2009-12-13 14:56:10

by Alexander Beregalov

[permalink] [raw]
Subject: [PATCH] Staging: dst: fix 'Client is not allowed' on sparc


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


2009-12-16 18:24:40

by Evgeniy Polyakov

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

Hi Alexander.

Sorry for late response.
Your patch looks good, I will forward it to GregKH for inclusion.
Thank you.

On Sun, Dec 13, 2009 at 05:55:47PM +0300, Alexander Beregalov ([email protected]) 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

2009-12-16 19:06:11

by Alexander Beregalov

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

2009/12/16 Evgeniy Polyakov <[email protected]>:
> 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 ([email protected]) 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
>