Revision 9e2b7fa2df4365e99934901da4fb4af52d81e820 authored by Martin Willi on 06 November 2020, 07:30:30 UTC, committed by Jakub Kicinski on 12 November 2020, 15:47:06 UTC
VRF devices use an optimized direct path on output if a default qdisc is involved, calling Netfilter hooks directly. This path, however, does not consider Netfilter rules completing asynchronously, such as with NFQUEUE. The Netfilter okfn() is called for asynchronously accepted packets, but the VRF never passes that packet down the stack to send it out over the slave device. Using the slower redirect path for this seems not feasible, as we do not know beforehand if a Netfilter hook has asynchronously completing rules. Fix the use of asynchronously completing Netfilter rules in OUTPUT and POSTROUTING by using a special completion function that additionally calls dst_output() to pass the packet down the stack. Also, slightly adjust the use of nf_reset_ct() so that is called in the asynchronous case, too. Fixes: dcdd43c41e60 ("net: vrf: performance improvements for IPv4") Fixes: a9ec54d1b0cd ("net: vrf: performance improvements for IPv6") Signed-off-by: Martin Willi <martin@strongswan.org> Link: https://lore.kernel.org/r/20201106073030.3974927-1-martin@strongswan.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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stackdepot.c
// SPDX-License-Identifier: GPL-2.0-only
/*
* Generic stack depot for storing stack traces.
*
* Some debugging tools need to save stack traces of certain events which can
* be later presented to the user. For example, KASAN needs to safe alloc and
* free stacks for each object, but storing two stack traces per object
* requires too much memory (e.g. SLUB_DEBUG needs 256 bytes per object for
* that).
*
* Instead, stack depot maintains a hashtable of unique stacktraces. Since alloc
* and free stacks repeat a lot, we save about 100x space.
* Stacks are never removed from depot, so we store them contiguously one after
* another in a contiguos memory allocation.
*
* Author: Alexander Potapenko <glider@google.com>
* Copyright (C) 2016 Google, Inc.
*
* Based on code by Dmitry Chernenkov.
*/
#include <linux/gfp.h>
#include <linux/interrupt.h>
#include <linux/jhash.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/percpu.h>
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/stacktrace.h>
#include <linux/stackdepot.h>
#include <linux/string.h>
#include <linux/types.h>
#define DEPOT_STACK_BITS (sizeof(depot_stack_handle_t) * 8)
#define STACK_ALLOC_NULL_PROTECTION_BITS 1
#define STACK_ALLOC_ORDER 2 /* 'Slab' size order for stack depot, 4 pages */
#define STACK_ALLOC_SIZE (1LL << (PAGE_SHIFT + STACK_ALLOC_ORDER))
#define STACK_ALLOC_ALIGN 4
#define STACK_ALLOC_OFFSET_BITS (STACK_ALLOC_ORDER + PAGE_SHIFT - \
STACK_ALLOC_ALIGN)
#define STACK_ALLOC_INDEX_BITS (DEPOT_STACK_BITS - \
STACK_ALLOC_NULL_PROTECTION_BITS - STACK_ALLOC_OFFSET_BITS)
#define STACK_ALLOC_SLABS_CAP 8192
#define STACK_ALLOC_MAX_SLABS \
(((1LL << (STACK_ALLOC_INDEX_BITS)) < STACK_ALLOC_SLABS_CAP) ? \
(1LL << (STACK_ALLOC_INDEX_BITS)) : STACK_ALLOC_SLABS_CAP)
/* The compact structure to store the reference to stacks. */
union handle_parts {
depot_stack_handle_t handle;
struct {
u32 slabindex : STACK_ALLOC_INDEX_BITS;
u32 offset : STACK_ALLOC_OFFSET_BITS;
u32 valid : STACK_ALLOC_NULL_PROTECTION_BITS;
};
};
struct stack_record {
struct stack_record *next; /* Link in the hashtable */
u32 hash; /* Hash in the hastable */
u32 size; /* Number of frames in the stack */
union handle_parts handle;
unsigned long entries[1]; /* Variable-sized array of entries. */
};
static void *stack_slabs[STACK_ALLOC_MAX_SLABS];
static int depot_index;
static int next_slab_inited;
static size_t depot_offset;
static DEFINE_SPINLOCK(depot_lock);
static bool init_stack_slab(void **prealloc)
{
if (!*prealloc)
return false;
/*
* This smp_load_acquire() pairs with smp_store_release() to
* |next_slab_inited| below and in depot_alloc_stack().
*/
if (smp_load_acquire(&next_slab_inited))
return true;
if (stack_slabs[depot_index] == NULL) {
stack_slabs[depot_index] = *prealloc;
*prealloc = NULL;
} else {
/* If this is the last depot slab, do not touch the next one. */
if (depot_index + 1 < STACK_ALLOC_MAX_SLABS) {
stack_slabs[depot_index + 1] = *prealloc;
*prealloc = NULL;
}
/*
* This smp_store_release pairs with smp_load_acquire() from
* |next_slab_inited| above and in stack_depot_save().
*/
smp_store_release(&next_slab_inited, 1);
}
return true;
}
/* Allocation of a new stack in raw storage */
static struct stack_record *depot_alloc_stack(unsigned long *entries, int size,
u32 hash, void **prealloc, gfp_t alloc_flags)
{
int required_size = offsetof(struct stack_record, entries) +
sizeof(unsigned long) * size;
struct stack_record *stack;
required_size = ALIGN(required_size, 1 << STACK_ALLOC_ALIGN);
if (unlikely(depot_offset + required_size > STACK_ALLOC_SIZE)) {
if (unlikely(depot_index + 1 >= STACK_ALLOC_MAX_SLABS)) {
WARN_ONCE(1, "Stack depot reached limit capacity");
return NULL;
}
depot_index++;
depot_offset = 0;
/*
* smp_store_release() here pairs with smp_load_acquire() from
* |next_slab_inited| in stack_depot_save() and
* init_stack_slab().
*/
if (depot_index + 1 < STACK_ALLOC_MAX_SLABS)
smp_store_release(&next_slab_inited, 0);
}
init_stack_slab(prealloc);
if (stack_slabs[depot_index] == NULL)
return NULL;
stack = stack_slabs[depot_index] + depot_offset;
stack->hash = hash;
stack->size = size;
stack->handle.slabindex = depot_index;
stack->handle.offset = depot_offset >> STACK_ALLOC_ALIGN;
stack->handle.valid = 1;
memcpy(stack->entries, entries, size * sizeof(unsigned long));
depot_offset += required_size;
return stack;
}
#define STACK_HASH_ORDER 20
#define STACK_HASH_SIZE (1L << STACK_HASH_ORDER)
#define STACK_HASH_MASK (STACK_HASH_SIZE - 1)
#define STACK_HASH_SEED 0x9747b28c
static struct stack_record *stack_table[STACK_HASH_SIZE] = {
[0 ... STACK_HASH_SIZE - 1] = NULL
};
/* Calculate hash for a stack */
static inline u32 hash_stack(unsigned long *entries, unsigned int size)
{
return jhash2((u32 *)entries,
size * sizeof(unsigned long) / sizeof(u32),
STACK_HASH_SEED);
}
/* Use our own, non-instrumented version of memcmp().
*
* We actually don't care about the order, just the equality.
*/
static inline
int stackdepot_memcmp(const unsigned long *u1, const unsigned long *u2,
unsigned int n)
{
for ( ; n-- ; u1++, u2++) {
if (*u1 != *u2)
return 1;
}
return 0;
}
/* Find a stack that is equal to the one stored in entries in the hash */
static inline struct stack_record *find_stack(struct stack_record *bucket,
unsigned long *entries, int size,
u32 hash)
{
struct stack_record *found;
for (found = bucket; found; found = found->next) {
if (found->hash == hash &&
found->size == size &&
!stackdepot_memcmp(entries, found->entries, size))
return found;
}
return NULL;
}
/**
* stack_depot_fetch - Fetch stack entries from a depot
*
* @handle: Stack depot handle which was returned from
* stack_depot_save().
* @entries: Pointer to store the entries address
*
* Return: The number of trace entries for this depot.
*/
unsigned int stack_depot_fetch(depot_stack_handle_t handle,
unsigned long **entries)
{
union handle_parts parts = { .handle = handle };
void *slab;
size_t offset = parts.offset << STACK_ALLOC_ALIGN;
struct stack_record *stack;
*entries = NULL;
if (parts.slabindex > depot_index) {
WARN(1, "slab index %d out of bounds (%d) for stack id %08x\n",
parts.slabindex, depot_index, handle);
return 0;
}
slab = stack_slabs[parts.slabindex];
if (!slab)
return 0;
stack = slab + offset;
*entries = stack->entries;
return stack->size;
}
EXPORT_SYMBOL_GPL(stack_depot_fetch);
/**
* stack_depot_save - Save a stack trace from an array
*
* @entries: Pointer to storage array
* @nr_entries: Size of the storage array
* @alloc_flags: Allocation gfp flags
*
* Return: The handle of the stack struct stored in depot
*/
depot_stack_handle_t stack_depot_save(unsigned long *entries,
unsigned int nr_entries,
gfp_t alloc_flags)
{
struct stack_record *found = NULL, **bucket;
depot_stack_handle_t retval = 0;
struct page *page = NULL;
void *prealloc = NULL;
unsigned long flags;
u32 hash;
if (unlikely(nr_entries == 0))
goto fast_exit;
hash = hash_stack(entries, nr_entries);
bucket = &stack_table[hash & STACK_HASH_MASK];
/*
* Fast path: look the stack trace up without locking.
* The smp_load_acquire() here pairs with smp_store_release() to
* |bucket| below.
*/
found = find_stack(smp_load_acquire(bucket), entries,
nr_entries, hash);
if (found)
goto exit;
/*
* Check if the current or the next stack slab need to be initialized.
* If so, allocate the memory - we won't be able to do that under the
* lock.
*
* The smp_load_acquire() here pairs with smp_store_release() to
* |next_slab_inited| in depot_alloc_stack() and init_stack_slab().
*/
if (unlikely(!smp_load_acquire(&next_slab_inited))) {
/*
* Zero out zone modifiers, as we don't have specific zone
* requirements. Keep the flags related to allocation in atomic
* contexts and I/O.
*/
alloc_flags &= ~GFP_ZONEMASK;
alloc_flags &= (GFP_ATOMIC | GFP_KERNEL);
alloc_flags |= __GFP_NOWARN;
page = alloc_pages(alloc_flags, STACK_ALLOC_ORDER);
if (page)
prealloc = page_address(page);
}
spin_lock_irqsave(&depot_lock, flags);
found = find_stack(*bucket, entries, nr_entries, hash);
if (!found) {
struct stack_record *new =
depot_alloc_stack(entries, nr_entries,
hash, &prealloc, alloc_flags);
if (new) {
new->next = *bucket;
/*
* This smp_store_release() pairs with
* smp_load_acquire() from |bucket| above.
*/
smp_store_release(bucket, new);
found = new;
}
} else if (prealloc) {
/*
* We didn't need to store this stack trace, but let's keep
* the preallocated memory for the future.
*/
WARN_ON(!init_stack_slab(&prealloc));
}
spin_unlock_irqrestore(&depot_lock, flags);
exit:
if (prealloc) {
/* Nobody used this memory, ok to free it. */
free_pages((unsigned long)prealloc, STACK_ALLOC_ORDER);
}
if (found)
retval = found->handle.handle;
fast_exit:
return retval;
}
EXPORT_SYMBOL_GPL(stack_depot_save);
static inline int in_irqentry_text(unsigned long ptr)
{
return (ptr >= (unsigned long)&__irqentry_text_start &&
ptr < (unsigned long)&__irqentry_text_end) ||
(ptr >= (unsigned long)&__softirqentry_text_start &&
ptr < (unsigned long)&__softirqentry_text_end);
}
unsigned int filter_irq_stacks(unsigned long *entries,
unsigned int nr_entries)
{
unsigned int i;
for (i = 0; i < nr_entries; i++) {
if (in_irqentry_text(entries[i])) {
/* Include the irqentry function into the stack. */
return i + 1;
}
}
return nr_entries;
}
EXPORT_SYMBOL_GPL(filter_irq_stacks);
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