services/arv-git-httpd/auth_handler.go

   1 // Copyright (C) The Arvados Authors. All rights reserved.
   2 //
   3 // SPDX-License-Identifier: AGPL-3.0
   4
   5 package main
   6
   7 import (
   8         "errors"
   9         "log"
  10         "net/http"
  11         "os"
  12         "regexp"
  13         "strings"
  14         "sync"
  15         "time"
  16
  17         "git.arvados.org/arvados.git/sdk/go/arvados"
  18         "git.arvados.org/arvados.git/sdk/go/arvadosclient"
  19         "git.arvados.org/arvados.git/sdk/go/auth"
  20         "git.arvados.org/arvados.git/sdk/go/httpserver"
  21 )
  22
  23 type authHandler struct {
  24         handler    http.Handler
  25         clientPool *arvadosclient.ClientPool
  26         cluster    *arvados.Cluster
  27         setupOnce  sync.Once
  28 }
  29
  30 func (h *authHandler) setup() {
  31         client, err := arvados.NewClientFromConfig(h.cluster)
  32         if err != nil {
  33                 log.Fatal(err)
  34         }
  35
  36         ac, err := arvadosclient.New(client)
  37         if err != nil {
  38                 log.Fatalf("Error setting up arvados client prototype %v", err)
  39         }
  40
  41         h.clientPool = &arvadosclient.ClientPool{Prototype: ac}
  42 }
  43
  44 func (h *authHandler) ServeHTTP(wOrig http.ResponseWriter, r *http.Request) {
  45         h.setupOnce.Do(h.setup)
  46
  47         var statusCode int
  48         var statusText string
  49         var apiToken string
  50         var repoName string
  51         var validApiToken bool
  52
  53         w := httpserver.WrapResponseWriter(wOrig)
  54
  55         if r.Method == "OPTIONS" {
  56                 method := r.Header.Get("Access-Control-Request-Method")
  57                 if method != "GET" && method != "POST" {
  58                         w.WriteHeader(http.StatusMethodNotAllowed)
  59                         return
  60                 }
  61                 w.Header().Set("Access-Control-Allow-Headers", "Authorization, Content-Type")
  62                 w.Header().Set("Access-Control-Allow-Methods", "GET, POST")
  63                 w.Header().Set("Access-Control-Allow-Origin", "*")
  64                 w.Header().Set("Access-Control-Max-Age", "86400")
  65                 w.WriteHeader(http.StatusOK)
  66                 return
  67         }
  68
  69         if r.Header.Get("Origin") != "" {
  70                 // Allow simple cross-origin requests without user
  71                 // credentials ("user credentials" as defined by CORS,
  72                 // i.e., cookies, HTTP authentication, and client-side
  73                 // SSL certificates. See
  74                 // http://www.w3.org/TR/cors/#user-credentials).
  75                 w.Header().Set("Access-Control-Allow-Origin", "*")
  76         }
  77
  78         defer func() {
  79                 if w.WroteStatus() == 0 {
  80                         // Nobody has called WriteHeader yet: that
  81                         // must be our job.
  82                         w.WriteHeader(statusCode)
  83                         if statusCode >= 400 {
  84                                 w.Write([]byte(statusText))
  85                         }
  86                 }
  87
  88                 // If the given password is a valid token, log the first 10 characters of the token.
  89                 // Otherwise: log the string <invalid> if a password is given, else an empty string.
  90                 passwordToLog := ""
  91                 if !validApiToken {
  92                         if len(apiToken) > 0 {
  93                                 passwordToLog = "<invalid>"
  94                         }
  95                 } else {
  96                         passwordToLog = apiToken[0:10]
  97                 }
  98
  99                 httpserver.Log(r.RemoteAddr, passwordToLog, w.WroteStatus(), statusText, repoName, r.Method, r.URL.Path)
 100         }()
 101
 102         creds := auth.CredentialsFromRequest(r)
 103         if len(creds.Tokens) == 0 {
 104                 statusCode, statusText = http.StatusUnauthorized, "no credentials provided"
 105                 w.Header().Add("WWW-Authenticate", "Basic realm=\"git\"")
 106                 return
 107         }
 108         apiToken = creds.Tokens[0]
 109
 110         // Access to paths "/foo/bar.git/*" and "/foo/bar/.git/*" are
 111         // protected by the permissions on the repository named
 112         // "foo/bar".
 113         pathParts := strings.SplitN(r.URL.Path[1:], ".git/", 2)
 114         if len(pathParts) != 2 {
 115                 statusCode, statusText = http.StatusNotFound, "not found"
 116                 return
 117         }
 118         repoName = pathParts[0]
 119         repoName = strings.TrimRight(repoName, "/")
 120
 121         arv := h.clientPool.Get()
 122         if arv == nil {
 123                 statusCode, statusText = http.StatusInternalServerError, "connection pool failed: "+h.clientPool.Err().Error()
 124                 return
 125         }
 126         defer h.clientPool.Put(arv)
 127
 128         // Ask API server whether the repository is readable using
 129         // this token (by trying to read it!)
 130         arv.ApiToken = apiToken
 131         repoUUID, err := h.lookupRepo(arv, repoName)
 132         if err != nil {
 133                 statusCode, statusText = http.StatusInternalServerError, err.Error()
 134                 return
 135         }
 136         validApiToken = true
 137         if repoUUID == "" {
 138                 statusCode, statusText = http.StatusNotFound, "not found"
 139                 return
 140         }
 141
 142         isWrite := strings.HasSuffix(r.URL.Path, "/git-receive-pack")
 143         if !isWrite {
 144                 statusText = "read"
 145         } else {
 146                 err := arv.Update("repositories", repoUUID, arvadosclient.Dict{
 147                         "repository": arvadosclient.Dict{
 148                                 "modified_at": time.Now().String(),
 149                         },
 150                 }, &arvadosclient.Dict{})
 151                 if err != nil {
 152                         statusCode, statusText = http.StatusForbidden, err.Error()
 153                         return
 154                 }
 155                 statusText = "write"
 156         }
 157
 158         // Regardless of whether the client asked for "/foo.git" or
 159         // "/foo/.git", we choose whichever variant exists in our repo
 160         // root, and we try {uuid}.git and {uuid}/.git first. If none
 161         // of these exist, we 404 even though the API told us the repo
 162         // _should_ exist (presumably this means the repo was just
 163         // created, and gitolite sync hasn't run yet).
 164         rewrittenPath := ""
 165         tryDirs := []string{
 166                 "/" + repoUUID + ".git",
 167                 "/" + repoUUID + "/.git",
 168                 "/" + repoName + ".git",
 169                 "/" + repoName + "/.git",
 170         }
 171         for _, dir := range tryDirs {
 172                 if fileInfo, err := os.Stat(h.cluster.Git.Repositories + dir); err != nil {
 173                         if !os.IsNotExist(err) {
 174                                 statusCode, statusText = http.StatusInternalServerError, err.Error()
 175                                 return
 176                         }
 177                 } else if fileInfo.IsDir() {
 178                         rewrittenPath = dir + "/" + pathParts[1]
 179                         break
 180                 }
 181         }
 182         if rewrittenPath == "" {
 183                 log.Println("WARNING:", repoUUID,
 184                         "git directory not found in", h.cluster.Git.Repositories, tryDirs)
 185                 // We say "content not found" to disambiguate from the
 186                 // earlier "API says that repo does not exist" error.
 187                 statusCode, statusText = http.StatusNotFound, "content not found"
 188                 return
 189         }
 190         r.URL.Path = rewrittenPath
 191
 192         h.handler.ServeHTTP(w, r)
 193 }
 194
 195 var uuidRegexp = regexp.MustCompile(`^[0-9a-z]{5}-s0uqq-[0-9a-z]{15}$`)
 196
 197 func (h *authHandler) lookupRepo(arv *arvadosclient.ArvadosClient, repoName string) (string, error) {
 198         reposFound := arvadosclient.Dict{}
 199         var column string
 200         if uuidRegexp.MatchString(repoName) {
 201                 column = "uuid"
 202         } else {
 203                 column = "name"
 204         }
 205         err := arv.List("repositories", arvadosclient.Dict{
 206                 "filters": [][]string{{column, "=", repoName}},
 207         }, &reposFound)
 208         if err != nil {
 209                 return "", err
 210         } else if avail, ok := reposFound["items_available"].(float64); !ok {
 211                 return "", errors.New("bad list response from API")
 212         } else if avail < 1 {
 213                 return "", nil
 214         } else if avail > 1 {
 215                 return "", errors.New("name collision")
 216         }
 217         return reposFound["items"].([]interface{})[0].(map[string]interface{})["uuid"].(string), nil
 218 }