BMC/Intel-BMC/linux.git/net/ipv4/sysctl_net_ipv4.c, branch dev-5.7

tcp: bind(0) remove the SO_REUSEADDR restriction when ephemeral ports are exhausted.

2020-03-12T19:08:09+00:00

Commit aacd9289af8b82f5fb01bcdd53d0e3406d1333c7 ("tcp: bind() use stronger condition for bind_conflict") introduced a restriction to forbid to bind SO_REUSEADDR enabled sockets to the same (addr, port) tuple in order to assign ports dispersedly so that we can connect to the same remote host. The change results in accelerating port depletion so that we fail to bind sockets to the same local port even if we want to connect to the different remote hosts. You can reproduce this issue by following instructions below. 1. # sysctl -w net.ipv4.ip_local_port_range="32768 32768" 2. set SO_REUSEADDR to two sockets. 3. bind two sockets to (localhost, 0) and the latter fails. Therefore, when ephemeral ports are exhausted, bind(0) should fallback to the legacy behaviour to enable the SO_REUSEADDR option and make it possible to connect to different remote (addr, port) tuples. This patch allows us to bind SO_REUSEADDR enabled sockets to the same (addr, port) only when net.ipv4.ip_autobind_reuse is set 1 and all ephemeral ports are exhausted. This also allows connect() and listen() to share ports in the following way and may break some applications. So the ip_autobind_reuse is 0 by default and disables the feature. 1. setsockopt(sk1, SO_REUSEADDR) 2. setsockopt(sk2, SO_REUSEADDR) 3. bind(sk1, saddr, 0) 4. bind(sk2, saddr, 0) 5. connect(sk1, daddr) 6. listen(sk2) If it is set 1, we can fully utilize the 4-tuples, but we should use IP_BIND_ADDRESS_NO_PORT for bind()+connect() as possible. The notable thing is that if all sockets bound to the same port have both SO_REUSEADDR and SO_REUSEPORT enabled, we can bind sockets to an ephemeral port and also do listen(). Signed-off-by: Kuniyuki Iwashima Signed-off-by: David S. Miller

net/ipv4/sysctl: show tcp_{allowed, available}_congestion_control in non-initial netns

2020-02-19T19:04:31+00:00

It is currenty possible to switch the TCP congestion control algorithm in non-initial network namespaces: unshare -U --map-root --net --fork --pid --mount-proc echo "reno" > /proc/sys/net/ipv4/tcp_congestion_control works just fine. But currently non-initial network namespaces have no way of kowing which congestion algorithms are available or allowed other than through trial and error by writing the names of the algorithms into the aforementioned file. Since we already allow changing the congestion algorithm in non-initial network namespaces by exposing the tcp_congestion_control file there is no reason to not also expose the tcp_{allowed,available}_congestion_control files to non-initial network namespaces. After this change a container with a separate network namespace will show: root@f1:~# ls -al /proc/sys/net/ipv4/tcp_* | grep congestion -rw-r--r-- 1 root root 0 Feb 19 11:54 /proc/sys/net/ipv4/tcp_allowed_congestion_control -r--r--r-- 1 root root 0 Feb 19 11:54 /proc/sys/net/ipv4/tcp_available_congestion_control -rw-r--r-- 1 root root 0 Feb 19 11:54 /proc/sys/net/ipv4/tcp_congestion_control Link: https://github.com/lxc/lxc/issues/3267 Reported-by: Haw Loeung Signed-off-by: Christian Brauner Signed-off-by: David S. Miller

net-tcp: Disable TCP ssthresh metrics cache by default

2019-12-10T04:17:48+00:00

This patch introduces a sysctl knob "net.ipv4.tcp_no_ssthresh_metrics_save" that disables TCP ssthresh metrics cache by default. Other parts of TCP metrics cache, e.g. rtt, cwnd, remain unchanged. As modern networks becoming more and more dynamic, TCP metrics cache today often causes more harm than benefits. For example, the same IP address is often shared by different subscribers behind NAT in residential networks. Even if the IP address is not shared by different users, caching the slow-start threshold of a previous short flow using loss-based congestion control (e.g. cubic) often causes the future longer flows of the same network path to exit slow-start prematurely with abysmal throughput. Caching ssthresh is very risky and can lead to terrible performance. Therefore it makes sense to make disabling ssthresh caching by default and opt-in for specific networks by the administrators. This practice also has worked well for several years of deployment with CUBIC congestion control at Google. Acked-by: Eric Dumazet Acked-by: Neal Cardwell Acked-by: Yuchung Cheng Signed-off-by: Kevin(Yudong) Yang Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2019-11-23T00:27:24+00:00

Minor conflict in drivers/s390/net/qeth_l2_main.c, kept the lock from commit c8183f548902 ("s390/qeth: fix potential deadlock on workqueue flush"), removed the code which was removed by commit 9897d583b015 ("s390/qeth: consolidate some duplicated HW cmd code"). Signed-off-by: Jakub Kicinski

tcp: warn if offset reach the maxlen limit when using snprintf

2019-11-21T06:23:36+00:00

snprintf returns the number of chars that would be written, not number of chars that were actually written. As such, 'offs' may get larger than 'tbl.maxlen', causing the 'tbl.maxlen - offs' being < 0, and since the parameter is size_t, it would overflow. Since using scnprintf may hide the limit error, while the buffer is still enough now, let's just add a WARN_ON_ONCE in case it reach the limit in future. v2: Use WARN_ON_ONCE as Jiri and Eric suggested. Suggested-by: Jiri Benc Signed-off-by: Hangbin Liu Signed-off-by: David S. Miller

net/ipv4: fix sysctl max for fib_multipath_hash_policy

2019-11-19T01:25:36+00:00

Commit eec4844fae7c ("proc/sysctl: add shared variables for range check") did: - .extra2 = &two, + .extra2 = SYSCTL_ONE, here, which doesn't seem to be intentional, given the changelog. This patch restores it to the previous, as the value of 2 still makes sense (used in fib_multipath_hash()). Fixes: eec4844fae7c ("proc/sysctl: add shared variables for range check") Cc: Matteo Croce Signed-off-by: Marcelo Ricardo Leitner Acked-by: Matteo Croce Signed-off-by: David S. Miller

tcp: add new tcp_mtu_probe_floor sysctl

2019-08-09T20:03:30+00:00

The current implementation of TCP MTU probing can considerably underestimate the MTU on lossy connections allowing the MSS to get down to 48. We have found that in almost all of these cases on our networks these paths can handle much larger MTUs meaning the connections are being artificially limited. Even though TCP MTU probing can raise the MSS back up we have seen this not to be the case causing connections to be "stuck" with an MSS of 48 when heavy loss is present. Prior to pushing out this change we could not keep TCP MTU probing enabled b/c of the above reasons. Now with a reasonble floor set we've had it enabled for the past 6 months. The new sysctl will still default to TCP_MIN_SND_MSS (48), but gives administrators the ability to control the floor of MSS probing. Signed-off-by: Josh Hunt Signed-off-by: Eric Dumazet Acked-by: Neal Cardwell Signed-off-by: David S. Miller

proc/sysctl: add shared variables for range check

2019-07-19T00:08:07+00:00

In the sysctl code the proc_dointvec_minmax() function is often used to validate the user supplied value between an allowed range. This function uses the extra1 and extra2 members from struct ctl_table as minimum and maximum allowed value. On sysctl handler declaration, in every source file there are some readonly variables containing just an integer which address is assigned to the extra1 and extra2 members, so the sysctl range is enforced. The special values 0, 1 and INT_MAX are very often used as range boundary, leading duplication of variables like zero=0, one=1, int_max=INT_MAX in different source files: $ git grep -E '\.extra[12].*&(zero|one|int_max)' |wc -l 248 Add a const int array containing the most commonly used values, some macros to refer more easily to the correct array member, and use them instead of creating a local one for every object file. This is the bloat-o-meter output comparing the old and new binary compiled with the default Fedora config: # scripts/bloat-o-meter -d vmlinux.o.old vmlinux.o add/remove: 2/2 grow/shrink: 0/2 up/down: 24/-188 (-164) Data old new delta sysctl_vals - 12 +12 __kstrtab_sysctl_vals - 12 +12 max 14 10 -4 int_max 16 - -16 one 68 - -68 zero 128 28 -100 Total: Before=20583249, After=20583085, chg -0.00% [mcroce@redhat.com: tipc: remove two unused variables] Link: http://lkml.kernel.org/r/20190530091952.4108-1-mcroce@redhat.com [akpm@linux-foundation.org: fix net/ipv6/sysctl_net_ipv6.c] [arnd@arndb.de: proc/sysctl: make firmware loader table conditional] Link: http://lkml.kernel.org/r/20190617130014.1713870-1-arnd@arndb.de [akpm@linux-foundation.org: fix fs/eventpoll.c] Link: http://lkml.kernel.org/r/20190430180111.10688-1-mcroce@redhat.com Signed-off-by: Matteo Croce Signed-off-by: Arnd Bergmann Acked-by: Kees Cook Reviewed-by: Aaron Tomlin Cc: Matthew Wilcox Cc: Stephen Rothwell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

net: fastopen: robustness and endianness fixes for SipHash

2019-06-22T23:30:37+00:00

Some changes to the TCP fastopen code to make it more robust against future changes in the choice of key/cookie size, etc. - Instead of keeping the SipHash key in an untyped u8[] buffer and casting it to the right type upon use, use the correct type directly. This ensures that the key will appear at the correct alignment if we ever change the way these data structures are allocated. (Currently, they are only allocated via kmalloc so they always appear at the correct alignment) - Use DIV_ROUND_UP when sizing the u64[] array to hold the cookie, so it is always of sufficient size, even if TCP_FASTOPEN_COOKIE_MAX is no longer a multiple of 8. - Drop the 'len' parameter from the tcp_fastopen_reset_cipher() function, which is no longer used. - Add endian swabbing when setting the keys and calculating the hash, to ensure that cookie values are the same for a given key and source/destination address pair regardless of the endianness of the server. Note that none of these are functional changes wrt the current state of the code, with the exception of the swabbing, which only affects big endian systems. Signed-off-by: Ard Biesheuvel Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2019-06-18T03:20:36+00:00

Honestly all the conflicts were simple overlapping changes, nothing really interesting to report. Signed-off-by: David S. Miller