executor, privilege: require CONFIG privilege for is.cluster_config (#26071)

[ti-srebot]

cherry-pick #26071 to release-5.1
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# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/26150

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git push git@github.com:ti-srebot/tidb.git pr/26150:release-5.1-13bad8579ff0

---

What problem does this PR solve?

Issue Number: close #26062

Problem Summary:

The cluster_config table should require the CONFIG privilege. This is consistent with the behavior change in #25379 which requires CONFIG for SHOW CONFIG.

It makes sense to cherry pick to 5.1, but not 5.0; because the behavior in 5.0 was not established yet, and SHOW CONFIG still requires no privileges.

What is changed and how it works?

What's Changed:

Reading from the table information_schema.cluster_config now requires the CONFIG privilege.

Related changes

• Need to cherry-pick to the release branch

Check List

Tests

• Unit test

Side effects

• Breaking backward compatibility (yes, but for security)

Release note

• Reading from the table information_schema.cluster_config now requires the CONFIG privilege.

[ti-srebot]

/run-all-tests

[ti-srebot]

@morgo you're already a collaborator in bot's repo.

[morgo]

/run-unit-test

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• djshow832
• tiancaiamao

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[AilinKid]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 834f070

[ti-chi-bot]

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