Support LDAP authentication #101
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,13 @@ | ||
| load("@io_bazel_rules_go//go:def.bzl", "go_library") | ||
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| go_library( | ||
| name = "go_default_library", | ||
| srcs = ["ldap.go"], | ||
| importpath = "github.com/buchgr/bazel-remote/ldap", | ||
| visibility = ["//visibility:public"], | ||
| deps = [ | ||
| "//config:go_default_library", | ||
| "@com_github_abbot_go_http_auth//:go_default_library", | ||
| "@in_gopkg_ldap_v3//:go_default_library", | ||
| ], | ||
| ) |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,156 @@ | ||
| package ldap | ||
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| import ( | ||
| "context" | ||
| "encoding/base64" | ||
| "fmt" | ||
| "net/http" | ||
| "strings" | ||
| "sync" | ||
| "time" | ||
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| "github.com/buchgr/bazel-remote/config" | ||
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| auth "github.com/abbot/go-http-auth" | ||
| ldap "gopkg.in/ldap.v3" | ||
| ) | ||
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| // Cache represents a cache of LDAP query results so that many concurrent | ||
| // requests don't DDoS the LDAP server. | ||
| type Cache struct { | ||
| *auth.BasicAuth | ||
| m sync.Map | ||
| config *config.LDAPConfig | ||
| } | ||
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| type cacheEntry struct { | ||
| sync.Mutex | ||
| // Poor man's enum; nil pointer means uninitialized | ||
| authed *bool | ||
| } | ||
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| func New(config *config.LDAPConfig) (*Cache, error) { | ||
| conn, err := ldap.DialURL(config.BaseURL) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| defer conn.Close() | ||
| // Test the configured bind credentials | ||
| if err = conn.Bind(config.BindUser, config.BindPassword); err != nil { | ||
| return nil, err | ||
| } | ||
| return &Cache{ | ||
| config: config, | ||
| BasicAuth: &auth.BasicAuth{ | ||
| Realm: "Bazel remote cache", | ||
|
There was a problem hiding this comment. Should this be a configuration option? |
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| }, | ||
| }, nil | ||
| } | ||
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| // Either query LDAP for a result or retrieve it from the cache | ||
| func (c *Cache) checkLdap(user, password string) bool { | ||
| k := [2]string{user, password} | ||
| v, _ := c.m.LoadOrStore(k, &cacheEntry{}) | ||
| ce := v.(*cacheEntry) | ||
| ce.Lock() | ||
| defer ce.Unlock() | ||
| if ce.authed != nil { | ||
| return *ce.authed | ||
| } | ||
|
There was a problem hiding this comment. Could this be changed to the below? That way you don't have to acquire a lock in the case where it was cached? There was a problem hiding this comment. I also think this should have a nice fast-path, but this suggestion might need some tweaking to avoid multiple identical queries in quick succession: after obtaining the lock, ce.authed should be re-checked. |
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| // Not initialized; actually do the query and record the result | ||
| authed := c.query(user, password) | ||
| ce.authed = &authed | ||
| timeout := c.config.CacheTime | ||
| // Don't cache a negative result for a long time; likely wrong password | ||
| if !authed { | ||
| timeout = 5 * time.Second | ||
|
There was a problem hiding this comment. Out of Curiosity: Why cache a negative result at all? There was a problem hiding this comment. If you build with invalid auth and large -j value, I guess you don't want to make several hundred LDAP requests before the client notices and stops/cancels the remaining jobs. |
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| } | ||
| go func() { | ||
| <-time.After(timeout) | ||
| c.m.Delete(k) | ||
| }() | ||
| return authed | ||
| } | ||
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| func (c *Cache) query(user, password string) bool { | ||
| // This should always succeed since it was tested at instantiation | ||
| conn, err := ldap.DialURL(c.config.BaseURL) | ||
| if err != nil { | ||
| panic(err) | ||
| } | ||
| defer conn.Close() | ||
| if err = conn.Bind(c.config.BindUser, c.config.BindPassword); err != nil { | ||
| panic(err) | ||
| } | ||
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| var groupsQuery strings.Builder | ||
| if len(c.config.Groups) != 0 { | ||
| groupsQuery.WriteString("(|") | ||
| for _, group := range c.config.Groups { | ||
| fmt.Fprintf(&groupsQuery, "(memberOf=%s)", group) | ||
| } | ||
| groupsQuery.WriteString(")") | ||
| } | ||
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| // Does the user exist? | ||
| query := fmt.Sprintf("(&(%s=%s)%s)", c.config.UsernameAttribute, user, groupsQuery.String()) | ||
| searchRequest := ldap.NewSearchRequest( | ||
| c.config.BaseDN, | ||
| ldap.ScopeWholeSubtree, ldap.NeverDerefAliases, 0, 0, false, | ||
| query, []string{"dn"}, nil, | ||
| ) | ||
| sr, err := conn.Search(searchRequest) | ||
| if err != nil || len(sr.Entries) != 1 { | ||
| return false | ||
| } | ||
| // Do they have the right credentials? | ||
| return conn.Bind(sr.Entries[0].DN, password) == nil | ||
| } | ||
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| // Below mostly copied from github.com/abbot/go-http-auth | ||
| // in order to "override" CheckAuth | ||
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| func (c *Cache) CheckAuth(r *http.Request) string { | ||
| s := strings.SplitN(r.Header.Get(c.Headers.V().Authorization), " ", 2) | ||
| if len(s) != 2 || s[0] != "Basic" { | ||
| return "" | ||
| } | ||
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| b, err := base64.StdEncoding.DecodeString(s[1]) | ||
| if err != nil { | ||
| return "" | ||
| } | ||
| pair := strings.SplitN(string(b), ":", 2) | ||
| if len(pair) != 2 { | ||
| return "" | ||
| } | ||
| user, password := pair[0], pair[1] | ||
| if !c.checkLdap(user, password) { | ||
| return "" | ||
| } | ||
| return user | ||
| } | ||
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| func (c *Cache) Wrap(wrapped auth.AuthenticatedHandlerFunc) http.HandlerFunc { | ||
| return func(w http.ResponseWriter, r *http.Request) { | ||
| if username := c.CheckAuth(r); username == "" { | ||
| c.RequireAuth(w, r) | ||
| } else { | ||
| ar := &auth.AuthenticatedRequest{Request: *r, Username: username} | ||
| wrapped(w, ar) | ||
| } | ||
| } | ||
| } | ||
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| type key int | ||
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| var infoKey key | ||
|
There was a problem hiding this comment. Why does this need to be package global? It's never written? |
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| func (c *Cache) NewContext(ctx context.Context, r *http.Request) context.Context { | ||
| info := &auth.Info{Username: c.CheckAuth(r), ResponseHeaders: make(http.Header)} | ||
| info.Authenticated = info.Username != "" | ||
| if !info.Authenticated { | ||
| info.ResponseHeaders.Set(c.Headers.V().Authenticate, `Basic realm="`+c.Realm+`"`) | ||
| } | ||
| return context.WithValue(ctx, infoKey, info) | ||
| } | ||
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Maybe check <= 0 here?