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Date: Sat, 07 Dec 2013 13:43:49 +0100
From: Daniel Borkmann <dborkman@...hat.com>
To: Wang Weidong <wangweidong1@...wei.com>
CC: vyasevich@...il.com, nhorman@...driver.com, davem@...emloft.net,
netdev@...r.kernel.org, linux-sctp@...r.kernel.org
Subject: Re: [PATCH v5 1/2] sctp: check the rto_min and rto_max
On 12/07/2013 08:17 AM, Wang Weidong wrote:
> rto_min should be smaller than rto_max while rto_max should be larger
> than rto_min. Add two proc_handler for the checking. Add the check in
> sctp_setsockopt_rtoinfo.
>
> Suggested-by: Vlad Yasevich <vyasevich@...il.com>
> Signed-off-by: Wang Weidong <wangweidong1@...wei.com>
> ---
Thanks Wang, also for your second patch.
Second one looks good to me, thanks for the cleanup!
I was wondering where 86400000 comes from? Looking through the git
history didn't give much clues and the RFC4960 neither. Clearly,
section 15 of RFC4960 *recommends* as initial values ...
RTO.Initial - 3 seconds
RTO.Min - 1 second
RTO.Max - 60 seconds
... which we have as constants in [1] and are assigned to globals
initially in [2,3] with those recommended values. That's all good.
But still [not *directly* related to your patch though], where does
86400000 come from? I expect that's for the max SCTP heartbeat
interval or max cookie lifetime?
Hence, timer_max is used in multiple contexts for timers here,
which seems a bit confusing. If it really makes sense to have such
a huge RTO max though, then it at least needs a comment explaining
so. ;)
Wang, just a minor nitpick, I would much rather name them those
defines like ...
SCTP_RTO_MIN_LIMIT
SCTP_RTO_MAX_LIMIT
... just so that we have recommended and upper limit constants with
a more clear naming as obviously SCTP_ONE doesn't make much sense.
[1] include/net/sctp/constants.h +269
[2] include/net/netns/sctp.h +39
[3] net/sctp/protocol.c +1169
More below ...
> include/net/sctp/constants.h | 3 ++
> net/sctp/socket.c | 5 +++
> net/sctp/sysctl.c | 73 ++++++++++++++++++++++++++++++++++++++++----
> 3 files changed, 75 insertions(+), 6 deletions(-)
>
> diff --git a/include/net/sctp/constants.h b/include/net/sctp/constants.h
> index 2f0a565..d276978 100644
> --- a/include/net/sctp/constants.h
> +++ b/include/net/sctp/constants.h
> @@ -279,6 +279,9 @@ enum { SCTP_MAX_GABS = 16 };
> #define SCTP_RTO_ALPHA 3 /* 1/8 when converted to right shifts. */
> #define SCTP_RTO_BETA 2 /* 1/4 when converted to right shifts. */
>
> +#define SCTP_ONE 1 /* 1 ms */
> +#define SCTP_TIMER_MAX 86400000 /* ms in one day */
> +
> /* Maximum number of new data packets that can be sent in a burst. */
> #define SCTP_DEFAULT_MAX_BURST 4
>
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index 72046b9..13411ad 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -2818,6 +2818,11 @@ static int sctp_setsockopt_rtoinfo(struct sock *sk, char __user *optval, unsigne
> if (copy_from_user(&rtoinfo, optval, optlen))
> return -EFAULT;
>
> + if (rtoinfo.srto_min < SCTP_ONE ||
> + rtoinfo.srto_max > SCTP_TIMER_MAX ||
> + rtoinfo.srto_max < rtoinfo.srto_min)
> + return -EINVAL;
> +
> asoc = sctp_id2assoc(sk, rtoinfo.srto_assoc_id);
>
> /* Set the values to the specific association */
> diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c
> index 6b36561..33c56c6 100644
> --- a/net/sctp/sysctl.c
> +++ b/net/sctp/sysctl.c
> @@ -40,8 +40,8 @@
> #include <linux/sysctl.h>
>
> static int zero = 0;
> -static int one = 1;
> -static int timer_max = 86400000; /* ms in one day */
> +static int one = SCTP_ONE;
> +static int timer_max = SCTP_TIMER_MAX;
So here, I'd do something like this ...
static int one = 1; (leaving this as is)
static int timer_max = 86400000; /* Max 1 day for HB interval, cookie life-time*/
static int rto_timer_min = SCTP_RTO_MIN_LIMIT;
static int rto_timer_max = SCTP_RTO_MAX_LIMIT;
... so that we have sack_timer_{min,max} and rto_timer_{min,max}.
Opinions, thoughts?
> static int int_max = INT_MAX;
> static int sack_timer_min = 1;
> static int sack_timer_max = 500;
> @@ -61,6 +61,13 @@ static int proc_sctp_do_hmac_alg(struct ctl_table *ctl,
> void __user *buffer, size_t *lenp,
>
> loff_t *ppos);
> +static int proc_sctp_do_rto_min(struct ctl_table *ctl, int write,
> + void __user *buffer, size_t *lenp,
> + loff_t *ppos);
> +static int proc_sctp_do_rto_max(struct ctl_table *ctl, int write,
> + void __user *buffer, size_t *lenp,
> + loff_t *ppos);
> +
> static struct ctl_table sctp_table[] = {
> {
> .procname = "sctp_mem",
> @@ -102,17 +109,17 @@ static struct ctl_table sctp_net_table[] = {
> .data = &init_net.sctp.rto_min,
> .maxlen = sizeof(unsigned int),
> .mode = 0644,
> - .proc_handler = proc_dointvec_minmax,
> + .proc_handler = proc_sctp_do_rto_min,
> .extra1 = &one,
> - .extra2 = &timer_max
> + .extra2 = &init_net.sctp.rto_max
> },
> {
> .procname = "rto_max",
> .data = &init_net.sctp.rto_max,
> .maxlen = sizeof(unsigned int),
> .mode = 0644,
> - .proc_handler = proc_dointvec_minmax,
> - .extra1 = &one,
> + .proc_handler = proc_sctp_do_rto_max,
> + .extra1 = &init_net.sctp.rto_min,
> .extra2 = &timer_max
> },
> {
> @@ -342,6 +349,60 @@ static int proc_sctp_do_hmac_alg(struct ctl_table *ctl,
> return ret;
> }
>
> +static int proc_sctp_do_rto_min(struct ctl_table *ctl, int write,
> + void __user*buffer, size_t *lenp,
> + loff_t *ppos)
> +{
> + struct net *net = current->nsproxy->net_ns;
> + int new_value;
> + struct ctl_table tbl;
> + unsigned int min = *(unsigned int *) ctl->extra1;
> + unsigned int max = *(unsigned int *) ctl->extra2;
> + int ret;
> +
> + memset(&tbl, 0, sizeof(struct ctl_table));
> + tbl.maxlen = sizeof(unsigned int);
> +
> + if (write)
> + tbl.data = &new_value;
> + else
> + tbl.data = &net->sctp.rto_min;
> + ret = proc_dointvec(&tbl, write, buffer, lenp, ppos);
> + if (write) {
> + if (ret || new_value > max || new_value < min)
> + return -EINVAL;
> + net->sctp.rto_min = new_value;
> + }
> + return ret;
> +}
> +
> +static int proc_sctp_do_rto_max(struct ctl_table *ctl, int write,
> + void __user*buffer, size_t *lenp,
> + loff_t *ppos)
> +{
> + struct net *net = current->nsproxy->net_ns;
> + int new_value;
> + struct ctl_table tbl;
> + unsigned int min = *(unsigned int *) ctl->extra1;
> + unsigned int max = *(unsigned int *) ctl->extra2;
> + int ret;
> +
> + memset(&tbl, 0, sizeof(struct ctl_table));
> + tbl.maxlen = sizeof(unsigned int);
> +
> + if (write)
> + tbl.data = &new_value;
> + else
> + tbl.data = &net->sctp.rto_max;
> + ret = proc_dointvec(&tbl, write, buffer, lenp, ppos);
> + if (write) {
> + if (ret || new_value > max || new_value < min)
> + return -EINVAL;
> + net->sctp.rto_max = new_value;
> + }
> + return ret;
> +}
> +
> int sctp_sysctl_net_register(struct net *net)
> {
> struct ctl_table *table;
>
--
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