[PATCH v2] netlink: fix NLMSG_DONE never enter family specific decoder

[Dmitry V. Levin]

On Mon, Jun 26, 2017 at 10:29:40AM +0800, JingPiao Chen wrote:
> * netlink.c (print_nlmsghdr): Add condition
> nlmsghdr->nlmsg_type != NLMSG_DONE.
> (decode_nlmsg_type): Add condition type != NLMSG_DONE.
> (decode_nlmsg_flags): Add condition type == NLMSG_DONE.
> (decode_netlink_sock_diag): Add condition
> nlmsghdr->nlmsg_type == NLMSG_DONE.

Now I don't follow.

What do you want to do with NLMSG_DONE messages, pass them to family
specific decoders or not?
Ditto with other control messages, do you want to pass them to family
specific decoders or not?

> ---
>  netlink.c           | 9 +++++++--
>  netlink_sock_diag.c | 3 +++
>  2 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/netlink.c b/netlink.c
> index 87b389c..f74c3a0 100644
> --- a/netlink.c
> +++ b/netlink.c
> @@ -177,7 +177,7 @@ decode_nlmsg_type(const uint16_t type, const unsigned int family)
>  	const struct xlat *xlat = netlink_types;
>  	const char *dflt = "NLMSG_???";
>  
> -	if (family < ARRAY_SIZE(nlmsg_types)) {
> +	if (type != NLMSG_DONE && family < ARRAY_SIZE(nlmsg_types)) {
>  		if (nlmsg_types[family].decoder)
>  			decoder = nlmsg_types[family].decoder;
>  		if (nlmsg_types[family].xlat)
> @@ -194,6 +194,9 @@ decode_nlmsg_flags(const uint16_t flags, const uint16_t type, const int family)
>  {
>  	const struct xlat *table = NULL;
>  
> +	if (type == NLMSG_DONE)
> +		goto end;
> +
>  	switch (family) {
>  	case NETLINK_SOCK_DIAG:
>  		table = netlink_get_flags;
> @@ -233,6 +236,7 @@ decode_nlmsg_flags(const uint16_t flags, const uint16_t type, const int family)
>  		break;
>  	}
>  
> +end:
>  	printflags_ex(flags, "NLM_F_???", netlink_flags, table, NULL);
>  }
>  
> @@ -246,7 +250,8 @@ print_nlmsghdr(struct tcb *tcp,
>  
>  	tprintf("{len=%u, type=", nlmsghdr->nlmsg_len);
>  
> -	const int hdr_family = (nlmsghdr->nlmsg_type < NLMSG_MIN_TYPE)
> +	const int hdr_family = (nlmsghdr->nlmsg_type < NLMSG_MIN_TYPE
> +				&& nlmsghdr->nlmsg_type != NLMSG_DONE)
>  			       ? NL_FAMILY_DEFAULT
>  			       : (family != NL_FAMILY_DEFAULT
>  				  ? family : get_fd_nl_family(tcp, fd));
> diff --git a/netlink_sock_diag.c b/netlink_sock_diag.c
> index d854808..4b096f8 100644
> --- a/netlink_sock_diag.c
> +++ b/netlink_sock_diag.c
> @@ -536,6 +536,9 @@ decode_netlink_sock_diag(struct tcb *const tcp,
>  {
>  	uint8_t family;
>  
> +	if (nlmsghdr->nlmsg_type == NLMSG_DONE)
> +		return false;
> +
>  	if (!umove_or_printaddr(tcp, addr, &family)) {
>  		if (family < ARRAY_SIZE(diag_decoders)
>  		    && len > sizeof(family)) {

-- 
ldv
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