Security - Git argument injection via untrusted Kptfile ref enables file overwrite#4604
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tgzsolt wants to merge 1 commit into
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Security - Git argument injection via untrusted Kptfile ref enables file overwrite#4604tgzsolt wants to merge 1 commit into
tgzsolt wants to merge 1 commit into
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Pull request overview
This PR addresses a Git argument-injection vulnerability where attacker-controlled refs/URIs could be interpreted as git command-line options (e.g. git show --output=...), potentially enabling arbitrary file overwrite during package fetch/update flows.
Changes:
- Introduces centralized validation (
validateGitArg) to reject git refs/commits/URIs that begin with-, preventing option injection. - Refactors
GitUpstreamRepofrom a concrete struct into an interface backed by a broker implementation, adding deterministic ordering forHeads()/Tags(). - Updates fetch/update/parse call sites and adds a regression test ensuring option-like refs are rejected.
Reviewed changes
Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.
Show a summary per file
| File | Description |
|---|---|
| pkg/lib/util/parse/parse.go | Simplifies branch listing by using gur.Heads() directly. |
| pkg/lib/util/fetch/fetch.go | Updates cached repo plumbing to store GitUpstreamRepo interface values; adjusts ref resolution API usage. |
| pkg/lib/update/update.go | Updates cached upstream repo cache type to the new GitUpstreamRepo interface. |
| pkg/lib/update/update_test.go | Updates upstream repo URI access to gur.Uri() to match refactor. |
| internal/gitutil/gitutil.go | Implements injection guard, refactors upstream repo into interface + broker, validates attacker-controlled inputs before invoking git. |
| internal/gitutil/gitutil_test.go | Updates tests for new APIs and adds option-injection regression coverage. |
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| Uri() string | ||
| Heads() []string | ||
| Tags() []string |
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| func (gur *gitUpstreamRepoBroker) Tags() []string { | ||
| tags := make([]string, 0, len(gur.commitByTag)) | ||
| for tag := range gur.commitByTag { | ||
| tags = append(tags, tag) | ||
| } | ||
| sort.Strings(tags) | ||
| return tags | ||
| } |
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| // and caches all refs and the commit they reference. Not that this doesn't | ||
| // download any objects, only refs. |
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| assert.EqualValues(t, tc.expectedHeads, gur.Heads()) | ||
| assert.EqualValues(t, tc.expectedTags, gur.Tags()) |
Contributor
|
Does this overlap with #4598 ? |
13 tasks
…es file overwrite
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Description
When kpt fetches a package, it recursively fetches sub-packages whose Kptfiles declare an
upstreamblock (internal/util/get/get.go fetchPackages). The sub-package Kptfile is attacker-controlled content from the remote repository. Itsupstream.git.reffield flows unmodified intoGitUpstreamRepo.cacheRepo()as arequiredRefsentry. In the default branch of the switch (when the ref is neither a known branch/tag nor a full SHA), the refsis passed directly togitRunner.Run(ctx, "show", s)at line 441 with no-{-}separator and no validation that it does not begin with{-}. The git process runs withcmd.Dirset to{~}/.kpt/repos/<sha>(lines 105, 385/393). A ref value such as-{-}output=../../../.bashrcis interpreted bygit showas the{-}{-}output=<file>option, causing git to write the HEAD commit display (whose commit message and diff are fully attacker-controlled in the attacker's second repository) to{-}{~}/.bashrc. A similar lack of-separator affectsgit reset --hard <commit>at internal/util/fetch/fetch.go:216 andgit remote add origin <uri>at gitutil.go:386Motivaton
Remove security vulnerability