Ertuğrul Erata
117 lines
4.6 KiB
Diff
117 lines
4.6 KiB
Diff
From foo@baz Wed Sep 30 05:25:07 CEST 2015
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From: Jesse Gross <jesse@nicira.com>
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Date: Mon, 21 Sep 2015 20:21:20 -0700
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Subject: openvswitch: Zero flows on allocation.
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From: Jesse Gross <jesse@nicira.com>
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[ Upstream commit ae5f2fb1d51fa128a460bcfbe3c56d7ab8bf6a43 ]
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When support for megaflows was introduced, OVS needed to start
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installing flows with a mask applied to them. Since masking is an
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expensive operation, OVS also had an optimization that would only
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take the parts of the flow keys that were covered by a non-zero
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mask. The values stored in the remaining pieces should not matter
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because they are masked out.
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While this works fine for the purposes of matching (which must always
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look at the mask), serialization to netlink can be problematic. Since
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the flow and the mask are serialized separately, the uninitialized
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portions of the flow can be encoded with whatever values happen to be
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present.
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In terms of functionality, this has little effect since these fields
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will be masked out by definition. However, it leaks kernel memory to
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userspace, which is a potential security vulnerability. It is also
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possible that other code paths could look at the masked key and get
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uninitialized data, although this does not currently appear to be an
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issue in practice.
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This removes the mask optimization for flows that are being installed.
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This was always intended to be the case as the mask optimizations were
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really targetting per-packet flow operations.
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Fixes: 03f0d916 ("openvswitch: Mega flow implementation")
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Signed-off-by: Jesse Gross <jesse@nicira.com>
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Acked-by: Pravin B Shelar <pshelar@nicira.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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net/openvswitch/datapath.c | 4 ++--
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net/openvswitch/flow_table.c | 23 ++++++++++++-----------
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net/openvswitch/flow_table.h | 2 +-
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3 files changed, 15 insertions(+), 14 deletions(-)
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--- a/net/openvswitch/datapath.c
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+++ b/net/openvswitch/datapath.c
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@@ -920,7 +920,7 @@ static int ovs_flow_cmd_new(struct sk_bu
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if (error)
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goto err_kfree_flow;
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- ovs_flow_mask_key(&new_flow->key, &key, &mask);
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+ ovs_flow_mask_key(&new_flow->key, &key, true, &mask);
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/* Extract flow identifier. */
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error = ovs_nla_get_identifier(&new_flow->id, a[OVS_FLOW_ATTR_UFID],
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@@ -1047,7 +1047,7 @@ static struct sw_flow_actions *get_flow_
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struct sw_flow_key masked_key;
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int error;
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- ovs_flow_mask_key(&masked_key, key, mask);
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+ ovs_flow_mask_key(&masked_key, key, true, mask);
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error = ovs_nla_copy_actions(a, &masked_key, &acts, log);
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if (error) {
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OVS_NLERR(log,
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--- a/net/openvswitch/flow_table.c
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+++ b/net/openvswitch/flow_table.c
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@@ -56,20 +56,21 @@ static u16 range_n_bytes(const struct sw
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}
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void ovs_flow_mask_key(struct sw_flow_key *dst, const struct sw_flow_key *src,
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- const struct sw_flow_mask *mask)
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+ bool full, const struct sw_flow_mask *mask)
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{
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- const long *m = (const long *)((const u8 *)&mask->key +
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- mask->range.start);
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- const long *s = (const long *)((const u8 *)src +
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- mask->range.start);
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- long *d = (long *)((u8 *)dst + mask->range.start);
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+ int start = full ? 0 : mask->range.start;
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+ int len = full ? sizeof *dst : range_n_bytes(&mask->range);
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+ const long *m = (const long *)((const u8 *)&mask->key + start);
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+ const long *s = (const long *)((const u8 *)src + start);
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+ long *d = (long *)((u8 *)dst + start);
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int i;
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- /* The memory outside of the 'mask->range' are not set since
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- * further operations on 'dst' only uses contents within
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- * 'mask->range'.
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+ /* If 'full' is true then all of 'dst' is fully initialized. Otherwise,
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+ * if 'full' is false the memory outside of the 'mask->range' is left
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+ * uninitialized. This can be used as an optimization when further
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+ * operations on 'dst' only use contents within 'mask->range'.
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*/
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- for (i = 0; i < range_n_bytes(&mask->range); i += sizeof(long))
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+ for (i = 0; i < len; i += sizeof(long))
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*d++ = *s++ & *m++;
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}
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@@ -473,7 +474,7 @@ static struct sw_flow *masked_flow_looku
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u32 hash;
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struct sw_flow_key masked_key;
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- ovs_flow_mask_key(&masked_key, unmasked, mask);
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+ ovs_flow_mask_key(&masked_key, unmasked, false, mask);
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hash = flow_hash(&masked_key, &mask->range);
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head = find_bucket(ti, hash);
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hlist_for_each_entry_rcu(flow, head, flow_table.node[ti->node_ver]) {
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--- a/net/openvswitch/flow_table.h
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+++ b/net/openvswitch/flow_table.h
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@@ -86,5 +86,5 @@ struct sw_flow *ovs_flow_tbl_lookup_ufid
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bool ovs_flow_cmp(const struct sw_flow *, const struct sw_flow_match *);
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void ovs_flow_mask_key(struct sw_flow_key *dst, const struct sw_flow_key *src,
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- const struct sw_flow_mask *mask);
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+ bool full, const struct sw_flow_mask *mask);
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#endif /* flow_table.h */
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