Files
caddy/internal/bindcap_linux_test.go
Francis LavoieandClaude Opus 5.5 0e392c89ba core: Retry privileged binds on EACCES instead of checking port < 1024 (#8253)
WithBindCapability assumed the kernel's privileged port range ends at
1024, but it is set by net.ipv4.ip_unprivileged_port_start, which can
be anywhere from 0 (Docker's default) to 65535. With a value above
1024, a non-root bind to e.g. :1500 failed even though the capability
was permitted.

Now listen is called normally first, and only if it fails with EACCES
on a TCP/UDP port, and CAP_NET_BIND_SERVICE is permitted but not
effective, the capability is raised and the bind retried. This also
skips raising it when the range starts lower than the port.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-19 19:19:28 +10:00

98 lines
2.7 KiB
Go

// Copyright 2015 Matthew Holt and The Caddy Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package internal
import (
"errors"
"net"
"os"
"testing"
"golang.org/x/sys/unix"
)
func TestIsPortBind(t *testing.T) {
for _, tc := range []struct {
network, address string
want bool
}{
{"tcp", ":80", true},
{"tcp4", "127.0.0.1:443", true},
{"udp6", "[::1]:443", true},
{"tcp", ":1023", true},
{"tcp", ":1024", true},
{"tcp", ":8080", true},
{"tcp", ":65535", true},
{"tcp", ":65536", false},
{"tcp", ":0", false},
{"unix", "/run/caddy.sock", false},
{"fd", "3", false},
{"ip4:icmp", "127.0.0.1", false},
} {
if got := isPortBind(tc.network, tc.address); got != tc.want {
t.Errorf("isPortBind(%q, %q) = %v, want %v", tc.network, tc.address, got, tc.want)
}
}
}
func TestWithBindCapabilityPassthrough(t *testing.T) {
before, err := shouldRaiseBindCapability()
if err != nil {
t.Fatalf("reading capabilities: %v", err)
}
// a privileged-port EACCES is retried only if the capability can be raised
retryCalls := 1
if before {
retryCalls = 2
}
// shaped like the error net.ListenConfig.Listen returns
eacces := &net.OpError{Op: "listen", Net: "tcp", Err: os.NewSyscallError("bind", unix.EACCES)}
sentinel := errors.New("sentinel")
for _, tc := range []struct {
network, address string
err error
wantCalls int
}{
{"tcp", "localhost:80", nil, 1},
{"tcp", "localhost:80", sentinel, 1},
{"udp", ":8080", sentinel, 1},
{"unix", "/tmp/caddy.sock", eacces, 1},
{"tcp", ":0", eacces, 1},
{"tcp", "localhost:80", eacces, retryCalls},
} {
calls := 0
ln, err := WithBindCapability(tc.network, tc.address, func() (any, error) {
calls++
return "listener", tc.err
})
if calls != tc.wantCalls {
t.Errorf("%s/%s/%v: listen called %d times, want %d", tc.network, tc.address, tc.err, calls, tc.wantCalls)
}
if ln != "listener" || !errors.Is(err, tc.err) {
t.Errorf("%s/%s/%v: got (%v, %v), want listen's return values", tc.network, tc.address, tc.err, ln, err)
}
}
after, err := shouldRaiseBindCapability()
if err != nil {
t.Fatalf("reading capabilities: %v", err)
}
if before != after {
t.Errorf("capabilities of calling thread changed")
}
}