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Subject[net-next PATCH v3 3/3] net: reserve ports for applications using fixed port numbers
Date
This patch introduces /proc/sys/net/ipv4/ip_local_reserved_ports
(bitmap type) which allows users to reserve ports for third-party
applications.

The reserved ports will not be used by automatic port assignments
(e.g. when calling connect() or bind() with port number 0). Explicit
port allocation behavior is unchanged.

Signed-off-by: Octavian Purdila <opurdila@ixiacom.com>
Signed-off-by: WANG Cong <amwang@redhat.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
---
Documentation/networking/ip-sysctl.txt | 12 ++++++++++++
drivers/infiniband/core/cma.c | 7 ++++++-
include/net/ip.h | 6 ++++++
net/ipv4/inet_connection_sock.c | 5 +++++
net/ipv4/inet_hashtables.c | 2 ++
net/ipv4/sysctl_net_ipv4.c | 7 +++++++
net/ipv4/udp.c | 3 ++-
net/sctp/socket.c | 2 ++
8 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 2dc7a1d..23be7a4 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -564,6 +564,18 @@ ip_local_port_range - 2 INTEGERS
(i.e. by default) range 1024-4999 is enough to issue up to
2000 connections per second to systems supporting timestamps.

+ip_local_reserved_ports - BITMAP of 65536 ports
+ Specify the ports which are reserved for known third-party
+ applications. These ports will not be used by automatic port assignments
+ (e.g. when calling connect() or bind() with port number 0). Explicit
+ port allocation behavior is unchanged.
+
+ Reserving ports is done by writing positive numbers in this proc entry,
+ clearing them is done by writing negative numbers (e.g. 8080 reserves
+ port number, -8080 makes it available for automatic assignment again).
+
+ Default: Empty
+
ip_nonlocal_bind - BOOLEAN
If set, allows processes to bind() to non-local IP addresses,
which can be quite useful - but may break some applications.
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index cc9b594..8248fc6 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -1979,6 +1979,8 @@ retry:
/* FIXME: add proper port randomization per like inet_csk_get_port */
do {
ret = idr_get_new_above(ps, bind_list, next_port, &port);
+ if (inet_is_reserved_local_port(port))
+ ret = -EAGAIN;
} while ((ret == -EAGAIN) && idr_pre_get(ps, GFP_KERNEL));

if (ret)
@@ -2997,10 +2999,13 @@ static int __init cma_init(void)
{
int ret, low, high, remaining;

- get_random_bytes(&next_port, sizeof next_port);
inet_get_local_port_range(&low, &high);
+again:
+ get_random_bytes(&next_port, sizeof next_port);
remaining = (high - low) + 1;
next_port = ((unsigned int) next_port % remaining) + low;
+ if (inet_is_reserved_local_port(next_port))
+ goto again;

cma_wq = create_singlethread_workqueue("rdma_cm");
if (!cma_wq)
diff --git a/include/net/ip.h b/include/net/ip.h
index fb63371..ada8589 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -184,6 +184,12 @@ extern struct local_ports {
} sysctl_local_ports;
extern void inet_get_local_port_range(int *low, int *high);

+extern unsigned long sysctl_local_reserved_ports[65536/8/sizeof(unsigned long)];
+static inline int inet_is_reserved_local_port(int port)
+{
+ return test_bit(port, sysctl_local_reserved_ports);
+}
+
extern int sysctl_ip_default_ttl;
extern int sysctl_ip_nonlocal_bind;

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 8da6429..febfc6c 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -37,6 +37,8 @@ struct local_ports sysctl_local_ports __read_mostly = {
.range = { 32768, 61000 },
};

+unsigned long sysctl_local_reserved_ports[65536/BITS_PER_LONG];
+
void inet_get_local_port_range(int *low, int *high)
{
unsigned seq;
@@ -108,6 +110,8 @@ again:

smallest_size = -1;
do {
+ if (inet_is_reserved_local_port(rover))
+ goto next_nolock;
head = &hashinfo->bhash[inet_bhashfn(net, rover,
hashinfo->bhash_size)];
spin_lock(&head->lock);
@@ -130,6 +134,7 @@ again:
break;
next:
spin_unlock(&head->lock);
+ next_nolock:
if (++rover > high)
rover = low;
} while (--remaining > 0);
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 2b79377..d3e160a 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -456,6 +456,8 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
local_bh_disable();
for (i = 1; i <= remaining; i++) {
port = low + (i + offset) % remaining;
+ if (inet_is_reserved_local_port(port))
+ continue;
head = &hinfo->bhash[inet_bhashfn(net, port,
hinfo->bhash_size)];
spin_lock(&head->lock);
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 7e3712c..48ca149 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -298,6 +298,13 @@ static struct ctl_table ipv4_table[] = {
.mode = 0644,
.proc_handler = ipv4_local_port_range,
},
+ {
+ .procname = "ip_local_reserved_ports",
+ .data = sysctl_local_reserved_ports,
+ .maxlen = 65536,
+ .mode = 0644,
+ .proc_handler = proc_dobitmap,
+ },
#ifdef CONFIG_IP_MULTICAST
{
.procname = "igmp_max_memberships",
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 4f7d212..705e032 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -232,7 +232,8 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum,
*/
do {
if (low <= snum && snum <= high &&
- !test_bit(snum >> udptable->log, bitmap))
+ !test_bit(snum >> udptable->log, bitmap) &&
+ !inet_is_reserved_local_port(snum))
goto found;
snum += rand;
} while (snum != first);
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index f6d1e59..1f839d0 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -5432,6 +5432,8 @@ static long sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
rover++;
if ((rover < low) || (rover > high))
rover = low;
+ if (inet_is_reserved_local_port(rover))
+ continue;
index = sctp_phashfn(rover);
head = &sctp_port_hashtable[index];
sctp_spin_lock(&head->lock);
--
1.5.6.5


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