[UDP]: Randomize port selection.
This patch causes UDP port allocation to be randomized like TCP. The earlier code would always choose same port (ie first empty list). Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Stephen Hemminger
David S. Miller
parent
356f89e12e
commit
32c1da7081
3 changed files with 45 additions and 40 deletions
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@ -113,9 +113,8 @@ DEFINE_SNMP_STAT(struct udp_mib, udp_statistics) __read_mostly;
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struct hlist_head udp_hash[UDP_HTABLE_SIZE];
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DEFINE_RWLOCK(udp_hash_lock);
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static int udp_port_rover;
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static inline int __udp_lib_lport_inuse(__u16 num, struct hlist_head udptable[])
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static inline int __udp_lib_lport_inuse(__u16 num,
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const struct hlist_head udptable[])
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{
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struct sock *sk;
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struct hlist_node *node;
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@ -132,11 +131,10 @@ static inline int __udp_lib_lport_inuse(__u16 num, struct hlist_head udptable[])
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* @sk: socket struct in question
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* @snum: port number to look up
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* @udptable: hash list table, must be of UDP_HTABLE_SIZE
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* @port_rover: pointer to record of last unallocated port
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* @saddr_comp: AF-dependent comparison of bound local IP addresses
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*/
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int __udp_lib_get_port(struct sock *sk, unsigned short snum,
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struct hlist_head udptable[], int *port_rover,
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struct hlist_head udptable[],
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int (*saddr_comp)(const struct sock *sk1,
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const struct sock *sk2 ) )
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{
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@ -146,49 +144,56 @@ int __udp_lib_get_port(struct sock *sk, unsigned short snum,
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int error = 1;
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write_lock_bh(&udp_hash_lock);
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if (snum == 0) {
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int best_size_so_far, best, result, i;
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if (*port_rover > sysctl_local_port_range[1] ||
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*port_rover < sysctl_local_port_range[0])
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*port_rover = sysctl_local_port_range[0];
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best_size_so_far = 32767;
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best = result = *port_rover;
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for (i = 0; i < UDP_HTABLE_SIZE; i++, result++) {
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int size;
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if (!snum) {
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int i;
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int low = sysctl_local_port_range[0];
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int high = sysctl_local_port_range[1];
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unsigned rover, best, best_size_so_far;
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head = &udptable[result & (UDP_HTABLE_SIZE - 1)];
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if (hlist_empty(head)) {
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if (result > sysctl_local_port_range[1])
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result = sysctl_local_port_range[0] +
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((result - sysctl_local_port_range[0]) &
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(UDP_HTABLE_SIZE - 1));
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best_size_so_far = UINT_MAX;
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best = rover = net_random() % (high - low) + low;
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/* 1st pass: look for empty (or shortest) hash chain */
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for (i = 0; i < UDP_HTABLE_SIZE; i++) {
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int size = 0;
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head = &udptable[rover & (UDP_HTABLE_SIZE - 1)];
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if (hlist_empty(head))
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goto gotit;
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}
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size = 0;
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sk_for_each(sk2, node, head) {
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if (++size >= best_size_so_far)
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goto next;
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}
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best_size_so_far = size;
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best = result;
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best = rover;
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next:
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;
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/* fold back if end of range */
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if (++rover > high)
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rover = low + ((rover - low)
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& (UDP_HTABLE_SIZE - 1));
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}
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result = best;
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for (i = 0; i < (1 << 16) / UDP_HTABLE_SIZE;
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i++, result += UDP_HTABLE_SIZE) {
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if (result > sysctl_local_port_range[1])
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result = sysctl_local_port_range[0]
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+ ((result - sysctl_local_port_range[0]) &
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(UDP_HTABLE_SIZE - 1));
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if (! __udp_lib_lport_inuse(result, udptable))
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break;
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/* 2nd pass: find hole in shortest hash chain */
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rover = best;
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for (i = 0; i < (1 << 16) / UDP_HTABLE_SIZE; i++) {
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if (! __udp_lib_lport_inuse(rover, udptable))
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goto gotit;
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rover += UDP_HTABLE_SIZE;
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if (rover > high)
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rover = low + ((rover - low)
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& (UDP_HTABLE_SIZE - 1));
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}
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if (i >= (1 << 16) / UDP_HTABLE_SIZE)
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goto fail;
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/* All ports in use! */
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goto fail;
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gotit:
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*port_rover = snum = result;
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snum = rover;
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} else {
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head = &udptable[snum & (UDP_HTABLE_SIZE - 1)];
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@ -201,6 +206,7 @@ int __udp_lib_get_port(struct sock *sk, unsigned short snum,
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(*saddr_comp)(sk, sk2) )
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goto fail;
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}
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inet_sk(sk)->num = snum;
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sk->sk_hash = snum;
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if (sk_unhashed(sk)) {
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@ -217,7 +223,7 @@ int __udp_lib_get_port(struct sock *sk, unsigned short snum,
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int udp_get_port(struct sock *sk, unsigned short snum,
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int (*scmp)(const struct sock *, const struct sock *))
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{
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return __udp_lib_get_port(sk, snum, udp_hash, &udp_port_rover, scmp);
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return __udp_lib_get_port(sk, snum, udp_hash, scmp);
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}
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int ipv4_rcv_saddr_equal(const struct sock *sk1, const struct sock *sk2)
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@ -9,7 +9,7 @@ extern int __udp4_lib_rcv(struct sk_buff *, struct hlist_head [], int );
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extern void __udp4_lib_err(struct sk_buff *, u32, struct hlist_head []);
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extern int __udp_lib_get_port(struct sock *sk, unsigned short snum,
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struct hlist_head udptable[], int *port_rover,
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struct hlist_head udptable[],
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int (*)(const struct sock*,const struct sock*));
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extern int ipv4_rcv_saddr_equal(const struct sock *, const struct sock *);
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@ -16,12 +16,11 @@
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DEFINE_SNMP_STAT(struct udp_mib, udplite_statistics) __read_mostly;
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struct hlist_head udplite_hash[UDP_HTABLE_SIZE];
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static int udplite_port_rover;
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int udplite_get_port(struct sock *sk, unsigned short p,
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int (*c)(const struct sock *, const struct sock *))
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{
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return __udp_lib_get_port(sk, p, udplite_hash, &udplite_port_rover, c);
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return __udp_lib_get_port(sk, p, udplite_hash, c);
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}
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static int udplite_v4_get_port(struct sock *sk, unsigned short snum)
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