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Message-ID: <3d04ff60-c01b-4718-ae3d-70d19ee2019a@quicinc.com>
Date: Wed, 29 May 2024 08:49:21 -0700
From: "Abhishek Chauhan (ABC)" <quic_abchauha@...cinc.com>
To: Willem de Bruijn <willemdebruijn.kernel@...il.com>,
"David S. Miller"
<davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski
<kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>, <netdev@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, Andrew Halaney <ahalaney@...hat.com>,
"Martin
KaFai Lau" <martin.lau@...nel.org>,
Martin KaFai Lau <martin.lau@...ux.dev>,
Daniel Borkmann <daniel@...earbox.net>, bpf <bpf@...r.kernel.org>
CC: <kernel@...cinc.com>,
<syzbot+d7b227731ec589e7f4f0@...kaller.appspotmail.com>,
<syzbot+30a35a2e9c5067cc43fa@...kaller.appspotmail.com>
Subject: Re: [PATCH net] net: validate SO_TXTIME clockid coming from userspace
On 5/29/2024 6:58 AM, Willem de Bruijn wrote:
> minor: double space before userspace
>
> Abhishek Chauhan wrote:
>> Currently there are no strict checks while setting SO_TXTIME
>> from userspace. With the recent development in skb->tstamp_type
>> clockid with unsupported clocks results in warn_on_once, which causes
>> unnecessary aborts in some systems which enables panic on warns.
>>
>> Add validation in setsockopt to support only CLOCK_REALTIME,
>> CLOCK_MONOTONIC and CLOCK_TAI to be set from userspace.
>>
>> Link: https://lore.kernel.org/netdev/bc037db4-58bb-4861-ac31-a361a93841d3@linux.dev/
>> Link: https://lore.kernel.org/lkml/20240509211834.3235191-1-quic_abchauha@quicinc.com/
>
> These discussions can be found directly from the referenced commit?
> If any, I'd like to the conversation we had that arrived at this
> approach.
>
Not Directly but from the patch series.
1. First link is for why we introduced skb->tstamp_type
2. Second link points to the series were we discussed on two approach to solve the problem
one being limit the skclockid to just TAI,MONO and REALTIME.
>> Fixes: 1693c5db6ab8 ("net: Add additional bit to support clockid_t timestamp type")
>> Reported-by: syzbot+d7b227731ec589e7f4f0@...kaller.appspotmail.com
>> Closes: https://syzkaller.appspot.com/bug?extid=d7b227731ec589e7f4f0
>> Reported-by: syzbot+30a35a2e9c5067cc43fa@...kaller.appspotmail.com
>> Closes: https://syzkaller.appspot.com/bug?extid=30a35a2e9c5067cc43fa
>> Signed-off-by: Abhishek Chauhan <quic_abchauha@...cinc.com>
>> ---
>> net/core/sock.c | 16 ++++++++++++++++
>> 1 file changed, 16 insertions(+)
>>
>> diff --git a/net/core/sock.c b/net/core/sock.c
>> index 8629f9aecf91..f8374be9d8c9 100644
>> --- a/net/core/sock.c
>> +++ b/net/core/sock.c
>> @@ -1083,6 +1083,17 @@ bool sockopt_capable(int cap)
>> }
>> EXPORT_SYMBOL(sockopt_capable);
>>
>> +static int sockopt_validate_clockid(int value)
>
> sock_txtime.clockid has type __kernel_clockid_t.
>
__kernel_clockid_t is typedef of int.
>> +{
>> + switch (value) {
>> + case CLOCK_REALTIME:
>> + case CLOCK_MONOTONIC:
>> + case CLOCK_TAI:
>> + return 0;
>> + }
>> + return -EINVAL;
>> +}
>> +
>> /*
>> * This is meant for all protocols to use and covers goings on
>> * at the socket level. Everything here is generic.
>> @@ -1497,6 +1508,11 @@ int sk_setsockopt(struct sock *sk, int level, int optname,
>> ret = -EPERM;
>> break;
>> }
>> +
>> + ret = sockopt_validate_clockid(sk_txtime.clockid);
>> + if (ret)
>> + break;
>> +
>> sock_valbool_flag(sk, SOCK_TXTIME, true);
>> sk->sk_clockid = sk_txtime.clockid;
>> sk->sk_txtime_deadline_mode =
>> --
>> 2.25.1
>>
>
>
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