1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
|
package main
import (
"log"
"net/http"
"net/http/cgi"
"os"
"path/filepath"
"regexp"
"strconv"
"strings"
"sync"
)
// gitBackend is git's own CGI, located by asking git. On first use, not at
// startup: the filter subcommands must not fork git.
var gitBackend = sync.OnceValue(func() string {
out, err := git("", nil, "--exec-path")
if err != nil {
log.Printf("git: no exec path, so no push or pull over http: %v", err)
return ""
}
return filepath.Join(strings.TrimSpace(string(out)), "git-http-backend")
})
var gitProtocolRE = regexp.MustCompile(`^[a-zA-Z0-9=:._-]+$`)
// transferring bounds the git-http-backend children in flight: an upload-pack
// packs with a thread per core.
var transferring = make(chan struct{}, 8)
// What one push may weigh; git has no bound of its own. The wiki is held to
// far less, because its knob can be set to any account at all.
const (
maxPushCode = 1 << 30
maxPushWiki = 16 << 20
)
// handleGitHTTP authorises before anything is exec'd. No form token and no
// session cookie: a push authenticated by a cookie could be driven from
// another site.
func (f *Forge) handleGitHTTP(w http.ResponseWriter, r *http.Request, path, kind, rest string) {
backend := gitBackend()
if backend == "" {
http.Error(w, "git-http-backend is not installed\n", http.StatusInternalServerError)
return
}
v, ok := f.gitViewer(w, r, path)
if !ok {
return
}
// What the viewer may not read does not exist, as on the web. Anonymous is
// challenged instead, so git sends credentials, and challenged whether or
// not the repository is there: a 401 beside a 404 would name the private
// ones.
repo, exists := f.store.Repo(path)
if !exists || !v.CanRead(repo) {
if v.SignedIn() {
http.NotFound(w, r)
} else {
f.gitChallenge(w, "authentication required")
}
return
}
// A feature turned off keeps its repository on disk.
if (kind == "issues" && repo.Issues == featDisabled) || (kind == "wiki" && repo.Wiki == featDisabled) {
http.NotFound(w, r)
return
}
dir := path + gitSuffix(kind)
if _, err := os.Stat(filepath.Join(f.store.reposDir, dir)); err != nil {
http.NotFound(w, r)
return
}
write := isPush(r, rest)
if write && kind == "issues" {
// The tracker is well formed because the server is its only writer.
http.Error(w, "the issue tracker is written by the forge, not by push. clone and read it, but file issues through the web\n",
http.StatusForbidden)
return
}
if write {
// The wiki knob, not the code write grant: documentation fixes and
// code are separate permissions.
allowed := v.CanWrite(repo)
if kind == "wiki" {
allowed = v.CanWiki(repo)
}
switch {
case allowed:
case v.SignedIn():
http.Error(w, "you do not have that access to this repository\n", http.StatusForbidden)
return
default:
f.gitChallenge(w, "authentication required")
return
}
}
weight := maxPushCode
if kind == "wiki" {
weight = maxPushWiki
}
// PATH_INFO comes from the resolved repository, not the URL. The receive
// settings come through the environment: nothing the forge writes goes
// inside a repository.
env := []string{
"GIT_PROJECT_ROOT=" + f.store.reposDir,
"GIT_HTTP_EXPORT_ALL=1",
"REMOTE_USER=" + v.Name,
"PATH_INFO=/" + dir + "/" + rest,
"SCRIPT_NAME=",
"GIT_CONFIG_NOSYSTEM=1",
"GIT_CONFIG_GLOBAL=/dev/null",
"GIT_CONFIG_COUNT=2",
"GIT_CONFIG_KEY_0=receive.unpackLimit",
"GIT_CONFIG_VALUE_0=1",
"GIT_CONFIG_KEY_1=receive.maxInputSize",
"GIT_CONFIG_VALUE_1=" + strconv.Itoa(weight),
}
// As HTTP_GIT_PROTOCOL git-http-backend would not read it, and every
// client would fall back to protocol v0.
if p := r.Header.Get("Git-Protocol"); p != "" && gitProtocolRE.MatchString(p) {
env = append(env, "GIT_PROTOCOL="+p)
}
// git sends a push past http.postBuffer chunked, which net/http/cgi
// refuses; the framing is already decoded here.
r.TransferEncoding = nil
release, ok := childSlot(transferring, r)
if !ok {
return
}
defer release()
(&cgi.Handler{Path: backend, Env: env, Stderr: os.Stdout}).ServeHTTP(w, r)
if write {
// A push that failed leaves nothing to collect.
gcAuto(filepath.Join(f.store.reposDir, dir))
}
}
// gitViewer reads Basic auth carrying a scoped push token, never a password:
// git cannot be asked for a second factor, and a token is separately scoped
// and separately revoked. No credential is the anonymous viewer.
func (f *Forge) gitViewer(w http.ResponseWriter, r *http.Request, path string) (Viewer, bool) {
given, secret, sent := r.BasicAuth()
if !sent {
return Viewer{}, true
}
name, u, ok := f.checkToken(given, secret, path)
if !ok {
f.gitChallenge(w, "bad account name or token")
return Viewer{}, false
}
// adminInEffect, not the raw flag: the web and git have to agree.
return Viewer{Name: name, Admin: u.adminInEffect()}, true
}
func (f *Forge) gitChallenge(w http.ResponseWriter, msg string) {
w.Header().Set("WWW-Authenticate", `Basic realm="`+f.siteName()+`", charset="UTF-8"`)
http.Error(w, msg+"\n", http.StatusUnauthorized)
}
// isPush reports whether this request is the start or the body of a push.
func isPush(r *http.Request, rest string) bool {
return rest == "git-receive-pack" || r.URL.Query().Get("service") == "git-receive-pack"
}
func gitSuffix(kind string) string {
if kind == "" {
return ".git"
}
return "." + kind + ".git"
}
|