mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 19:29:37 +00:00
![Eric Dumazet](/assets/img/avatar_default.png)
We need to explicitely forbid read/store tearing in inet_peer_gc()
and inet_putpeer().
The following syzbot report reminds us about inet_putpeer()
running without a lock held.
BUG: KCSAN: data-race in inet_putpeer / inet_putpeer
write to 0xffff888121fb2ed0 of 4 bytes by interrupt on cpu 0:
inet_putpeer+0x37/0xa0 net/ipv4/inetpeer.c:240
ip4_frag_free+0x3d/0x50 net/ipv4/ip_fragment.c:102
inet_frag_destroy_rcu+0x58/0x80 net/ipv4/inet_fragment.c:228
__rcu_reclaim kernel/rcu/rcu.h:222 [inline]
rcu_do_batch+0x256/0x5b0 kernel/rcu/tree.c:2157
rcu_core+0x369/0x4d0 kernel/rcu/tree.c:2377
rcu_core_si+0x12/0x20 kernel/rcu/tree.c:2386
__do_softirq+0x115/0x33f kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0xbb/0xe0 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0xe6/0x280 arch/x86/kernel/apic/apic.c:1137
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
native_safe_halt+0xe/0x10 arch/x86/kernel/paravirt.c:71
arch_cpu_idle+0x1f/0x30 arch/x86/kernel/process.c:571
default_idle_call+0x1e/0x40 kernel/sched/idle.c:94
cpuidle_idle_call kernel/sched/idle.c:154 [inline]
do_idle+0x1af/0x280 kernel/sched/idle.c:263
write to 0xffff888121fb2ed0 of 4 bytes by interrupt on cpu 1:
inet_putpeer+0x37/0xa0 net/ipv4/inetpeer.c:240
ip4_frag_free+0x3d/0x50 net/ipv4/ip_fragment.c:102
inet_frag_destroy_rcu+0x58/0x80 net/ipv4/inet_fragment.c:228
__rcu_reclaim kernel/rcu/rcu.h:222 [inline]
rcu_do_batch+0x256/0x5b0 kernel/rcu/tree.c:2157
rcu_core+0x369/0x4d0 kernel/rcu/tree.c:2377
rcu_core_si+0x12/0x20 kernel/rcu/tree.c:2386
__do_softirq+0x115/0x33f kernel/softirq.c:292
run_ksoftirqd+0x46/0x60 kernel/softirq.c:603
smpboot_thread_fn+0x37d/0x4a0 kernel/smpboot.c:165
kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352
Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 16 Comm: ksoftirqd/1 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Fixes: 4b9d9be839
("inetpeer: remove unused list")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
311 lines
8.5 KiB
C
311 lines
8.5 KiB
C
/*
|
|
* INETPEER - A storage for permanent information about peers
|
|
*
|
|
* This source is covered by the GNU GPL, the same as all kernel sources.
|
|
*
|
|
* Authors: Andrey V. Savochkin <saw@msu.ru>
|
|
*/
|
|
|
|
#include <linux/cache.h>
|
|
#include <linux/module.h>
|
|
#include <linux/types.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/random.h>
|
|
#include <linux/timer.h>
|
|
#include <linux/time.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/net.h>
|
|
#include <linux/workqueue.h>
|
|
#include <net/ip.h>
|
|
#include <net/inetpeer.h>
|
|
#include <net/secure_seq.h>
|
|
|
|
/*
|
|
* Theory of operations.
|
|
* We keep one entry for each peer IP address. The nodes contains long-living
|
|
* information about the peer which doesn't depend on routes.
|
|
*
|
|
* Nodes are removed only when reference counter goes to 0.
|
|
* When it's happened the node may be removed when a sufficient amount of
|
|
* time has been passed since its last use. The less-recently-used entry can
|
|
* also be removed if the pool is overloaded i.e. if the total amount of
|
|
* entries is greater-or-equal than the threshold.
|
|
*
|
|
* Node pool is organised as an RB tree.
|
|
* Such an implementation has been chosen not just for fun. It's a way to
|
|
* prevent easy and efficient DoS attacks by creating hash collisions. A huge
|
|
* amount of long living nodes in a single hash slot would significantly delay
|
|
* lookups performed with disabled BHs.
|
|
*
|
|
* Serialisation issues.
|
|
* 1. Nodes may appear in the tree only with the pool lock held.
|
|
* 2. Nodes may disappear from the tree only with the pool lock held
|
|
* AND reference count being 0.
|
|
* 3. Global variable peer_total is modified under the pool lock.
|
|
* 4. struct inet_peer fields modification:
|
|
* rb_node: pool lock
|
|
* refcnt: atomically against modifications on other CPU;
|
|
* usually under some other lock to prevent node disappearing
|
|
* daddr: unchangeable
|
|
*/
|
|
|
|
static struct kmem_cache *peer_cachep __ro_after_init;
|
|
|
|
void inet_peer_base_init(struct inet_peer_base *bp)
|
|
{
|
|
bp->rb_root = RB_ROOT;
|
|
seqlock_init(&bp->lock);
|
|
bp->total = 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(inet_peer_base_init);
|
|
|
|
#define PEER_MAX_GC 32
|
|
|
|
/* Exported for sysctl_net_ipv4. */
|
|
int inet_peer_threshold __read_mostly = 65536 + 128; /* start to throw entries more
|
|
* aggressively at this stage */
|
|
int inet_peer_minttl __read_mostly = 120 * HZ; /* TTL under high load: 120 sec */
|
|
int inet_peer_maxttl __read_mostly = 10 * 60 * HZ; /* usual time to live: 10 min */
|
|
|
|
/* Called from ip_output.c:ip_init */
|
|
void __init inet_initpeers(void)
|
|
{
|
|
struct sysinfo si;
|
|
|
|
/* Use the straight interface to information about memory. */
|
|
si_meminfo(&si);
|
|
/* The values below were suggested by Alexey Kuznetsov
|
|
* <kuznet@ms2.inr.ac.ru>. I don't have any opinion about the values
|
|
* myself. --SAW
|
|
*/
|
|
if (si.totalram <= (32768*1024)/PAGE_SIZE)
|
|
inet_peer_threshold >>= 1; /* max pool size about 1MB on IA32 */
|
|
if (si.totalram <= (16384*1024)/PAGE_SIZE)
|
|
inet_peer_threshold >>= 1; /* about 512KB */
|
|
if (si.totalram <= (8192*1024)/PAGE_SIZE)
|
|
inet_peer_threshold >>= 2; /* about 128KB */
|
|
|
|
peer_cachep = kmem_cache_create("inet_peer_cache",
|
|
sizeof(struct inet_peer),
|
|
0, SLAB_HWCACHE_ALIGN | SLAB_PANIC,
|
|
NULL);
|
|
}
|
|
|
|
/* Called with rcu_read_lock() or base->lock held */
|
|
static struct inet_peer *lookup(const struct inetpeer_addr *daddr,
|
|
struct inet_peer_base *base,
|
|
unsigned int seq,
|
|
struct inet_peer *gc_stack[],
|
|
unsigned int *gc_cnt,
|
|
struct rb_node **parent_p,
|
|
struct rb_node ***pp_p)
|
|
{
|
|
struct rb_node **pp, *parent, *next;
|
|
struct inet_peer *p;
|
|
|
|
pp = &base->rb_root.rb_node;
|
|
parent = NULL;
|
|
while (1) {
|
|
int cmp;
|
|
|
|
next = rcu_dereference_raw(*pp);
|
|
if (!next)
|
|
break;
|
|
parent = next;
|
|
p = rb_entry(parent, struct inet_peer, rb_node);
|
|
cmp = inetpeer_addr_cmp(daddr, &p->daddr);
|
|
if (cmp == 0) {
|
|
if (!refcount_inc_not_zero(&p->refcnt))
|
|
break;
|
|
return p;
|
|
}
|
|
if (gc_stack) {
|
|
if (*gc_cnt < PEER_MAX_GC)
|
|
gc_stack[(*gc_cnt)++] = p;
|
|
} else if (unlikely(read_seqretry(&base->lock, seq))) {
|
|
break;
|
|
}
|
|
if (cmp == -1)
|
|
pp = &next->rb_left;
|
|
else
|
|
pp = &next->rb_right;
|
|
}
|
|
*parent_p = parent;
|
|
*pp_p = pp;
|
|
return NULL;
|
|
}
|
|
|
|
static void inetpeer_free_rcu(struct rcu_head *head)
|
|
{
|
|
kmem_cache_free(peer_cachep, container_of(head, struct inet_peer, rcu));
|
|
}
|
|
|
|
/* perform garbage collect on all items stacked during a lookup */
|
|
static void inet_peer_gc(struct inet_peer_base *base,
|
|
struct inet_peer *gc_stack[],
|
|
unsigned int gc_cnt)
|
|
{
|
|
struct inet_peer *p;
|
|
__u32 delta, ttl;
|
|
int i;
|
|
|
|
if (base->total >= inet_peer_threshold)
|
|
ttl = 0; /* be aggressive */
|
|
else
|
|
ttl = inet_peer_maxttl
|
|
- (inet_peer_maxttl - inet_peer_minttl) / HZ *
|
|
base->total / inet_peer_threshold * HZ;
|
|
for (i = 0; i < gc_cnt; i++) {
|
|
p = gc_stack[i];
|
|
|
|
/* The READ_ONCE() pairs with the WRITE_ONCE()
|
|
* in inet_putpeer()
|
|
*/
|
|
delta = (__u32)jiffies - READ_ONCE(p->dtime);
|
|
|
|
if (delta < ttl || !refcount_dec_if_one(&p->refcnt))
|
|
gc_stack[i] = NULL;
|
|
}
|
|
for (i = 0; i < gc_cnt; i++) {
|
|
p = gc_stack[i];
|
|
if (p) {
|
|
rb_erase(&p->rb_node, &base->rb_root);
|
|
base->total--;
|
|
call_rcu(&p->rcu, inetpeer_free_rcu);
|
|
}
|
|
}
|
|
}
|
|
|
|
struct inet_peer *inet_getpeer(struct inet_peer_base *base,
|
|
const struct inetpeer_addr *daddr,
|
|
int create)
|
|
{
|
|
struct inet_peer *p, *gc_stack[PEER_MAX_GC];
|
|
struct rb_node **pp, *parent;
|
|
unsigned int gc_cnt, seq;
|
|
int invalidated;
|
|
|
|
/* Attempt a lockless lookup first.
|
|
* Because of a concurrent writer, we might not find an existing entry.
|
|
*/
|
|
rcu_read_lock();
|
|
seq = read_seqbegin(&base->lock);
|
|
p = lookup(daddr, base, seq, NULL, &gc_cnt, &parent, &pp);
|
|
invalidated = read_seqretry(&base->lock, seq);
|
|
rcu_read_unlock();
|
|
|
|
if (p)
|
|
return p;
|
|
|
|
/* If no writer did a change during our lookup, we can return early. */
|
|
if (!create && !invalidated)
|
|
return NULL;
|
|
|
|
/* retry an exact lookup, taking the lock before.
|
|
* At least, nodes should be hot in our cache.
|
|
*/
|
|
parent = NULL;
|
|
write_seqlock_bh(&base->lock);
|
|
|
|
gc_cnt = 0;
|
|
p = lookup(daddr, base, seq, gc_stack, &gc_cnt, &parent, &pp);
|
|
if (!p && create) {
|
|
p = kmem_cache_alloc(peer_cachep, GFP_ATOMIC);
|
|
if (p) {
|
|
p->daddr = *daddr;
|
|
p->dtime = (__u32)jiffies;
|
|
refcount_set(&p->refcnt, 2);
|
|
atomic_set(&p->rid, 0);
|
|
p->metrics[RTAX_LOCK-1] = INETPEER_METRICS_NEW;
|
|
p->rate_tokens = 0;
|
|
p->n_redirects = 0;
|
|
/* 60*HZ is arbitrary, but chosen enough high so that the first
|
|
* calculation of tokens is at its maximum.
|
|
*/
|
|
p->rate_last = jiffies - 60*HZ;
|
|
|
|
rb_link_node(&p->rb_node, parent, pp);
|
|
rb_insert_color(&p->rb_node, &base->rb_root);
|
|
base->total++;
|
|
}
|
|
}
|
|
if (gc_cnt)
|
|
inet_peer_gc(base, gc_stack, gc_cnt);
|
|
write_sequnlock_bh(&base->lock);
|
|
|
|
return p;
|
|
}
|
|
EXPORT_SYMBOL_GPL(inet_getpeer);
|
|
|
|
void inet_putpeer(struct inet_peer *p)
|
|
{
|
|
/* The WRITE_ONCE() pairs with itself (we run lockless)
|
|
* and the READ_ONCE() in inet_peer_gc()
|
|
*/
|
|
WRITE_ONCE(p->dtime, (__u32)jiffies);
|
|
|
|
if (refcount_dec_and_test(&p->refcnt))
|
|
call_rcu(&p->rcu, inetpeer_free_rcu);
|
|
}
|
|
EXPORT_SYMBOL_GPL(inet_putpeer);
|
|
|
|
/*
|
|
* Check transmit rate limitation for given message.
|
|
* The rate information is held in the inet_peer entries now.
|
|
* This function is generic and could be used for other purposes
|
|
* too. It uses a Token bucket filter as suggested by Alexey Kuznetsov.
|
|
*
|
|
* Note that the same inet_peer fields are modified by functions in
|
|
* route.c too, but these work for packet destinations while xrlim_allow
|
|
* works for icmp destinations. This means the rate limiting information
|
|
* for one "ip object" is shared - and these ICMPs are twice limited:
|
|
* by source and by destination.
|
|
*
|
|
* RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate
|
|
* SHOULD allow setting of rate limits
|
|
*
|
|
* Shared between ICMPv4 and ICMPv6.
|
|
*/
|
|
#define XRLIM_BURST_FACTOR 6
|
|
bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout)
|
|
{
|
|
unsigned long now, token;
|
|
bool rc = false;
|
|
|
|
if (!peer)
|
|
return true;
|
|
|
|
token = peer->rate_tokens;
|
|
now = jiffies;
|
|
token += now - peer->rate_last;
|
|
peer->rate_last = now;
|
|
if (token > XRLIM_BURST_FACTOR * timeout)
|
|
token = XRLIM_BURST_FACTOR * timeout;
|
|
if (token >= timeout) {
|
|
token -= timeout;
|
|
rc = true;
|
|
}
|
|
peer->rate_tokens = token;
|
|
return rc;
|
|
}
|
|
EXPORT_SYMBOL(inet_peer_xrlim_allow);
|
|
|
|
void inetpeer_invalidate_tree(struct inet_peer_base *base)
|
|
{
|
|
struct rb_node *p = rb_first(&base->rb_root);
|
|
|
|
while (p) {
|
|
struct inet_peer *peer = rb_entry(p, struct inet_peer, rb_node);
|
|
|
|
p = rb_next(p);
|
|
rb_erase(&peer->rb_node, &base->rb_root);
|
|
inet_putpeer(peer);
|
|
cond_resched();
|
|
}
|
|
|
|
base->total = 0;
|
|
}
|
|
EXPORT_SYMBOL(inetpeer_invalidate_tree);
|