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    Subject[PATCH 5.10 382/563] xfrm: rate limit SA mapping change message to user space
    Date
    From: Antony Antony <antony.antony@secunet.com>

    [ Upstream commit 4e484b3e969b52effd95c17f7a86f39208b2ccf4 ]

    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>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    include/net/xfrm.h | 5 +++++
    include/uapi/linux/xfrm.h | 1 +
    net/xfrm/xfrm_compat.c | 6 ++++--
    net/xfrm/xfrm_state.c | 23 ++++++++++++++++++++++-
    net/xfrm/xfrm_user.c | 18 +++++++++++++++++-
    5 files changed, 49 insertions(+), 4 deletions(-)

    diff --git a/include/net/xfrm.h b/include/net/xfrm.h
    index 6232a5f048bde..337d29875e518 100644
    --- a/include/net/xfrm.h
    +++ b/include/net/xfrm.h
    @@ -193,6 +193,11 @@ 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;
    diff --git a/include/uapi/linux/xfrm.h b/include/uapi/linux/xfrm.h
    index ffc6a5391bb7b..2290c98b47cf8 100644
    --- a/include/uapi/linux/xfrm.h
    +++ b/include/uapi/linux/xfrm.h
    @@ -308,6 +308,7 @@ 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 */
    diff --git a/net/xfrm/xfrm_compat.c b/net/xfrm/xfrm_compat.c
    index 2bf2693901631..a0f62fa02e06e 100644
    --- a/net/xfrm/xfrm_compat.c
    +++ b/net/xfrm/xfrm_compat.c
    @@ -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;
    }
    diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
    index c158e70e8ae10..65e2805fa113a 100644
    --- a/net/xfrm/xfrm_state.c
    +++ b/net/xfrm/xfrm_state.c
    @@ -1557,6 +1557,9 @@ 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;

    @@ -2208,7 +2211,7 @@ 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;
    @@ -2223,6 +2226,24 @@ 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)
    diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
    index ddf1b3a5f7c1f..d0fdfbf4c5f72 100644
    --- a/net/xfrm/xfrm_user.c
    +++ b/net/xfrm/xfrm_user.c
    @@ -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)
    @@ -969,8 +977,13 @@ 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;
    }
    @@ -2924,6 +2937,9 @@ 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;
    }

    --
    2.34.1


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