From: Florian Westphal fw@strlen.de
[ Upstream commit b1fd94e704571f98b21027340eecf821b2bdffba ]
bh might occur while updating per-cpu rnd_state from user context, ie. local_out path.
BUG: using smp_processor_id() in preemptible [00000000] code: nginx/2725 caller is nft_ng_random_eval+0x24/0x54 [nft_numgen] Call Trace: check_preemption_disabled+0xde/0xe0 nft_ng_random_eval+0x24/0x54 [nft_numgen]
Use the random driver instead, this also avoids need for local prandom state. Moreover, prandom now uses the random driver since d4150779e60f ("random32: use real rng for non-deterministic randomness").
Based on earlier patch from Pablo Neira.
Fixes: 6b2faee0ca91 ("netfilter: nft_meta: place prandom handling in a helper") Fixes: 978d8f9055c3 ("netfilter: nft_numgen: add map lookups for numgen random operations") Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/netfilter/nft_meta.c | 13 ++----------- net/netfilter/nft_numgen.c | 12 +++--------- 2 files changed, 5 insertions(+), 20 deletions(-)
diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c index a7e01e9952f1..44d9b38e5f90 100644 --- a/net/netfilter/nft_meta.c +++ b/net/netfilter/nft_meta.c @@ -14,6 +14,7 @@ #include <linux/in.h> #include <linux/ip.h> #include <linux/ipv6.h> +#include <linux/random.h> #include <linux/smp.h> #include <linux/static_key.h> #include <net/dst.h> @@ -32,8 +33,6 @@ #define NFT_META_SECS_PER_DAY 86400 #define NFT_META_DAYS_PER_WEEK 7
-static DEFINE_PER_CPU(struct rnd_state, nft_prandom_state); - static u8 nft_meta_weekday(void) { time64_t secs = ktime_get_real_seconds(); @@ -267,13 +266,6 @@ static bool nft_meta_get_eval_ifname(enum nft_meta_keys key, u32 *dest, return true; }
-static noinline u32 nft_prandom_u32(void) -{ - struct rnd_state *state = this_cpu_ptr(&nft_prandom_state); - - return prandom_u32_state(state); -} - #ifdef CONFIG_IP_ROUTE_CLASSID static noinline bool nft_meta_get_eval_rtclassid(const struct sk_buff *skb, u32 *dest) @@ -385,7 +377,7 @@ void nft_meta_get_eval(const struct nft_expr *expr, break; #endif case NFT_META_PRANDOM: - *dest = nft_prandom_u32(); + *dest = get_random_u32(); break; #ifdef CONFIG_XFRM case NFT_META_SECPATH: @@ -514,7 +506,6 @@ int nft_meta_get_init(const struct nft_ctx *ctx, len = IFNAMSIZ; break; case NFT_META_PRANDOM: - prandom_init_once(&nft_prandom_state); len = sizeof(u32); break; #ifdef CONFIG_XFRM diff --git a/net/netfilter/nft_numgen.c b/net/netfilter/nft_numgen.c index 722cac1e90e0..4e43214e88de 100644 --- a/net/netfilter/nft_numgen.c +++ b/net/netfilter/nft_numgen.c @@ -9,12 +9,11 @@ #include <linux/netlink.h> #include <linux/netfilter.h> #include <linux/netfilter/nf_tables.h> +#include <linux/random.h> #include <linux/static_key.h> #include <net/netfilter/nf_tables.h> #include <net/netfilter/nf_tables_core.h>
-static DEFINE_PER_CPU(struct rnd_state, nft_numgen_prandom_state); - struct nft_ng_inc { u8 dreg; u32 modulus; @@ -104,12 +103,9 @@ struct nft_ng_random { u32 offset; };
-static u32 nft_ng_random_gen(struct nft_ng_random *priv) +static u32 nft_ng_random_gen(const struct nft_ng_random *priv) { - struct rnd_state *state = this_cpu_ptr(&nft_numgen_prandom_state); - - return reciprocal_scale(prandom_u32_state(state), priv->modulus) + - priv->offset; + return reciprocal_scale(get_random_u32(), priv->modulus) + priv->offset; }
static void nft_ng_random_eval(const struct nft_expr *expr, @@ -137,8 +133,6 @@ static int nft_ng_random_init(const struct nft_ctx *ctx, if (priv->offset + priv->modulus - 1 < priv->offset) return -EOVERFLOW;
- prandom_init_once(&nft_numgen_prandom_state); - return nft_parse_register_store(ctx, tb[NFTA_NG_DREG], &priv->dreg, NULL, NFT_DATA_VALUE, sizeof(u32)); }