diff mbox

[RFC,1/2] unix sockets: add ability for search for peer from passed root

Message ID 20120810125730.7115.96005.stgit@localhost.localdomain (mailing list archive)
State New, archived
Headers show

Commit Message

Stanislav Kinsbursky Aug. 10, 2012, 12:57 p.m. UTC 
This helper is used stream sockets yet.
All is simple: if non-NULL struct path was passed to unix_find_other(), then
vfs_path_lookup() is called instead of kern_path().

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
---
 include/net/af_unix.h |    2 ++
 net/unix/af_unix.c    |   25 ++++++++++++++++++-------
 2 files changed, 20 insertions(+), 7 deletions(-)


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Comments

J. Bruce Fields Aug. 10, 2012, 6:10 p.m. UTC | #1 
On Fri, Aug 10, 2012 at 04:57:30PM +0400, Stanislav Kinsbursky wrote:
> This helper is used stream sockets yet.
> All is simple: if non-NULL struct path was passed to unix_find_other(), then
> vfs_path_lookup() is called instead of kern_path().

I'm having some trouble parsing the changelog.  Maybe something like?:

	unix sockets: add ability to look up using passed-in root

	Export a unix_stream_connect_root() helper that allows a caller
	to optionally pass in a root path, in which case the lookup will
	be done relative to the given path instead of the current
	working directory.

I guess this is a question for the networking people, but: will it cause
problems to have sunrpc calling directly into the unix socket code?

(And if so, what would be the alternative: define some variant of
sockaddr_un that includes the root path?  Something better?)

--b.

> 
> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
> ---
>  include/net/af_unix.h |    2 ++
>  net/unix/af_unix.c    |   25 ++++++++++++++++++-------
>  2 files changed, 20 insertions(+), 7 deletions(-)
> 
> diff --git a/include/net/af_unix.h b/include/net/af_unix.h
> index 2ee33da..559467e 100644
> --- a/include/net/af_unix.h
> +++ b/include/net/af_unix.h
> @@ -67,6 +67,8 @@ struct unix_sock {
>  
>  long unix_inq_len(struct sock *sk);
>  long unix_outq_len(struct sock *sk);
> +int unix_stream_connect_root(struct path *root, struct socket *sock,
> +			     struct sockaddr *uaddr, int addr_len, int flags);
>  
>  #ifdef CONFIG_SYSCTL
>  extern int unix_sysctl_register(struct net *net);
> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
> index 641f2e4..a790ebc 100644
> --- a/net/unix/af_unix.c
> +++ b/net/unix/af_unix.c
> @@ -759,7 +759,7 @@ out:	mutex_unlock(&u->readlock);
>  	return err;
>  }
>  
> -static struct sock *unix_find_other(struct net *net,
> +static struct sock *unix_find_other(struct net *net, struct path *root,
>  				    struct sockaddr_un *sunname, int len,
>  				    int type, unsigned int hash, int *error)
>  {
> @@ -769,7 +769,11 @@ static struct sock *unix_find_other(struct net *net,
>  
>  	if (sunname->sun_path[0]) {
>  		struct inode *inode;
> -		err = kern_path(sunname->sun_path, LOOKUP_FOLLOW, &path);
> +
> +		if (root)
> +			err = vfs_path_lookup(root->dentry, root->mnt, sunname->sun_path, LOOKUP_FOLLOW, &path);
> +		else
> +			err = kern_path(sunname->sun_path, LOOKUP_FOLLOW, &path);
>  		if (err)
>  			goto fail;
>  		inode = path.dentry->d_inode;
> @@ -979,7 +983,7 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
>  			goto out;
>  
>  restart:
> -		other = unix_find_other(net, sunaddr, alen, sock->type, hash, &err);
> +		other = unix_find_other(net, NULL, sunaddr, alen, sock->type, hash, &err);
>  		if (!other)
>  			goto out;
>  
> @@ -1053,8 +1057,8 @@ static long unix_wait_for_peer(struct sock *other, long timeo)
>  	return timeo;
>  }
>  
> -static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
> -			       int addr_len, int flags)
> +int unix_stream_connect_root(struct path *root, struct socket *sock,
> +			     struct sockaddr *uaddr, int addr_len, int flags)
>  {
>  	struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr;
>  	struct sock *sk = sock->sk;
> @@ -1098,7 +1102,7 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
>  
>  restart:
>  	/*  Find listening sock. */
> -	other = unix_find_other(net, sunaddr, addr_len, sk->sk_type, hash, &err);
> +	other = unix_find_other(net, root, sunaddr, addr_len, sk->sk_type, hash, &err);
>  	if (!other)
>  		goto out;
>  
> @@ -1227,6 +1231,13 @@ out:
>  		sock_put(other);
>  	return err;
>  }
> +EXPORT_SYMBOL_GPL(unix_stream_connect_root);
> +
> +static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
> +				    int addr_len, int flags)
> +{
> +	return unix_stream_connect_root(NULL, sock, uaddr, addr_len, flags);
> +}
>  
>  static int unix_socketpair(struct socket *socka, struct socket *sockb)
>  {
> @@ -1508,7 +1519,7 @@ restart:
>  		if (sunaddr == NULL)
>  			goto out_free;
>  
> -		other = unix_find_other(net, sunaddr, namelen, sk->sk_type,
> +		other = unix_find_other(net, NULL, sunaddr, namelen, sk->sk_type,
>  					hash, &err);
>  		if (other == NULL)
>  			goto out_free;
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
> the body of a message to majordomo@vger.kernel.org
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Stanislav Kinsbursky Aug. 10, 2012, 6:43 p.m. UTC | #2 
10.08.2012 22:10, J. Bruce Fields ?????:
> On Fri, Aug 10, 2012 at 04:57:30PM +0400, Stanislav Kinsbursky wrote:
>> This helper is used stream sockets yet.
>> All is simple: if non-NULL struct path was passed to unix_find_other(), then
>> vfs_path_lookup() is called instead of kern_path().
> I'm having some trouble parsing the changelog.  Maybe something like?:
>
> 	unix sockets: add ability to look up using passed-in root
>
> 	Export a unix_stream_connect_root() helper that allows a caller
> 	to optionally pass in a root path, in which case the lookup will
> 	be done relative to the given path instead of the current
> 	working directory.

Yep, your variant is much better. Thanks.

>
> I guess this is a question for the networking people, but: will it cause
> problems to have sunrpc calling directly into the unix socket code?
>
> (And if so, what would be the alternative: define some variant of
> sockaddr_un that includes the root path?  Something better?)

That was my first idea. But there are problems with this solution (add 
root path to sockaddr_un) :
1) sockaddr_un size will change. I don't know, how this will affect 
user-space. Of course, we can introduce something like:

struct sockaddr_un_kern {
struct sockaddr_un un;
struct path *path;
}

But even in this case we need to color this structure somehow (for 
example, set path to NULL for simple connect or bind call) . And to add 
this color, we have to separate sys_connect () from our 
sock->ops->connect() call. And I don't really know how to do it since we 
don't have any info about socket type in sys_connect () in hands. I.e. 
we have it, but then we have to add some specific UNIX socket logic to 
completely generic sys_connect () and sys_bind () .

> --b.
>
>> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
>> ---
>>   include/net/af_unix.h |    2 ++
>>   net/unix/af_unix.c    |   25 ++++++++++++++++++-------
>>   2 files changed, 20 insertions(+), 7 deletions(-)
>>
>> diff --git a/include/net/af_unix.h b/include/net/af_unix.h
>> index 2ee33da..559467e 100644
>> --- a/include/net/af_unix.h
>> +++ b/include/net/af_unix.h
>> @@ -67,6 +67,8 @@ struct unix_sock {
>>   
>>   long unix_inq_len(struct sock *sk);
>>   long unix_outq_len(struct sock *sk);
>> +int unix_stream_connect_root(struct path *root, struct socket *sock,
>> +			     struct sockaddr *uaddr, int addr_len, int flags);
>>   
>>   #ifdef CONFIG_SYSCTL
>>   extern int unix_sysctl_register(struct net *net);
>> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
>> index 641f2e4..a790ebc 100644
>> --- a/net/unix/af_unix.c
>> +++ b/net/unix/af_unix.c
>> @@ -759,7 +759,7 @@ out:	mutex_unlock(&u->readlock);
>>   	return err;
>>   }
>>   
>> -static struct sock *unix_find_other(struct net *net,
>> +static struct sock *unix_find_other(struct net *net, struct path *root,
>>   				    struct sockaddr_un *sunname, int len,
>>   				    int type, unsigned int hash, int *error)
>>   {
>> @@ -769,7 +769,11 @@ static struct sock *unix_find_other(struct net *net,
>>   
>>   	if (sunname->sun_path[0]) {
>>   		struct inode *inode;
>> -		err = kern_path(sunname->sun_path, LOOKUP_FOLLOW, &path);
>> +
>> +		if (root)
>> +			err = vfs_path_lookup(root->dentry, root->mnt, sunname->sun_path, LOOKUP_FOLLOW, &path);
>> +		else
>> +			err = kern_path(sunname->sun_path, LOOKUP_FOLLOW, &path);
>>   		if (err)
>>   			goto fail;
>>   		inode = path.dentry->d_inode;
>> @@ -979,7 +983,7 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
>>   			goto out;
>>   
>>   restart:
>> -		other = unix_find_other(net, sunaddr, alen, sock->type, hash, &err);
>> +		other = unix_find_other(net, NULL, sunaddr, alen, sock->type, hash, &err);
>>   		if (!other)
>>   			goto out;
>>   
>> @@ -1053,8 +1057,8 @@ static long unix_wait_for_peer(struct sock *other, long timeo)
>>   	return timeo;
>>   }
>>   
>> -static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
>> -			       int addr_len, int flags)
>> +int unix_stream_connect_root(struct path *root, struct socket *sock,
>> +			     struct sockaddr *uaddr, int addr_len, int flags)
>>   {
>>   	struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr;
>>   	struct sock *sk = sock->sk;
>> @@ -1098,7 +1102,7 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
>>   
>>   restart:
>>   	/*  Find listening sock. */
>> -	other = unix_find_other(net, sunaddr, addr_len, sk->sk_type, hash, &err);
>> +	other = unix_find_other(net, root, sunaddr, addr_len, sk->sk_type, hash, &err);
>>   	if (!other)
>>   		goto out;
>>   
>> @@ -1227,6 +1231,13 @@ out:
>>   		sock_put(other);
>>   	return err;
>>   }
>> +EXPORT_SYMBOL_GPL(unix_stream_connect_root);
>> +
>> +static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
>> +				    int addr_len, int flags)
>> +{
>> +	return unix_stream_connect_root(NULL, sock, uaddr, addr_len, flags);
>> +}
>>   
>>   static int unix_socketpair(struct socket *socka, struct socket *sockb)
>>   {
>> @@ -1508,7 +1519,7 @@ restart:
>>   		if (sunaddr == NULL)
>>   			goto out_free;
>>   
>> -		other = unix_find_other(net, sunaddr, namelen, sk->sk_type,
>> +		other = unix_find_other(net, NULL, sunaddr, namelen, sk->sk_type,
>>   					hash, &err);
>>   		if (other == NULL)
>>   			goto out_free;
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html

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diff mbox

Patch

diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index 2ee33da..559467e 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -67,6 +67,8 @@  struct unix_sock {
 
 long unix_inq_len(struct sock *sk);
 long unix_outq_len(struct sock *sk);
+int unix_stream_connect_root(struct path *root, struct socket *sock,
+			     struct sockaddr *uaddr, int addr_len, int flags);
 
 #ifdef CONFIG_SYSCTL
 extern int unix_sysctl_register(struct net *net);
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 641f2e4..a790ebc 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -759,7 +759,7 @@  out:	mutex_unlock(&u->readlock);
 	return err;
 }
 
-static struct sock *unix_find_other(struct net *net,
+static struct sock *unix_find_other(struct net *net, struct path *root,
 				    struct sockaddr_un *sunname, int len,
 				    int type, unsigned int hash, int *error)
 {
@@ -769,7 +769,11 @@  static struct sock *unix_find_other(struct net *net,
 
 	if (sunname->sun_path[0]) {
 		struct inode *inode;
-		err = kern_path(sunname->sun_path, LOOKUP_FOLLOW, &path);
+
+		if (root)
+			err = vfs_path_lookup(root->dentry, root->mnt, sunname->sun_path, LOOKUP_FOLLOW, &path);
+		else
+			err = kern_path(sunname->sun_path, LOOKUP_FOLLOW, &path);
 		if (err)
 			goto fail;
 		inode = path.dentry->d_inode;
@@ -979,7 +983,7 @@  static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
 			goto out;
 
 restart:
-		other = unix_find_other(net, sunaddr, alen, sock->type, hash, &err);
+		other = unix_find_other(net, NULL, sunaddr, alen, sock->type, hash, &err);
 		if (!other)
 			goto out;
 
@@ -1053,8 +1057,8 @@  static long unix_wait_for_peer(struct sock *other, long timeo)
 	return timeo;
 }
 
-static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
-			       int addr_len, int flags)
+int unix_stream_connect_root(struct path *root, struct socket *sock,
+			     struct sockaddr *uaddr, int addr_len, int flags)
 {
 	struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr;
 	struct sock *sk = sock->sk;
@@ -1098,7 +1102,7 @@  static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 
 restart:
 	/*  Find listening sock. */
-	other = unix_find_other(net, sunaddr, addr_len, sk->sk_type, hash, &err);
+	other = unix_find_other(net, root, sunaddr, addr_len, sk->sk_type, hash, &err);
 	if (!other)
 		goto out;
 
@@ -1227,6 +1231,13 @@  out:
 		sock_put(other);
 	return err;
 }
+EXPORT_SYMBOL_GPL(unix_stream_connect_root);
+
+static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
+				    int addr_len, int flags)
+{
+	return unix_stream_connect_root(NULL, sock, uaddr, addr_len, flags);
+}
 
 static int unix_socketpair(struct socket *socka, struct socket *sockb)
 {
@@ -1508,7 +1519,7 @@  restart:
 		if (sunaddr == NULL)
 			goto out_free;
 
-		other = unix_find_other(net, sunaddr, namelen, sk->sk_type,
+		other = unix_find_other(net, NULL, sunaddr, namelen, sk->sk_type,
 					hash, &err);
 		if (other == NULL)
 			goto out_free;