fix(trtllm): load embedding URLs through the shared HTTP client by nnshah1 · Pull Request #14373 · ai-dynamo/dynamo

nnshah1 · 2026-09-05T02:41:00Z

Linear: OPS-8830

Summary

MultimodalRequestProcessor.load_tensor_from_path_or_url loads a .safetensors embedding from a URL in the request. On main, it opens its own aiohttp session for that, and its comment says that the path "applies no destination policy". The image and video paths of the same worker already use the shared HTTP client with a URL policy. This change moves the embedding download to that client:

timeout = max(
    _EMBEDDING_FETCH_MIN_TIMEOUT_S,  # 300.0
    self.max_file_size_bytes / _EMBEDDING_FETCH_MIN_RATE,  # 64 KiB/s
)
content = await fetch_bytes(
    path,
    timeout,
    policy=self._url_policy,
    max_bytes=self.max_file_size_bytes,
    read_timeout=_EMBEDDING_FETCH_READ_TIMEOUT_S,  # 300.0
)

fetch_bytes takes an optional read_timeout, which the aiohttp client passes as sock_read. The default, None, keeps every other caller as it was.

The shared client checks self._url_policy on the URL and on each redirect hop (base.py:161). When it connects, it filters blocked addresses again (BlocklistResolver, set at aiohttp_client.py:139). If an egress proxy applies to the URL, it refuses the fetch, unless DYN_MM_TRUST_EGRESS_PROXY=1 (aiohttp_client.py:94). It stops reading past --max-file-size-mb. The .safetensors-only rule stays.

Errors keep their type, so that each caller can report them correctly:

Error	Aggregated and prefill path (`process_openai_request`)	Encode worker
`UrlValidationError`: the policy rejects the URL or a redirect hop, or the file is over the cap	Raised. The bindings map a `ValueError` to `InvalidArgument` (`engine.rs:406`), so the client gets a 400.	Raised. The client gets a 400.
`HttpStatusError`: the host answers with an error status	Raised with that status, for example 404, as for image URLs.	Raised. The client gets a 400.
`HttpConfigurationError`: a proxy applies, and the deployment does not trust it	Raised. It is not a `ValueError` and has no status, so the client gets a 500.	Yielded as an error payload. The prefill worker raises `RuntimeError` for it (`encode_helper.py:169`), so the client gets a 500.

The encode worker yields the configuration error instead of raising it. The prefill worker reads any error from the encode worker as a ValueError (errors.rs:141). A raised error therefore reaches the client as a 400.

Changes in behavior:

A redirect is followed, because each hop is checked. Before, every redirect failed.
The download keeps the 300 s read timeout of main: a server that sends nothing for 300 s fails it. It also gets a budget for the whole request, max(300 s, size cap / 64 KiB/s). That is 300 s up to an 18.75 MiB cap, and 800 s at the default cap of 50 MiB. At the default cap, a 50 MiB file loads at a steady 70 KiB/s in 731.3 s. The connect timeout is DYN_HTTP_CONNECT_TIMEOUT, 5 s by default.
If DYN_HTTP_TIMEOUT is set when the worker starts, it replaces the budget, as it does for every fetch of the shared client (aiohttp_client.py:73). It also replaces a longer budget: a value of 30 s set for images limits this download to 30 s too. Before, it did not apply to this download. It does not change the read timeout.
A plain http:// URL needs DYN_MM_ALLOW_INTERNAL=1, as for images and video.
If an egress proxy applies, the download needs DYN_MM_TRUST_EGRESS_PROXY=1, as for images and video.
On the aggregated and prefill path, a file over the cap now reaches the client as a 400. An error status from the host reaches it as that status. Before, both were a 500.

Validation

The Python runs used the x86_64 trtllm-runtime-test image built at 06c2ff404e, the image user, --network none, and the tree on PYTHONPATH. _core came from the image. Between that build and main, the Python interface of the bindings (_core.pyi) changed only in one argument of register_model. This code does not call register_model. Each run printed the module paths of the code under test. The pytest runs set HF_HUB_OFFLINE=1 and TRANSFORMERS_OFFLINE=1. Without them, each processor in a test asks the Hugging Face hub for unused. With no network, the hub client retries for a long time. The first run did 15 tests in about 8 minutes.

Run	Result
`trtllm/tests/test_trtllm_multimodal_processor.py`, `--gpus all`	`main`: 27 passed. This branch: 44 passed. No skips.
`common/tests/http`, `common/tests/multimodal` and the module above, `--gpus all`, the image built at `6e99032266`	`caf9db0c82`: 428 passed. This branch: 441 passed. Both skip the same 2 tests, because vLLM is not installed.
The new tests against the sources before this change	13 of 15 fail. The other 2 are a control and the `.safetensors` guard.
The budget test against the fixed 300 s of `1138413edb`	The 19 MiB and 50 MiB cases fail.
Eight mutants, one for each part of the change. Five remove the policy, the cap, or one of the three error clauses. Three change the budget: `min` for `max`, half the floor rate, and a 30 s floor.	Each mutant fails 1 to 10 of the new tests.
`mypy` 1.18.2 over `components/src/dynamo`, as in CI, with the stubs of the image and `--cache-dir=/dev/null`	`main` and this branch: no issues in 879 source files. Without that flag, `mypy` crashed on both trees while it wrote its cache.

The probes for errors, the proxy, and DNS ran on 1138413edb. The timing probes ran on the budget commit, which changes only the timeout. The stall and 70 KiB/s rows ran again on 1e8a7af2a0, in the image built at 6e99032266.

Probe, through the embedding loader	`main`	This branch
A loopback URL, with a policy that blocks private addresses	Loaded. The server got 1 request.	`UrlValidationError`. The server got no request.
50 MiB at a steady 150 KiB/s, with the default cap	Loaded in 341.3 s.	Loaded in 341.3 s. The budget is 800 s.
50 MiB at a steady 70 KiB/s, with the default cap	Not run.	Loaded in 731.3 s.
A server that stops after 64 KiB, with the default cap	Cut off at 300.1 s, the read timeout.	Cut off at 300.0 s, the read timeout. Without it (`caf9db0c82`), 800.8 s.
1 MiB at a steady 64 KiB/s, with `DYN_HTTP_TIMEOUT=5`	Loaded in 15.9 s. The variable did not apply.	Timed out at 5.1 s. Without the variable, loaded in 15.9 s.
`HTTPS_PROXY` set to a loopback proxy	The proxy got `CONNECT 8.8.8.8:443`.	`HttpConfigurationError`. The proxy got nothing. With `DYN_MM_TRUST_EGRESS_PROXY=1`, the proxy got the `CONNECT`.
A host name that resolves to a public address for the check and to the test server for the connection	No check.	Refused at connect ("resolves only to blocked IPs"). The server got no request. With `DYN_MM_ALLOW_INTERNAL=1`, loaded.
The host answers 404, aggregated path	`None`, then a 500 from the handler.	`HttpStatusError` with status 404.

The tests and probes stop at the Python boundary. The client statuses above come from the code of map_python_exception (engine.rs:381), check_response_error (errors.rs:141), and the frontend (error.rs:61). No run used a frontend with workers.

pre-commit run --all-files passes all 35 hooks.

🤖 Generated with Claude Code

Summary by CodeRabbit

Bug Fixes
- Improved security for remote embedding downloads by blocking requests to restricted network addresses.
- Disabled redirects and rejected redirect responses during remote embedding retrieval.

load_tensor_from_path_or_url fetched a request-supplied URL with no address validation. Resolve the host and reject non-public targets (private/loopback/link-local/reserved/multicast/unspecified) before fetching, and disable redirect-following so a public URL cannot redirect into an internal or metadata address. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Signed-off-by: nnshah1 <neelays@nvidia.com>

coderabbitai · 2026-09-05T02:48:38Z

Walkthrough

Remote embedding downloads now validate HTTP(S) URLs against non-public addresses, disable automatic redirects, and reject redirect responses before downloading.

Changes

Remote embedding security

Layer / File(s)	Summary
Public URL and download validation `components/src/dynamo/trtllm/multimodal_processor.py`	`_assert_public_url` rejects unsupported schemes and hostnames that resolve to non-public addresses. Remote embedding downloads validate the URL, disable redirects, and reject redirect responses.

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

Merge Risk: 🟠 High · up to 047e0

Remote embedding downloads are safer because redirects and many internal addresses are blocked, but attackers can still bypass the destination policy through shared-address targets, configured proxies, or DNS rebinding. These SSRF paths should be closed before merge.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description is detailed and includes the Linear issue reference, but it says redirects are followed after validating each hop. The raw summary and objectives say redirects are disabled and rejecte…	Confirm the redirect behavior against the implementation. If redirects are disabled and rejected, update the description to say so and remove the claims about following and validating redirect hops. If redirects are followed, update the obj…

✅ Passed checks (4 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 4 functions across 1 files.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly describes moving embedding downloads to the shared HTTP client, a real part of the changeset, though it does not highlight the SSRF protections emphasized in the objectives.

Full details: Description check

Explanation

The description is detailed and includes the Linear issue reference, but it says redirects are followed after validating each hop. The raw summary and objectives say redirects are disabled and rejected, so the description conflicts with the stated behavior of the change.

Resolution

Confirm the redirect behavior against the implementation. If redirects are disabled and rejected, update the description to say so and remove the claims about following and validating redirect hops. If redirects are followed, update the objectives and raw summary to match. Consider adding a specific reviewer-start section from the template as well.

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Actionable comments posted: 4

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Inline comments:
In `@components/src/dynamo/trtllm/multimodal_processor.py`:
- Around line 109-116: Update the address validation condition around addr to
reject every non-global address by checking not addr.is_global, replacing the
individual private, loopback, reserved, multicast, and related checks while
preserving the existing rejection behavior.
- Line 161: Update the httpx.Client construction in the embedding download path
to set trust_env=False, ensuring environment-selected proxies cannot bypass the
existing SSRF destination policy while preserving the current timeout and
redirect settings.
- Line 162: Update the request flow around _assert_public_url and client.stream
so the connection is bound to the already validated DNS address, preventing
hostname rebinding while retaining the original hostname for the HTTP Host
header and TLS SNI. Reuse the existing client/transport abstractions where
possible and preserve the current GET path behavior.
- Around line 97-98: Update _assert_public_url to reject resolved addresses that
are not global, including shared address space, and prevent DNS rebinding by
binding the HTTPX connection to the validated address while preserving Host,
SNI, and TLS verification or revalidating at transport time. Configure
httpx.Client with environment proxy trust disabled unless explicitly validated.
Move ipaddress and socket into the sorted module-level standard-library imports.

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components/src/dynamo/trtllm/multimodal_processor.py

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The merge conflicted in load_tensor_from_path_or_url. The branch changed an httpx fetch there. When main removed httpx (#14563), it replaced that fetch with aiohttp. The resolution takes the whole function from main. The _assert_public_url helper merged without a conflict and is not called now. The next commit removes it and moves the URL download to the shared HTTP client. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Signed-off-by: Dmitry Tokarev <dtokarev@nvidia.com>

load_tensor_from_path_or_url opened its own aiohttp session for an embedding URL, so self._url_policy did not apply to that download. It now calls fetch_bytes with policy=self._url_policy and max_bytes=self.max_file_size_bytes, as the video path in this file does. The shared client checks the policy on the URL and on each redirect hop. When it connects, it filters blocked addresses again. If an egress proxy applies to the URL, it refuses the fetch, unless DYN_MM_TRUST_EGRESS_PROXY=1. The .safetensors rule and the size cap stay. The _assert_public_url helper, which nothing calls after the merge of main, is removed. Errors keep their type. A rejected URL now leaves process_openai_request as UrlValidationError, and an error status from the host as HttpStatusError. Before, both became a None return, which the handler reports as a 500. A file over the size cap also raises UrlValidationError. A proxy configuration fault (HttpConfigurationError) stays a server error. The encode worker yields it as an error payload, because the prefill worker turns an exception from the encode worker into a 400. Other changes in behavior: - A redirect is followed, because each hop is checked. - The 300 s timeout is one budget for the whole download, not one per read. A 50 MiB file needs about 171 KiB/s. The connect timeout is DYN_HTTP_CONNECT_TIMEOUT (5 s by default). - An http:// URL needs DYN_MM_ALLOW_INTERNAL=1, as for images and video. Of the 11 new tests, 9 fail on the code before this change. The other two, a control and the .safetensors guard, pass on both. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Signed-off-by: Dmitry Tokarev <dtokarev@nvidia.com>

The embedding download had one 300 s budget for the whole request. A file at the default 50 MiB cap then needed about 171 KiB/s. Main loaded such a file at 150 KiB/s in 341.3 s, because it timed each read instead. The budget is now max(300 s, size cap / 64 KiB/s). That is 300 s up to an 18.75 MiB cap, and 800 s at the default cap. At the default cap, a 50 MiB file now loads at 150 KiB/s in 341.3 s, and at 70 KiB/s in 731.4 s. A server that stops sending is cut off at the budget: after 300.3 s with a 10 MiB cap, and after 800.9 s with the default cap. Main cut it off after 300 s without data, whatever the cap. If DYN_HTTP_TIMEOUT is set when the worker starts, it replaces this budget, as it does for every fetch of the shared client. test_embedding_fetch_budget_scales_with_the_size_cap pins the budget at caps of 1, 18, 19 and 50 MiB. The 19 and 50 MiB cases fail with the fixed 300 s. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Signed-off-by: Dmitry Tokarev <dtokarev@nvidia.com>

devin-ai-integration · 2026-10-02T20:27:25Z

✅ Dynamo PR CI passed — run 37053487343 (attempt 1) on `caf9db0c82`

Gate checks: ✅ backend-status-check · ✅ deploy-status-check · ✅ dynamo-status-check

_{Posted automatically by Devin for run 37053487343. Updated on every full-CI run of this PR.}

peilii

Routing the embedding download through the shared client is the right fix: it gets the URL and per-hop policy, the connect-time blocklist resolver, proxy refusal, and the streaming size cap that images and video already had, and 53 lines of hand-rolled session code become one call. Checked the status table against the bindings: UrlValidationError is a ValueError (400), HttpStatusError carries status and goes through http_like_error_to_dynamo (so a 404 stays a 404), and HttpConfigurationError falls to Unknown (500); the encode-worker yield/raise split matches check_response_error. One comment inline on the timeout shape.

furionw

Thank you

On main, the embedding loader set sock_read=300, so a server that sent nothing for 300 s failed the download. The shared HTTP client sets only a whole-request budget. Since the move to that client, such a server held the download for the whole budget: 800 s at the default 50 MiB cap. fetch_bytes now takes an optional read_timeout, and the aiohttp client passes it as sock_read next to total. DYN_HTTP_TIMEOUT still replaces only total. The default, None, builds the same ClientTimeout as before. No other caller passes the argument, so no other caller changes. The embedding loader passes 300 s and keeps its budget of max(300 s, cap / 64 KiB/s). Through the loader, at the default cap, a server that stops after 64 KiB now fails after 300.0 s. Main failed it after 300.1 s, and the previous commit after 800.8 s. A 50 MiB file at a steady 70 KiB/s still loads, in 731.3 s. The new tests use a 1 s read timeout and a 4 s budget. Through the shared client and through the loader, a stalled server fails at the read timeout. A slow steady server completes within the budget. Another test pins that a fetch without read_timeout builds the same ClientTimeout as before. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Signed-off-by: Dmitry Tokarev <dtokarev@nvidia.com>

nnshah1 requested review from a team as code owners September 5, 2026 02:41

pull-request-size Bot added the size/M label Sep 5, 2026

github-actions Bot added fix backend::trtllm Relates to the trtllm backend multimodal labels Sep 5, 2026

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rmccorm4 mentioned this pull request Sep 27, 2026

spam #15291

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dmitry-tokarev-nv self-assigned this Oct 1, 2026

dmitry-tokarev-nv and others added 3 commits October 1, 2026 17:17

pull-request-size Bot added size/L and removed size/M labels Oct 2, 2026

dmitry-tokarev-nv changed the title ~~fix(trtllm): validate embedding URL against non-public addresses~~ fix(trtllm): nvbug/6544950 load embedding URLs through the shared HTTP client Oct 2, 2026

peilii approved these changes Oct 2, 2026

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Comment thread components/src/dynamo/trtllm/multimodal_processor.py

nv-yna approved these changes Oct 2, 2026

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nnshah1 changed the title ~~fix(trtllm): nvbug/6544950 load embedding URLs through the shared HTTP client~~ fix(trtllm): load embedding URLs through the shared HTTP client Oct 3, 2026

nnshah1 mentioned this pull request Oct 4, 2026

refactor(multimodal): read all client media through one validated, bounded entrypoint #15118

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furionw approved these changes Oct 5, 2026

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dmitry-tokarev-nv requested review from a team as code owners October 6, 2026 19:35

pull-request-size Bot added size/XL and removed size/L labels Oct 6, 2026

dmitry-tokarev-nv enabled auto-merge (squash) October 6, 2026 21:50

dmitry-tokarev-nv merged commit 1e1a9e4 into main Oct 6, 2026
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dmitry-tokarev-nv deleted the neelays/harden-embedding-url-validation branch October 6, 2026 23:35

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fix(trtllm): load embedding URLs through the shared HTTP client - #14373

fix(trtllm): load embedding URLs through the shared HTTP client#14373
dmitry-tokarev-nv merged 5 commits into
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neelays/harden-embedding-url-validation

nnshah1 commented Sep 5, 2026 •

edited by dmitry-tokarev-nv

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nnshah1 commented Sep 5, 2026 •

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