fix: Various sec fixes 2 (#38108)

- Enforce repository token scope on RSS/Atom feed endpoints so a PAT
without repo scope can no longer read private repo commit data.
- Block HTTP redirects during repository migration clones to prevent
SSRF reaching internal addresses via an attacker-controlled redirect.
- Redact the notification subject after repo access is revoked so
private issue/PR metadata is no longer leaked through the notification
API.

---------

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

routers/web/feed/branch.go

@@ -15,6 +15,9 @@ import (
 
 // ShowBranchFeed shows tags and/or releases on the repo as RSS / Atom feed
 func ShowBranchFeed(ctx *context.Context, repo *repo.Repository, formatType string) {
+	if !checkRepoFeedTokenScope(ctx) {
+		return
+	}
 	var commits []*git.Commit
 	var err error
 	if ctx.Repo.Commit != nil {

routers/web/feed/file.go

@@ -16,6 +16,9 @@ import (
 
 // ShowFileFeed shows tags and/or releases on the repo as RSS / Atom feed
 func ShowFileFeed(ctx *context.Context, repo *repo.Repository, formatType string) {
+	if !checkRepoFeedTokenScope(ctx) {
+		return
+	}
 	fileName := ctx.Repo.TreePath
 	if len(fileName) == 0 {
 		return

routers/web/feed/release.go

@@ -15,6 +15,9 @@ import (
 
 // shows tags and/or releases on the repo as RSS / Atom feed
 func ShowReleaseFeed(ctx *context.Context, repo *repo_model.Repository, isReleasesOnly bool, formatType string) {
+	if !checkRepoFeedTokenScope(ctx) {
+		return
+	}
 	releases, err := db.Find[repo_model.Release](ctx, repo_model.FindReleasesOptions{
 		IncludeTags: !isReleasesOnly,
 		RepoID:      ctx.Repo.Repository.ID,

routers/web/feed/render.go

@@ -4,9 +4,18 @@
 package feed
 
 import (
+	auth_model "gitea.dev/models/auth"
 	"gitea.dev/services/context"
 )
 
+// checkRepoFeedTokenScope ensures an API token has repository read scope before a
+// feed serves private repository content, mirroring checkDownloadTokenScope for
+// downloads. Returns false (and writes the response) when the token is denied.
+func checkRepoFeedTokenScope(ctx *context.Context) bool {
+	context.CheckRepoScopedToken(ctx, ctx.Repo.Repository, auth_model.Read)
+	return !ctx.Written()
+}
+
 // RenderBranchFeed render format for branch or file
 func RenderBranchFeed(ctx *context.Context, feedType string) {
 	if ctx.Repo.TreePath == "" {

routers/web/feed/repo.go

@@ -16,6 +16,9 @@ import (
 
 // ShowRepoFeed shows user activity on the repo as RSS / Atom feed
 func ShowRepoFeed(ctx *context.Context, repo *repo_model.Repository, formatType string) {
+	if !checkRepoFeedTokenScope(ctx) {
+		return
+	}
 	actions, _, err := feed_service.GetFeeds(ctx, activities_model.GetFeedsOptions{
 		RequestedRepo:  repo,
 		Actor:          ctx.Doer,