Reject bogus configs where internal token counter wraps around.
This only occurs with very very large requests, such as 17gbyte/s.
Its better to reject this rather than having incorrect ratelimit.
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
---
net/netfilter/nft_limit.c | 23 ++++++++++++++++-------
1 file changed, 16 insertions(+), 7 deletions(-)
diff --git a/net/netfilter/nft_limit.c b/net/netfilter/nft_limit.c
index 79039afde34e..cefa25e0dbb0 100644
--- a/net/netfilter/nft_limit.c
+++ b/net/netfilter/nft_limit.c
@@ -58,17 +58,19 @@ static inline bool nft_limit_eval(struct nft_limit_priv *priv, u64 cost)
static int nft_limit_init(struct nft_limit_priv *priv,
const struct nlattr * const tb[], bool pkts)
{
+ u64 unit, tokens, rate_with_burst;
bool invert = false;
- u64 unit, tokens;
if (tb[NFTA_LIMIT_RATE] == NULL ||
tb[NFTA_LIMIT_UNIT] == NULL)
return -EINVAL;
priv->rate = be64_to_cpu(nla_get_be64(tb[NFTA_LIMIT_RATE]));
+ if (priv->rate == 0)
+ return -EINVAL;
+
unit = be64_to_cpu(nla_get_be64(tb[NFTA_LIMIT_UNIT]));
- priv->nsecs = unit * NSEC_PER_SEC;
- if (priv->rate == 0 || priv->nsecs < unit)
+ if (check_mul_overflow(unit, NSEC_PER_SEC, &priv->nsecs))
return -EOVERFLOW;
if (tb[NFTA_LIMIT_BURST])
@@ -77,18 +79,25 @@ static int nft_limit_init(struct nft_limit_priv *priv,
if (pkts && priv->burst == 0)
priv->burst = NFT_LIMIT_PKT_BURST_DEFAULT;
- if (priv->rate + priv->burst < priv->rate)
+ if (check_add_overflow(priv->rate, priv->burst, &rate_with_burst))
return -EOVERFLOW;
if (pkts) {
- tokens = div64_u64(priv->nsecs, priv->rate) * priv->burst;
+ u64 tmp = div64_u64(priv->nsecs, priv->rate);
+
+ if (check_mul_overflow(tmp, priv->burst, &tokens))
+ return -EOVERFLOW;
} else {
+ u64 tmp;
+
/* The token bucket size limits the number of tokens can be
* accumulated. tokens_max specifies the bucket size.
* tokens_max = unit * (rate + burst) / rate.
*/
- tokens = div64_u64(priv->nsecs * (priv->rate + priv->burst),
- priv->rate);
+ if (check_mul_overflow(priv->nsecs, rate_with_burst, &tmp))
+ return -EOVERFLOW;
+
+ tokens = div64_u64(tmp, priv->rate);
}
if (tb[NFTA_LIMIT_FLAGS]) {
--
2.43.0
