Re: [PATCH nf-next] netfilter: log: Check param to avoid overflow in nf_log_set

[Pablo Neira Ayuso]

On Sun, Aug 28, 2016 at 10:30:18PM +0800, f...@ikuai8.com wrote:
> From: Gao Feng 
> 
> The nf_log_set is an interface function, so it should do the strict sanity
> check of parameters. Add  one sanity check for pf, it could not exceed
> NFPROTO_NUMPROTO, and print error log when pf is invalid.
> 
> Signed-off-by: Gao Feng 
> ---
>  net/netfilter/nf_log.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c
> index aa5847a..02ce0b9 100644
> --- a/net/netfilter/nf_log.c
> +++ b/net/netfilter/nf_log.c
> @@ -43,8 +43,10 @@ void nf_log_set(struct net *net, u_int8_t pf, const struct 
> nf_logger *logger)
>  {
>   const struct nf_logger *log;
>  
> - if (pf == NFPROTO_UNSPEC)
> + if (pf == NFPROTO_UNSPEC || pf >= NFPROTO_NUMPROTO) {
> + pr_err("Wrong pf(%d) for nf log", pf);
>   return;

I'd suggest you change this function nf_log_set() to:

int nf_log_set(struct net *net, ...)

And update the callsites.

Then, you can simply return -EOPNOTSUPP instead and remove that
pr_err() message. This message is very unlikely to be displayed.

Thanks!

Re: [PATCH nf-next] netfilter: log: Check param to avoid overflow in nf_log_set

[Feng Gao]

On Sun, Aug 28, 2016 at 10:30 PM,   wrote:
> From: Gao Feng 
>
> The nf_log_set is an interface function, so it should do the strict sanity
> check of parameters. Add  one sanity check for pf, it could not exceed
> NFPROTO_NUMPROTO, and print error log when pf is invalid.
>
> Signed-off-by: Gao Feng 
> ---
>  net/netfilter/nf_log.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c
> index aa5847a..02ce0b9 100644
> --- a/net/netfilter/nf_log.c
> +++ b/net/netfilter/nf_log.c
> @@ -43,8 +43,10 @@ void nf_log_set(struct net *net, u_int8_t pf, const struct 
> nf_logger *logger)
>  {
> const struct nf_logger *log;
>
> -   if (pf == NFPROTO_UNSPEC)
> +   if (pf == NFPROTO_UNSPEC || pf >= NFPROTO_NUMPROTO) {
> +   pr_err("Wrong pf(%d) for nf log", pf);
> return;
> +   }
>
> mutex_lock(_log_mutex);
> log = nft_log_dereference(net->nf.nf_loggers[pf]);
> --
> 1.9.1
>
>

BTW, another similar interface function "nf_log_register" checks
sanity of param "pf".
So I think nf_log_set also need to check if param "pf" exceeds the valid range.

[PATCH nf-next] netfilter: log: Check param to avoid overflow in nf_log_set

[fgao]

From: Gao Feng 

The nf_log_set is an interface function, so it should do the strict sanity
check of parameters. Add  one sanity check for pf, it could not exceed
NFPROTO_NUMPROTO, and print error log when pf is invalid.

Signed-off-by: Gao Feng 
---
 net/netfilter/nf_log.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c
index aa5847a..02ce0b9 100644
--- a/net/netfilter/nf_log.c
+++ b/net/netfilter/nf_log.c
@@ -43,8 +43,10 @@ void nf_log_set(struct net *net, u_int8_t pf, const struct 
nf_logger *logger)
 {
const struct nf_logger *log;
 
-   if (pf == NFPROTO_UNSPEC)
+   if (pf == NFPROTO_UNSPEC || pf >= NFPROTO_NUMPROTO) {
+   pr_err("Wrong pf(%d) for nf log", pf);
return;
+   }
 
mutex_lock(_log_mutex);
log = nft_log_dereference(net->nf.nf_loggers[pf]);
-- 
1.9.1