Re: git: c3d3f3594fdf - stable/13 - netlink: allow to override sb_max for netlink sockets.

> On 10 Feb 2023, at 17:00, Mike Karels <mike@karels.net> wrote:
> 
> On 10 Feb 2023, at 10:19, Alexander V. Chernikov wrote:
> 
>> The branch stable/13 has been updated by melifaro:
>> 
>> URL: https://cgit.FreeBSD.org/src/commit/?id=c3d3f3594fdf653392936594b75ec330af12d7fa
>> 
>> commit c3d3f3594fdf653392936594b75ec330af12d7fa
>> Author:     Alexander V. Chernikov <melifaro@FreeBSD.org>
>> AuthorDate: 2023-02-10 16:07:17 +0000
>> Commit:     Alexander V. Chernikov <melifaro@FreeBSD.org>
>> CommitDate: 2023-02-10 16:07:22 +0000
>> 
>>   netlink: allow to override sb_max for netlink sockets.
>> 
>>   Netlink sockets sometimes require larger buffers than other sockets.
>>   For example, full-view IPv4 dump sent via netlink may consume 50+ megabytes.
>>   The desired buffer may be bigger than the system maximum `sb_max`.
>>   FreeBSD HEAD has a mechanism for overriding protocol `setsockopt()` handler,
>>    which netlink  uses to permit buffer reservations beyond `sb_max`.
>>    This behaviour is handy as it doesn't require system administrator to lift
>>    the limits for other sockets.
>>   Stable/13 lack such muchanism, so a different approach has to be used.
>>   This diff is a direct commit to stable/13 and it simply copies the logic from
>>    Netlink in -HEAD for checking if the larger buffer size should be permitted.
>> 
>>   Differential Revision: https://reviews.freebsd.org/D38472
>> ---
>> sys/kern/uipc_sockbuf.c |  3 ++-
>> sys/kern/uipc_socket.c  | 10 ++++++++++
>> sys/sys/sockopt.h       |  1 +
>> 3 files changed, 13 insertions(+), 1 deletion(-)
>> 
>> diff --git a/sys/kern/uipc_sockbuf.c b/sys/kern/uipc_sockbuf.c
>> index cbfcc0e5fe95..277965412779 100644
>> --- a/sys/kern/uipc_sockbuf.c
>> +++ b/sys/kern/uipc_sockbuf.c
>> @@ -693,7 +693,8 @@ sbsetopt(struct socket *so, int cmd, u_long cc)
>> if (*lowat > *hiwat)
>> *lowat = *hiwat;
>> } else {
>> - if (!sbreserve_locked(sb, cc, so, curthread))
>> +                        u_long limit = sogetmaxbuf(so);
> 
> Spaces instead of tabs.
> 
> Mike
Ups. Haven’t noticed that one.
Fixed in f9f0d2f475e05ad88120ef1c0a645d2aa6dc3e94.
Thank you!
> 
>> + if (!sbreserve_locked_limit(sb, cc, so, limit, curthread))
>> error = ENOBUFS;
>> }
>> if (error == 0)
>> diff --git a/sys/kern/uipc_socket.c b/sys/kern/uipc_socket.c
>> index f8931b653a4d..fdf718de2483 100644
>> --- a/sys/kern/uipc_socket.c
>> +++ b/sys/kern/uipc_socket.c
>> @@ -128,6 +128,7 @@ __FBSDID("$FreeBSD$");
>> #include <sys/event.h>
>> #include <sys/eventhandler.h>
>> #include <sys/poll.h>
>> +#include <sys/priv.h>
>> #include <sys/proc.h>
>> #include <sys/protosw.h>
>> #include <sys/sbuf.h>
>> @@ -2975,6 +2976,15 @@ sooptcopyin(struct sockopt *sopt, void *buf, size_t len, size_t minlen)
>> return (0);
>> }
>> 
>> +u_long
>> +sogetmaxbuf(struct socket *so)
>> +{
>> + if (so->so_proto->pr_domain->dom_family != PF_NETLINK)
>> + return (sb_max);
>> + u_long nl_maxsockbuf = 512 * 1024 * 1024; /* 512M, XXX: init based on physmem */
>> + return ((priv_check(curthread, PRIV_NET_ROUTE) == 0) ? nl_maxsockbuf : sb_max);
>> +}
>> +
>> /*
>> * Kernel version of setsockopt(2).
>> *
>> diff --git a/sys/sys/sockopt.h b/sys/sys/sockopt.h
>> index cb7fc3ffca27..d01d62f21680 100644
>> --- a/sys/sys/sockopt.h
>> +++ b/sys/sys/sockopt.h
>> @@ -68,5 +68,6 @@ int accept_filt_getopt(struct socket *, struct sockopt *);
>> int accept_filt_setopt(struct socket *, struct sockopt *);
>> int so_setsockopt(struct socket *so, int level, int optname,
>>   void *optval, size_t optlen);
>> +u_long sogetmaxbuf(struct socket *so);
>> 
>> #endif /* _SYS_SOCKOPT_H_ */