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![Greg Hackmann](/assets/img/avatar_default.png)
f7c83bcbfa
("net: xfrm: use __this_cpu_read per-cpu helper") added a
__this_cpu_read() call inside ipcomp_alloc_tfms().
At the time, __this_cpu_read() required the caller to either not care
about races or to handle preemption/interrupt issues. 3.15 tightened
the rules around some per-cpu operations, and now __this_cpu_read()
should never be used in a preemptible context. On 3.15 and later, we
need to use this_cpu_read() instead.
syzkaller reported this leading to the following kernel BUG while
fuzzing sendmsg:
BUG: using __this_cpu_read() in preemptible [00000000] code: repro/3101
caller is ipcomp_init_state+0x185/0x990
CPU: 3 PID: 3101 Comm: repro Not tainted 4.16.0-rc4-00123-g86f84779d8e9 #154
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
Call Trace:
dump_stack+0xb9/0x115
check_preemption_disabled+0x1cb/0x1f0
ipcomp_init_state+0x185/0x990
? __xfrm_init_state+0x876/0xc20
? lock_downgrade+0x5e0/0x5e0
ipcomp4_init_state+0xaa/0x7c0
__xfrm_init_state+0x3eb/0xc20
xfrm_init_state+0x19/0x60
pfkey_add+0x20df/0x36f0
? pfkey_broadcast+0x3dd/0x600
? pfkey_sock_destruct+0x340/0x340
? pfkey_seq_stop+0x80/0x80
? __skb_clone+0x236/0x750
? kmem_cache_alloc+0x1f6/0x260
? pfkey_sock_destruct+0x340/0x340
? pfkey_process+0x62a/0x6f0
pfkey_process+0x62a/0x6f0
? pfkey_send_new_mapping+0x11c0/0x11c0
? mutex_lock_io_nested+0x1390/0x1390
pfkey_sendmsg+0x383/0x750
? dump_sp+0x430/0x430
sock_sendmsg+0xc0/0x100
___sys_sendmsg+0x6c8/0x8b0
? copy_msghdr_from_user+0x3b0/0x3b0
? pagevec_lru_move_fn+0x144/0x1f0
? find_held_lock+0x32/0x1c0
? do_huge_pmd_anonymous_page+0xc43/0x11e0
? lock_downgrade+0x5e0/0x5e0
? get_kernel_page+0xb0/0xb0
? _raw_spin_unlock+0x29/0x40
? do_huge_pmd_anonymous_page+0x400/0x11e0
? __handle_mm_fault+0x553/0x2460
? __fget_light+0x163/0x1f0
? __sys_sendmsg+0xc7/0x170
__sys_sendmsg+0xc7/0x170
? SyS_shutdown+0x1a0/0x1a0
? __do_page_fault+0x5a0/0xca0
? lock_downgrade+0x5e0/0x5e0
SyS_sendmsg+0x27/0x40
? __sys_sendmsg+0x170/0x170
do_syscall_64+0x19f/0x640
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x7f0ee73dfb79
RSP: 002b:00007ffe14fc15a8 EFLAGS: 00000207 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f0ee73dfb79
RDX: 0000000000000000 RSI: 00000000208befc8 RDI: 0000000000000004
RBP: 00007ffe14fc15b0 R08: 00007ffe14fc15c0 R09: 00007ffe14fc15c0
R10: 0000000000000000 R11: 0000000000000207 R12: 0000000000400440
R13: 00007ffe14fc16b0 R14: 0000000000000000 R15: 0000000000000000
Signed-off-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
386 lines
7.6 KiB
C
386 lines
7.6 KiB
C
/*
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* IP Payload Compression Protocol (IPComp) - RFC3173.
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*
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* Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
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* Copyright (c) 2003-2008 Herbert Xu <herbert@gondor.apana.org.au>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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* Todo:
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* - Tunable compression parameters.
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* - Compression stats.
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* - Adaptive compression.
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*/
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#include <linux/crypto.h>
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#include <linux/err.h>
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#include <linux/list.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/percpu.h>
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#include <linux/slab.h>
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#include <linux/smp.h>
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#include <linux/vmalloc.h>
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#include <net/ip.h>
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#include <net/ipcomp.h>
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#include <net/xfrm.h>
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struct ipcomp_tfms {
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struct list_head list;
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struct crypto_comp * __percpu *tfms;
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int users;
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};
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static DEFINE_MUTEX(ipcomp_resource_mutex);
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static void * __percpu *ipcomp_scratches;
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static int ipcomp_scratch_users;
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static LIST_HEAD(ipcomp_tfms_list);
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static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
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{
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struct ipcomp_data *ipcd = x->data;
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const int plen = skb->len;
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int dlen = IPCOMP_SCRATCH_SIZE;
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const u8 *start = skb->data;
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const int cpu = get_cpu();
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u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
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struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
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int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
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int len;
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if (err)
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goto out;
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if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
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err = -EINVAL;
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goto out;
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}
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len = dlen - plen;
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if (len > skb_tailroom(skb))
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len = skb_tailroom(skb);
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__skb_put(skb, len);
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len += plen;
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skb_copy_to_linear_data(skb, scratch, len);
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while ((scratch += len, dlen -= len) > 0) {
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skb_frag_t *frag;
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struct page *page;
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err = -EMSGSIZE;
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if (WARN_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS))
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goto out;
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frag = skb_shinfo(skb)->frags + skb_shinfo(skb)->nr_frags;
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page = alloc_page(GFP_ATOMIC);
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err = -ENOMEM;
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if (!page)
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goto out;
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__skb_frag_set_page(frag, page);
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len = PAGE_SIZE;
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if (dlen < len)
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len = dlen;
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frag->page_offset = 0;
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skb_frag_size_set(frag, len);
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memcpy(skb_frag_address(frag), scratch, len);
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skb->truesize += len;
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skb->data_len += len;
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skb->len += len;
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skb_shinfo(skb)->nr_frags++;
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}
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err = 0;
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out:
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put_cpu();
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return err;
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}
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int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
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{
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int nexthdr;
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int err = -ENOMEM;
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struct ip_comp_hdr *ipch;
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if (skb_linearize_cow(skb))
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goto out;
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skb->ip_summed = CHECKSUM_NONE;
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/* Remove ipcomp header and decompress original payload */
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ipch = (void *)skb->data;
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nexthdr = ipch->nexthdr;
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skb->transport_header = skb->network_header + sizeof(*ipch);
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__skb_pull(skb, sizeof(*ipch));
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err = ipcomp_decompress(x, skb);
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if (err)
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goto out;
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err = nexthdr;
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out:
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return err;
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}
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EXPORT_SYMBOL_GPL(ipcomp_input);
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static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
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{
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struct ipcomp_data *ipcd = x->data;
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const int plen = skb->len;
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int dlen = IPCOMP_SCRATCH_SIZE;
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u8 *start = skb->data;
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struct crypto_comp *tfm;
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u8 *scratch;
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int err;
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local_bh_disable();
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scratch = *this_cpu_ptr(ipcomp_scratches);
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tfm = *this_cpu_ptr(ipcd->tfms);
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err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
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if (err)
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goto out;
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if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
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err = -EMSGSIZE;
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goto out;
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}
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memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
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local_bh_enable();
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pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
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return 0;
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out:
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local_bh_enable();
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return err;
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}
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int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
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{
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int err;
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struct ip_comp_hdr *ipch;
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struct ipcomp_data *ipcd = x->data;
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if (skb->len < ipcd->threshold) {
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/* Don't bother compressing */
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goto out_ok;
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}
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if (skb_linearize_cow(skb))
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goto out_ok;
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err = ipcomp_compress(x, skb);
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if (err) {
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goto out_ok;
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}
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/* Install ipcomp header, convert into ipcomp datagram. */
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ipch = ip_comp_hdr(skb);
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ipch->nexthdr = *skb_mac_header(skb);
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ipch->flags = 0;
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ipch->cpi = htons((u16 )ntohl(x->id.spi));
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*skb_mac_header(skb) = IPPROTO_COMP;
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out_ok:
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skb_push(skb, -skb_network_offset(skb));
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return 0;
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}
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EXPORT_SYMBOL_GPL(ipcomp_output);
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static void ipcomp_free_scratches(void)
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{
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int i;
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void * __percpu *scratches;
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if (--ipcomp_scratch_users)
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return;
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scratches = ipcomp_scratches;
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if (!scratches)
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return;
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for_each_possible_cpu(i)
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vfree(*per_cpu_ptr(scratches, i));
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free_percpu(scratches);
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}
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static void * __percpu *ipcomp_alloc_scratches(void)
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{
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void * __percpu *scratches;
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int i;
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if (ipcomp_scratch_users++)
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return ipcomp_scratches;
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scratches = alloc_percpu(void *);
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if (!scratches)
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return NULL;
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ipcomp_scratches = scratches;
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for_each_possible_cpu(i) {
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void *scratch;
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scratch = vmalloc_node(IPCOMP_SCRATCH_SIZE, cpu_to_node(i));
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if (!scratch)
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return NULL;
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*per_cpu_ptr(scratches, i) = scratch;
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}
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return scratches;
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}
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static void ipcomp_free_tfms(struct crypto_comp * __percpu *tfms)
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{
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struct ipcomp_tfms *pos;
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int cpu;
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list_for_each_entry(pos, &ipcomp_tfms_list, list) {
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if (pos->tfms == tfms)
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break;
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}
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WARN_ON(!pos);
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if (--pos->users)
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return;
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list_del(&pos->list);
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kfree(pos);
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if (!tfms)
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return;
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for_each_possible_cpu(cpu) {
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struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
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crypto_free_comp(tfm);
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}
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free_percpu(tfms);
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}
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static struct crypto_comp * __percpu *ipcomp_alloc_tfms(const char *alg_name)
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{
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struct ipcomp_tfms *pos;
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struct crypto_comp * __percpu *tfms;
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int cpu;
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list_for_each_entry(pos, &ipcomp_tfms_list, list) {
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struct crypto_comp *tfm;
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/* This can be any valid CPU ID so we don't need locking. */
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tfm = this_cpu_read(*pos->tfms);
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if (!strcmp(crypto_comp_name(tfm), alg_name)) {
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pos->users++;
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return pos->tfms;
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}
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}
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pos = kmalloc(sizeof(*pos), GFP_KERNEL);
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if (!pos)
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return NULL;
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pos->users = 1;
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INIT_LIST_HEAD(&pos->list);
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list_add(&pos->list, &ipcomp_tfms_list);
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pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
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if (!tfms)
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goto error;
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for_each_possible_cpu(cpu) {
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struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
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CRYPTO_ALG_ASYNC);
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if (IS_ERR(tfm))
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goto error;
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*per_cpu_ptr(tfms, cpu) = tfm;
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}
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return tfms;
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error:
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ipcomp_free_tfms(tfms);
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return NULL;
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}
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static void ipcomp_free_data(struct ipcomp_data *ipcd)
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{
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if (ipcd->tfms)
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ipcomp_free_tfms(ipcd->tfms);
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ipcomp_free_scratches();
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}
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void ipcomp_destroy(struct xfrm_state *x)
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{
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struct ipcomp_data *ipcd = x->data;
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if (!ipcd)
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return;
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xfrm_state_delete_tunnel(x);
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mutex_lock(&ipcomp_resource_mutex);
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ipcomp_free_data(ipcd);
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mutex_unlock(&ipcomp_resource_mutex);
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kfree(ipcd);
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}
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EXPORT_SYMBOL_GPL(ipcomp_destroy);
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int ipcomp_init_state(struct xfrm_state *x)
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{
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int err;
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struct ipcomp_data *ipcd;
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struct xfrm_algo_desc *calg_desc;
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err = -EINVAL;
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if (!x->calg)
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goto out;
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if (x->encap)
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goto out;
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err = -ENOMEM;
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ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
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if (!ipcd)
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goto out;
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mutex_lock(&ipcomp_resource_mutex);
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if (!ipcomp_alloc_scratches())
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goto error;
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ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
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if (!ipcd->tfms)
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goto error;
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mutex_unlock(&ipcomp_resource_mutex);
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calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
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BUG_ON(!calg_desc);
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ipcd->threshold = calg_desc->uinfo.comp.threshold;
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x->data = ipcd;
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err = 0;
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out:
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return err;
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error:
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ipcomp_free_data(ipcd);
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mutex_unlock(&ipcomp_resource_mutex);
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kfree(ipcd);
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goto out;
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}
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EXPORT_SYMBOL_GPL(ipcomp_init_state);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
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MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
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