[TCP]: Restrict congestion control choices.

Allow normal users to only choose among a restricted set of congestion
control choices.  The default is reno and what ever has been configured
as default. But the policy can be changed by administrator at any time.

For example, to allow any choice:
    cp /proc/sys/net/ipv4/tcp_available_congestion_control \
       /proc/sys/net/ipv4/tcp_allowed_congestion_control

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Stephen Hemminger 2006-11-09 16:35:15 -08:00 committed by David S. Miller
parent 3ff825b28d
commit ce7bc3bf15
5 changed files with 125 additions and 0 deletions

View File

@ -351,6 +351,12 @@ tcp_frto - BOOLEAN
where packet loss is typically due to random radio interference
rather than intermediate router congestion.
tcp_allowed_congestion_control - STRING
Show/set the congestion control choices available to non-privileged
processes. The list is a subset of those listed in
tcp_available_congestion_control.
Default is "reno" and the default setting (tcp_congestion_control).
tcp_available_congestion_control - STRING
Shows the available congestion control choices that are registered.
More congestion control algorithms may be available as modules,

View File

@ -427,6 +427,7 @@ enum
NET_CIPSOV4_RBM_OPTFMT=120,
NET_CIPSOV4_RBM_STRICTVALID=121,
NET_TCP_AVAIL_CONG_CONTROL=122,
NET_TCP_ALLOWED_CONG_CONTROL=123,
};
enum {

View File

@ -625,6 +625,7 @@ enum tcp_ca_event {
struct tcp_congestion_ops {
struct list_head list;
int non_restricted;
/* initialize private data (optional) */
void (*init)(struct sock *sk);
@ -663,6 +664,8 @@ extern void tcp_cleanup_congestion_control(struct sock *sk);
extern int tcp_set_default_congestion_control(const char *name);
extern void tcp_get_default_congestion_control(char *name);
extern void tcp_get_available_congestion_control(char *buf, size_t len);
extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
extern int tcp_set_allowed_congestion_control(char *allowed);
extern int tcp_set_congestion_control(struct sock *sk, const char *name);
extern void tcp_slow_start(struct tcp_sock *tp);

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@ -146,6 +146,50 @@ static int proc_tcp_available_congestion_control(ctl_table *ctl,
return ret;
}
static int proc_allowed_congestion_control(ctl_table *ctl,
int write, struct file * filp,
void __user *buffer, size_t *lenp,
loff_t *ppos)
{
ctl_table tbl = { .maxlen = TCP_CA_BUF_MAX };
int ret;
tbl.data = kmalloc(tbl.maxlen, GFP_USER);
if (!tbl.data)
return -ENOMEM;
tcp_get_allowed_congestion_control(tbl.data, tbl.maxlen);
ret = proc_dostring(&tbl, write, filp, buffer, lenp, ppos);
if (write && ret == 0)
ret = tcp_set_allowed_congestion_control(tbl.data);
kfree(tbl.data);
return ret;
}
static int strategy_allowed_congestion_control(ctl_table *table, int __user *name,
int nlen, void __user *oldval,
size_t __user *oldlenp,
void __user *newval, size_t newlen,
void **context)
{
ctl_table tbl = { .maxlen = TCP_CA_BUF_MAX };
int ret;
tbl.data = kmalloc(tbl.maxlen, GFP_USER);
if (!tbl.data)
return -ENOMEM;
tcp_get_available_congestion_control(tbl.data, tbl.maxlen);
ret = sysctl_string(&tbl, name, nlen, oldval, oldlenp, newval, newlen,
context);
if (ret == 0 && newval && newlen)
ret = tcp_set_allowed_congestion_control(tbl.data);
kfree(tbl.data);
return ret;
}
ctl_table ipv4_table[] = {
{
.ctl_name = NET_IPV4_TCP_TIMESTAMPS,
@ -755,6 +799,14 @@ ctl_table ipv4_table[] = {
.mode = 0444,
.proc_handler = &proc_tcp_available_congestion_control,
},
{
.ctl_name = NET_TCP_ALLOWED_CONG_CONTROL,
.procname = "tcp_allowed_congestion_control",
.maxlen = TCP_CA_BUF_MAX,
.mode = 0644,
.proc_handler = &proc_allowed_congestion_control,
.strategy = &strategy_allowed_congestion_control,
},
{ .ctl_name = 0 }
};

View File

@ -123,6 +123,7 @@ int tcp_set_default_congestion_control(const char *name)
#endif
if (ca) {
ca->non_restricted = 1; /* default is always allowed */
list_move(&ca->list, &tcp_cong_list);
ret = 0;
}
@ -168,6 +169,64 @@ void tcp_get_default_congestion_control(char *name)
rcu_read_unlock();
}
/* Built list of non-restricted congestion control values */
void tcp_get_allowed_congestion_control(char *buf, size_t maxlen)
{
struct tcp_congestion_ops *ca;
size_t offs = 0;
*buf = '\0';
rcu_read_lock();
list_for_each_entry_rcu(ca, &tcp_cong_list, list) {
if (!ca->non_restricted)
continue;
offs += snprintf(buf + offs, maxlen - offs,
"%s%s",
offs == 0 ? "" : " ", ca->name);
}
rcu_read_unlock();
}
/* Change list of non-restricted congestion control */
int tcp_set_allowed_congestion_control(char *val)
{
struct tcp_congestion_ops *ca;
char *clone, *name;
int ret = 0;
clone = kstrdup(val, GFP_USER);
if (!clone)
return -ENOMEM;
spin_lock(&tcp_cong_list_lock);
/* pass 1 check for bad entries */
while ((name = strsep(&clone, " ")) && *name) {
ca = tcp_ca_find(name);
if (!ca) {
ret = -ENOENT;
goto out;
}
}
/* pass 2 clear */
list_for_each_entry_rcu(ca, &tcp_cong_list, list)
ca->non_restricted = 0;
/* pass 3 mark as allowed */
while ((name = strsep(&val, " ")) && *name) {
ca = tcp_ca_find(name);
WARN_ON(!ca);
if (ca)
ca->non_restricted = 1;
}
out:
spin_unlock(&tcp_cong_list_lock);
return ret;
}
/* Change congestion control for socket */
int tcp_set_congestion_control(struct sock *sk, const char *name)
{
@ -183,6 +242,9 @@ int tcp_set_congestion_control(struct sock *sk, const char *name)
if (!ca)
err = -ENOENT;
else if (!(ca->non_restricted || capable(CAP_NET_ADMIN)))
err = -EPERM;
else if (!try_module_get(ca->owner))
err = -EBUSY;
@ -284,6 +346,7 @@ EXPORT_SYMBOL_GPL(tcp_reno_min_cwnd);
struct tcp_congestion_ops tcp_reno = {
.name = "reno",
.non_restricted = 1,
.owner = THIS_MODULE,
.ssthresh = tcp_reno_ssthresh,
.cong_avoid = tcp_reno_cong_avoid,