linux/net/xfrm/xfrm_ipcomp.c
Sabrina Dubroca 747b67088f xfrm: ipcomp: remove unnecessary get_cpu()
While testing ipcomp on a realtime kernel, Xiumei reported a "sleeping
in atomic" bug, caused by a memory allocation while preemption is
disabled (ipcomp_decompress -> alloc_page -> ... get_page_from_freelist).

As Sebastian noted [1], this get_cpu() isn't actually needed, since
ipcomp_decompress() is called in napi context anyway, so BH is already
disabled.

This patch replaces get_cpu + per_cpu_ptr with this_cpu_ptr, then
simplifies the error returns, since there isn't any common operation
left.

[1] https://lore.kernel.org/lkml/20190820082810.ixkmi56fp7u7eyn2@linutronix.de/

Cc: Juri Lelli <jlelli@redhat.com>
Reported-by: Xiumei Mu <xmu@redhat.com>
Suggested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
2021-04-19 12:49:29 +02:00

374 lines
7.3 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* IP Payload Compression Protocol (IPComp) - RFC3173.
*
* Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
* Copyright (c) 2003-2008 Herbert Xu <herbert@gondor.apana.org.au>
*
* Todo:
* - Tunable compression parameters.
* - Compression stats.
* - Adaptive compression.
*/
#include <linux/crypto.h>
#include <linux/err.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/percpu.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/vmalloc.h>
#include <net/ip.h>
#include <net/ipcomp.h>
#include <net/xfrm.h>
struct ipcomp_tfms {
struct list_head list;
struct crypto_comp * __percpu *tfms;
int users;
};
static DEFINE_MUTEX(ipcomp_resource_mutex);
static void * __percpu *ipcomp_scratches;
static int ipcomp_scratch_users;
static LIST_HEAD(ipcomp_tfms_list);
static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
{
struct ipcomp_data *ipcd = x->data;
const int plen = skb->len;
int dlen = IPCOMP_SCRATCH_SIZE;
const u8 *start = skb->data;
u8 *scratch = *this_cpu_ptr(ipcomp_scratches);
struct crypto_comp *tfm = *this_cpu_ptr(ipcd->tfms);
int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
int len;
if (err)
return err;
if (dlen < (plen + sizeof(struct ip_comp_hdr)))
return -EINVAL;
len = dlen - plen;
if (len > skb_tailroom(skb))
len = skb_tailroom(skb);
__skb_put(skb, len);
len += plen;
skb_copy_to_linear_data(skb, scratch, len);
while ((scratch += len, dlen -= len) > 0) {
skb_frag_t *frag;
struct page *page;
if (WARN_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS))
return -EMSGSIZE;
frag = skb_shinfo(skb)->frags + skb_shinfo(skb)->nr_frags;
page = alloc_page(GFP_ATOMIC);
if (!page)
return -ENOMEM;
__skb_frag_set_page(frag, page);
len = PAGE_SIZE;
if (dlen < len)
len = dlen;
skb_frag_off_set(frag, 0);
skb_frag_size_set(frag, len);
memcpy(skb_frag_address(frag), scratch, len);
skb->truesize += len;
skb->data_len += len;
skb->len += len;
skb_shinfo(skb)->nr_frags++;
}
return 0;
}
int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
{
int nexthdr;
int err = -ENOMEM;
struct ip_comp_hdr *ipch;
if (skb_linearize_cow(skb))
goto out;
skb->ip_summed = CHECKSUM_NONE;
/* Remove ipcomp header and decompress original payload */
ipch = (void *)skb->data;
nexthdr = ipch->nexthdr;
skb->transport_header = skb->network_header + sizeof(*ipch);
__skb_pull(skb, sizeof(*ipch));
err = ipcomp_decompress(x, skb);
if (err)
goto out;
err = nexthdr;
out:
return err;
}
EXPORT_SYMBOL_GPL(ipcomp_input);
static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
{
struct ipcomp_data *ipcd = x->data;
const int plen = skb->len;
int dlen = IPCOMP_SCRATCH_SIZE;
u8 *start = skb->data;
struct crypto_comp *tfm;
u8 *scratch;
int err;
local_bh_disable();
scratch = *this_cpu_ptr(ipcomp_scratches);
tfm = *this_cpu_ptr(ipcd->tfms);
err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
if (err)
goto out;
if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
err = -EMSGSIZE;
goto out;
}
memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
local_bh_enable();
pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
return 0;
out:
local_bh_enable();
return err;
}
int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
{
int err;
struct ip_comp_hdr *ipch;
struct ipcomp_data *ipcd = x->data;
if (skb->len < ipcd->threshold) {
/* Don't bother compressing */
goto out_ok;
}
if (skb_linearize_cow(skb))
goto out_ok;
err = ipcomp_compress(x, skb);
if (err) {
goto out_ok;
}
/* Install ipcomp header, convert into ipcomp datagram. */
ipch = ip_comp_hdr(skb);
ipch->nexthdr = *skb_mac_header(skb);
ipch->flags = 0;
ipch->cpi = htons((u16 )ntohl(x->id.spi));
*skb_mac_header(skb) = IPPROTO_COMP;
out_ok:
skb_push(skb, -skb_network_offset(skb));
return 0;
}
EXPORT_SYMBOL_GPL(ipcomp_output);
static void ipcomp_free_scratches(void)
{
int i;
void * __percpu *scratches;
if (--ipcomp_scratch_users)
return;
scratches = ipcomp_scratches;
if (!scratches)
return;
for_each_possible_cpu(i)
vfree(*per_cpu_ptr(scratches, i));
free_percpu(scratches);
}
static void * __percpu *ipcomp_alloc_scratches(void)
{
void * __percpu *scratches;
int i;
if (ipcomp_scratch_users++)
return ipcomp_scratches;
scratches = alloc_percpu(void *);
if (!scratches)
return NULL;
ipcomp_scratches = scratches;
for_each_possible_cpu(i) {
void *scratch;
scratch = vmalloc_node(IPCOMP_SCRATCH_SIZE, cpu_to_node(i));
if (!scratch)
return NULL;
*per_cpu_ptr(scratches, i) = scratch;
}
return scratches;
}
static void ipcomp_free_tfms(struct crypto_comp * __percpu *tfms)
{
struct ipcomp_tfms *pos;
int cpu;
list_for_each_entry(pos, &ipcomp_tfms_list, list) {
if (pos->tfms == tfms)
break;
}
WARN_ON(!pos);
if (--pos->users)
return;
list_del(&pos->list);
kfree(pos);
if (!tfms)
return;
for_each_possible_cpu(cpu) {
struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
crypto_free_comp(tfm);
}
free_percpu(tfms);
}
static struct crypto_comp * __percpu *ipcomp_alloc_tfms(const char *alg_name)
{
struct ipcomp_tfms *pos;
struct crypto_comp * __percpu *tfms;
int cpu;
list_for_each_entry(pos, &ipcomp_tfms_list, list) {
struct crypto_comp *tfm;
/* This can be any valid CPU ID so we don't need locking. */
tfm = this_cpu_read(*pos->tfms);
if (!strcmp(crypto_comp_name(tfm), alg_name)) {
pos->users++;
return pos->tfms;
}
}
pos = kmalloc(sizeof(*pos), GFP_KERNEL);
if (!pos)
return NULL;
pos->users = 1;
INIT_LIST_HEAD(&pos->list);
list_add(&pos->list, &ipcomp_tfms_list);
pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
if (!tfms)
goto error;
for_each_possible_cpu(cpu) {
struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
CRYPTO_ALG_ASYNC);
if (IS_ERR(tfm))
goto error;
*per_cpu_ptr(tfms, cpu) = tfm;
}
return tfms;
error:
ipcomp_free_tfms(tfms);
return NULL;
}
static void ipcomp_free_data(struct ipcomp_data *ipcd)
{
if (ipcd->tfms)
ipcomp_free_tfms(ipcd->tfms);
ipcomp_free_scratches();
}
void ipcomp_destroy(struct xfrm_state *x)
{
struct ipcomp_data *ipcd = x->data;
if (!ipcd)
return;
xfrm_state_delete_tunnel(x);
mutex_lock(&ipcomp_resource_mutex);
ipcomp_free_data(ipcd);
mutex_unlock(&ipcomp_resource_mutex);
kfree(ipcd);
}
EXPORT_SYMBOL_GPL(ipcomp_destroy);
int ipcomp_init_state(struct xfrm_state *x)
{
int err;
struct ipcomp_data *ipcd;
struct xfrm_algo_desc *calg_desc;
err = -EINVAL;
if (!x->calg)
goto out;
if (x->encap)
goto out;
err = -ENOMEM;
ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
if (!ipcd)
goto out;
mutex_lock(&ipcomp_resource_mutex);
if (!ipcomp_alloc_scratches())
goto error;
ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
if (!ipcd->tfms)
goto error;
mutex_unlock(&ipcomp_resource_mutex);
calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
BUG_ON(!calg_desc);
ipcd->threshold = calg_desc->uinfo.comp.threshold;
x->data = ipcd;
err = 0;
out:
return err;
error:
ipcomp_free_data(ipcd);
mutex_unlock(&ipcomp_resource_mutex);
kfree(ipcd);
goto out;
}
EXPORT_SYMBOL_GPL(ipcomp_init_state);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");