Files
llmgw/internal/mirror/safefetch.go
T
Ilker ManapandClaude Opus 5.5 9853936e0b Give every engine a key only the router holds
Engines listen on every address their node has, with no key. Checked on the
live cluster: from a neighbouring node, a request straight to an engine's
port was answered — past the gateway's authentication, quotas and
accounting, by anyone who could reach the node.

Each replica's engine is now started with a key and refuses requests without
it. The key is derived from the replica id with an HMAC over a secret kept
in the store, rather than stored per replica: the router has to send the
right key to replicas this process never started — adopted after a restart,
or placed by the other control plane — and a function of a shared secret
gives that without a table to keep in step. A key taken from one node opens
that replica only. The secret is made on first use and copied with the rest
of the store when moving to PostgreSQL; a new one would lock the router out
of every running engine at the moment of the move.

The key reaches llama.cpp and vLLM through their environment
(LLAMA_API_KEY, VLLM_API_KEY) rather than their command line, which every
user on the node can read; SGLang only takes it as an argument. The agent's
readiness check, the router's proxy and its metrics scrape send it, the
client's own Authorization still never reaches the engine, and `ctl bench`
fetches the key of the replica it is pointed at from the admin API.

Engines started before this keep running without a key until their replica
is next started. With no store there is nowhere to keep the secret, and
engines start without one, with a warning.

Also formats two files that went in unformatted.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
2026-09-30 00:38:29 +02:00

87 lines
2.7 KiB
Go

package mirror
import (
"errors"
"fmt"
"net"
"net/http"
"net/netip"
"net/url"
"syscall"
"time"
)
// errPrivateSource is a fetch refused because it would reach this machine or
// the network behind it rather than the internet.
var errPrivateSource = errors.New("refusing to fetch from a loopback, private or link-local address")
// fetchClient downloads sources for the management API.
//
// The API fetches whatever URL it is given and the file server then hands the
// result to anyone. Without this, "fetch http://169.254.169.254/..." was a way
// to read a cloud's instance metadata — or anything else on the network the
// mirror sits in — through the mirror. The check is made on the address
// actually dialled, after resolution and on every redirect, so a name that
// resolves somewhere public and then somewhere private is caught too.
func fetchClient(allowPrivate bool) *http.Client {
d := &net.Dialer{Timeout: 30 * time.Second, KeepAlive: 30 * time.Second}
if !allowPrivate {
d.Control = func(_, address string, _ syscall.RawConn) error {
host, _, err := net.SplitHostPort(address)
if err != nil {
return err
}
a, err := netip.ParseAddr(host)
if err != nil {
return err
}
if blockedAddr(a.Unmap()) {
return fmt.Errorf("%w (%s)", errPrivateSource, a)
}
return nil
}
}
return &http.Client{
Transport: &http.Transport{
Proxy: http.ProxyFromEnvironment,
DialContext: d.DialContext,
TLSHandshakeTimeout: 30 * time.Second,
ResponseHeaderTimeout: 2 * time.Minute,
ForceAttemptHTTP2: true,
},
// No overall timeout: a model is tens of gigabytes. The dial, the
// handshake and the first byte are bounded above; after that a stall
// is the context's to end.
CheckRedirect: func(req *http.Request, via []*http.Request) error {
if len(via) >= 10 {
return errors.New("too many redirects")
}
return checkScheme(req.URL)
},
}
}
func blockedAddr(a netip.Addr) bool {
cgnat := netip.MustParsePrefix("100.64.0.0/10")
return a.IsLoopback() || a.IsPrivate() || a.IsLinkLocalUnicast() ||
a.IsLinkLocalMulticast() || a.IsMulticast() || a.IsUnspecified() || cgnat.Contains(a)
}
// checkScheme allows the two schemes a model is published over. file:// and
// the rest would read this machine's own disk.
func checkScheme(u *url.URL) error {
if u.Scheme != "http" && u.Scheme != "https" {
return fmt.Errorf("%q is not an http or https source", u.Redacted())
}
return nil
}
// validSource checks a source before a download is started for it.
func validSource(source string) error {
u, err := url.Parse(source)
if err != nil || u.Host == "" {
return fmt.Errorf("%q is not a URL", source)
}
return checkScheme(u)
}