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netfilter: nf_tables: report use refcount overflow

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commit 1689f25924 upstream.

Overflow use refcount checks are not complete.

Add helper function to deal with object reference counter tracking.
Report -EMFILE in case UINT_MAX is reached.

nft_use_dec() splats in case that reference counter underflows,
which should not ever happen.

Add nft_use_inc_restore() and nft_use_dec_restore() which are used
to restore reference counter from error and abort paths.

Use u32 in nft_flowtable and nft_object since helper functions cannot
work on bitfields.

Remove the few early incomplete checks now that the helper functions
are in place and used to check for refcount overflow.

Fixes: 96518518cc ("netfilter: add nftables")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Pablo Neira Ayuso
2023-08-13 00:07:58 +02:00
committed by Greg Kroah-Hartman
parent 93b3195d37
commit 039ce5eb6b
5 changed files with 145 additions and 79 deletions
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31
include/net/netfilter/nf_tables.h
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@ -1073,6 +1073,29 @@ int __nft_release_basechain(struct nft_ctx *ctx);
unsigned int nft_do_chain(struct nft_pktinfo *pkt, void *priv);
static inline bool nft_use_inc(u32 *use)
{
if (*use == UINT_MAX)
return false;
(*use)++;
return true;
}
static inline void nft_use_dec(u32 *use)
{
WARN_ON_ONCE((*use)-- == 0);
}
/* For error and abort path: restore use counter to previous state. */
static inline void nft_use_inc_restore(u32 *use)
{
WARN_ON_ONCE(!nft_use_inc(use));
}
#define nft_use_dec_restore nft_use_dec
/**
* struct nft_table - nf_tables table
*
@ -1150,8 +1173,8 @@ struct nft_object {
struct list_head list;
struct rhlist_head rhlhead;
struct nft_object_hash_key key;
u32 genmask:2,
use:30;
u32 genmask:2;
u32 use;
u64 handle;
u16 udlen;
u8 *udata;
@ -1253,8 +1276,8 @@ struct nft_flowtable {
char *name;
int hooknum;
int ops_len;
u32 genmask:2,
use:30;
u32 genmask:2;
u32 use;
u64 handle;
/* runtime data below here */
struct list_head hook_list ____cacheline_aligned;