Re: [PATCH 2/3] net/unix: hook unix_socketpair() into LSM

[Paul Moore]

On Tue, Apr 24, 2018 at 1:56 PM, David Miller  wrote:
> From: Paul Moore 
> Date: Tue, 24 Apr 2018 13:55:31 -0400
>
>> On Mon, Apr 23, 2018 at 9:30 AM, David Herrmann  
>> wrote:
>>> Use the newly created LSM-hook for unix_socketpair(). The default hook
>>> return-value is 0, so behavior stays the same unless LSMs start using
>>> this hook.
>>>
>>> Signed-off-by: David Herrmann 
>>> ---
>>>  net/unix/af_unix.c | 5 +
>>>  1 file changed, 5 insertions(+)
>>>
>>> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
>>> index 68bb70a62afe..bc9705ace9b1 100644
>>> --- a/net/unix/af_unix.c
>>> +++ b/net/unix/af_unix.c
>>> @@ -1371,6 +1371,11 @@ static int unix_stream_connect(struct socket *sock, 
>>> struct sockaddr *uaddr,
>>>  static int unix_socketpair(struct socket *socka, struct socket *sockb)
>>>  {
>>> struct sock *ska = socka->sk, *skb = sockb->sk;
>>> +   int err;
>>> +
>>> +   err = security_unix_stream_socketpair(ska, skb);
>>> +   if (err)
>>> +   return err;
>>
>> I recognize that AF_UNIX is really the only protocol that supports
>> socketpair(2) at the moment, but I like to avoid protocol specific LSM
>> hooks whenever possible.  Unless someone can think of a good
>> objection, I would prefer to see the hook placed in __sys_socketpair()
>> instead (and obviously drop the "unix_stream" portion from the hook
>> name).
>
> The counterargument is that after 30 years no other protocol has grown
> usage of this operation. :-)

Call me a an optimist ;)

-- 
paul moore
www.paul-moore.com

Re: [PATCH 2/3] net/unix: hook unix_socketpair() into LSM

[David Miller]

From: Paul Moore 
Date: Tue, 24 Apr 2018 13:55:31 -0400

> On Mon, Apr 23, 2018 at 9:30 AM, David Herrmann  wrote:
>> Use the newly created LSM-hook for unix_socketpair(). The default hook
>> return-value is 0, so behavior stays the same unless LSMs start using
>> this hook.
>>
>> Signed-off-by: David Herrmann 
>> ---
>>  net/unix/af_unix.c | 5 +
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
>> index 68bb70a62afe..bc9705ace9b1 100644
>> --- a/net/unix/af_unix.c
>> +++ b/net/unix/af_unix.c
>> @@ -1371,6 +1371,11 @@ static int unix_stream_connect(struct socket *sock, 
>> struct sockaddr *uaddr,
>>  static int unix_socketpair(struct socket *socka, struct socket *sockb)
>>  {
>> struct sock *ska = socka->sk, *skb = sockb->sk;
>> +   int err;
>> +
>> +   err = security_unix_stream_socketpair(ska, skb);
>> +   if (err)
>> +   return err;
> 
> I recognize that AF_UNIX is really the only protocol that supports
> socketpair(2) at the moment, but I like to avoid protocol specific LSM
> hooks whenever possible.  Unless someone can think of a good
> objection, I would prefer to see the hook placed in __sys_socketpair()
> instead (and obviously drop the "unix_stream" portion from the hook
> name).

The counterargument is that after 30 years no other protocol has grown
usage of this operation. :-)

Re: [PATCH 2/3] net/unix: hook unix_socketpair() into LSM

[Paul Moore]

On Mon, Apr 23, 2018 at 9:30 AM, David Herrmann  wrote:
> Use the newly created LSM-hook for unix_socketpair(). The default hook
> return-value is 0, so behavior stays the same unless LSMs start using
> this hook.
>
> Signed-off-by: David Herrmann 
> ---
>  net/unix/af_unix.c | 5 +
>  1 file changed, 5 insertions(+)
>
> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
> index 68bb70a62afe..bc9705ace9b1 100644
> --- a/net/unix/af_unix.c
> +++ b/net/unix/af_unix.c
> @@ -1371,6 +1371,11 @@ static int unix_stream_connect(struct socket *sock, 
> struct sockaddr *uaddr,
>  static int unix_socketpair(struct socket *socka, struct socket *sockb)
>  {
> struct sock *ska = socka->sk, *skb = sockb->sk;
> +   int err;
> +
> +   err = security_unix_stream_socketpair(ska, skb);
> +   if (err)
> +   return err;

I recognize that AF_UNIX is really the only protocol that supports
socketpair(2) at the moment, but I like to avoid protocol specific LSM
hooks whenever possible.  Unless someone can think of a good
objection, I would prefer to see the hook placed in __sys_socketpair()
instead (and obviously drop the "unix_stream" portion from the hook
name).

> /* Join our sockets back to back */
> sock_hold(ska);
> --
> 2.17.0

-- 
paul moore
www.paul-moore.com

[PATCH 2/3] net/unix: hook unix_socketpair() into LSM

[David Herrmann]

Use the newly created LSM-hook for unix_socketpair(). The default hook
return-value is 0, so behavior stays the same unless LSMs start using
this hook.

Signed-off-by: David Herrmann 
---
 net/unix/af_unix.c | 5 +
 1 file changed, 5 insertions(+)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 68bb70a62afe..bc9705ace9b1 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1371,6 +1371,11 @@ static int unix_stream_connect(struct socket *sock, 
struct sockaddr *uaddr,
 static int unix_socketpair(struct socket *socka, struct socket *sockb)
 {
struct sock *ska = socka->sk, *skb = sockb->sk;
+   int err;
+
+   err = security_unix_stream_socketpair(ska, skb);
+   if (err)
+   return err;
 
/* Join our sockets back to back */
sock_hold(ska);
-- 
2.17.0