forgejo-federation/services/lfs/server.go
zeripath 17c5c654a5
Prevent double-login for Git HTTP and LFS and simplify login (#15303)
* Prevent double-login for Git HTTP and LFS and simplify login

There are a number of inconsistencies with our current methods for
logging in for git and lfs. The first is that there is a double login
process. This is particularly evident in 1.13 where there are no less
than 4 hash checks for basic authentication due to the previous
IsPasswordSet behaviour.

This duplicated code had individual inconsistencies that were not
helpful and caused confusion.

This PR does the following:

* Remove the specific login code from the git and lfs handlers except
for the lfs special bearer token
* Simplify the meaning of DisableBasicAuthentication to allow Token and
Oauth2 sign-in.
* The removal of the specific code from git and lfs means that these
both now have the same login semantics and can - if not
DisableBasicAuthentication - login from external services. Further it
allows Oauth2 token authentication as per our standard mechanisms.
* The change in the recovery handler prevents the service from
re-attempting to login - primarily because this could easily cause a
further panic and it is wasteful.

* add test

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: Andrew Thornton <art27@cantab.net>
2021-05-15 17:32:09 +02:00

649 lines
19 KiB
Go

// Copyright 2020 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package lfs
import (
"encoding/base64"
"fmt"
"io"
"net/http"
"path"
"regexp"
"strconv"
"strings"
"code.gitea.io/gitea/models"
"code.gitea.io/gitea/modules/context"
lfs_module "code.gitea.io/gitea/modules/lfs"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/setting"
"github.com/dgrijalva/jwt-go"
jsoniter "github.com/json-iterator/go"
)
// requestContext contain variables from the HTTP request.
type requestContext struct {
User string
Repo string
Authorization string
}
// Claims is a JWT Token Claims
type Claims struct {
RepoID int64
Op string
UserID int64
jwt.StandardClaims
}
// ObjectLink builds a URL linking to the object.
func (rc *requestContext) ObjectLink(oid string) string {
return setting.AppURL + path.Join(rc.User, rc.Repo+".git", "info/lfs/objects", oid)
}
// VerifyLink builds a URL for verifying the object.
func (rc *requestContext) VerifyLink() string {
return setting.AppURL + path.Join(rc.User, rc.Repo+".git", "info/lfs/verify")
}
var oidRegExp = regexp.MustCompile(`^[A-Fa-f0-9]+$`)
func isOidValid(oid string) bool {
return oidRegExp.MatchString(oid)
}
// ObjectOidHandler is the main request routing entry point into LFS server functions
func ObjectOidHandler(ctx *context.Context) {
if !setting.LFS.StartServer {
log.Debug("Attempt to access LFS server but LFS server is disabled")
writeStatus(ctx, 404)
return
}
if ctx.Req.Method == "GET" || ctx.Req.Method == "HEAD" {
if MetaMatcher(ctx.Req) {
getMetaHandler(ctx)
return
}
getContentHandler(ctx)
return
} else if ctx.Req.Method == "PUT" {
PutHandler(ctx)
return
}
log.Warn("Unhandled LFS method: %s for %s/%s OID[%s]", ctx.Req.Method, ctx.Params("username"), ctx.Params("reponame"), ctx.Params("oid"))
writeStatus(ctx, 404)
}
func getAuthenticatedRepoAndMeta(ctx *context.Context, rc *requestContext, p lfs_module.Pointer, requireWrite bool) (*models.LFSMetaObject, *models.Repository) {
if !isOidValid(p.Oid) {
log.Info("Attempt to access invalid LFS OID[%s] in %s/%s", p.Oid, rc.User, rc.Repo)
writeStatus(ctx, 404)
return nil, nil
}
repository, err := models.GetRepositoryByOwnerAndName(rc.User, rc.Repo)
if err != nil {
log.Error("Unable to get repository: %s/%s Error: %v", rc.User, rc.Repo, err)
writeStatus(ctx, 404)
return nil, nil
}
if !authenticate(ctx, repository, rc.Authorization, false, requireWrite) {
requireAuth(ctx)
return nil, nil
}
meta, err := repository.GetLFSMetaObjectByOid(p.Oid)
if err != nil {
log.Error("Unable to get LFS OID[%s] Error: %v", p.Oid, err)
writeStatus(ctx, 404)
return nil, nil
}
return meta, repository
}
// getContentHandler gets the content from the content store
func getContentHandler(ctx *context.Context) {
rc, p := unpack(ctx)
meta, _ := getAuthenticatedRepoAndMeta(ctx, rc, p, false)
if meta == nil {
// Status already written in getAuthenticatedRepoAndMeta
return
}
// Support resume download using Range header
var fromByte, toByte int64
toByte = meta.Size - 1
statusCode := 200
if rangeHdr := ctx.Req.Header.Get("Range"); rangeHdr != "" {
regex := regexp.MustCompile(`bytes=(\d+)\-(\d*).*`)
match := regex.FindStringSubmatch(rangeHdr)
if len(match) > 1 {
statusCode = 206
fromByte, _ = strconv.ParseInt(match[1], 10, 32)
if fromByte >= meta.Size {
writeStatus(ctx, http.StatusRequestedRangeNotSatisfiable)
return
}
if match[2] != "" {
_toByte, _ := strconv.ParseInt(match[2], 10, 32)
if _toByte >= fromByte && _toByte < toByte {
toByte = _toByte
}
}
ctx.Resp.Header().Set("Content-Range", fmt.Sprintf("bytes %d-%d/%d", fromByte, toByte, meta.Size-fromByte))
ctx.Resp.Header().Set("Access-Control-Expose-Headers", "Content-Range")
}
}
contentStore := lfs_module.NewContentStore()
content, err := contentStore.Get(meta.Pointer)
if err != nil {
// Errors are logged in contentStore.Get
writeStatus(ctx, http.StatusNotFound)
return
}
defer content.Close()
if fromByte > 0 {
_, err = content.Seek(fromByte, io.SeekStart)
if err != nil {
log.Error("Whilst trying to read LFS OID[%s]: Unable to seek to %d Error: %v", meta.Oid, fromByte, err)
writeStatus(ctx, http.StatusInternalServerError)
return
}
}
contentLength := toByte + 1 - fromByte
ctx.Resp.Header().Set("Content-Length", strconv.FormatInt(contentLength, 10))
ctx.Resp.Header().Set("Content-Type", "application/octet-stream")
filename := ctx.Params("filename")
if len(filename) > 0 {
decodedFilename, err := base64.RawURLEncoding.DecodeString(filename)
if err == nil {
ctx.Resp.Header().Set("Content-Disposition", "attachment; filename=\""+string(decodedFilename)+"\"")
ctx.Resp.Header().Set("Access-Control-Expose-Headers", "Content-Disposition")
}
}
ctx.Resp.WriteHeader(statusCode)
if written, err := io.CopyN(ctx.Resp, content, contentLength); err != nil {
log.Error("Error whilst copying LFS OID[%s] to the response after %d bytes. Error: %v", meta.Oid, written, err)
}
logRequest(ctx.Req, statusCode)
}
// getMetaHandler retrieves metadata about the object
func getMetaHandler(ctx *context.Context) {
rc, p := unpack(ctx)
meta, _ := getAuthenticatedRepoAndMeta(ctx, rc, p, false)
if meta == nil {
// Status already written in getAuthenticatedRepoAndMeta
return
}
ctx.Resp.Header().Set("Content-Type", lfs_module.MediaType)
if ctx.Req.Method == "GET" {
json := jsoniter.ConfigCompatibleWithStandardLibrary
enc := json.NewEncoder(ctx.Resp)
if err := enc.Encode(represent(rc, meta.Pointer, true, false)); err != nil {
log.Error("Failed to encode representation as json. Error: %v", err)
}
}
logRequest(ctx.Req, 200)
}
// PostHandler instructs the client how to upload data
func PostHandler(ctx *context.Context) {
if !setting.LFS.StartServer {
log.Debug("Attempt to access LFS server but LFS server is disabled")
writeStatus(ctx, 404)
return
}
if !MetaMatcher(ctx.Req) {
log.Info("Attempt to POST without accepting the correct media type: %s", lfs_module.MediaType)
writeStatus(ctx, 400)
return
}
rc, p := unpack(ctx)
repository, err := models.GetRepositoryByOwnerAndName(rc.User, rc.Repo)
if err != nil {
log.Error("Unable to get repository: %s/%s Error: %v", rc.User, rc.Repo, err)
writeStatus(ctx, 404)
return
}
if !authenticate(ctx, repository, rc.Authorization, false, true) {
requireAuth(ctx)
return
}
if !isOidValid(p.Oid) {
log.Info("Invalid LFS OID[%s] attempt to POST in %s/%s", p.Oid, rc.User, rc.Repo)
writeStatus(ctx, 404)
return
}
if setting.LFS.MaxFileSize > 0 && p.Size > setting.LFS.MaxFileSize {
log.Info("Denied LFS OID[%s] upload of size %d to %s/%s because of LFS_MAX_FILE_SIZE=%d", p.Oid, p.Size, rc.User, rc.Repo, setting.LFS.MaxFileSize)
writeStatus(ctx, 413)
return
}
meta, err := models.NewLFSMetaObject(&models.LFSMetaObject{Pointer: p, RepositoryID: repository.ID})
if err != nil {
log.Error("Unable to write LFS OID[%s] size %d meta object in %v/%v to database. Error: %v", p.Oid, p.Size, rc.User, rc.Repo, err)
writeStatus(ctx, 404)
return
}
ctx.Resp.Header().Set("Content-Type", lfs_module.MediaType)
sentStatus := 202
contentStore := lfs_module.NewContentStore()
exist, err := contentStore.Exists(p)
if err != nil {
log.Error("Unable to check if LFS OID[%s] exist on %s / %s. Error: %v", p.Oid, rc.User, rc.Repo, err)
writeStatus(ctx, 500)
return
}
if meta.Existing && exist {
sentStatus = 200
}
ctx.Resp.WriteHeader(sentStatus)
json := jsoniter.ConfigCompatibleWithStandardLibrary
enc := json.NewEncoder(ctx.Resp)
if err := enc.Encode(represent(rc, meta.Pointer, meta.Existing, true)); err != nil {
log.Error("Failed to encode representation as json. Error: %v", err)
}
logRequest(ctx.Req, sentStatus)
}
// BatchHandler provides the batch api
func BatchHandler(ctx *context.Context) {
if !setting.LFS.StartServer {
log.Debug("Attempt to access LFS server but LFS server is disabled")
writeStatus(ctx, 404)
return
}
if !MetaMatcher(ctx.Req) {
log.Info("Attempt to BATCH without accepting the correct media type: %s", lfs_module.MediaType)
writeStatus(ctx, 400)
return
}
bv := unpackbatch(ctx)
reqCtx := &requestContext{
User: ctx.Params("username"),
Repo: strings.TrimSuffix(ctx.Params("reponame"), ".git"),
Authorization: ctx.Req.Header.Get("Authorization"),
}
var responseObjects []*lfs_module.ObjectResponse
// Create a response object
for _, object := range bv.Objects {
if !isOidValid(object.Oid) {
log.Info("Invalid LFS OID[%s] attempt to BATCH in %s/%s", object.Oid, reqCtx.User, reqCtx.Repo)
continue
}
repository, err := models.GetRepositoryByOwnerAndName(reqCtx.User, reqCtx.Repo)
if err != nil {
log.Error("Unable to get repository: %s/%s Error: %v", reqCtx.User, reqCtx.Repo, err)
writeStatus(ctx, 404)
return
}
requireWrite := false
if bv.Operation == "upload" {
requireWrite = true
}
if !authenticate(ctx, repository, reqCtx.Authorization, false, requireWrite) {
requireAuth(ctx)
return
}
contentStore := lfs_module.NewContentStore()
meta, err := repository.GetLFSMetaObjectByOid(object.Oid)
if err == nil { // Object is found and exists
exist, err := contentStore.Exists(meta.Pointer)
if err != nil {
log.Error("Unable to check if LFS OID[%s] exist on %s / %s. Error: %v", object.Oid, reqCtx.User, reqCtx.Repo, err)
writeStatus(ctx, 500)
return
}
if exist {
responseObjects = append(responseObjects, represent(reqCtx, meta.Pointer, true, false))
continue
}
}
if requireWrite && setting.LFS.MaxFileSize > 0 && object.Size > setting.LFS.MaxFileSize {
log.Info("Denied LFS OID[%s] upload of size %d to %s/%s because of LFS_MAX_FILE_SIZE=%d", object.Oid, object.Size, reqCtx.User, reqCtx.Repo, setting.LFS.MaxFileSize)
writeStatus(ctx, 413)
return
}
// Object is not found
meta, err = models.NewLFSMetaObject(&models.LFSMetaObject{Pointer: object, RepositoryID: repository.ID})
if err == nil {
exist, err := contentStore.Exists(meta.Pointer)
if err != nil {
log.Error("Unable to check if LFS OID[%s] exist on %s / %s. Error: %v", object.Oid, reqCtx.User, reqCtx.Repo, err)
writeStatus(ctx, 500)
return
}
responseObjects = append(responseObjects, represent(reqCtx, meta.Pointer, meta.Existing, !exist))
} else {
log.Error("Unable to write LFS OID[%s] size %d meta object in %v/%v to database. Error: %v", object.Oid, object.Size, reqCtx.User, reqCtx.Repo, err)
}
}
ctx.Resp.Header().Set("Content-Type", lfs_module.MediaType)
respobj := &lfs_module.BatchResponse{Objects: responseObjects}
json := jsoniter.ConfigCompatibleWithStandardLibrary
enc := json.NewEncoder(ctx.Resp)
if err := enc.Encode(respobj); err != nil {
log.Error("Failed to encode representation as json. Error: %v", err)
}
logRequest(ctx.Req, 200)
}
// PutHandler receives data from the client and puts it into the content store
func PutHandler(ctx *context.Context) {
rc, p := unpack(ctx)
meta, repository := getAuthenticatedRepoAndMeta(ctx, rc, p, true)
if meta == nil {
// Status already written in getAuthenticatedRepoAndMeta
return
}
contentStore := lfs_module.NewContentStore()
defer ctx.Req.Body.Close()
if err := contentStore.Put(meta.Pointer, ctx.Req.Body); err != nil {
// Put will log the error itself
ctx.Resp.WriteHeader(500)
if err == lfs_module.ErrSizeMismatch || err == lfs_module.ErrHashMismatch {
fmt.Fprintf(ctx.Resp, `{"message":"%s"}`, err)
} else {
fmt.Fprintf(ctx.Resp, `{"message":"Internal Server Error"}`)
}
if _, err = repository.RemoveLFSMetaObjectByOid(p.Oid); err != nil {
log.Error("Whilst removing metaobject for LFS OID[%s] due to preceding error there was another Error: %v", p.Oid, err)
}
return
}
logRequest(ctx.Req, 200)
}
// VerifyHandler verify oid and its size from the content store
func VerifyHandler(ctx *context.Context) {
if !setting.LFS.StartServer {
log.Debug("Attempt to access LFS server but LFS server is disabled")
writeStatus(ctx, 404)
return
}
if !MetaMatcher(ctx.Req) {
log.Info("Attempt to VERIFY without accepting the correct media type: %s", lfs_module.MediaType)
writeStatus(ctx, 400)
return
}
rc, p := unpack(ctx)
meta, _ := getAuthenticatedRepoAndMeta(ctx, rc, p, true)
if meta == nil {
// Status already written in getAuthenticatedRepoAndMeta
return
}
contentStore := lfs_module.NewContentStore()
ok, err := contentStore.Verify(meta.Pointer)
if err != nil {
// Error will be logged in Verify
ctx.Resp.WriteHeader(500)
fmt.Fprintf(ctx.Resp, `{"message":"Internal Server Error"}`)
return
}
if !ok {
writeStatus(ctx, 422)
return
}
logRequest(ctx.Req, 200)
}
// represent takes a requestContext and Meta and turns it into a ObjectResponse suitable
// for json encoding
func represent(rc *requestContext, pointer lfs_module.Pointer, download, upload bool) *lfs_module.ObjectResponse {
rep := &lfs_module.ObjectResponse{
Pointer: pointer,
Actions: make(map[string]*lfs_module.Link),
}
header := make(map[string]string)
if rc.Authorization == "" {
//https://github.com/github/git-lfs/issues/1088
header["Authorization"] = "Authorization: Basic dummy"
} else {
header["Authorization"] = rc.Authorization
}
if download {
rep.Actions["download"] = &lfs_module.Link{Href: rc.ObjectLink(pointer.Oid), Header: header}
}
if upload {
rep.Actions["upload"] = &lfs_module.Link{Href: rc.ObjectLink(pointer.Oid), Header: header}
}
if upload && !download {
// Force client side verify action while gitea lacks proper server side verification
verifyHeader := make(map[string]string)
for k, v := range header {
verifyHeader[k] = v
}
// This is only needed to workaround https://github.com/git-lfs/git-lfs/issues/3662
verifyHeader["Accept"] = lfs_module.MediaType
rep.Actions["verify"] = &lfs_module.Link{Href: rc.VerifyLink(), Header: verifyHeader}
}
return rep
}
// MetaMatcher provides a mux.MatcherFunc that only allows requests that contain
// an Accept header with the lfs_module.MediaType
func MetaMatcher(r *http.Request) bool {
mediaParts := strings.Split(r.Header.Get("Accept"), ";")
mt := mediaParts[0]
return mt == lfs_module.MediaType
}
func unpack(ctx *context.Context) (*requestContext, lfs_module.Pointer) {
r := ctx.Req
rc := &requestContext{
User: ctx.Params("username"),
Repo: strings.TrimSuffix(ctx.Params("reponame"), ".git"),
Authorization: r.Header.Get("Authorization"),
}
p := lfs_module.Pointer{Oid: ctx.Params("oid")}
if r.Method == "POST" { // Maybe also check if +json
var p2 lfs_module.Pointer
bodyReader := r.Body
defer bodyReader.Close()
json := jsoniter.ConfigCompatibleWithStandardLibrary
dec := json.NewDecoder(bodyReader)
err := dec.Decode(&p2)
if err != nil {
// The error is logged as a WARN here because this may represent misbehaviour rather than a true error
log.Warn("Unable to decode POST request vars for LFS OID[%s] in %s/%s: Error: %v", p.Oid, rc.User, rc.Repo, err)
return rc, p
}
p.Oid = p2.Oid
p.Size = p2.Size
}
return rc, p
}
// TODO cheap hack, unify with unpack
func unpackbatch(ctx *context.Context) *lfs_module.BatchRequest {
r := ctx.Req
var bv lfs_module.BatchRequest
bodyReader := r.Body
defer bodyReader.Close()
json := jsoniter.ConfigCompatibleWithStandardLibrary
dec := json.NewDecoder(bodyReader)
err := dec.Decode(&bv)
if err != nil {
// The error is logged as a WARN here because this may represent misbehaviour rather than a true error
log.Warn("Unable to decode BATCH request vars in %s/%s: Error: %v", ctx.Params("username"), strings.TrimSuffix(ctx.Params("reponame"), ".git"), err)
return &bv
}
return &bv
}
func writeStatus(ctx *context.Context, status int) {
message := http.StatusText(status)
mediaParts := strings.Split(ctx.Req.Header.Get("Accept"), ";")
mt := mediaParts[0]
if strings.HasSuffix(mt, "+json") {
message = `{"message":"` + message + `"}`
}
ctx.Resp.WriteHeader(status)
fmt.Fprint(ctx.Resp, message)
logRequest(ctx.Req, status)
}
func logRequest(r *http.Request, status int) {
log.Debug("LFS request - Method: %s, URL: %s, Status %d", r.Method, r.URL, status)
}
// authenticate uses the authorization string to determine whether
// or not to proceed. This server assumes an HTTP Basic auth format.
func authenticate(ctx *context.Context, repository *models.Repository, authorization string, requireSigned, requireWrite bool) bool {
accessMode := models.AccessModeRead
if requireWrite {
accessMode = models.AccessModeWrite
}
// ctx.IsSigned is unnecessary here, this will be checked in perm.CanAccess
perm, err := models.GetUserRepoPermission(repository, ctx.User)
if err != nil {
log.Error("Unable to GetUserRepoPermission for user %-v in repo %-v Error: %v", ctx.User, repository)
return false
}
canRead := perm.CanAccess(accessMode, models.UnitTypeCode)
if canRead && (!requireSigned || ctx.IsSigned) {
return true
}
user, err := parseToken(authorization, repository, accessMode)
if err != nil {
// Most of these are Warn level - the true internal server errors are logged in parseToken already
log.Warn("Authentication failure for provided token with Error: %v", err)
return false
}
ctx.User = user
return true
}
func handleLFSToken(tokenSHA string, target *models.Repository, mode models.AccessMode) (*models.User, error) {
if !strings.Contains(tokenSHA, ".") {
return nil, nil
}
token, err := jwt.ParseWithClaims(tokenSHA, &Claims{}, func(t *jwt.Token) (interface{}, error) {
if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
return nil, fmt.Errorf("unexpected signing method: %v", t.Header["alg"])
}
return setting.LFS.JWTSecretBytes, nil
})
if err != nil {
return nil, nil
}
claims, claimsOk := token.Claims.(*Claims)
if !token.Valid || !claimsOk {
return nil, fmt.Errorf("invalid token claim")
}
if claims.RepoID != target.ID {
return nil, fmt.Errorf("invalid token claim")
}
if mode == models.AccessModeWrite && claims.Op != "upload" {
return nil, fmt.Errorf("invalid token claim")
}
u, err := models.GetUserByID(claims.UserID)
if err != nil {
log.Error("Unable to GetUserById[%d]: Error: %v", claims.UserID, err)
return nil, err
}
return u, nil
}
func parseToken(authorization string, target *models.Repository, mode models.AccessMode) (*models.User, error) {
if authorization == "" {
return nil, fmt.Errorf("no token")
}
parts := strings.SplitN(authorization, " ", 2)
if len(parts) != 2 {
return nil, fmt.Errorf("no token")
}
tokenSHA := parts[1]
switch strings.ToLower(parts[0]) {
case "bearer":
fallthrough
case "token":
return handleLFSToken(tokenSHA, target, mode)
}
return nil, fmt.Errorf("token not found")
}
func requireAuth(ctx *context.Context) {
ctx.Resp.Header().Set("WWW-Authenticate", "Basic realm=gitea-lfs")
writeStatus(ctx, 401)
}