[PATCH v4 5/6] Netlink: Introduce nlmsg_* functions

[Dmitry V. Levin]

On Fri, Jun 17, 2016 at 04:29:57PM +0000, Fabien Siron wrote:
> Since our target is not in the same process, the netlink macros NLMSG_*
> must be rewritten for strace.
> 
> * netlink.c (nlmsg_fetch, nlmsg_next): New functions.
> ---
>  netlink.c | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
> 
> diff --git a/netlink.c b/netlink.c
> index c43f6e7..1211d57 100644
> --- a/netlink.c
> +++ b/netlink.c
> @@ -31,6 +31,32 @@
>  #include "xlat/netlink_flags.h"
>  #include "xlat/netlink_types.h"
>  
> +/* since our target is not in the same process, here are some utils for nlmsg */
> +static int
> +nlmsg_ok(struct tcb *tcp, unsigned long nlh, unsigned long len) {
> +	struct nlmsghdr nlmsghdr;
> +
> +	if (umoven(tcp, nlh, sizeof(struct nlmsghdr), &nlmsghdr) == -1)
> +		return 0;
> +
> +	return (len >= (int)sizeof(struct nlmsghdr)) &&
> +		nlmsghdr.nlmsg_len >= sizeof(struct nlmsghdr) &&
> +		nlmsghdr.nlmsg_len <= len;
> +}
> +
> +static unsigned long
> +nlmsg_next(struct tcb *tcp, unsigned long nlh, unsigned long *len) {
> +	struct nlmsghdr nlmsghdr;
> +
> +	if (umoven(tcp, nlh, sizeof(struct nlmsghdr), &nlmsghdr) == -1)
> +		return 0;
> +
> +	*len -= NLMSG_ALIGN(nlmsghdr.nlmsg_len);
> +
> +	return (unsigned long)
> +		((char *)(nlh) + NLMSG_ALIGN(nlmsghdr.nlmsg_len));
> +}
> +
>  void
>  decode_netlink(struct tcb *tcp, unsigned long addr, unsigned long size)
>  {
On Fri, Jun 17, 2016 at 04:29:58PM +0000, Fabien Siron wrote:
> * netlink.c (decode_netlink_or_printaddr_msg): From
> decode_netlink_or_printaddr().
> (decode_netlink_or_printaddr): Call decode_netlink_or_printaddr_msg().
> ---
>  netlink.c | 42 ++++++++++++++++++++++++++----------------
>  1 file changed, 26 insertions(+), 16 deletions(-)
> 
> diff --git a/netlink.c b/netlink.c
> index 1211d57..a2beec6 100644
> --- a/netlink.c
> +++ b/netlink.c
> @@ -33,32 +33,33 @@
>  
>  /* since our target is not in the same process, here are some utils for nlmsg */
>  static int
> -nlmsg_ok(struct tcb *tcp, unsigned long nlh, unsigned long len) {
> -	struct nlmsghdr nlmsghdr;
> +nlmsg_fetch(struct tcb *tcp, struct nlmsghdr *nlmsghdr, unsigned long addr,
> +	    unsigned long len) {
> +
> +	if (len < (int)sizeof(struct nlmsghdr)) {
> +		if (len != 0)
> +			printstr(tcp, (unsigned long)addr, len);
> +		return 0;
> +	}
>  
> -	if (umoven(tcp, nlh, sizeof(struct nlmsghdr), &nlmsghdr) == -1)
> +	if (umove_or_printaddr(tcp, addr, nlmsghdr) == -1)
>  		return 0;
>  
> -	return (len >= (int)sizeof(struct nlmsghdr)) &&
> -		nlmsghdr.nlmsg_len >= sizeof(struct nlmsghdr) &&
> -		nlmsghdr.nlmsg_len <= len;
> +	return 	nlmsghdr->nlmsg_len >= sizeof(struct nlmsghdr) &&
> +		nlmsghdr->nlmsg_len <= len;
>  }
>  
>  static unsigned long
> -nlmsg_next(struct tcb *tcp, unsigned long nlh, unsigned long *len) {
> -	struct nlmsghdr nlmsghdr;
> -
> -	if (umoven(tcp, nlh, sizeof(struct nlmsghdr), &nlmsghdr) == -1)
> -		return 0;
> -
> -	*len -= NLMSG_ALIGN(nlmsghdr.nlmsg_len);
> +nlmsg_next(struct nlmsghdr *nlmsghdr, unsigned long addr, unsigned long *len) {
> +	*len -= NLMSG_ALIGN(nlmsghdr->nlmsg_len);
>  
>  	return (unsigned long)
> -		((char *)(nlh) + NLMSG_ALIGN(nlmsghdr.nlmsg_len));
> +		((char *)(addr) + NLMSG_ALIGN(nlmsghdr->nlmsg_len));
>  }

Please squash these two commits into one.

> -void
> -decode_netlink(struct tcb *tcp, unsigned long addr, unsigned long size)
> +static void
> +decode_netlink_msg(struct tcb *tcp, unsigned long addr,
> +			    unsigned long size)
>  {
>  	struct nlmsghdr nlmsghdr;
>  
> @@ -88,3 +89,12 @@ decode_netlink(struct tcb *tcp, unsigned long addr, unsigned long size)
>  
>  	tprints("}");
>  }
> +
> +void
> +decode_netlink(struct tcb *tcp, unsigned long addr, unsigned long size) {
> +	struct nlmsghdr nlmsghdr;
> +
> +	for (; nlmsg_fetch(tcp, &nlmsghdr, addr, size);
> +	     addr = nlmsg_next(&nlmsghdr, addr, &size))
> +		decode_netlink_msg(tcp, addr, size);
> +}

Shouldn't output from subsequent decode_netlink_msg calls be delimited?


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