diff options
Diffstat (limited to 'net')
| -rw-r--r-- | net/Kconfig | 12 | ||||
| -rw-r--r-- | net/core/dev.c | 48 | ||||
| -rw-r--r-- | net/core/net-procfs.c | 16 | ||||
| -rw-r--r-- | net/core/sysctl_net_core.c | 104 |
4 files changed, 177 insertions, 3 deletions
diff --git a/net/Kconfig b/net/Kconfig index 2ddc9046868e..08de901415ee 100644 --- a/net/Kconfig +++ b/net/Kconfig @@ -259,6 +259,18 @@ config BPF_JIT packet sniffing (libpcap/tcpdump). Note : Admin should enable this feature changing /proc/sys/net/core/bpf_jit_enable +config NET_FLOW_LIMIT + boolean + depends on RPS + default y + ---help--- + The network stack has to drop packets when a receive processing CPU's + backlog reaches netdev_max_backlog. If a few out of many active flows + generate the vast majority of load, drop their traffic earlier to + maintain capacity for the other flows. This feature provides servers + with many clients some protection against DoS by a single (spoofed) + flow that greatly exceeds average workload. + menu "Network testing" config NET_PKTGEN diff --git a/net/core/dev.c b/net/core/dev.c index 18e9730cc4be..7229bc30e509 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3064,6 +3064,46 @@ static int rps_ipi_queued(struct softnet_data *sd) return 0; } +#ifdef CONFIG_NET_FLOW_LIMIT +int netdev_flow_limit_table_len __read_mostly = (1 << 12); +#endif + +static bool skb_flow_limit(struct sk_buff *skb, unsigned int qlen) +{ +#ifdef CONFIG_NET_FLOW_LIMIT + struct sd_flow_limit *fl; + struct softnet_data *sd; + unsigned int old_flow, new_flow; + + if (qlen < (netdev_max_backlog >> 1)) + return false; + + sd = &__get_cpu_var(softnet_data); + + rcu_read_lock(); + fl = rcu_dereference(sd->flow_limit); + if (fl) { + new_flow = skb_get_rxhash(skb) & (fl->num_buckets - 1); + old_flow = fl->history[fl->history_head]; + fl->history[fl->history_head] = new_flow; + + fl->history_head++; + fl->history_head &= FLOW_LIMIT_HISTORY - 1; + + if (likely(fl->buckets[old_flow])) + fl->buckets[old_flow]--; + + if (++fl->buckets[new_flow] > (FLOW_LIMIT_HISTORY >> 1)) { + fl->count++; + rcu_read_unlock(); + return true; + } + } + rcu_read_unlock(); +#endif + return false; +} + /* * enqueue_to_backlog is called to queue an skb to a per CPU backlog * queue (may be a remote CPU queue). @@ -3073,13 +3113,15 @@ static int enqueue_to_backlog(struct sk_buff *skb, int cpu, { struct softnet_data *sd; unsigned long flags; + unsigned int qlen; sd = &per_cpu(softnet_data, cpu); local_irq_save(flags); rps_lock(sd); - if (skb_queue_len(&sd->input_pkt_queue) <= netdev_max_backlog) { + qlen = skb_queue_len(&sd->input_pkt_queue); + if (qlen <= netdev_max_backlog && !skb_flow_limit(skb, qlen)) { if (skb_queue_len(&sd->input_pkt_queue)) { enqueue: __skb_queue_tail(&sd->input_pkt_queue, skb); @@ -6269,6 +6311,10 @@ static int __init net_dev_init(void) sd->backlog.weight = weight_p; sd->backlog.gro_list = NULL; sd->backlog.gro_count = 0; + +#ifdef CONFIG_NET_FLOW_LIMIT + sd->flow_limit = NULL; +#endif } dev_boot_phase = 0; diff --git a/net/core/net-procfs.c b/net/core/net-procfs.c index 569d355fec3e..2bf83299600a 100644 --- a/net/core/net-procfs.c +++ b/net/core/net-procfs.c @@ -146,11 +146,23 @@ static void softnet_seq_stop(struct seq_file *seq, void *v) static int softnet_seq_show(struct seq_file *seq, void *v) { struct softnet_data *sd = v; + unsigned int flow_limit_count = 0; - seq_printf(seq, "%08x %08x %08x %08x %08x %08x %08x %08x %08x %08x\n", +#ifdef CONFIG_NET_FLOW_LIMIT + struct sd_flow_limit *fl; + + rcu_read_lock(); + fl = rcu_dereference(sd->flow_limit); + if (fl) + flow_limit_count = fl->count; + rcu_read_unlock(); +#endif + + seq_printf(seq, + "%08x %08x %08x %08x %08x %08x %08x %08x %08x %08x %08x\n", sd->processed, sd->dropped, sd->time_squeeze, 0, 0, 0, 0, 0, /* was fastroute */ - sd->cpu_collision, sd->received_rps); + sd->cpu_collision, sd->received_rps, flow_limit_count); return 0; } diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c index cfdb46ab3a7f..741db5fc7806 100644 --- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -87,6 +87,96 @@ static int rps_sock_flow_sysctl(ctl_table *table, int write, } #endif /* CONFIG_RPS */ +#ifdef CONFIG_NET_FLOW_LIMIT +static DEFINE_MUTEX(flow_limit_update_mutex); + +static int flow_limit_cpu_sysctl(ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos) +{ + struct sd_flow_limit *cur; + struct softnet_data *sd; + cpumask_var_t mask; + int i, len, ret = 0; + + if (!alloc_cpumask_var(&mask, GFP_KERNEL)) + return -ENOMEM; + + if (write) { + ret = cpumask_parse_user(buffer, *lenp, mask); + if (ret) + goto done; + + mutex_lock(&flow_limit_update_mutex); + len = sizeof(*cur) + netdev_flow_limit_table_len; + for_each_possible_cpu(i) { + sd = &per_cpu(softnet_data, i); + cur = rcu_dereference_protected(sd->flow_limit, + lockdep_is_held(&flow_limit_update_mutex)); + if (cur && !cpumask_test_cpu(i, mask)) { + RCU_INIT_POINTER(sd->flow_limit, NULL); + synchronize_rcu(); + kfree(cur); + } else if (!cur && cpumask_test_cpu(i, mask)) { + cur = kzalloc(len, GFP_KERNEL); + if (!cur) { + /* not unwinding previous changes */ + ret = -ENOMEM; + goto write_unlock; + } + cur->num_buckets = netdev_flow_limit_table_len; + rcu_assign_pointer(sd->flow_limit, cur); + } + } +write_unlock: + mutex_unlock(&flow_limit_update_mutex); + } else { + if (*ppos || !*lenp) { + *lenp = 0; + goto done; + } + + cpumask_clear(mask); + rcu_read_lock(); + for_each_possible_cpu(i) { + sd = &per_cpu(softnet_data, i); + if (rcu_dereference(sd->flow_limit)) + cpumask_set_cpu(i, mask); + } + rcu_read_unlock(); + + len = cpumask_scnprintf(buffer, *lenp, mask); + *lenp = len + 1; + *ppos += len + 1; + } + +done: + free_cpumask_var(mask); + return ret; +} + +static int flow_limit_table_len_sysctl(ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos) +{ + unsigned int old, *ptr; + int ret; + + mutex_lock(&flow_limit_update_mutex); + + ptr = table->data; + old = *ptr; + ret = proc_dointvec(table, write, buffer, lenp, ppos); + if (!ret && write && !is_power_of_2(*ptr)) { + *ptr = old; + ret = -EINVAL; + } + + mutex_unlock(&flow_limit_update_mutex); + return ret; +} +#endif /* CONFIG_NET_FLOW_LIMIT */ + static struct ctl_table net_core_table[] = { #ifdef CONFIG_NET { @@ -180,6 +270,20 @@ static struct ctl_table net_core_table[] = { .proc_handler = rps_sock_flow_sysctl }, #endif +#ifdef CONFIG_NET_FLOW_LIMIT + { + .procname = "flow_limit_cpu_bitmap", + .mode = 0644, + .proc_handler = flow_limit_cpu_sysctl + }, + { + .procname = "flow_limit_table_len", + .data = &netdev_flow_limit_table_len, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = flow_limit_table_len_sysctl + }, +#endif /* CONFIG_NET_FLOW_LIMIT */ #endif /* CONFIG_NET */ { .procname = "netdev_budget", |