mcp: reject relative paths in tool handlers by Shrey327 · Pull Request #3694 · knative/func

Shrey327 · 2026-05-10T14:24:39Z

Description

Adds validatePath() to the MCP server that rejects non-absolute path arguments before shelling out to the func CLI. Since cmd.Dir is never set in the executor, relative paths silently resolved against the MCP server's working directory instead of the user's project turning a wrong directory failure into a silent misbehavior. This change turns that into an actionable error, matching the guidance already documented in instructions.md.All existing tests updated to use t.TempDir() and a TestValidatePath unit test added.

linux-foundation-easycla · 2026-05-10T14:24:47Z

The committers listed above are authorized under a signed CLA.

✅ login: Shrey327 / name: Shrey327 (766fda2, f45998b)

knative-prow · 2026-05-10T14:24:49Z

Welcome @Shrey327! It looks like this is your first PR to knative/func 🎉

knative-prow · 2026-05-10T14:24:50Z

Hi @Shrey327. Thanks for your PR.

I'm waiting for a knative member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work.

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lkingland

Thanks for the PR. Just two small suggestions.

codecov · 2026-05-11T11:46:21Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 57.10%. Comparing base (584c11e) to head (e777f09).
⚠️ Report is 166 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3694      +/-   ##
==========================================
+ Coverage   57.03%   57.10%   +0.07%     
==========================================
  Files         182      182              
  Lines       21376    21421      +45     
==========================================
+ Hits        12191    12233      +42     
- Misses       7953     7955       +2     
- Partials     1232     1233       +1

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e2e-config-ci	`28.10% <0.00%> (-0.06%)`	⬇️
integration	`17.15% <0.00%> (-0.03%)`	⬇️
unit macos-14	`45.19% <100.00%> (+0.10%)`	⬆️
unit macos-latest	`45.19% <100.00%> (+0.10%)`	⬆️
unit ubuntu-24.04-arm	`45.45% <100.00%> (+0.11%)`	⬆️
unit ubuntu-latest	`46.14% <100.00%> (+0.10%)`	⬆️
unit windows-latest	`45.24% <100.00%> (+0.10%)`	⬆️

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gauron99 · 2026-05-11T15:37:59Z

/ok-to-test

knative-prow · 2026-05-16T21:58:49Z

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lkingland, Shrey327

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lkingland · 2026-10-28T05:09:50Z

Thanks @Shrey327.

Both my points were addressed. However, since this was submitted, several new tools taking a path have landed on main (config_ci, config_git, invoke, run, run_stop).

Please rebase, extend validatePath() to those new tools as well, and we can merge this.

One suggestion to keep this from regressing again: rather than per-tool tests alone, a single test that iterates over all registered tools with a path input and asserts a relative path is rejected would catch any future tool that forgets the check. Feel free to include that more advanced approach in this PR, or a separate one, at your discretion.

…ed tests Signed-off-by: Shrey327 <shreyansh.pathak273@gmail.com>

Signed-off-by: Shrey327 <shreyansh.pathak273@gmail.com>

Tools that landed after knative#3694 (config_ci, config_git, invoke, run, run_stop) now reject relative paths before they shell out. describe and logs are included so a registry-wide test can walk every tool whose schema has a path input and fail if a future tool skips the check. Success-path tests that still passed "." now use an absolute directory. Signed-off-by: Luke Kingland <luke@lukekingland.com>

woke flags the previous name as insensitive. Signed-off-by: Luke Kingland <luke@lukekingland.com>

filepath.IsAbs rejects POSIX literals such as /home/user/myfunc on Windows, so the new validatePath checks failed the Windows unit job. Tests now use testAbsPath, which joins os.TempDir. Signed-off-by: Luke Kingland <luke@lukekingland.com>

lkingland · 2026-10-29T08:24:03Z

Rebased onto main, extended validatePath() to the newer path-taking tools (config_ci, config_git, invoke, run, run_stop, plus describe/logs), and added a registry-wide relative-path test. Thanks @Shrey327!

/lgtm

Shrey327 · 2026-10-29T12:57:35Z

Thanks @lkingland for rebasing and extending the checks to the new tools! I’ll be quicker on follow-ups next time.

knative-prow Bot requested review from dsimansk and jrangelramos May 10, 2026 14:24

knative-prow Bot added the size/L 🤖 PR changes 100-499 lines, ignoring generated files. label May 10, 2026

knative-prow Bot added the needs-ok-to-test 🤖 Needs an org member to approve testing label May 10, 2026

lkingland reviewed May 11, 2026

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Comment thread pkg/mcp/tools.go Resolved

Comment thread pkg/mcp/tools_test.go Resolved

lkingland mentioned this pull request May 11, 2026

feat(mcp): add secret and ConfigMap support to config_envs_add tool #3685

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Shrey327 requested a review from lkingland May 11, 2026 13:16

knative-prow Bot added ok-to-test 🤖 Non-member PR verified by an org member that is safe to test. and removed needs-ok-to-test 🤖 Needs an org member to approve testing labels May 11, 2026

lkingland approved these changes May 16, 2026

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knative-prow Bot assigned lkingland May 16, 2026

knative-prow Bot added the lgtm 🤖 PR is ready to be merged. label May 16, 2026

knative-prow Bot added the approved 🤖 PR has been approved by an approver from all required OWNERS files. label May 16, 2026

knative-prow-robot added the needs-rebase Cannot be merged due to conflicts with HEAD. label May 16, 2026

Shrey327 force-pushed the mcp-validate-absolute-path branch from 766fda2 to 7995a39 Compare May 17, 2026 05:04

knative-prow Bot removed the lgtm 🤖 PR is ready to be merged. label May 17, 2026

knative-prow-robot removed the needs-rebase Cannot be merged due to conflicts with HEAD. label May 17, 2026

lkingland added the status/new label Jun 2, 2026

lkingland moved this to New in Functions Traige Jun 2, 2026

lkingland added this to Functions Traige Jun 2, 2026

knative-prow-robot added the needs-rebase Cannot be merged due to conflicts with HEAD. label Jun 12, 2026

lkingland removed the status/new label Jul 29, 2026

lkingland mentioned this pull request Oct 29, 2026

[pre-check] knative/func#3694 rebased (mcp: reject relative paths) lkingland/func#257

Closed

Shrey327 and others added 6 commits October 29, 2026 17:20

feat: enforce absolute path validation in MCP tool handlers and updat…

cc7a1f3

…ed tests Signed-off-by: Shrey327 <shreyansh.pathak273@gmail.com>

fix: added handler-level tests and updated the error message

e46160b

Signed-off-by: Shrey327 <shreyansh.pathak273@gmail.com>

use t.TempDir() in config_envs_add tests

858883e

Signed-off-by: Shrey327 <shreyansh.pathak273@gmail.com>

mcp: rename schema placeholder helper

38c0b86

woke flags the previous name as insensitive. Signed-off-by: Luke Kingland <luke@lukekingland.com>

lkingland force-pushed the mcp-validate-absolute-path branch from e777f09 to 7eb46f8 Compare October 29, 2026 08:23

knative-prow-robot removed the needs-rebase Cannot be merged due to conflicts with HEAD. label Oct 29, 2026

knative-prow Bot added the lgtm 🤖 PR is ready to be merged. label Oct 29, 2026

knative-prow Bot merged commit 4fa6c16 into knative:main Oct 29, 2026
45 checks passed

github-project-automation Bot moved this from New to Done in Functions Traige Oct 29, 2026

lkingland mentioned this pull request Oct 29, 2026

mcp: add describe tool for Function inspection #3736

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mcp: reject relative paths in tool handlers - #3694

mcp: reject relative paths in tool handlers#3694
knative-prow[bot] merged 6 commits into
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Shrey327:mcp-validate-absolute-path

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