaMj8FjpU34d/SkeAmnxEkrEkd/bDmH0Fv45y3yRpFOh9TgK71d6+pHR+Nbb7cU0RoNZw5Vt7KFG7gM4xbiD0pmP78CJM= 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=Bccwq6DA; arc=none smtp.client-ip=95.215.58.189 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="Bccwq6DA" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1712332394; 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=YeFplG003BsPVqzbc/lEZ6wk0FP/62I+Mj9G6/iBL+g=; b=Bccwq6DAcFUssYepWmbFEL9Tyr5Svrw6ofGcRtNpGv340Tf0CxLQClZkrkC3URL8qp/oKW iZzynqToox34w2PIuN/NeVz/3HEzhRV7w62jbDuoGn8vEVnNH9p4h3vdA0FKfnDg4pOlpO +Np5lOv45Ugn51cea9mNlgmhmhWdI9o= Date: Fri, 5 Apr 2024 08:53:06 -0700 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf-next v4 1/5] bpf: Add bpf_link support for sk_msg and sk_skb progs Content-Language: en-GB To: John Fastabend , bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Jakub Sitnicki , kernel-team@fb.com, Martin KaFai Lau References: <20240404025305.2210999-1-yonghong.song@linux.dev> <20240404025310.2211688-1-yonghong.song@linux.dev> <66101695d69a7_5803020833@john.notmuch> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yonghong Song In-Reply-To: <66101695d69a7_5803020833@john.notmuch> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 4/5/24 8:19 AM, John Fastabend wrote: > Yonghong Song wrote: >> Add bpf_link support for sk_msg and sk_skb programs. We have an >> internal request to support bpf_link for sk_msg programs so user >> space can have a uniform handling with bpf_link based libbpf >> APIs. Using bpf_link based libbpf API also has a benefit which >> makes system robust by decoupling prog life cycle and >> attachment life cycle. >> >> Signed-off-by: Yonghong Song >> --- >> include/linux/bpf.h | 6 + >> include/linux/skmsg.h | 4 + >> include/uapi/linux/bpf.h | 5 + >> kernel/bpf/syscall.c | 4 + >> net/core/sock_map.c | 268 ++++++++++++++++++++++++++++++++- >> tools/include/uapi/linux/bpf.h | 5 + >> 6 files changed, 284 insertions(+), 8 deletions(-) >> > LGTM one question below. > >> +/* Handle the following two cases: >> + * case 1: link != NULL, prog != NULL, old != NULL >> + * case 2: link != NULL, prog != NULL, old == NULL >> + */ >> +static int sock_map_link_update_prog(struct bpf_link *link, >> + struct bpf_prog *prog, >> + struct bpf_prog *old) >> +{ >> + const struct sockmap_link *sockmap_link = container_of(link, struct sockmap_link, link); >> + struct bpf_prog **pprog; >> + struct bpf_link **plink; >> + int ret = 0; >> + >> + mutex_lock(&sockmap_mutex); >> + >> + /* If old prog is not NULL, ensure old prog is the same as link->prog. */ >> + if (old && link->prog != old) { >> + ret = -EINVAL; >> + goto out; >> + } >> + /* Ensure link->prog has the same type/attach_type as the new prog. */ >> + if (link->prog->type != prog->type || >> + link->prog->expected_attach_type != prog->expected_attach_type) { >> + ret = -EINVAL; >> + goto out; >> + } >> + >> + ret = sock_map_prog_lookup(sockmap_link->map, &pprog, >> + sockmap_link->attach_type); >> + if (ret) >> + goto out; >> + >> + /* Ensure the same link between the one in map and the passed-in. */ >> + ret = sock_map_link_lookup(sockmap_link->map, &plink, link, false, >> + sockmap_link->attach_type); >> + if (ret) >> + goto out; >> + >> + if (old) { >> + ret = psock_replace_prog(pprog, prog, old); >> + goto out; >> + } >> + >> + psock_set_prog(pprog, prog); >> + >> +out: >> + if (!ret) { >> + bpf_prog_inc(prog); >> + old = xchg(&link->prog, prog); >> + bpf_prog_put(old); > Need to check old? I don't think we can clal bpf_prog_put on null? > > if (old) > bpf_prog_put(old) The 'old' here represents the *old* link->prog program and link->prog should not be NULL at this point. If sock_map_link_update_prog() is called here, that means, the kernel already holds a reference for the bpf link. See kernel/bpf/syscall.c, link_update(). So the bpf_link is valid and not in released stage, and link->prog should not be NULL. > >> + } >> + mutex_unlock(&sockmap_mutex); >> + return ret; >> +} >> +