[dpdk-dev] [PATCH] net/memif: fix abstract socket addr_len

[Andrew Rybchenko]

On 6/17/21 7:22 PM, Nathan Skrzypczak wrote:
> This fixes using abstract sockets with memifs.
> we were not passing the exact addr_len, which
> requires zeroing the remaining sun_path and
> doesn't appear well in other utilities (e.g.
> lsof -U)
> 
> Signed-off-by: Nathan Skrzypczak <nathan.skrzypczak at gmail.com>
> ---
>  drivers/net/memif/memif_socket.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/memif/memif_socket.c b/drivers/net/memif/memif_socket.c
> index 5b373738e6..7498a2f58d 100644
> --- a/drivers/net/memif/memif_socket.c
> +++ b/drivers/net/memif/memif_socket.c
> @@ -866,6 +866,7 @@ memif_socket_create(char *key, uint8_t listener, bool is_abstract)
>  {
>  	struct memif_socket *sock;
>  	struct sockaddr_un un = { 0 };
> +	uint32_t sunlen;
>  	int sockfd;
>  	int ret;
>  	int on = 1;
> @@ -890,7 +891,10 @@ memif_socket_create(char *key, uint8_t listener, bool is_abstract)
>  			/* abstract address */
>  			un.sun_path[0] = '\0';
>  			strlcpy(un.sun_path + 1, sock->filename, MEMIF_SOCKET_UN_SIZE - 1);
> +			sunlen = 1 + strlen(sock->filename) +
> +				 sizeof(un.sun_family);

It assumes that sockaddr_un consists of two fields. It is
better to avoid the assumption and subtract sizeof(un.sun_path)
from sizeof(un). It assumes fields order, but it is essential
for the patch anyway. Also always true as far as I know.

What I don't understand is why we don't care about the case
when filename does not fit into sun_path. If so, strlcpy()
will truncate it and sunlen will be incorrect.

>  		} else {
> +			sunlen = sizeof(un);
>  			strlcpy(un.sun_path, sock->filename, MEMIF_SOCKET_UN_SIZE);
>  		}
>  
> @@ -899,7 +903,7 @@ memif_socket_create(char *key, uint8_t listener, bool is_abstract)
>  		if (ret < 0)
>  			goto error;
>  
> -		ret = bind(sockfd, (struct sockaddr *)&un, sizeof(un));
> +		ret = bind(sockfd, (struct sockaddr *)&un, sunlen);
>  		if (ret < 0)
>  			goto error;
>  
> @@ -1061,6 +1065,7 @@ memif_connect_client(struct rte_eth_dev *dev)
>  {
>  	int sockfd;
>  	int ret;
> +	uint32_t sunlen;
>  	struct sockaddr_un sun = { 0 };
>  	struct pmd_internals *pmd = dev->data->dev_private;
>  
> @@ -1075,16 +1080,18 @@ memif_connect_client(struct rte_eth_dev *dev)
>  	}
>  
>  	sun.sun_family = AF_UNIX;
> +	sunlen = sizeof(struct sockaddr_un);
>  	if (pmd->flags & ETH_MEMIF_FLAG_SOCKET_ABSTRACT) {
>  		/* abstract address */
>  		sun.sun_path[0] = '\0';
>  		strlcpy(sun.sun_path + 1,  pmd->socket_filename, MEMIF_SOCKET_UN_SIZE - 1);
> +		sunlen = strlen(pmd->socket_filename) + 1 +
> +			 sizeof(sun.sun_family);

same as above

>  	} else {
>  		strlcpy(sun.sun_path,  pmd->socket_filename, MEMIF_SOCKET_UN_SIZE);
>  	}
>  
> -	ret = connect(sockfd, (struct sockaddr *)&sun,
> -		      sizeof(struct sockaddr_un));
> +	ret = connect(sockfd, (struct sockaddr *)&sun, sunlen);
>  	if (ret < 0) {
>  		MIF_LOG(ERR, "Failed to connect socket: %s.", pmd->socket_filename);
>  		goto error;
>