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net: port < inet_prot_sock(net) --> inet_port_requires_bind_service(net, port)

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Note that the sysctl write accessor functions guarantee that:
  net->ipv4.sysctl_ip_prot_sock <= net->ipv4.ip_local_ports.range[0]
invariant is maintained, and as such the max() in selinux hooks is actually spurious.

ie. even though
  if (snum < max(inet_prot_sock(sock_net(sk)), low) || snum > high) {
per logic is the same as
  if ((snum < inet_prot_sock(sock_net(sk)) && snum < low) || snum > high) {
it is actually functionally equivalent to:
  if (snum < low || snum > high) {
which is equivalent to:
  if (snum < inet_prot_sock(sock_net(sk)) || snum < low || snum > high) {
even though the first clause is spurious.

But we want to hold on to it in case we ever want to change what what
inet_port_requires_bind_service() means (for example by changing
it from a, by default, [0..1024) range to some sort of set).

Test: builds, git 'grep inet_prot_sock' finds no other references
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Maciej Żenczykowski
2019-11-25 15:37:04 -08:00
committed by David S. Miller
parent e94a5d1681
commit 82f31ebf61
6 changed files with 11 additions and 11 deletions
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2
net/ipv4/af_inet.c
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@@ -495,7 +495,7 @@ int __inet_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len,
snum = ntohs(addr->sin_port);
err = -EACCES;
if (snum && snum < inet_prot_sock(net) &&
if (snum && inet_port_requires_bind_service(net, snum) &&
!ns_capable(net->user_ns, CAP_NET_BIND_SERVICE))
goto out;