From 34cc9e52884a16c62acbfb309863fb60e4c24f55 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Mon, 14 Mar 2022 18:23:01 +0100 Subject: netfilter: nf_tables: cancel tracking for clobbered destination registers Output of expressions might be larger than one single register, this might clobber existing data. Reset tracking for all destination registers that required to store the expression output. This patch adds three new helper functions: - nft_reg_track_update: cancel previous register tracking and update it. - nft_reg_track_cancel: cancel any previous register tracking info. - __nft_reg_track_cancel: cancel only one single register tracking info. Partial register clobbering detection is also supported by checking the .num_reg field which describes the number of register that are used. This patch updates the following expressions: - meta_bridge - bitwise - byteorder - meta - payload to use these helper functions. Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/nf_tables.h | 14 ++++++++++++++ include/net/netfilter/nft_meta.h | 1 + 2 files changed, 15 insertions(+) (limited to 'include/net/netfilter') diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h index edabfb9e97ce..20af9d3557b9 100644 --- a/include/net/netfilter/nf_tables.h +++ b/include/net/netfilter/nf_tables.h @@ -126,6 +126,7 @@ struct nft_regs_track { struct { const struct nft_expr *selector; const struct nft_expr *bitwise; + u8 num_reg; } regs[NFT_REG32_NUM]; const struct nft_expr *cur; @@ -1641,4 +1642,17 @@ static inline bool nft_reduce_is_readonly(const struct nft_expr *expr) return expr->ops->reduce == NFT_REDUCE_READONLY; } +void nft_reg_track_update(struct nft_regs_track *track, + const struct nft_expr *expr, u8 dreg, u8 len); +void nft_reg_track_cancel(struct nft_regs_track *track, u8 dreg, u8 len); +void __nft_reg_track_cancel(struct nft_regs_track *track, u8 dreg); + +static inline bool nft_reg_track_cmp(struct nft_regs_track *track, + const struct nft_expr *expr, u8 dreg) +{ + return track->regs[dreg].selector && + track->regs[dreg].selector->ops == expr->ops && + track->regs[dreg].num_reg == 0; +} + #endif /* _NET_NF_TABLES_H */ diff --git a/include/net/netfilter/nft_meta.h b/include/net/netfilter/nft_meta.h index 2dce55c736f4..246fd023dcf4 100644 --- a/include/net/netfilter/nft_meta.h +++ b/include/net/netfilter/nft_meta.h @@ -6,6 +6,7 @@ struct nft_meta { enum nft_meta_keys key:8; + u8 len; union { u8 dreg; u8 sreg; -- cgit v1.2.3