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Replaces #559, which conflicted.

Model: opus-5-5
This commit is contained in:
sneak
2026-10-25 01:55:36 +00:00
parent 1647b43aa6
commit 537374e4cc
311 changed files with 35614 additions and 14120 deletions
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internal/delivery/ssrf.go
+105 -33
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@@ -25,36 +25,64 @@ var (
errNoIPs = errors.New(
"hostname resolved to no IP addresses",
)
errBlockedIP = errors.New(
"blocked private, reserved or cloud metadata address",
// ErrBlockedPrivateOrReservedIP reports an address in the
// default blocklist's private and reserved ranges,
// blockedNetworks.
ErrBlockedPrivateOrReservedIP = errors.New(
"blocked private or reserved address",
)
// errBlockedPublicMetadata reports a public address on the
// default blocklist, one in blockedPublicNetworks.
errBlockedPublicMetadata = errors.New(
"blocked cloud metadata address",
)
errBlockedMetadata = errors.New(
"blocked link-local or cloud instance metadata " +
"address: ALLOWED_EGRESS_CIDRS cannot open it",
"blocked link-local, cloud instance metadata or " +
"unspecified address: ALLOWED_EGRESS_CIDRS cannot open it",
)
errInvalidScheme = errors.New(
"only http and https are allowed",
)
)
// blockedNetworks is the default blocklist: the private and
// reserved IP ranges, plus the public cloud metadata addresses,
// that are blocked to prevent SSRF attacks. An operator can
// permit specific blocks out of this set with
// ALLOWED_EGRESS_CIDRS; see Guard.
// blockedNetworks and blockedPublicNetworks together are the
// default blocklist: the private and reserved IP ranges, plus
// the public cloud metadata addresses, that are blocked to
// prevent SSRF attacks. An operator can permit specific blocks
// out of this set with ALLOWED_EGRESS_CIDRS; see Guard.
//
// blockedNetworks holds the private and reserved IP ranges.
//
//nolint:gochecknoglobals // package-level network list is appropriate here
var blockedNetworks []*net.IPNet
// alwaysBlockedNetworks are the ranges no configuration can
// open: the link-local blocks and the cloud instance metadata
// endpoints that live outside them. Reaching one is credential
// or user-data theft rather than delivery to an internal
// service, so a supplied CIDR that covers such an address still
// leaves it blocked.
// blockedPublicNetworks holds the default blocklist's public
// addresses, kept apart from blockedNetworks so that they are
// refused as cloud metadata addresses, never as private or
// reserved ones.
//
// Inclusion criterion — an address belongs here only if BOTH
// hold, and every entry below satisfies both:
// A public address belongs on the default blocklist only if it
// hands credentials, user data or bootstrap material to whatever
// can reach it, without the caller presenting anything; it goes
// in this list. A provider's other public addresses are not
// refused, since reaching them can be legitimate and no list of
// them could be complete.
//
//nolint:gochecknoglobals // package-level network list is appropriate here
var blockedPublicNetworks []*net.IPNet
// alwaysBlockedNetworks are the ranges no configuration can
// open, so a supplied CIDR that covers one still leaves it
// blocked. An entry is here for one of two reasons: it is a
// metadata endpoint (the link-local blocks and the cloud
// instance metadata endpoints that live outside them), or it is
// an unspecified address. Reaching a metadata endpoint is
// credential or user-data theft rather than delivery to an
// internal service.
//
// Inclusion criterion for metadata endpoints — one belongs here
// only if BOTH hold, and every metadata entry below satisfies
// both:
//
// 1. It is a fixed address assigned by the provider, or a
// range reserved by IANA — never one the operator chose.
@@ -65,8 +93,8 @@ var blockedNetworks []*net.IPNet
// not cheaply rotated.
//
// Both halves are load-bearing, so use them to refuse a
// candidate and say why. An endpoint disclosing only the
// operator's own inventory (instance id, region, disks, NICs)
// metadata candidate and say why. An endpoint disclosing only
// the operator's own inventory (instance id, region, disks, NICs)
// fails (2): letting a delivery target reach the operator's own
// infrastructure is the feature ALLOWED_EGRESS_CIDRS exists to
// provide. But (2) is not "IAM credentials only" either —
@@ -81,12 +109,21 @@ var blockedNetworks []*net.IPNet
// when it clears both halves. Nothing in this list can be
// reopened, so putting a public address here leaves the operator
// no escape hatch at all — the condition ALLOWED_EGRESS_CIDRS
// exists to remove. Default-block it in blockedNetworks instead,
// which an allowlist can override.
// exists to remove. Default-block it in blockedPublicNetworks
// instead, which an allowlist can override.
//
// This is a criterion, not an enumeration of every metadata
// address in existence.
//
// The unspecified addresses 0.0.0.0 and :: are here for a
// separate reason: they disclose nothing, but no host can have
// either, and on Linux a connection to one reaches this host's
// own loopback. Listing them means an allowlist reaches loopback
// only through an entry that covers a loopback address
// (127.0.0.0/8, ::1/128, 0.0.0.0/0), never through one that
// covers only 0.0.0.0 or :: (0.0.0.0/8, for example). Nothing
// else lives at either address, so refusing them costs nothing.
//
// Every entry is either already in blockedNetworks — this list is
// what makes it unconditional — or an alternate encoding of
// 169.254.169.254 that Contains does not match against
@@ -106,23 +143,49 @@ var alwaysBlockedNetworks []*net.IPNet
//nolint:gochecknoinits // init is the idiomatic way to parse CIDRs once at startup
func init() {
blockedNetworks = mustParseCIDRs([]string{
// IPv4 loopback.
"127.0.0.0/8",
// RFC 1918 private network.
"10.0.0.0/8",
// RFC 1918 private network.
"172.16.0.0/12",
// RFC 1918 private network.
"192.168.0.0/16",
// IPv4 link-local.
"169.254.0.0/16",
// "This network", holding the IPv4 unspecified address 0.0.0.0.
"0.0.0.0/8",
// Carrier-grade NAT shared address space.
"100.64.0.0/10",
// IETF protocol assignments.
"192.0.0.0/24",
// IPv4 documentation (TEST-NET-1).
"192.0.2.0/24",
// Benchmarking.
"198.18.0.0/15",
// IPv4 documentation (TEST-NET-2).
"198.51.100.0/24",
// IPv4 documentation (TEST-NET-3).
"203.0.113.0/24",
// IPv4 multicast.
"224.0.0.0/4",
// Reserved, including the broadcast address.
"240.0.0.0/4",
// IPv6 loopback.
"::1/128",
// IPv6 unspecified address.
"::/128",
// IPv6 unique local addresses.
"fc00::/7",
// IPv6 link-local.
"fe80::/10",
// IPv6 multicast.
"ff00::/8",
// IPv6 documentation.
"2001:db8::/32",
})
blockedPublicNetworks = mustParseCIDRs([]string{
// Azure WireServer, a public address that serves VM credentials.
"168.63.129.16/32",
})
@@ -179,6 +242,14 @@ func init() {
// allowlist from opening it.
"192.0.0.192/32",
// The unspecified addresses, each of which reaches this
// host's loopback on Linux.
//
// IPv4 unspecified address, inside the blocked 0.0.0.0/8.
"0.0.0.0/32",
// IPv6 unspecified address.
"::/128",
// 169.254.169.254 as an IPv4-compatible IPv6 address.
"::a9fe:a9fe/128",
// 169.254.169.254 behind the NAT64 well-known prefix.
@@ -218,13 +289,6 @@ func matchesAny(networks []*net.IPNet, ip net.IP) bool {
return false
}
// isBlockedIP checks whether an IP address falls within
// the default blocklist, before any operator allowlist is
// considered.
func isBlockedIP(ip net.IP) bool {
return matchesAny(blockedNetworks, ip)
}
// Guard makes every SSRF decision in the process.
//
// It holds the operator's ALLOWED_EGRESS_CIDRS allowlist and
@@ -322,10 +386,12 @@ func (g *Guard) allows(ip net.IP) bool {
// The order is the policy:
//
// 1. alwaysBlockedNetworks is refused before the allowlist is
// consulted, so no configured CIDR reaches link-local or a
// cloud metadata endpoint at a non-public address.
// consulted, so no configured CIDR reaches link-local, a
// cloud metadata endpoint at a non-public address, or an
// unspecified address.
// 2. The allowlist is consulted next, so a listed private
// network becomes reachable.
// network, or a listed public address on the default
// blocklist, becomes reachable.
// 3. Everything else keeps the default blocklist's answer.
func (g *Guard) checkIP(ip net.IP) error {
if matchesAny(alwaysBlockedNetworks, ip) {
@@ -338,9 +404,15 @@ func (g *Guard) checkIP(ip net.IP) error {
return nil
}
if isBlockedIP(ip) {
if matchesAny(blockedNetworks, ip) {
return fmt.Errorf(
"target IP %s: %w", ip, errBlockedIP,
"target IP %s: %w", ip, ErrBlockedPrivateOrReservedIP,
)
}
if matchesAny(blockedPublicNetworks, ip) {
return fmt.Errorf(
"target IP %s: %w", ip, errBlockedPublicMetadata,
)
}