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net: mpls: bump maximum number of labels
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Allow users to push down more labels per MPLS route. With the previous
patches, no memory allocations are based on MAX_NEW_LABELS; the limit
is only used to keep userspace in check.

At this point MAX_NEW_LABELS is only used for mpls_route_config (copying
route data from userspace) and processing nexthops looking for the max
number of labels across the route spec.

Signed-off-by: David Ahern <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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@davem330
David Ahern authored and davem330 committed Apr 2, 2017
1 parent df1c631 commit a4ac8c9
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Showing 2 changed files with 71 additions and 34 deletions.
103 changes: 70 additions & 33 deletions net/mpls/af_mpls.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,10 @@
#include <net/nexthop.h>
#include "internal.h"

#define MAX_NEW_LABELS 2
/* put a reasonable limit on the number of labels
* we will accept from userspace
*/
#define MAX_NEW_LABELS 30

/* max memory we will use for mpls_route */
#define MAX_MPLS_ROUTE_MEM 4096
Expand Down Expand Up @@ -698,9 +701,6 @@ static int mpls_nh_build_from_cfg(struct mpls_route_config *cfg,
return -ENOMEM;

err = -EINVAL;
/* Ensure only a supported number of labels are present */
if (cfg->rc_output_labels > MAX_NEW_LABELS)
goto errout;

nh->nh_labels = cfg->rc_output_labels;
for (i = 0; i < nh->nh_labels; i++)
Expand All @@ -725,15 +725,15 @@ static int mpls_nh_build_from_cfg(struct mpls_route_config *cfg,

static int mpls_nh_build(struct net *net, struct mpls_route *rt,
struct mpls_nh *nh, int oif, struct nlattr *via,
struct nlattr *newdst)
struct nlattr *newdst, u8 max_labels)
{
int err = -ENOMEM;

if (!nh)
goto errout;

if (newdst) {
err = nla_get_labels(newdst, MAX_NEW_LABELS,
err = nla_get_labels(newdst, max_labels,
&nh->nh_labels, nh->nh_label);
if (err)
goto errout;
Expand All @@ -759,21 +759,19 @@ static int mpls_nh_build(struct net *net, struct mpls_route *rt,
}

static u8 mpls_count_nexthops(struct rtnexthop *rtnh, int len,
u8 cfg_via_alen, u8 *max_via_alen)
u8 cfg_via_alen, u8 *max_via_alen,
u8 *max_labels)
{
int remaining = len;
u8 nhs = 0;

if (!rtnh) {
*max_via_alen = cfg_via_alen;
return 1;
}

*max_via_alen = 0;
*max_labels = 0;

while (rtnh_ok(rtnh, remaining)) {
struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
int attrlen;
u8 n_labels = 0;

attrlen = rtnh_attrlen(rtnh);
nla = nla_find(attrs, attrlen, RTA_VIA);
Expand All @@ -787,6 +785,13 @@ static u8 mpls_count_nexthops(struct rtnexthop *rtnh, int len,
via_alen);
}

nla = nla_find(attrs, attrlen, RTA_NEWDST);
if (nla &&
nla_get_labels(nla, MAX_NEW_LABELS, &n_labels, NULL) != 0)
return 0;

*max_labels = max_t(u8, *max_labels, n_labels);

/* number of nexthops is tracked by a u8.
* Check for overflow.
*/
Expand All @@ -802,7 +807,7 @@ static u8 mpls_count_nexthops(struct rtnexthop *rtnh, int len,
}

static int mpls_nh_build_multi(struct mpls_route_config *cfg,
struct mpls_route *rt)
struct mpls_route *rt, u8 max_labels)
{
struct rtnexthop *rtnh = cfg->rc_mp;
struct nlattr *nla_via, *nla_newdst;
Expand Down Expand Up @@ -835,7 +840,8 @@ static int mpls_nh_build_multi(struct mpls_route_config *cfg,
}

err = mpls_nh_build(cfg->rc_nlinfo.nl_net, rt, nh,
rtnh->rtnh_ifindex, nla_via, nla_newdst);
rtnh->rtnh_ifindex, nla_via, nla_newdst,
max_labels);
if (err)
goto errout;

Expand All @@ -862,6 +868,7 @@ static int mpls_route_add(struct mpls_route_config *cfg)
int err = -EINVAL;
u8 max_via_alen;
unsigned index;
u8 max_labels;
u8 nhs;

index = cfg->rc_label;
Expand Down Expand Up @@ -900,13 +907,21 @@ static int mpls_route_add(struct mpls_route_config *cfg)
goto errout;

err = -EINVAL;
nhs = mpls_count_nexthops(cfg->rc_mp, cfg->rc_mp_len,
cfg->rc_via_alen, &max_via_alen);
if (cfg->rc_mp) {
nhs = mpls_count_nexthops(cfg->rc_mp, cfg->rc_mp_len,
cfg->rc_via_alen, &max_via_alen,
&max_labels);
} else {
max_via_alen = cfg->rc_via_alen;
max_labels = cfg->rc_output_labels;
nhs = 1;
}

if (nhs == 0)
goto errout;

err = -ENOMEM;
rt = mpls_rt_alloc(nhs, max_via_alen, MAX_NEW_LABELS);
rt = mpls_rt_alloc(nhs, max_via_alen, max_labels);
if (IS_ERR(rt)) {
err = PTR_ERR(rt);
goto errout;
Expand All @@ -917,7 +932,7 @@ static int mpls_route_add(struct mpls_route_config *cfg)
rt->rt_ttl_propagate = cfg->rc_ttl_propagate;

if (cfg->rc_mp)
err = mpls_nh_build_multi(cfg, rt);
err = mpls_nh_build_multi(cfg, rt, max_labels);
else
err = mpls_nh_build_from_cfg(cfg, rt);
if (err)
Expand Down Expand Up @@ -1531,23 +1546,29 @@ int nla_put_labels(struct sk_buff *skb, int attrtype,
EXPORT_SYMBOL_GPL(nla_put_labels);

int nla_get_labels(const struct nlattr *nla,
u32 max_labels, u8 *labels, u32 label[])
u8 max_labels, u8 *labels, u32 label[])
{
unsigned len = nla_len(nla);
unsigned nla_labels;
struct mpls_shim_hdr *nla_label;
u8 nla_labels;
bool bos;
int i;

/* len needs to be an even multiple of 4 (the label size) */
if (len & 3)
/* len needs to be an even multiple of 4 (the label size). Number
* of labels is a u8 so check for overflow.
*/
if (len & 3 || len / 4 > 255)
return -EINVAL;

/* Limit the number of new labels allowed */
nla_labels = len/4;
if (nla_labels > max_labels)
return -EINVAL;

/* when label == NULL, caller wants number of labels */
if (!label)
goto out;

nla_label = nla_data(nla);
bos = true;
for (i = nla_labels - 1; i >= 0; i--, bos = false) {
Expand All @@ -1571,6 +1592,7 @@ int nla_get_labels(const struct nlattr *nla,

label[i] = dec.label;
}
out:
*labels = nla_labels;
return 0;
}
Expand Down Expand Up @@ -1632,7 +1654,6 @@ static int rtm_to_route_config(struct sk_buff *skb, struct nlmsghdr *nlh,

err = -EINVAL;
rtm = nlmsg_data(nlh);
memset(cfg, 0, sizeof(*cfg));

if (rtm->rtm_family != AF_MPLS)
goto errout;
Expand Down Expand Up @@ -1731,27 +1752,43 @@ static int rtm_to_route_config(struct sk_buff *skb, struct nlmsghdr *nlh,

static int mpls_rtm_delroute(struct sk_buff *skb, struct nlmsghdr *nlh)
{
struct mpls_route_config cfg;
struct mpls_route_config *cfg;
int err;

err = rtm_to_route_config(skb, nlh, &cfg);
cfg = kzalloc(sizeof(*cfg), GFP_KERNEL);
if (!cfg)
return -ENOMEM;

err = rtm_to_route_config(skb, nlh, cfg);
if (err < 0)
return err;
goto out;

return mpls_route_del(&cfg);
err = mpls_route_del(cfg);
out:
kfree(cfg);

return err;
}


static int mpls_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh)
{
struct mpls_route_config cfg;
struct mpls_route_config *cfg;
int err;

err = rtm_to_route_config(skb, nlh, &cfg);
cfg = kzalloc(sizeof(*cfg), GFP_KERNEL);
if (!cfg)
return -ENOMEM;

err = rtm_to_route_config(skb, nlh, cfg);
if (err < 0)
return err;
goto out;

return mpls_route_add(&cfg);
err = mpls_route_add(cfg);
out:
kfree(cfg);

return err;
}

static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event,
Expand Down Expand Up @@ -1980,7 +2017,7 @@ static int resize_platform_label_table(struct net *net, size_t limit)
/* In case the predefined labels need to be populated */
if (limit > MPLS_LABEL_IPV4NULL) {
struct net_device *lo = net->loopback_dev;
rt0 = mpls_rt_alloc(1, lo->addr_len, MAX_NEW_LABELS);
rt0 = mpls_rt_alloc(1, lo->addr_len, 0);
if (IS_ERR(rt0))
goto nort0;
RCU_INIT_POINTER(rt0->rt_nh->nh_dev, lo);
Expand All @@ -1994,7 +2031,7 @@ static int resize_platform_label_table(struct net *net, size_t limit)
}
if (limit > MPLS_LABEL_IPV6NULL) {
struct net_device *lo = net->loopback_dev;
rt2 = mpls_rt_alloc(1, lo->addr_len, MAX_NEW_LABELS);
rt2 = mpls_rt_alloc(1, lo->addr_len, 0);
if (IS_ERR(rt2))
goto nort2;
RCU_INIT_POINTER(rt2->rt_nh->nh_dev, lo);
Expand Down
2 changes: 1 addition & 1 deletion net/mpls/internal.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -197,7 +197,7 @@ static inline struct mpls_dev *mpls_dev_get(const struct net_device *dev)

int nla_put_labels(struct sk_buff *skb, int attrtype, u8 labels,
const u32 label[]);
int nla_get_labels(const struct nlattr *nla, u32 max_labels, u8 *labels,
int nla_get_labels(const struct nlattr *nla, u8 max_labels, u8 *labels,
u32 label[]);
int nla_get_via(const struct nlattr *nla, u8 *via_alen, u8 *via_table,
u8 via[]);
Expand Down

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