Merge branch 'lfs-ssh-authorization-fix' into 'master'

Do not regenerate the `lfs_token` every time `git-lfs-authenticate` is called

## What does this MR do?

 Do not regenerate the `lfs_token` every time `git-lfs-authenticate` is called, instead return the saved token if one is present.

This was causing a lot of 401s, leading to 403s, as state in #22527

As it turns out, when pushing a lot of LFS objects, the LFS client was calling `git-lfs-authenticate` in the middle of the request again. This caused the `lfs_token` to be regenerated. The problem lies in that the LFS client was not aware of this change, and was still using the old token. This caused all subsequent requests to fail with a 401 error.

Since HTTP Auth is protected by Rack Attack, this 401s where immediately flagged and resulted in the IP of the user being banned. 

With this change, GitLab returns the value stored in Redis, if one is present, thus if the LFS client calls `git-lfs-authenticate` again during the request, the auth header will remain unchanged, allowing all subsequent requests to continue without issues.

## What are the relevant issue numbers?

Fixes #22527

cc @SeanPackham @jacobvosmaer-gitlab

See merge request !6551

lib/api/internal.rb

@@ -90,7 +90,7 @@ module API
         {
           username: token_handler.actor_name,
-          lfs_token: token_handler.generate,
+          lfs_token: token_handler.token,
           repository_http_path: project.http_url_to_repo
         }
       end

lib/gitlab/auth.rb

@@ -124,7 +124,7 @@ module Gitlab
             read_authentication_abilities
           end
-        Result.new(actor, nil, token_handler.type, authentication_abilities) if Devise.secure_compare(token_handler.value, password)
+        Result.new(actor, nil, token_handler.type, authentication_abilities) if Devise.secure_compare(token_handler.token, password)
       end
       def build_access_token_check(login, password)

lib/gitlab/lfs_token.rb

@@ -17,19 +17,18 @@ module Gitlab
         end
     end
-    def generate
-      token = Devise.friendly_token(TOKEN_LENGTH)
-
+    def token
       Gitlab::Redis.with do |redis|
-        redis.set(redis_key, token, ex: EXPIRY_TIME)
-      end
-      token
-    end
-    def value
-      Gitlab::Redis.with do |redis|
-        redis.get(redis_key)
+        token = redis.get(redis_key)
+        if token
+          redis.expire(redis_key, EXPIRY_TIME)
+        else
+          token = Devise.friendly_token(TOKEN_LENGTH)
+          redis.set(redis_key, token, ex: EXPIRY_TIME)
+        end
+        token
       end
     end

spec/lib/gitlab/auth_spec.rb

@@ -64,7 +64,7 @@ describe Gitlab::Auth, lib: true do
     it 'recognizes user lfs tokens' do
       user = create(:user)
       ip = 'ip'
-      token = Gitlab::LfsToken.new(user).generate
+      token = Gitlab::LfsToken.new(user).token
       expect(gl_auth).to receive(:rate_limit!).with(ip, success: true, login: user.username)
       expect(gl_auth.find_for_git_client(user.username, token, project: nil, ip: ip)).to eq(Gitlab::Auth::Result.new(user, nil, :lfs_token, full_authentication_abilities))
@@ -73,7 +73,7 @@ describe Gitlab::Auth, lib: true do
     it 'recognizes deploy key lfs tokens' do
       key = create(:deploy_key)
       ip = 'ip'
-      token = Gitlab::LfsToken.new(key).generate
+      token = Gitlab::LfsToken.new(key).token
       expect(gl_auth).to receive(:rate_limit!).with(ip, success: true, login: "lfs+deploy-key-#{key.id}")
       expect(gl_auth.find_for_git_client("lfs+deploy-key-#{key.id}", token, project: nil, ip: ip)).to eq(Gitlab::Auth::Result.new(key, nil, :lfs_deploy_token, read_authentication_abilities))

spec/lib/gitlab/lfs_token_spec.rb

 require 'spec_helper'
 describe Gitlab::LfsToken, lib: true do
-  describe '#generate and #value' do
+  describe '#token' do
     shared_examples 'an LFS token generator' do
       it 'returns a randomly generated token' do
-        token = handler.generate
+        token = handler.token
         expect(token).not_to be_nil
         expect(token).to be_a String
@@ -12,9 +12,9 @@ describe Gitlab::LfsToken, lib: true do
       end
       it 'returns the correct token based on the key' do
-        token = handler.generate
-        expect(handler.value).to eq(token)
+        token = handler.token
+        expect(handler.token).to eq(token)
       end
     end

spec/requests/api/internal_spec.rb

@@ -111,7 +111,7 @@ describe API::API, api: true  do
         expect(response).to have_http_status(200)
         expect(json_response['username']).to eq(user.username)
-        expect(json_response['lfs_token']).to eq(Gitlab::LfsToken.new(key).value)
+        expect(json_response['lfs_token']).to eq(Gitlab::LfsToken.new(key).token)
         expect(json_response['repository_http_path']).to eq(project.http_url_to_repo)
       end
@@ -131,7 +131,7 @@ describe API::API, api: true  do
         expect(response).to have_http_status(200)
         expect(json_response['username']).to eq("lfs+deploy-key-#{key.id}")
-        expect(json_response['lfs_token']).to eq(Gitlab::LfsToken.new(key).value)
+        expect(json_response['lfs_token']).to eq(Gitlab::LfsToken.new(key).token)
         expect(json_response['repository_http_path']).to eq(project.http_url_to_repo)
       end
     end

spec/requests/lfs_http_spec.rb

@@ -257,6 +257,29 @@ describe 'Git LFS API and storage' do
           it_behaves_like 'responds with a file'
         end
+        describe 'when using a user key' do
+          let(:authorization) { authorize_user_key }
+
+          context 'when user allowed' do
+            let(:update_permissions) do
+              project.team << [user, :master]
+              project.lfs_objects << lfs_object
+            end
+
+            it_behaves_like 'responds with a file'
+          end
+
+          context 'when user not allowed' do
+            let(:update_permissions) do
+              project.lfs_objects << lfs_object
+            end
+
+            it 'responds with status 404' do
+              expect(response).to have_http_status(404)
+            end
+          end
+        end
+
         context 'when build is authorized as' do
           let(:authorization) { authorize_ci_project }
@@ -1110,7 +1133,11 @@ describe 'Git LFS API and storage' do
   end
   def authorize_deploy_key
-    ActionController::HttpAuthentication::Basic.encode_credentials("lfs+deploy-key-#{key.id}", Gitlab::LfsToken.new(key).generate)
+    ActionController::HttpAuthentication::Basic.encode_credentials("lfs+deploy-key-#{key.id}", Gitlab::LfsToken.new(key).token)
+  end
+
+  def authorize_user_key
+    ActionController::HttpAuthentication::Basic.encode_credentials(user.username, Gitlab::LfsToken.new(user).token)
   end
   def fork_project(project, user, object = nil)