forgejo/routers/private/hook_pre_receive.go
Gergely Nagy aacc13fca8 hooks: Harden when we accept push options that change repo settings
It is possible to change some repo settings (its visibility, and
template status) via `git push` options: `-o repo.private=true`, `-o
repo.template=true`.

Previously, there weren't sufficient permission checks on these, and
anyone who could `git push` to a repository - including via an AGit
workflow! - was able to change either of these settings. To guard
against this, the pre-receive hook will now check if either of these
options are present, and if so, will perform additional permission
checks to ensure that these can only be set by a repository owner or
an administrator. Additionally, changing these settings is disabled for
forks, even for the fork's owner.

There's still a case where the owner of a repository can change the
visibility of it, and it will not propagate to forks (it propagates to
forks when changing the visibility via the API), but that's an
inconsistency, not a security issue.

Signed-off-by: Gergely Nagy <forgejo@gergo.csillger.hu>
Signed-off-by: Earl Warren <contact@earl-warren.org>
(cherry picked from commit 8eba631f8d)
2024-04-20 05:58:39 +00:00

585 lines
19 KiB
Go

// Copyright 2019 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package private
import (
"errors"
"fmt"
"net/http"
"os"
"code.gitea.io/gitea/models"
asymkey_model "code.gitea.io/gitea/models/asymkey"
git_model "code.gitea.io/gitea/models/git"
issues_model "code.gitea.io/gitea/models/issues"
perm_model "code.gitea.io/gitea/models/perm"
access_model "code.gitea.io/gitea/models/perm/access"
"code.gitea.io/gitea/models/unit"
user_model "code.gitea.io/gitea/models/user"
"code.gitea.io/gitea/modules/git"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/private"
"code.gitea.io/gitea/modules/web"
gitea_context "code.gitea.io/gitea/services/context"
pull_service "code.gitea.io/gitea/services/pull"
)
type preReceiveContext struct {
*gitea_context.PrivateContext
// loadedPusher indicates that where the following information are loaded
loadedPusher bool
user *user_model.User // it's the org user if a DeployKey is used
userPerm access_model.Permission
deployKeyAccessMode perm_model.AccessMode
canCreatePullRequest bool
checkedCanCreatePullRequest bool
canWriteCode bool
checkedCanWriteCode bool
protectedTags []*git_model.ProtectedTag
gotProtectedTags bool
env []string
opts *private.HookOptions
branchName string
}
// CanWriteCode returns true if pusher can write code
func (ctx *preReceiveContext) CanWriteCode() bool {
if !ctx.checkedCanWriteCode {
if !ctx.loadPusherAndPermission() {
return false
}
ctx.canWriteCode = issues_model.CanMaintainerWriteToBranch(ctx, ctx.userPerm, ctx.branchName, ctx.user) || ctx.deployKeyAccessMode >= perm_model.AccessModeWrite
ctx.checkedCanWriteCode = true
}
return ctx.canWriteCode
}
// AssertCanWriteCode returns true if pusher can write code
func (ctx *preReceiveContext) AssertCanWriteCode() bool {
if !ctx.CanWriteCode() {
if ctx.Written() {
return false
}
ctx.JSON(http.StatusForbidden, private.Response{
UserMsg: "User permission denied for writing.",
})
return false
}
return true
}
// CanCreatePullRequest returns true if pusher can create pull requests
func (ctx *preReceiveContext) CanCreatePullRequest() bool {
if !ctx.checkedCanCreatePullRequest {
if !ctx.loadPusherAndPermission() {
return false
}
ctx.canCreatePullRequest = ctx.userPerm.CanRead(unit.TypePullRequests)
ctx.checkedCanCreatePullRequest = true
}
return ctx.canCreatePullRequest
}
// AssertCreatePullRequest returns true if can create pull requests
func (ctx *preReceiveContext) AssertCreatePullRequest() bool {
if !ctx.CanCreatePullRequest() {
if ctx.Written() {
return false
}
ctx.JSON(http.StatusForbidden, private.Response{
UserMsg: "User permission denied for creating pull-request.",
})
return false
}
return true
}
var errPermissionDenied = errors.New("permission denied for changing repo settings")
func (ctx *preReceiveContext) canChangeSettings() error {
if !ctx.loadPusherAndPermission() {
return errPermissionDenied
}
if !ctx.userPerm.IsOwner() && !ctx.userPerm.IsAdmin() {
return errPermissionDenied
}
if ctx.Repo.Repository.IsFork {
return errPermissionDenied
}
return nil
}
func (ctx *preReceiveContext) validatePushOptions() error {
opts := web.GetForm(ctx).(*private.HookOptions)
if len(opts.GitPushOptions) == 0 {
return nil
}
changesRepoSettings := false
for key := range opts.GitPushOptions {
switch key {
case private.GitPushOptionRepoPrivate, private.GitPushOptionRepoTemplate:
changesRepoSettings = true
case "topic", "force-push", "title", "description":
// Agit options
default:
return fmt.Errorf("unknown option %s", key)
}
}
if changesRepoSettings {
return ctx.canChangeSettings()
}
return nil
}
func (ctx *preReceiveContext) assertPushOptions() bool {
if err := ctx.validatePushOptions(); err != nil {
ctx.JSON(http.StatusForbidden, private.Response{
UserMsg: fmt.Sprintf("options validation failed: %v", err),
})
return false
}
return true
}
// HookPreReceive checks whether a individual commit is acceptable
func HookPreReceive(ctx *gitea_context.PrivateContext) {
opts := web.GetForm(ctx).(*private.HookOptions)
ourCtx := &preReceiveContext{
PrivateContext: ctx,
env: generateGitEnv(opts), // Generate git environment for checking commits
opts: opts,
}
if !ourCtx.assertPushOptions() {
log.Trace("Git push options validation failed")
return
}
log.Trace("Git push options validation succeeded")
// Iterate across the provided old commit IDs
for i := range opts.OldCommitIDs {
oldCommitID := opts.OldCommitIDs[i]
newCommitID := opts.NewCommitIDs[i]
refFullName := opts.RefFullNames[i]
switch {
case refFullName.IsBranch():
preReceiveBranch(ourCtx, oldCommitID, newCommitID, refFullName)
case refFullName.IsTag():
preReceiveTag(ourCtx, oldCommitID, newCommitID, refFullName)
case git.SupportProcReceive && refFullName.IsFor():
preReceiveFor(ourCtx, oldCommitID, newCommitID, refFullName)
default:
ourCtx.AssertCanWriteCode()
}
if ctx.Written() {
return
}
}
ctx.PlainText(http.StatusOK, "ok")
}
func preReceiveBranch(ctx *preReceiveContext, oldCommitID, newCommitID string, refFullName git.RefName) {
branchName := refFullName.BranchName()
ctx.branchName = branchName
if !ctx.AssertCanWriteCode() {
return
}
repo := ctx.Repo.Repository
gitRepo := ctx.Repo.GitRepo
objectFormat := ctx.Repo.GetObjectFormat()
if branchName == repo.DefaultBranch && newCommitID == objectFormat.EmptyObjectID().String() {
log.Warn("Forbidden: Branch: %s is the default branch in %-v and cannot be deleted", branchName, repo)
ctx.JSON(http.StatusForbidden, private.Response{
UserMsg: fmt.Sprintf("branch %s is the default branch and cannot be deleted", branchName),
})
return
}
protectBranch, err := git_model.GetFirstMatchProtectedBranchRule(ctx, repo.ID, branchName)
if err != nil {
log.Error("Unable to get protected branch: %s in %-v Error: %v", branchName, repo, err)
ctx.JSON(http.StatusInternalServerError, private.Response{
Err: err.Error(),
})
return
}
// Allow pushes to non-protected branches
if protectBranch == nil {
return
}
protectBranch.Repo = repo
// This ref is a protected branch.
//
// First of all we need to enforce absolutely:
//
// 1. Detect and prevent deletion of the branch
if newCommitID == objectFormat.EmptyObjectID().String() {
log.Warn("Forbidden: Branch: %s in %-v is protected from deletion", branchName, repo)
ctx.JSON(http.StatusForbidden, private.Response{
UserMsg: fmt.Sprintf("branch %s is protected from deletion", branchName),
})
return
}
// 2. Disallow force pushes to protected branches
if oldCommitID != objectFormat.EmptyObjectID().String() {
output, _, err := git.NewCommand(ctx, "rev-list", "--max-count=1").AddDynamicArguments(oldCommitID, "^"+newCommitID).RunStdString(&git.RunOpts{Dir: repo.RepoPath(), Env: ctx.env})
if err != nil {
log.Error("Unable to detect force push between: %s and %s in %-v Error: %v", oldCommitID, newCommitID, repo, err)
ctx.JSON(http.StatusInternalServerError, private.Response{
Err: fmt.Sprintf("Fail to detect force push: %v", err),
})
return
} else if len(output) > 0 {
log.Warn("Forbidden: Branch: %s in %-v is protected from force push", branchName, repo)
ctx.JSON(http.StatusForbidden, private.Response{
UserMsg: fmt.Sprintf("branch %s is protected from force push", branchName),
})
return
}
}
// 3. Enforce require signed commits
if protectBranch.RequireSignedCommits {
err := verifyCommits(oldCommitID, newCommitID, gitRepo, ctx.env)
if err != nil {
if !isErrUnverifiedCommit(err) {
log.Error("Unable to check commits from %s to %s in %-v: %v", oldCommitID, newCommitID, repo, err)
ctx.JSON(http.StatusInternalServerError, private.Response{
Err: fmt.Sprintf("Unable to check commits from %s to %s: %v", oldCommitID, newCommitID, err),
})
return
}
unverifiedCommit := err.(*errUnverifiedCommit).sha
log.Warn("Forbidden: Branch: %s in %-v is protected from unverified commit %s", branchName, repo, unverifiedCommit)
ctx.JSON(http.StatusForbidden, private.Response{
UserMsg: fmt.Sprintf("branch %s is protected from unverified commit %s", branchName, unverifiedCommit),
})
return
}
}
// Now there are several tests which can be overridden:
//
// 4. Check protected file patterns - this is overridable from the UI
changedProtectedfiles := false
protectedFilePath := ""
globs := protectBranch.GetProtectedFilePatterns()
if len(globs) > 0 {
_, err := pull_service.CheckFileProtection(gitRepo, oldCommitID, newCommitID, globs, 1, ctx.env)
if err != nil {
if !models.IsErrFilePathProtected(err) {
log.Error("Unable to check file protection for commits from %s to %s in %-v: %v", oldCommitID, newCommitID, repo, err)
ctx.JSON(http.StatusInternalServerError, private.Response{
Err: fmt.Sprintf("Unable to check file protection for commits from %s to %s: %v", oldCommitID, newCommitID, err),
})
return
}
changedProtectedfiles = true
protectedFilePath = err.(models.ErrFilePathProtected).Path
}
}
// 5. Check if the doer is allowed to push
var canPush bool
if ctx.opts.DeployKeyID != 0 {
canPush = !changedProtectedfiles && protectBranch.CanPush && (!protectBranch.EnableWhitelist || protectBranch.WhitelistDeployKeys)
} else {
user, err := user_model.GetUserByID(ctx, ctx.opts.UserID)
if err != nil {
log.Error("Unable to GetUserByID for commits from %s to %s in %-v: %v", oldCommitID, newCommitID, repo, err)
ctx.JSON(http.StatusInternalServerError, private.Response{
Err: fmt.Sprintf("Unable to GetUserByID for commits from %s to %s: %v", oldCommitID, newCommitID, err),
})
return
}
canPush = !changedProtectedfiles && protectBranch.CanUserPush(ctx, user)
}
// 6. If we're not allowed to push directly
if !canPush {
// Is this is a merge from the UI/API?
if ctx.opts.PullRequestID == 0 {
// 6a. If we're not merging from the UI/API then there are two ways we got here:
//
// We are changing a protected file and we're not allowed to do that
if changedProtectedfiles {
log.Warn("Forbidden: Branch: %s in %-v is protected from changing file %s", branchName, repo, protectedFilePath)
ctx.JSON(http.StatusForbidden, private.Response{
UserMsg: fmt.Sprintf("branch %s is protected from changing file %s", branchName, protectedFilePath),
})
return
}
// Allow commits that only touch unprotected files
globs := protectBranch.GetUnprotectedFilePatterns()
if len(globs) > 0 {
unprotectedFilesOnly, err := pull_service.CheckUnprotectedFiles(gitRepo, oldCommitID, newCommitID, globs, ctx.env)
if err != nil {
log.Error("Unable to check file protection for commits from %s to %s in %-v: %v", oldCommitID, newCommitID, repo, err)
ctx.JSON(http.StatusInternalServerError, private.Response{
Err: fmt.Sprintf("Unable to check file protection for commits from %s to %s: %v", oldCommitID, newCommitID, err),
})
return
}
if unprotectedFilesOnly {
// Commit only touches unprotected files, this is allowed
return
}
}
// Or we're simply not able to push to this protected branch
log.Warn("Forbidden: User %d is not allowed to push to protected branch: %s in %-v", ctx.opts.UserID, branchName, repo)
ctx.JSON(http.StatusForbidden, private.Response{
UserMsg: fmt.Sprintf("Not allowed to push to protected branch %s", branchName),
})
return
}
// 6b. Merge (from UI or API)
// Get the PR, user and permissions for the user in the repository
pr, err := issues_model.GetPullRequestByID(ctx, ctx.opts.PullRequestID)
if err != nil {
log.Error("Unable to get PullRequest %d Error: %v", ctx.opts.PullRequestID, err)
ctx.JSON(http.StatusInternalServerError, private.Response{
Err: fmt.Sprintf("Unable to get PullRequest %d Error: %v", ctx.opts.PullRequestID, err),
})
return
}
// although we should have called `loadPusherAndPermission` before, here we call it explicitly again because we need to access ctx.user below
if !ctx.loadPusherAndPermission() {
// if error occurs, loadPusherAndPermission had written the error response
return
}
// Now check if the user is allowed to merge PRs for this repository
// Note: we can use ctx.perm and ctx.user directly as they will have been loaded above
allowedMerge, err := pull_service.IsUserAllowedToMerge(ctx, pr, ctx.userPerm, ctx.user)
if err != nil {
log.Error("Error calculating if allowed to merge: %v", err)
ctx.JSON(http.StatusInternalServerError, private.Response{
Err: fmt.Sprintf("Error calculating if allowed to merge: %v", err),
})
return
}
if !allowedMerge {
log.Warn("Forbidden: User %d is not allowed to push to protected branch: %s in %-v and is not allowed to merge pr #%d", ctx.opts.UserID, branchName, repo, pr.Index)
ctx.JSON(http.StatusForbidden, private.Response{
UserMsg: fmt.Sprintf("Not allowed to push to protected branch %s", branchName),
})
return
}
// It's not allowed t overwrite protected files. Unless if the user is an
// admin and the protected branch rule doesn't apply to admins.
if changedProtectedfiles && (!ctx.user.IsAdmin || protectBranch.ApplyToAdmins) {
log.Warn("Forbidden: Branch: %s in %-v is protected from changing file %s", branchName, repo, protectedFilePath)
ctx.JSON(http.StatusForbidden, private.Response{
UserMsg: fmt.Sprintf("branch %s is protected from changing file %s", branchName, protectedFilePath),
})
return
}
// Check all status checks and reviews are ok
if pb, err := pull_service.CheckPullBranchProtections(ctx, pr, true); err != nil {
if models.IsErrDisallowedToMerge(err) {
// Allow this if the rule doesn't apply to admins and the user is an admin.
if ctx.user.IsAdmin && !pb.ApplyToAdmins {
return
}
log.Warn("Forbidden: User %d is not allowed push to protected branch %s in %-v and pr #%d is not ready to be merged: %s", ctx.opts.UserID, branchName, repo, pr.Index, err.Error())
ctx.JSON(http.StatusForbidden, private.Response{
UserMsg: fmt.Sprintf("Not allowed to push to protected branch %s and pr #%d is not ready to be merged: %s", branchName, ctx.opts.PullRequestID, err.Error()),
})
return
}
log.Error("Unable to check if mergable: protected branch %s in %-v and pr #%d. Error: %v", ctx.opts.UserID, branchName, repo, pr.Index, err)
ctx.JSON(http.StatusInternalServerError, private.Response{
Err: fmt.Sprintf("Unable to get status of pull request %d. Error: %v", ctx.opts.PullRequestID, err),
})
return
}
}
}
func preReceiveTag(ctx *preReceiveContext, oldCommitID, newCommitID string, refFullName git.RefName) {
if !ctx.AssertCanWriteCode() {
return
}
tagName := refFullName.TagName()
if !ctx.gotProtectedTags {
var err error
ctx.protectedTags, err = git_model.GetProtectedTags(ctx, ctx.Repo.Repository.ID)
if err != nil {
log.Error("Unable to get protected tags for %-v Error: %v", ctx.Repo.Repository, err)
ctx.JSON(http.StatusInternalServerError, private.Response{
Err: err.Error(),
})
return
}
ctx.gotProtectedTags = true
}
isAllowed, err := git_model.IsUserAllowedToControlTag(ctx, ctx.protectedTags, tagName, ctx.opts.UserID)
if err != nil {
ctx.JSON(http.StatusInternalServerError, private.Response{
Err: err.Error(),
})
return
}
if !isAllowed {
log.Warn("Forbidden: Tag %s in %-v is protected", tagName, ctx.Repo.Repository)
ctx.JSON(http.StatusForbidden, private.Response{
UserMsg: fmt.Sprintf("Tag %s is protected", tagName),
})
return
}
}
func preReceiveFor(ctx *preReceiveContext, oldCommitID, newCommitID string, refFullName git.RefName) {
if !ctx.AssertCreatePullRequest() {
return
}
if ctx.Repo.Repository.IsEmpty {
ctx.JSON(http.StatusForbidden, private.Response{
UserMsg: "Can't create pull request for an empty repository.",
})
return
}
if ctx.opts.IsWiki {
ctx.JSON(http.StatusForbidden, private.Response{
UserMsg: "Pull requests are not supported on the wiki.",
})
return
}
baseBranchName := refFullName.ForBranchName()
baseBranchExist := false
if ctx.Repo.GitRepo.IsBranchExist(baseBranchName) {
baseBranchExist = true
}
if !baseBranchExist {
for p, v := range baseBranchName {
if v == '/' && ctx.Repo.GitRepo.IsBranchExist(baseBranchName[:p]) && p != len(baseBranchName)-1 {
baseBranchExist = true
break
}
}
}
if !baseBranchExist {
ctx.JSON(http.StatusForbidden, private.Response{
UserMsg: fmt.Sprintf("Unexpected ref: %s", refFullName),
})
return
}
}
func generateGitEnv(opts *private.HookOptions) (env []string) {
env = os.Environ()
if opts.GitAlternativeObjectDirectories != "" {
env = append(env,
private.GitAlternativeObjectDirectories+"="+opts.GitAlternativeObjectDirectories)
}
if opts.GitObjectDirectory != "" {
env = append(env,
private.GitObjectDirectory+"="+opts.GitObjectDirectory)
}
if opts.GitQuarantinePath != "" {
env = append(env,
private.GitQuarantinePath+"="+opts.GitQuarantinePath)
}
return env
}
// loadPusherAndPermission returns false if an error occurs, and it writes the error response
func (ctx *preReceiveContext) loadPusherAndPermission() bool {
if ctx.loadedPusher {
return true
}
if ctx.opts.UserID == user_model.ActionsUserID {
ctx.user = user_model.NewActionsUser()
ctx.userPerm.AccessMode = perm_model.AccessMode(ctx.opts.ActionPerm)
if err := ctx.Repo.Repository.LoadUnits(ctx); err != nil {
log.Error("Unable to get User id %d Error: %v", ctx.opts.UserID, err)
ctx.JSON(http.StatusInternalServerError, private.Response{
Err: fmt.Sprintf("Unable to get User id %d Error: %v", ctx.opts.UserID, err),
})
return false
}
ctx.userPerm.Units = ctx.Repo.Repository.Units
ctx.userPerm.UnitsMode = make(map[unit.Type]perm_model.AccessMode)
for _, u := range ctx.Repo.Repository.Units {
ctx.userPerm.UnitsMode[u.Type] = ctx.userPerm.AccessMode
}
} else {
user, err := user_model.GetUserByID(ctx, ctx.opts.UserID)
if err != nil {
log.Error("Unable to get User id %d Error: %v", ctx.opts.UserID, err)
ctx.JSON(http.StatusInternalServerError, private.Response{
Err: fmt.Sprintf("Unable to get User id %d Error: %v", ctx.opts.UserID, err),
})
return false
}
ctx.user = user
userPerm, err := access_model.GetUserRepoPermission(ctx, ctx.Repo.Repository, user)
if err != nil {
log.Error("Unable to get Repo permission of repo %s/%s of User %s: %v", ctx.Repo.Repository.OwnerName, ctx.Repo.Repository.Name, user.Name, err)
ctx.JSON(http.StatusInternalServerError, private.Response{
Err: fmt.Sprintf("Unable to get Repo permission of repo %s/%s of User %s: %v", ctx.Repo.Repository.OwnerName, ctx.Repo.Repository.Name, user.Name, err),
})
return false
}
ctx.userPerm = userPerm
}
if ctx.opts.DeployKeyID != 0 {
deployKey, err := asymkey_model.GetDeployKeyByID(ctx, ctx.opts.DeployKeyID)
if err != nil {
log.Error("Unable to get DeployKey id %d Error: %v", ctx.opts.DeployKeyID, err)
ctx.JSON(http.StatusInternalServerError, private.Response{
Err: fmt.Sprintf("Unable to get DeployKey id %d Error: %v", ctx.opts.DeployKeyID, err),
})
return false
}
ctx.deployKeyAccessMode = deployKey.Mode
}
ctx.loadedPusher = true
return true
}