linux/net/core/flow.c
Herbert Xu e0e8f1c822 [IPSEC] flow: Fix potential memory leak
When old flow cache entries that are not at the head of their chain
trigger a transient security error they get unlinked along with all
the entries preceding them in the chain.  The preceding entries are
not freed correctly.

This patch fixes this by simply leaving the entry around.  It's based
on a suggestion by Venkat Yekkirala.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-01-23 20:25:39 -08:00

373 lines
8.1 KiB
C

/* flow.c: Generic flow cache.
*
* Copyright (C) 2003 Alexey N. Kuznetsov (kuznet@ms2.inr.ac.ru)
* Copyright (C) 2003 David S. Miller (davem@redhat.com)
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/jhash.h>
#include <linux/interrupt.h>
#include <linux/mm.h>
#include <linux/random.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/completion.h>
#include <linux/percpu.h>
#include <linux/bitops.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <linux/mutex.h>
#include <net/flow.h>
#include <asm/atomic.h>
#include <asm/semaphore.h>
#include <linux/security.h>
struct flow_cache_entry {
struct flow_cache_entry *next;
u16 family;
u8 dir;
struct flowi key;
u32 genid;
void *object;
atomic_t *object_ref;
};
atomic_t flow_cache_genid = ATOMIC_INIT(0);
static u32 flow_hash_shift;
#define flow_hash_size (1 << flow_hash_shift)
static DEFINE_PER_CPU(struct flow_cache_entry **, flow_tables) = { NULL };
#define flow_table(cpu) (per_cpu(flow_tables, cpu))
static struct kmem_cache *flow_cachep __read_mostly;
static int flow_lwm, flow_hwm;
struct flow_percpu_info {
int hash_rnd_recalc;
u32 hash_rnd;
int count;
} ____cacheline_aligned;
static DEFINE_PER_CPU(struct flow_percpu_info, flow_hash_info) = { 0 };
#define flow_hash_rnd_recalc(cpu) \
(per_cpu(flow_hash_info, cpu).hash_rnd_recalc)
#define flow_hash_rnd(cpu) \
(per_cpu(flow_hash_info, cpu).hash_rnd)
#define flow_count(cpu) \
(per_cpu(flow_hash_info, cpu).count)
static struct timer_list flow_hash_rnd_timer;
#define FLOW_HASH_RND_PERIOD (10 * 60 * HZ)
struct flow_flush_info {
atomic_t cpuleft;
struct completion completion;
};
static DEFINE_PER_CPU(struct tasklet_struct, flow_flush_tasklets) = { NULL };
#define flow_flush_tasklet(cpu) (&per_cpu(flow_flush_tasklets, cpu))
static void flow_cache_new_hashrnd(unsigned long arg)
{
int i;
for_each_possible_cpu(i)
flow_hash_rnd_recalc(i) = 1;
flow_hash_rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
add_timer(&flow_hash_rnd_timer);
}
static void flow_entry_kill(int cpu, struct flow_cache_entry *fle)
{
if (fle->object)
atomic_dec(fle->object_ref);
kmem_cache_free(flow_cachep, fle);
flow_count(cpu)--;
}
static void __flow_cache_shrink(int cpu, int shrink_to)
{
struct flow_cache_entry *fle, **flp;
int i;
for (i = 0; i < flow_hash_size; i++) {
int k = 0;
flp = &flow_table(cpu)[i];
while ((fle = *flp) != NULL && k < shrink_to) {
k++;
flp = &fle->next;
}
while ((fle = *flp) != NULL) {
*flp = fle->next;
flow_entry_kill(cpu, fle);
}
}
}
static void flow_cache_shrink(int cpu)
{
int shrink_to = flow_lwm / flow_hash_size;
__flow_cache_shrink(cpu, shrink_to);
}
static void flow_new_hash_rnd(int cpu)
{
get_random_bytes(&flow_hash_rnd(cpu), sizeof(u32));
flow_hash_rnd_recalc(cpu) = 0;
__flow_cache_shrink(cpu, 0);
}
static u32 flow_hash_code(struct flowi *key, int cpu)
{
u32 *k = (u32 *) key;
return (jhash2(k, (sizeof(*key) / sizeof(u32)), flow_hash_rnd(cpu)) &
(flow_hash_size - 1));
}
#if (BITS_PER_LONG == 64)
typedef u64 flow_compare_t;
#else
typedef u32 flow_compare_t;
#endif
extern void flowi_is_missized(void);
/* I hear what you're saying, use memcmp. But memcmp cannot make
* important assumptions that we can here, such as alignment and
* constant size.
*/
static int flow_key_compare(struct flowi *key1, struct flowi *key2)
{
flow_compare_t *k1, *k1_lim, *k2;
const int n_elem = sizeof(struct flowi) / sizeof(flow_compare_t);
if (sizeof(struct flowi) % sizeof(flow_compare_t))
flowi_is_missized();
k1 = (flow_compare_t *) key1;
k1_lim = k1 + n_elem;
k2 = (flow_compare_t *) key2;
do {
if (*k1++ != *k2++)
return 1;
} while (k1 < k1_lim);
return 0;
}
void *flow_cache_lookup(struct flowi *key, u16 family, u8 dir,
flow_resolve_t resolver)
{
struct flow_cache_entry *fle, **head;
unsigned int hash;
int cpu;
local_bh_disable();
cpu = smp_processor_id();
fle = NULL;
/* Packet really early in init? Making flow_cache_init a
* pre-smp initcall would solve this. --RR */
if (!flow_table(cpu))
goto nocache;
if (flow_hash_rnd_recalc(cpu))
flow_new_hash_rnd(cpu);
hash = flow_hash_code(key, cpu);
head = &flow_table(cpu)[hash];
for (fle = *head; fle; fle = fle->next) {
if (fle->family == family &&
fle->dir == dir &&
flow_key_compare(key, &fle->key) == 0) {
if (fle->genid == atomic_read(&flow_cache_genid)) {
void *ret = fle->object;
if (ret)
atomic_inc(fle->object_ref);
local_bh_enable();
return ret;
}
break;
}
}
if (!fle) {
if (flow_count(cpu) > flow_hwm)
flow_cache_shrink(cpu);
fle = kmem_cache_alloc(flow_cachep, GFP_ATOMIC);
if (fle) {
fle->next = *head;
*head = fle;
fle->family = family;
fle->dir = dir;
memcpy(&fle->key, key, sizeof(*key));
fle->object = NULL;
flow_count(cpu)++;
}
}
nocache:
{
int err;
void *obj;
atomic_t *obj_ref;
err = resolver(key, family, dir, &obj, &obj_ref);
if (fle && !err) {
fle->genid = atomic_read(&flow_cache_genid);
if (fle->object)
atomic_dec(fle->object_ref);
fle->object = obj;
fle->object_ref = obj_ref;
if (obj)
atomic_inc(fle->object_ref);
}
local_bh_enable();
if (err)
obj = ERR_PTR(err);
return obj;
}
}
static void flow_cache_flush_tasklet(unsigned long data)
{
struct flow_flush_info *info = (void *)data;
int i;
int cpu;
cpu = smp_processor_id();
for (i = 0; i < flow_hash_size; i++) {
struct flow_cache_entry *fle;
fle = flow_table(cpu)[i];
for (; fle; fle = fle->next) {
unsigned genid = atomic_read(&flow_cache_genid);
if (!fle->object || fle->genid == genid)
continue;
fle->object = NULL;
atomic_dec(fle->object_ref);
}
}
if (atomic_dec_and_test(&info->cpuleft))
complete(&info->completion);
}
static void flow_cache_flush_per_cpu(void *) __attribute__((__unused__));
static void flow_cache_flush_per_cpu(void *data)
{
struct flow_flush_info *info = data;
int cpu;
struct tasklet_struct *tasklet;
cpu = smp_processor_id();
tasklet = flow_flush_tasklet(cpu);
tasklet->data = (unsigned long)info;
tasklet_schedule(tasklet);
}
void flow_cache_flush(void)
{
struct flow_flush_info info;
static DEFINE_MUTEX(flow_flush_sem);
/* Don't want cpus going down or up during this. */
lock_cpu_hotplug();
mutex_lock(&flow_flush_sem);
atomic_set(&info.cpuleft, num_online_cpus());
init_completion(&info.completion);
local_bh_disable();
smp_call_function(flow_cache_flush_per_cpu, &info, 1, 0);
flow_cache_flush_tasklet((unsigned long)&info);
local_bh_enable();
wait_for_completion(&info.completion);
mutex_unlock(&flow_flush_sem);
unlock_cpu_hotplug();
}
static void __devinit flow_cache_cpu_prepare(int cpu)
{
struct tasklet_struct *tasklet;
unsigned long order;
for (order = 0;
(PAGE_SIZE << order) <
(sizeof(struct flow_cache_entry *)*flow_hash_size);
order++)
/* NOTHING */;
flow_table(cpu) = (struct flow_cache_entry **)
__get_free_pages(GFP_KERNEL|__GFP_ZERO, order);
if (!flow_table(cpu))
panic("NET: failed to allocate flow cache order %lu\n", order);
flow_hash_rnd_recalc(cpu) = 1;
flow_count(cpu) = 0;
tasklet = flow_flush_tasklet(cpu);
tasklet_init(tasklet, flow_cache_flush_tasklet, 0);
}
static int flow_cache_cpu(struct notifier_block *nfb,
unsigned long action,
void *hcpu)
{
if (action == CPU_DEAD)
__flow_cache_shrink((unsigned long)hcpu, 0);
return NOTIFY_OK;
}
static int __init flow_cache_init(void)
{
int i;
flow_cachep = kmem_cache_create("flow_cache",
sizeof(struct flow_cache_entry),
0, SLAB_HWCACHE_ALIGN|SLAB_PANIC,
NULL, NULL);
flow_hash_shift = 10;
flow_lwm = 2 * flow_hash_size;
flow_hwm = 4 * flow_hash_size;
init_timer(&flow_hash_rnd_timer);
flow_hash_rnd_timer.function = flow_cache_new_hashrnd;
flow_hash_rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
add_timer(&flow_hash_rnd_timer);
for_each_possible_cpu(i)
flow_cache_cpu_prepare(i);
hotcpu_notifier(flow_cache_cpu, 0);
return 0;
}
module_init(flow_cache_init);
EXPORT_SYMBOL(flow_cache_genid);
EXPORT_SYMBOL(flow_cache_lookup);