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| author | Gleb Mazovetskiy <glex.spb@gmail.com> | 2022-11-14 22:56:16 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-12-08 11:15:40 +0100 |
| commit | 39e2c51405fba983442de8fd973bf723ea21102a (patch) | |
| tree | 8da9bd6c3104c86a4b3e0397bdabfa7f8f360e96 /net | |
| parent | d3490ae8218ba182b7c4e62d8ff4990fff98a548 (diff) | |
| download | linux-stable-39e2c51405fba983442de8fd973bf723ea21102a.tar.gz linux-stable-39e2c51405fba983442de8fd973bf723ea21102a.tar.bz2 linux-stable-39e2c51405fba983442de8fd973bf723ea21102a.zip | |
tcp: configurable source port perturb table size
[ Upstream commit aeac4ec8f46d610a10adbaeff5e2edf6a88ffc62 ]
On embedded systems with little memory and no relevant
security concerns, it is beneficial to reduce the size
of the table.
Reducing the size from 2^16 to 2^8 saves 255 KiB
of kernel RAM.
Makes the table size configurable as an expert option.
The size was previously increased from 2^8 to 2^16
in commit 4c2c8f03a5ab ("tcp: increase source port perturb table to
2^16").
Signed-off-by: Gleb Mazovetskiy <glex.spb@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/Kconfig | 10 | ||||
| -rw-r--r-- | net/ipv4/inet_hashtables.c | 10 |
2 files changed, 15 insertions, 5 deletions
diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig index 4d265d4a0dbe..29be5bcbe7ac 100644 --- a/net/ipv4/Kconfig +++ b/net/ipv4/Kconfig @@ -371,6 +371,16 @@ config INET_IPCOMP If unsure, say Y. +config INET_TABLE_PERTURB_ORDER + int "INET: Source port perturbation table size (as power of 2)" if EXPERT + default 16 + help + Source port perturbation table size (as power of 2) for + RFC 6056 3.3.4. Algorithm 4: Double-Hash Port Selection Algorithm. + + The default is almost always what you want. + Only change this if you know what you are doing. + config INET_XFRM_TUNNEL tristate select INET_TUNNEL diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index db47e1c407d9..9958850b6cee 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -541,13 +541,13 @@ EXPORT_SYMBOL_GPL(inet_unhash); * Note that we use 32bit integers (vs RFC 'short integers') * because 2^16 is not a multiple of num_ephemeral and this * property might be used by clever attacker. + * * RFC claims using TABLE_LENGTH=10 buckets gives an improvement, though - * attacks were since demonstrated, thus we use 65536 instead to really - * give more isolation and privacy, at the expense of 256kB of kernel - * memory. + * attacks were since demonstrated, thus we use 65536 by default instead + * to really give more isolation and privacy, at the expense of 256kB + * of kernel memory. */ -#define INET_TABLE_PERTURB_SHIFT 16 -#define INET_TABLE_PERTURB_SIZE (1 << INET_TABLE_PERTURB_SHIFT) +#define INET_TABLE_PERTURB_SIZE (1 << CONFIG_INET_TABLE_PERTURB_ORDER) static u32 *table_perturb; int __inet_hash_connect(struct inet_timewait_death_row *death_row, |