Files
LocalAI/pkg/utils/base64.go
Richard Palethorpe 12d1f3a697 security(http): refuse redirects on outbound clients via hardened pkg/httpclient (#10087)
LocalAI's outbound HTTP clients used Go's default redirect policy, which
follows up to 10 redirects. On a cross-host redirect Go forwards custom
request headers — including credential headers such as Anthropic's
x-api-key — to the redirect target (Go strips Authorization, Cookie and
WWW-Authenticate cross-host, but NOT arbitrary custom headers). An
attacker able to elicit a redirect from an upstream (a hijacked or
spoofed upstream, DNS trickery, or a malicious upstream_url) then
harvests the operator's provider API key.

This was first reported against the cloud-proxy / MITM PII path
(GHSA-3mj3-57v2-4636); the same class affects every other outbound
client. Rather than patch each call site, add pkg/httpclient as the one
sanctioned constructor for outbound HTTP and route everything through it.

pkg/httpclient:
  - New(...)             refuses redirects, TLS 1.2 floor, no body
                         deadline (streaming/SSE safe)
  - NewWithTimeout(d)    simple request/response calls
  - WithFollowRedirects  opt-in following that still strips credential
                         headers on any cross-host hop; different
                         scheme/host/port == different origin, guarding
                         the curl CVE-2022-27774 port-confusion class
  - WithTransport(rt)    keep a custom transport (IP-pin, HTTP/2, a
                         credential-injecting RoundTripper)
  - HardenedTransport()  base transport with the TLS floor + bounded setup
  - Harden(c)            apply the policy to a library-supplied *http.Client
  - NoRedirect           the CheckRedirect policy; wraps ErrRedirectBlocked

Lint: a forbidigo rule flags http.DefaultClient and http.Get/Post/
PostForm/Head, pointing at pkg/httpclient (.golangci.yml,
.agents/coding-style.md). forbidigo cannot match the &http.Client{}
composite literal without also flagging legitimate *http.Client type
references, so that form is enforced by review.

Migrates every non-test outbound call site across core/, pkg/, cmd/, and
the Go backend (backend/go/cloud-proxy). Credential-bearing and
internal-RPC clients refuse redirects; download / CDN / registry clients
use WithFollowRedirects so they keep working while stripping secrets
cross-host. The only credential-bearing client that follows redirects is
the gated-download path (pkg/downloader/uri.go), which strips the token
on the cross-host hop to the CDN. Hardening this closes, in passing:
  - MCP remote-server bearer token leaking via a redirect (the
    RoundTripper re-injected Authorization on every hop)
  - agent multimedia/webhook clients leaking user-supplied auth headers
  - cors_proxy following redirects, bypassing its SSRF IP-pin
  - downloader's authorized read path leaking the token cross-host

Fixes: GHSA-3mj3-57v2-4636 (cloud-proxy leaks operator provider API key
(x-api-key) to attacker host on cross-host redirect)
Reported-by: tonghuaroot
Assisted-by: Claude:claude-opus-4-8 [Claude Code]

Signed-off-by: Richard Palethorpe <io@richiejp.com>
2026-05-30 12:04:10 +02:00

61 lines
1.8 KiB
Go

package utils
import (
"encoding/base64"
"fmt"
"io"
"regexp"
"strings"
"time"
"github.com/mudler/xlog"
"github.com/mudler/LocalAI/pkg/httpclient"
)
var base64DownloadClient = httpclient.NewWithTimeout(30*time.Second, httpclient.WithFollowRedirects())
// Match `data:<mime>[;param=value...];base64,` — browser-produced data URIs
// often carry codec/charset params between the mime type and `;base64,`
// (e.g. MediaRecorder's `data:audio/webm;codecs=opus;base64,...`). The old
// `([^;]+)` form only tolerated exactly one segment, so anything with
// extra params failed the strip and tripped the downstream base64 decoder
// on the `data:` literal.
var dataURIPattern = regexp.MustCompile(`^data:[^,]+?;base64,`)
// GetContentURIAsBase64 checks if the string is an URL, if it's an URL downloads the content in memory encodes it in base64 and returns the base64 string, otherwise returns the string by stripping base64 data headers
func GetContentURIAsBase64(s string) (string, error) {
if strings.HasPrefix(s, "http") || strings.HasPrefix(s, "https") {
if err := ValidateExternalURL(s); err != nil {
return "", fmt.Errorf("URL validation failed: %w", err)
}
// download the image
resp, err := base64DownloadClient.Get(s)
if err != nil {
return "", err
}
defer resp.Body.Close()
// read the image data into memory
data, err := io.ReadAll(resp.Body)
if err != nil {
return "", err
}
// encode the image data in base64
encoded := base64.StdEncoding.EncodeToString(data)
// return the base64 string
return encoded, nil
}
// Match any data URI prefix pattern
if match := dataURIPattern.FindString(s); match != "" {
xlog.Debug("Found data URI prefix", "prefix", match)
return strings.Replace(s, match, "", 1), nil
}
return "", fmt.Errorf("not valid base64 data type string")
}