f08b2d078c
commit 2580d3f40022642452dd8422bfb8c22e54cf84bb upstream.
xfrm_bydst_resize() calls synchronize_rcu() while holding
hash_resize_mutex. But then on PREEMPT_RT configurations,
xfrm_policy_lookup_bytype() may acquire that mutex while running in an
RCU read side critical section. This results in a deadlock.
In fact the scope of hash_resize_mutex is way beyond the purpose of
xfrm_policy_lookup_bytype() to just fetch a coherent and stable policy
for a given destination/direction, along with other details.
The lower level net->xfrm.xfrm_policy_lock, which among other things
protects per destination/direction references to policy entries, is
enough to serialize and benefit from priority inheritance against the
write side. As a bonus, it makes it officially a per network namespace
synchronization business where a policy table resize on namespace A
shouldn't block a policy lookup on namespace B.
Fixes: 77cc278f7b (xfrm: policy: Use sequence counters with associated lock)
Cc: stable@vger.kernel.org
Cc: Ahmed S. Darwish <a.darwish@linutronix.de>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Varad Gautam <varad.gautam@suse.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
84 lines
2.0 KiB
C
84 lines
2.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __NETNS_XFRM_H
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#define __NETNS_XFRM_H
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#include <linux/list.h>
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#include <linux/wait.h>
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#include <linux/workqueue.h>
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#include <linux/rhashtable-types.h>
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#include <linux/xfrm.h>
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#include <net/dst_ops.h>
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struct ctl_table_header;
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struct xfrm_policy_hash {
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struct hlist_head __rcu *table;
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unsigned int hmask;
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u8 dbits4;
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u8 sbits4;
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u8 dbits6;
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u8 sbits6;
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};
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struct xfrm_policy_hthresh {
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struct work_struct work;
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seqlock_t lock;
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u8 lbits4;
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u8 rbits4;
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u8 lbits6;
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u8 rbits6;
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};
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struct netns_xfrm {
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struct list_head state_all;
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/*
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* Hash table to find appropriate SA towards given target (endpoint of
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* tunnel or destination of transport mode) allowed by selector.
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*
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* Main use is finding SA after policy selected tunnel or transport
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* mode. Also, it can be used by ah/esp icmp error handler to find
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* offending SA.
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*/
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struct hlist_head __rcu *state_bydst;
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struct hlist_head __rcu *state_bysrc;
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struct hlist_head __rcu *state_byspi;
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unsigned int state_hmask;
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unsigned int state_num;
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struct work_struct state_hash_work;
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struct list_head policy_all;
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struct hlist_head *policy_byidx;
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unsigned int policy_idx_hmask;
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struct hlist_head policy_inexact[XFRM_POLICY_MAX];
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struct xfrm_policy_hash policy_bydst[XFRM_POLICY_MAX];
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unsigned int policy_count[XFRM_POLICY_MAX * 2];
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struct work_struct policy_hash_work;
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struct xfrm_policy_hthresh policy_hthresh;
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struct list_head inexact_bins;
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struct sock *nlsk;
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struct sock *nlsk_stash;
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u32 sysctl_aevent_etime;
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u32 sysctl_aevent_rseqth;
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int sysctl_larval_drop;
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u32 sysctl_acq_expires;
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#ifdef CONFIG_SYSCTL
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struct ctl_table_header *sysctl_hdr;
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#endif
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struct dst_ops xfrm4_dst_ops;
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#if IS_ENABLED(CONFIG_IPV6)
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struct dst_ops xfrm6_dst_ops;
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#endif
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spinlock_t xfrm_state_lock;
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seqcount_t xfrm_state_hash_generation;
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seqcount_spinlock_t xfrm_policy_hash_generation;
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spinlock_t xfrm_policy_lock;
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struct mutex xfrm_cfg_mutex;
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};
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#endif
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