Re: [PATCH] Staging: dst: fix 'Client is not allowed' on sparc

[Alexander Beregalov <a.beregalov@gmail.com>]

2009/12/16 Evgeniy Polyakov <zbr@ioremap.net>:
> Hi Alexander.
>
> Sorry for late response.
> Your patch looks good, I will forward it to GregKH for inclusion.

But how does inet_getname() set sa_data_len to 0.
I can't imagine.
My patch is a workaround, not a fix.

Btw, it does not work on sparc anyway, it needs further digging.

> Thank you.
>
> On Sun, Dec 13, 2009 at 05:55:47PM +0300, Alexander Beregalov (a.beregalov@gmail.com) wrote:
>>
>> Not for applying, only describe the problem.
>>
>>
>> There is a warning on sparc
>>  Kernel unaligned access at TPC[6c0dec] inet_getname+0x4c/0xc0
>> which goes from
>>       net/ipv4/af_inet.c:
>>       int inet_getname(
>>               ...
>>               *uaddr_len = sizeof(*sin);
>>
>> sizeof(*sin) is 16, but inet_getname sets sa_data_len to 0.
>> That is why client is denied to access the device.
>> inet_getname() does not read uaddr_len, only
>> writes, so move initialization of sa_data_len after it.
>> Make struct saddr aligned similar to
>> struct __kernel_sockaddr_storage. This fixes the warning.
>>
>> ---
>>  drivers/staging/dst/export.c |    2 +-
>>  include/linux/dst.h          |    4 ++--
>>  2 files changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/staging/dst/export.c b/drivers/staging/dst/export.c
>> index c324230..4644804 100644
>> --- a/drivers/staging/dst/export.c
>> +++ b/drivers/staging/dst/export.c
>> @@ -166,12 +166,12 @@ static struct dst_state *dst_accept_client(struct dst_state *st)
>>       }
>>       new->socket = sock;
>>
>> -     new->ctl.addr.sa_data_len = sizeof(struct sockaddr);
>>       err = kernel_getpeername(sock, (struct sockaddr *)&new->ctl.addr,
>>                       (int *)&new->ctl.addr.sa_data_len);
>>       if (err)
>>               goto err_out_put;
>>
>> +     new->ctl.addr.sa_data_len = sizeof(struct sockaddr);
>>       new->permissions = dst_check_permissions(st, new);
>>       if (new->permissions == 0) {
>>               err = -EPERM;
>> diff --git a/include/linux/dst.h b/include/linux/dst.h
>> index e26fed8..454b15a 100644
>> --- a/include/linux/dst.h
>> +++ b/include/linux/dst.h
>> @@ -74,10 +74,10 @@ struct saddr {
>>       /* address family, AF_xxx       */
>>       unsigned short          sa_family;
>>       /* 14 bytes of protocol address */
>> -     char                    sa_data[SADDR_MAX_DATA];
>> +     char                    sa_data[SADDR_MAX_DATA - sizeof(unsigned short)];
>>       /* Number of bytes used in sa_data */
>>       unsigned short          sa_data_len;
>> -};
>> +} __attribute__((aligned(16)));      /* sizeof(struct sockaddr) */
>>
>>  /* Address structure */
>>  struct dst_network_ctl
>> --
>> 1.6.5.6
>
> --
>        Evgeniy Polyakov
>