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xfrm: Stop using dst->next in bundle construction.
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While building ipsec bundles, blocks of xfrm dsts are linked together
using dst->next from bottom to the top.

The only thing this is used for is initializing the pmtu values of the
xfrm stack, and for updating the mtu values at xfrm_bundle_ok() time.

The bundle pmtu entries must be processed in this order so that pmtu
values lower in the stack of routes can propagate up to the higher
ones.

Avoid using dst->next by simply maintaining an array of dst pointers
as we already do for the xfrm_state objects when building the bundle.

Signed-off-by: David S. Miller <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
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@davem330
davem330 committed Nov 30, 2017
1 parent 8b207e7 commit 5492093
Showing 1 changed file with 32 additions and 24 deletions.
56 changes: 32 additions & 24 deletions net/xfrm/xfrm_policy.c
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Original file line number Diff line number Diff line change
Expand Up @@ -54,7 +54,7 @@ static struct xfrm_policy_afinfo const __rcu *xfrm_policy_afinfo[AF_INET6 + 1]
static struct kmem_cache *xfrm_dst_cache __read_mostly;
static __read_mostly seqcount_t xfrm_policy_hash_generation;

static void xfrm_init_pmtu(struct dst_entry *dst);
static void xfrm_init_pmtu(struct xfrm_dst **bundle, int nr);
static int stale_bundle(struct dst_entry *dst);
static int xfrm_bundle_ok(struct xfrm_dst *xdst);
static void xfrm_policy_queue_process(struct timer_list *t);
Expand Down Expand Up @@ -1538,7 +1538,9 @@ static inline int xfrm_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
*/

static struct dst_entry *xfrm_bundle_create(struct xfrm_policy *policy,
struct xfrm_state **xfrm, int nx,
struct xfrm_state **xfrm,
struct xfrm_dst **bundle,
int nx,
const struct flowi *fl,
struct dst_entry *dst)
{
Expand Down Expand Up @@ -1573,6 +1575,7 @@ static struct dst_entry *xfrm_bundle_create(struct xfrm_policy *policy,
goto put_states;
}

bundle[i] = xdst;
if (!xdst_prev)
xdst0 = xdst;
else
Expand Down Expand Up @@ -1616,7 +1619,6 @@ static struct dst_entry *xfrm_bundle_create(struct xfrm_policy *policy,
dst1->input = dst_discard;
dst1->output = inner_mode->afinfo->output;

dst1->next = &xdst_prev->u.dst;
xdst_prev = xdst;

header_len += xfrm[i]->props.header_len;
Expand All @@ -1634,7 +1636,7 @@ static struct dst_entry *xfrm_bundle_create(struct xfrm_policy *policy,
goto free_dst;

xfrm_init_path(xdst0, dst, nfheader_len);
xfrm_init_pmtu(&xdst_prev->u.dst);
xfrm_init_pmtu(bundle, nx);

for (xdst_prev = xdst0; xdst_prev != (struct xfrm_dst *)dst;
xdst_prev = (struct xfrm_dst *) xfrm_dst_child(&xdst_prev->u.dst)) {
Expand Down Expand Up @@ -1812,6 +1814,7 @@ xfrm_resolve_and_create_bundle(struct xfrm_policy **pols, int num_pols,
{
struct net *net = xp_net(pols[0]);
struct xfrm_state *xfrm[XFRM_MAX_DEPTH];
struct xfrm_dst *bundle[XFRM_MAX_DEPTH];
struct xfrm_dst *xdst, *old;
struct dst_entry *dst;
int err;
Expand Down Expand Up @@ -1839,7 +1842,7 @@ xfrm_resolve_and_create_bundle(struct xfrm_policy **pols, int num_pols,

old = xdst;

dst = xfrm_bundle_create(pols[0], xfrm, err, fl, dst_orig);
dst = xfrm_bundle_create(pols[0], xfrm, bundle, err, fl, dst_orig);
if (IS_ERR(dst)) {
XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTBUNDLEGENERROR);
return ERR_CAST(dst);
Expand Down Expand Up @@ -2599,12 +2602,14 @@ static struct dst_entry *xfrm_negative_advice(struct dst_entry *dst)
return dst;
}

static void xfrm_init_pmtu(struct dst_entry *dst)
static void xfrm_init_pmtu(struct xfrm_dst **bundle, int nr)
{
do {
struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
while (nr--) {
struct xfrm_dst *xdst = bundle[nr];
u32 pmtu, route_mtu_cached;
struct dst_entry *dst;

dst = &xdst->u.dst;
pmtu = dst_mtu(xfrm_dst_child(dst));
xdst->child_mtu_cached = pmtu;

Expand All @@ -2617,7 +2622,7 @@ static void xfrm_init_pmtu(struct dst_entry *dst)
pmtu = route_mtu_cached;

dst_metric_set(dst, RTAX_MTU, pmtu);
} while ((dst = dst->next));
}
}

/* Check that the bundle accepts the flow and its components are
Expand All @@ -2626,8 +2631,10 @@ static void xfrm_init_pmtu(struct dst_entry *dst)

static int xfrm_bundle_ok(struct xfrm_dst *first)
{
struct xfrm_dst *bundle[XFRM_MAX_DEPTH];
struct dst_entry *dst = &first->u.dst;
struct xfrm_dst *last;
struct xfrm_dst *xdst;
int start_from, nr;
u32 mtu;

if (!dst_check(xfrm_dst_path(dst), ((struct xfrm_dst *)dst)->path_cookie) ||
Expand All @@ -2637,8 +2644,7 @@ static int xfrm_bundle_ok(struct xfrm_dst *first)
if (dst->flags & DST_XFRM_QUEUE)
return 1;

last = NULL;

start_from = nr = 0;
do {
struct xfrm_dst *xdst = (struct xfrm_dst *)dst;

Expand All @@ -2650,40 +2656,42 @@ static int xfrm_bundle_ok(struct xfrm_dst *first)
xdst->policy_genid != atomic_read(&xdst->pols[0]->genid))
return 0;

bundle[nr++] = xdst;

mtu = dst_mtu(xfrm_dst_child(dst));
if (xdst->child_mtu_cached != mtu) {
last = xdst;
start_from = nr;
xdst->child_mtu_cached = mtu;
}

if (!dst_check(xdst->route, xdst->route_cookie))
return 0;
mtu = dst_mtu(xdst->route);
if (xdst->route_mtu_cached != mtu) {
last = xdst;
start_from = nr;
xdst->route_mtu_cached = mtu;
}

dst = xfrm_dst_child(dst);
} while (dst->xfrm);

if (likely(!last))
if (likely(!start_from))
return 1;

mtu = last->child_mtu_cached;
for (;;) {
dst = &last->u.dst;
xdst = bundle[start_from - 1];
mtu = xdst->child_mtu_cached;
while (start_from--) {
dst = &xdst->u.dst;

mtu = xfrm_state_mtu(dst->xfrm, mtu);
if (mtu > last->route_mtu_cached)
mtu = last->route_mtu_cached;
if (mtu > xdst->route_mtu_cached)
mtu = xdst->route_mtu_cached;
dst_metric_set(dst, RTAX_MTU, mtu);

if (last == first)
if (!start_from)
break;

last = (struct xfrm_dst *)last->u.dst.next;
last->child_mtu_cached = mtu;
xdst = bundle[start_from - 1];
xdst->child_mtu_cached = mtu;
}

return 1;
Expand Down

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