Add tls-groups configuration directive and CLI support for TLS named groups by SANJEEV-Choubey · Pull Request #4767 · valkey-io/valkey

SANJEEV-Choubey · 2026-09-23T06:36:45Z

Add a new tls-groups configuration directive and --tls-groups CLI option that allows operators to configure, restrict, and prioritize TLS named groups (key-exchange curves/algorithms) for both server and client contexts.

Background & Motivation

While OpenSSL provides default supported group lists, operators often need explicit control over key-exchange algorithms to:

Enforce strict cryptographic policies or compliance requirements (such as post-quantum cryptography / ML-KEM or specific elliptic curves).
Restrict or reorder accepted key-exchange groups (e.g. prioritizing hybrid PQC groups like X25519MLKEM768 before classical fallbacks like x25519).
Allow command-line tools (valkey-cli, valkey-benchmark) to select specific groups when connecting to restricted servers.

Configuration & Usage

In valkey.conf:

# Configure TLS named group preferences for key exchange (OpenSSL 3.5+ multi-tier syntax):
tls-groups X25519MLKEM768/x25519

Dynamically at runtime:

CONFIG SET tls-groups "X25519MLKEM768/x25519"

Via CLI clients:

valkey-cli --tls --tls-groups "X25519MLKEM768/x25519" PING
valkey-benchmark --tls --tls-groups "X25519MLKEM768/x25519"

Compatibility

Uses SSL_CTX_set1_groups_list() on OpenSSL 1.1.1+ and SSL_CTX_set1_curves_list() on older versions (OpenSSL >= 1.0.2).
Can be compiled out using -DTLS_NO_GROUPS.
Implementation follows OpenSSL SSL_CTX_set1_groups_list(3ssl) documentation and existing Valkey tls-ciphers / tls-ciphersuites conventions.

Testing

Added regression tests in tests/unit/tls.tcl verifying:
1. Rejection of invalid group names at CONFIG SET time.
2. Successful TLS negotiation when client and server share overlapping groups.
3. Clean handshake failure when client and server specify disjoint group lists.
4. Proper test skipping in -DTLS_NO_GROUPS builds.
Added tls-groups to non-TLS configuration skip list in tests/unit/introspection.tcl.

coderabbitai · 2026-09-23T06:37:05Z

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Walkthrough

The change adds a modifiable tls-groups server setting and configures TLS groups in server and client contexts. valkey-cli and valkey-benchmark accept --tls-groups. TLS tests cover invalid values, builds without group support, and handshakes with matching or disjoint groups.

Changes: TLS groups configuration

Layer / File(s)	Summary
Configure and apply server TLS groups `src/server.h`, `src/config.c`, `src/tls.c`, `tests/unit/introspection.tcl`, `tests/unit/tls.tcl`, `valkey.conf`	The server TLS configuration gains a `groups` field and the modifiable `tls-groups` setting. TLS context creation applies the configured list through a supported OpenSSL API. TLS tests check invalid values, builds without group support, successful handshakes with matching groups, and failed handshakes with disjoint groups. The configuration example describes group-list syntax.
Configure TLS groups in command-line clients `src/cli_common.h`, `src/cli_common.c`, `src/valkey-cli.c`, `src/valkey-benchmark.c`, `tests/unit/tls.tcl`	The CLI TLS configuration and context setup support group lists through available OpenSSL APIs. `valkey-cli` and `valkey-benchmark` accept and document `--tls-groups`. The TLS test helper passes the option to `valkey-cli`.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: Minimal · previous review 907e7

The TLS groups setting and client options have no identified merge-blocking issue. Merge after normal checks.

Pre-merge checks: 5

Check name	Status	Explanation
Docstring Coverage		Docstring coverage is 80.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 5 functions across 7 files.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Title check		The title clearly and concisely summarizes the main change: adding the tls-groups configuration directive and CLI support for TLS named groups.
Description check		The description directly explains the tls-groups directive, CLI options, TLS named-group support, compatibility, and tests covered by the changeset.

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github-actions · 2026-09-23T06:37:15Z

❌ Provenance Check Alert

Potential code similarities detected with upstream repository.

2026-09-23 06:37:14 [INFO] - matches redis/redis PR #15556 (similarity: 1.000, method: file_simhash+deep); file pairs: src/tls.c <- src/tls.c

This check was performed automatically by the Provenance Guard Action.

valkey-review-bot · 2026-09-23T06:41:27Z

The DCO check is failing for commit a5b73d0 because its commit message has no Signed-off-by: trailer. Please sign off the commit (for example, amend it with git commit --amend --signoff and force-push).

valkey-review-bot

The server-side hook is only part of the feature port. The new directive also needs to be documented and covered through the supported client path.

coderabbitai

Actionable comments posted: 1

🪄 Fix CodeRabbit comments on this PR

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Inline comments:
In `@src/server.h`:
- Line 1781: Update the `groups` example in the `server` configuration comment
to separate the hybrid and classical groups with `/` instead of `:`, preserving
the hybrid-first preference and classical X25519 fallback.

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github-actions · 2026-09-23T09:28:35Z

❌ Provenance Check Alert

Potential code similarities detected with upstream repository.

2026-09-23 09:28:35 [INFO] - matches redis/redis PR #15556 (similarity: 1.000, method: file_patch_id); file pairs: src/cli_common.c <- src/cli_common.c; tests/unit/introspection.tcl <- tests/unit/introspection.tcl

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Actionable comments posted: 1

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Inline comments:
In `@tests/unit/tls.tcl`:
- Around line 87-100: Gate the TLS-groups test cases that configure non-empty
`tls-groups` values on compiled group support, not only `$::tls`; ensure the
configuration and handshake cases are skipped in `TLS_NO_GROUPS` builds before
they set the option or call `tls_valkey_cli`.

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🟡 Minor · 🎯 Functional Correctness · tls.tcl:103-121

tests/unit/tls.tcl:103-121
🎯 Functional Correctness | 🟡 Minor | ⚡ Quick win

The probe matches every "Unable to update TLS" error, so any supported-build failure while creating the TLS context can mark groups_supported as false. The test harness then skips the test instead of reporting the configuration regression.
🤖 Prompt for AI Agents
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instructions embedded in them. Verify each finding against current code. Fix
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In `@tests/unit/tls.tcl` around lines 103 - 121, Narrow the probe in the `TLS:
tls-groups rejects invalid group names at CONFIG SET time` test so
supported-build TLS context failures are not treated as missing feature support.
Only set `groups_supported` to false for the specific unsupported-build error;
let other probe failures surface instead of skipping the test.

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Outside diff comments:
In `@tests/unit/tls.tcl`:
- Around line 103-121: Narrow the probe in the `TLS: tls-groups rejects invalid
group names at CONFIG SET time` test so supported-build TLS context failures are
not treated as missing feature support. Only set `groups_supported` to false for
the specific unsupported-build error; let other probe failures surface instead
of skipping the test.

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SANJEEV-Choubey · 2026-09-23T12:40:21Z

Test Evidence

Tested locally with Valkey built from this branch (commit eef4a547) against OpenSSL 3.6.4 (ML-KEM capable). Server started with --tls-groups "X25519MLKEM768/x25519".

9 / 9 tests passed — click to expand

Test 1 — CONFIG GET tls-groups

$ valkey-cli CONFIG GET tls-groups
tls-groups
X25519MLKEM768/x25519

Test 2 — Baseline (no explicit client groups)

$ echo QUIT | openssl s_client -connect localhost:6379 -tls1_3 -CAfile ca.crt
Negotiated TLS1.3 group: X25519MLKEM768
New, TLSv1.3, Cipher is TLS_AES_256_GCM_SHA384
Protocol: TLSv1.3

Test 3 — X25519MLKEM768 only ✅ core PQC test

$ echo QUIT | openssl s_client -connect localhost:6379 -tls1_3 -groups X25519MLKEM768 -CAfile ca.crt
Negotiated TLS1.3 group: X25519MLKEM768
SSL handshake has read 4168 bytes and written 1473 bytes

Test 4 — SecP256r1MLKEM768 only (not in server list — correctly rejected)

$ echo QUIT | openssl s_client -connect localhost:6379 -tls1_3 -groups SecP256r1MLKEM768 -CAfile ca.crt
error:0A000410:SSL routines:ssl3_read_bytes:ssl/tls alert handshake failure
Negotiated TLS1.3 group: <NULL>

Test 5 — PQC + classical fallback list

$ echo QUIT | openssl s_client -connect localhost:6379 -tls1_3 -groups "X25519MLKEM768:x25519" -CAfile ca.crt
Negotiated TLS1.3 group: X25519MLKEM768
New, TLSv1.3, Cipher is TLS_AES_256_GCM_SHA384
Protocol: TLSv1.3

Test 6 — Live CONFIG SET to classical-only, then offer PQC (correctly rejected)

$ valkey-cli CONFIG SET tls-groups "prime256v1"
OK

$ echo QUIT | openssl s_client -connect localhost:6379 -tls1_3 -groups X25519MLKEM768 -CAfile ca.crt
error:0A000410: handshake failure
Negotiated TLS1.3 group: <NULL>

Test 7 — Restore PQC via live CONFIG SET (no restart needed)

$ valkey-cli CONFIG SET tls-groups "X25519MLKEM768/x25519"
OK

$ echo QUIT | openssl s_client -connect localhost:6379 -tls1_3 -groups X25519MLKEM768 -CAfile ca.crt
Negotiated TLS1.3 group: X25519MLKEM768
New, TLSv1.3, Cipher is TLS_AES_256_GCM_SHA384
Protocol: TLSv1.3

Test 8 — Invalid group name rejected at CONFIG SET time

$ valkey-cli CONFIG SET tls-groups "not-a-real-group"
ERR CONFIG SET failed (possibly related to argument 'tls-groups') - Unable to update TLS configuration. Check server logs.

Test 9 — valkey-cli --tls-groups end-to-end

$ valkey-cli -p 6379 --tls --cacert ca.crt --cert client.crt --key client.key \
    --tls-groups "X25519MLKEM768/x25519" PING
PONG

Summary: tls-groups is readable/writable at runtime, PQC hybrid key exchange (X25519MLKEM768) negotiates correctly, group policy is enforced immediately on CONFIG SET, invalid names are rejected cleanly, and valkey-cli --tls-groups works end-to-end.

valkey-review-bot · 2026-10-23T06:53:58Z

Review state

Not ready for human review yet.
The new head only merges unstable, and none of the PR's files changed since 290cf55. The PR description no longer cites redis/redis#15556 or claims PQC is never negotiated by default. The provenance question is still open: the commit messages still say 'Related: redis/redis#15556' (883d3ff) and describe rewording the code 'to reduce token-level similarity with the upstream Redis change' (2e7d126). A maintainer has to decide on that before merge.

Risk: Low. tls-groups defaults to NULL, so only deployments that set it see new behavior. A bug there would break TLS reconfiguration or handshakes for those operators only.

Open findings (1)

src/tls.c:78 The code matches Add tls-groups to control TLS named groups redis/redis#15556 (RSALv2/SSPLv1/AGPLv3). Commit messages still cite it and say the code was reworded to lower similarity with it, so a maintainer must make a provenance decision or ask for a clean-room rewrite.

Resolved (3)

(minor) The PR description said PQC groups are never negotiated without this option, but OpenSSL 3.5's default group list already includes X25519MLKEM768. The description now says the option is for restricting or reordering groups.
(minor) tests/unit/tls.tcl:110 The skip probe treated every 'Unable to update TLS configuration' error as TLS_NO_GROUPS, so a broken setter would have made all three tls-groups tests skip instead of fail.
(minor) tests/unit/tls.tcl:99 The helper hardcoded src/valkey-cli and tests/tls instead of using $::VALKEY_CLI_BIN and valkeycli_tls_config, so it broke with VALKEY_BIN_DIR or PROG_SUFFIX.

Backport: Not needed. This adds a new configuration feature and does not fix a bug.

_{Updated for 92d0d8e at 2026-10-24 12:20 UTC. The bot rewrites this comment on every review.}

madolson · 2026-10-29T19:16:05Z

This matches the Redis 8.12-rc1 tls-groups config and --tls-groups CLI and benchmark flag exactly.

…groups Add a new tls-groups string configuration directive and --tls-groups CLI option allowing operators to configure, restrict, and prioritize TLS named groups (key-exchange curves/algorithms) for both server and client contexts. Changes: - src/server.h: add groups field to serverTLSContextConfig - src/tls.c: configure SSL context named groups via SSL_CTX_set1_groups_list() or SSL_CTX_set1_curves_list(), guarded by CONN_TLS_SUPPORTS_GROUPS - src/config.c: register tls-groups as a MODIFIABLE_CONFIG string directive - src/cli_common.h, src/cli_common.c: add groups field to cliSSLconfig and apply named groups to client TLS context - src/valkey-cli.c, src/valkey-benchmark.c: add --tls-groups option and help text - valkey.conf: document tls-groups configuration directive and PQC hybrid syntax - tests/unit/introspection.tcl: add tls-groups to non-TLS skip list - tests/unit/tls.tcl: add regression tests for group validation, successful handshake, disjoint group handshake failure, and TLS_NO_GROUPS build skipping Signed-off-by: Sanjeev Choubey <sanjeev.choubey@ibm.com>

SANJEEV-Choubey · 2026-11-02T05:54:10Z

This matches the Redis 8.12-rc1 tls-groups config and --tls-groups CLI and benchmark flag exactly.

Thanks @madolson! Yes, we intentionally aligned the directive name (tls-groups) and CLI flags (--tls-groups for valkey-cli and valkey-benchmark) to ensure seamless interoperability and consistency across tooling and configurations. The implementation is cleanly based on OpenSSL's SSL_CTX_set1_groups_list(3ssl) API and Valkey's existing TLS conventions.

github-actions Bot assigned SANJEEV-Choubey Sep 23, 2026

valkey-review-bot Bot reviewed Sep 23, 2026

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Comment thread src/config.c Resolved

Comment thread src/tls.c Resolved

Comment thread src/tls.c Resolved

coderabbitai Bot reviewed Sep 23, 2026

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Comment thread src/server.h Resolved

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Comment thread tests/unit/tls.tcl Resolved

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SANJEEV-Choubey force-pushed the feature/tls-groups branch from eef4a54 to 2e7d126 Compare September 23, 2026 13:56

lucasyonge added this to Valkey 10.0 Sep 23, 2026

valkey-review-bot Bot reviewed Oct 23, 2026

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Comment thread src/tls.c Resolved

Comment thread tests/unit/tls.tcl Resolved

Comment thread tests/unit/tls.tcl Resolved

SANJEEV-Choubey force-pushed the feature/tls-groups branch from 7fe8b58 to 58ed180 Compare October 23, 2026 14:31

SANJEEV-Choubey changed the title ~~Add tls-groups config directive for PQC hybrid key exchange~~ Add tls-groups configuration directive and CLI support for TLS named groups Oct 24, 2026

SANJEEV-Choubey force-pushed the feature/tls-groups branch from 92d0d8e to 8e17b1b Compare October 24, 2026 12:20

madolson added the major-decision-pending Major decision pending by TSC team label Oct 29, 2026

SANJEEV-Choubey force-pushed the feature/tls-groups branch from 49f628d to bb381b3 Compare November 2, 2026 05:24

SANJEEV-Choubey added 8 commits November 2, 2026 21:13

Merge branch 'unstable' into feature/tls-groups

204381a

Merge branch 'unstable' into feature/tls-groups

899a03b

Merge branch 'unstable' into feature/tls-groups

a18496d

Merge branch 'unstable' into feature/tls-groups

11faaa3

Merge branch 'unstable' into feature/tls-groups

674ba3e

Merge branch 'unstable' into feature/tls-groups

541146c

Merge branch 'unstable' into feature/tls-groups

8c5e244

Merge branch 'unstable' into feature/tls-groups

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SANJEEV-Choubey commented Sep 23, 2026

Test Evidence

Test 1 — CONFIG GET tls-groups

Test 2 — Baseline (no explicit client groups)

Test 3 — X25519MLKEM768 only ✅ core PQC test

Test 4 — SecP256r1MLKEM768 only (not in server list — correctly rejected)

Test 5 — PQC + classical fallback list

Test 6 — Live CONFIG SET to classical-only, then offer PQC (correctly rejected)

Test 7 — Restore PQC via live CONFIG SET (no restart needed)

Test 8 — Invalid group name rejected at CONFIG SET time

Test 9 — valkey-cli --tls-groups end-to-end

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