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xfrm: rate limit SA mapping change message to user space

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Kernel generates mapping change message, XFRM_MSG_MAPPING,
when a source port chage is detected on a input state with UDP
encapsulation set.  Kernel generates a message for each IPsec packet
with new source port.  For a high speed flow per packet mapping change
message can be excessive, and can overload the user space listener.

Introduce rate limiting for XFRM_MSG_MAPPING message to the user space.

The rate limiting is configurable via netlink, when adding a new SA or
updating it. Use the new attribute XFRMA_MTIMER_THRESH in seconds.

v1->v2 change:
	update xfrm_sa_len()

v2->v3 changes:
	use u32 insted unsigned long to reduce size of struct xfrm_state
	fix xfrm_ompat size Reported-by: kernel test robot <lkp@intel.com>
	accept XFRM_MSG_MAPPING only when XFRMA_ENCAP is present

Co-developed-by: Thomas Egerer <thomas.egerer@secunet.com>
Signed-off-by: Thomas Egerer <thomas.egerer@secunet.com>
Signed-off-by: Antony Antony <antony.antony@secunet.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
This commit is contained in:
Antony Antony 2021-12-22 14:11:18 +01:00 committed by Steffen Klassert
parent 23b6a6df94
commit 4e484b3e96
5 changed files with 49 additions and 4 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

5
include/net/xfrm.h
View file

@ -200,6 +200,11 @@ struct xfrm_state {
struct xfrm_algo_aead *aead;
const char *geniv;
/* mapping change rate limiting */
__be16 new_mapping_sport;
u32 new_mapping; /* seconds */
u32 mapping_maxage; /* seconds for input SA */
/* Data for encapsulator */
struct xfrm_encap_tmpl *encap;
struct sock __rcu *encap_sk;

1
include/uapi/linux/xfrm.h
View file

@ -313,6 +313,7 @@ enum xfrm_attr_type_t {
XFRMA_SET_MARK, /* __u32 */
XFRMA_SET_MARK_MASK, /* __u32 */
XFRMA_IF_ID, /* __u32 */
XFRMA_MTIMER_THRESH, /* __u32 in seconds for input SA */
__XFRMA_MAX
#define XFRMA_OUTPUT_MARK XFRMA_SET_MARK /* Compatibility */

6
net/xfrm/xfrm_compat.c
View file

@ -127,6 +127,7 @@ static const struct nla_policy compat_policy[XFRMA_MAX+1] = {
[XFRMA_SET_MARK] = { .type = NLA_U32 },
[XFRMA_SET_MARK_MASK] = { .type = NLA_U32 },
[XFRMA_IF_ID] = { .type = NLA_U32 },
[XFRMA_MTIMER_THRESH] = { .type = NLA_U32 },
};
static struct nlmsghdr *xfrm_nlmsg_put_compat(struct sk_buff *skb,
@ -274,9 +275,10 @@ static int xfrm_xlate64_attr(struct sk_buff *dst, const struct nlattr *src)
case XFRMA_SET_MARK:
case XFRMA_SET_MARK_MASK:
case XFRMA_IF_ID:
case XFRMA_MTIMER_THRESH:
return xfrm_nla_cpy(dst, src, nla_len(src));
default:
BUILD_BUG_ON(XFRMA_MAX != XFRMA_IF_ID);
BUILD_BUG_ON(XFRMA_MAX != XFRMA_MTIMER_THRESH);
pr_warn_once("unsupported nla_type %d\n", src->nla_type);
return -EOPNOTSUPP;
}
@ -431,7 +433,7 @@ static int xfrm_xlate32_attr(void *dst, const struct nlattr *nla,
int err;
if (type > XFRMA_MAX) {
BUILD_BUG_ON(XFRMA_MAX != XFRMA_IF_ID);
BUILD_BUG_ON(XFRMA_MAX != XFRMA_MTIMER_THRESH);
NL_SET_ERR_MSG(extack, "Bad attribute");
return -EOPNOTSUPP;
}

23
net/xfrm/xfrm_state.c
View file

@ -1593,6 +1593,9 @@ static struct xfrm_state *xfrm_state_clone(struct xfrm_state *orig,
x->km.seq = orig->km.seq;
x->replay = orig->replay;
x->preplay = orig->preplay;
x->mapping_maxage = orig->mapping_maxage;
x->new_mapping = 0;
x->new_mapping_sport = 0;
return x;
@ -2242,7 +2245,7 @@ int km_query(struct xfrm_state *x, struct xfrm_tmpl *t, struct xfrm_policy *pol)
}
EXPORT_SYMBOL(km_query);
int km_new_mapping(struct xfrm_state *x, xfrm_address_t *ipaddr, __be16 sport)
static int __km_new_mapping(struct xfrm_state *x, xfrm_address_t *ipaddr, __be16 sport)
{
int err = -EINVAL;
struct xfrm_mgr *km;
@ -2257,6 +2260,24 @@ int km_new_mapping(struct xfrm_state *x, xfrm_address_t *ipaddr, __be16 sport)
rcu_read_unlock();
return err;
}
int km_new_mapping(struct xfrm_state *x, xfrm_address_t *ipaddr, __be16 sport)
{
int ret = 0;
if (x->mapping_maxage) {
if ((jiffies / HZ - x->new_mapping) > x->mapping_maxage ||
x->new_mapping_sport != sport) {
x->new_mapping_sport = sport;
x->new_mapping = jiffies / HZ;
ret = __km_new_mapping(x, ipaddr, sport);
}
} else {
ret = __km_new_mapping(x, ipaddr, sport);
}
return ret;
}
EXPORT_SYMBOL(km_new_mapping);
void km_policy_expired(struct xfrm_policy *pol, int dir, int hard, u32 portid)

18
net/xfrm/xfrm_user.c
View file

@ -282,6 +282,10 @@ static int verify_newsa_info(struct xfrm_usersa_info *p,
err = 0;
if (attrs[XFRMA_MTIMER_THRESH])
if (!attrs[XFRMA_ENCAP])
err = -EINVAL;
out:
return err;
}
@ -521,6 +525,7 @@ static void xfrm_update_ae_params(struct xfrm_state *x, struct nlattr **attrs,
struct nlattr *lt = attrs[XFRMA_LTIME_VAL];
struct nlattr *et = attrs[XFRMA_ETIMER_THRESH];
struct nlattr *rt = attrs[XFRMA_REPLAY_THRESH];
struct nlattr *mt = attrs[XFRMA_MTIMER_THRESH];
if (re) {
struct xfrm_replay_state_esn *replay_esn;
@ -552,6 +557,9 @@ static void xfrm_update_ae_params(struct xfrm_state *x, struct nlattr **attrs,
if (rt)
x->replay_maxdiff = nla_get_u32(rt);
if (mt)
x->mapping_maxage = nla_get_u32(mt);
}
static void xfrm_smark_init(struct nlattr **attrs, struct xfrm_mark *m)
@ -1024,8 +1032,13 @@ static int copy_to_user_state_extra(struct xfrm_state *x,
if (ret)
goto out;
}
if (x->security)
if (x->security) {
ret = copy_sec_ctx(x->security, skb);
if (ret)
goto out;
}
if (x->mapping_maxage)
ret = nla_put_u32(skb, XFRMA_MTIMER_THRESH, x->mapping_maxage);
out:
return ret;
}
@ -3069,6 +3082,9 @@ static inline unsigned int xfrm_sa_len(struct xfrm_state *x)
/* Must count x->lastused as it may become non-zero behind our back. */
l += nla_total_size_64bit(sizeof(u64));
if (x->mapping_maxage)
l += nla_total_size(sizeof(x->mapping_maxage));
return l;
}