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Ensure builtin hashlib implementations honor usedforsecurity=True when _hashlib is in FIPS mode #127298

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xnox opened this issue Nov 26, 2024 · 3 comments
Open

Ensure builtin hashlib implementations honor usedforsecurity=True when _hashlib is in FIPS mode #127298

xnox opened this issue Nov 26, 2024 · 3 comments
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extension-modules C modules in the Modules dir topic-SSL type-feature A feature request or enhancement type-security A security issue

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@xnox
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xnox commented Nov 26, 2024 •
edited by bedevere-app bot
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Feature or enhancement

Proposal:

When OpenSSL is not available, or is not in FIPS mode:

  • no change of behaviour

When OpenSSL is available and is in FIPS mode:

  • ensure that only OpenSSL implementations are used when usedforsecurity=True
  • ensure that all built-in (fallback) implementations require usedforsecurity=False

This addresses all needs of FIPS users that expect approved only cryptography from hashlib by default.
It satisfies Python guarantees of always available algorithms, as built-in fallbacks remain accessible with an explicit consent from the user that unapproved (an FIPS/ISO term) implementation is acceptable to the user.

In FIPS mode it means that all users can gain access to blake2/shake/md5, even when these algorithms are either blocked or unavailable from the runtime OpenSSL in FIPS mode. As long as usedforsecurity=False is used.

This also removes need to recompile or configure python somehow different for a non-fips & fips build, specifically one can safely compile python with all with-builtin-hashlib-hashes enabled.

Diagrams and full details of the current state of hashlib; and FIPS user desires are documented in this issue is opened as a reference for potential implementations to resolve all needs and desires listed there.

This issue will be used as a reference for potential implementations.

Has this already been discussed elsewhere?

I have already discussed this feature proposal on Discourse

Links to previous discussion of this feature:

Discuss:

(note there are some off-topic messages there)

Linked PRs
@xnox xnox added the type-feature A feature request or enhancement label Nov 26, 2024
@picnixz
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picnixz commented Nov 26, 2024

Didn't we have a similar feature request for that? cc @encukou (I can't find it on mobile but I remember you participated in a similar discussion)

@xnox
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xnox commented Nov 26, 2024

Didn't we have a similar feature request for that? cc @encukou (I can't find it on mobile but I remember you participated in a similar discussion)

I previously opened #118224 but this issue is related; but is a different approach / design / end-goal. I don't know if you meant that one or something else.

xnox added a commit to xnox/cpython that referenced this issue Nov 26, 2024
@xnox
pythongh-127298: When in FIPS mode ensure builtin hashes check for us…
8e5d01f 
…edforsecurity=False

When _hashlib/OpenSSL is available, and OpenSSL is in FIPS mode,
ensure that builtin (fallback) hash implementations are wrapped with a
check for usedforsecurity=False. It is likely that buitin
implementations are FIPS unapproved (either algorithm disallowed; or
the implementation not certified by NIST).

This enables strict approved-only compliance when usedforsecurity=True
on FIPS systems only.

And yet it also enables fallback access with usedforsecurity=False for
any missing (historical, disallowed or missing certified
implementation) algorithms (i.e. blake2, md5, shake/sha3) depending on
the runtime configuration of OpenSSL.
@bedevere-app bedevere-app bot mentioned this issue Nov 26, 2024
Open
xnox added a commit to xnox/cpython that referenced this issue Nov 26, 2024
@xnox
pythongh-127298: When in FIPS mode ensure builtin hashes check for us…
82e72d9 
…edforsecurity=False

When _hashlib/OpenSSL is available, and OpenSSL is in FIPS mode,
ensure that builtin (fallback) hash implementations are wrapped with a
check for usedforsecurity=False. It is likely that buitin
implementations are FIPS unapproved (either algorithm disallowed; or
the implementation not certified by NIST).

This enables strict approved-only compliance when usedforsecurity=True
on FIPS systems only.

And yet it also enables fallback access with usedforsecurity=False for
any missing (historical, disallowed or missing certified
implementation) algorithms (i.e. blake2, md5, shake/sha3) depending on
the runtime configuration of OpenSSL.
xnox added a commit to xnox/cpython that referenced this issue Nov 26, 2024
@xnox
pythongh-127298: When in FIPS mode ensure builtin hashes check for us…
9d6fd91 
…edforsecurity=False

When _hashlib/OpenSSL is available, and OpenSSL is in FIPS mode,
ensure that builtin (fallback) hash implementations are wrapped with a
check for usedforsecurity=False. It is likely that buitin
implementations are FIPS unapproved (either algorithm disallowed; or
the implementation not certified by NIST).

This enables strict approved-only compliance when usedforsecurity=True
on FIPS systems only.

And yet it also enables fallback access with usedforsecurity=False for
any missing (historical, disallowed or missing certified
implementation) algorithms (i.e. blake2, md5, shake/sha3) depending on
the runtime configuration of OpenSSL.
xnox added a commit to xnox/cpython that referenced this issue Nov 26, 2024
@xnox
pythongh-127298: When in FIPS mode ensure builtin hashes check for us…
756cd93 
…edforsecurity=False

When _hashlib/OpenSSL is available, and OpenSSL is in FIPS mode,
ensure that builtin (fallback) hash implementations are wrapped with a
check for usedforsecurity=False. It is likely that buitin
implementations are FIPS unapproved (either algorithm disallowed; or
the implementation not certified by NIST).

This enables strict approved-only compliance when usedforsecurity=True
on FIPS systems only.

And yet it also enables fallback access with usedforsecurity=False for
any missing (historical, disallowed or missing certified
implementation) algorithms (i.e. blake2, md5, shake/sha3) depending on
the runtime configuration of OpenSSL.
xnox added a commit to xnox/cpython that referenced this issue Nov 26, 2024
@xnox
pythongh-127298: When in FIPS mode ensure builtin hashes check for us…
db5c976 
…edforsecurity=False

When _hashlib/OpenSSL is available, and OpenSSL is in FIPS mode,
ensure that builtin (fallback) hash implementations are wrapped with a
check for usedforsecurity=False. It is likely that buitin
implementations are FIPS unapproved (either algorithm disallowed; or
the implementation not certified by NIST).

This enables strict approved-only compliance when usedforsecurity=True
on FIPS systems only.

And yet it also enables fallback access with usedforsecurity=False for
any missing (historical, disallowed or missing certified
implementation) algorithms (i.e. blake2, md5, shake/sha3) depending on
the runtime configuration of OpenSSL.
xnox added a commit to xnox/cpython that referenced this issue Nov 26, 2024
@xnox
pythongh-127298: When in FIPS mode ensure builtin hashes check for us…
ad0fab8 
…edforsecurity=False

When _hashlib/OpenSSL is available, and OpenSSL is in FIPS mode,
ensure that builtin (fallback) hash implementations are wrapped with a
check for usedforsecurity=False. It is likely that buitin
implementations are FIPS unapproved (either algorithm disallowed; or
the implementation not certified by NIST).

This enables strict approved-only compliance when usedforsecurity=True
on FIPS systems only.

And yet it also enables fallback access with usedforsecurity=False for
any missing (historical, disallowed or missing certified
implementation) algorithms (i.e. blake2, md5, shake/sha3) depending on
the runtime configuration of OpenSSL.
xnox added a commit to xnox/cpython that referenced this issue Nov 26, 2024
@xnox
pythongh-127298: When in FIPS mode ensure builtin hashes check for us…
28d8035 
…edforsecurity=False

When _hashlib/OpenSSL is available, and OpenSSL is in FIPS mode,
ensure that builtin (fallback) hash implementations are wrapped with a
check for usedforsecurity=False. It is likely that buitin
implementations are FIPS unapproved (either algorithm disallowed; or
the implementation not certified by NIST).

This enables strict approved-only compliance when usedforsecurity=True
on FIPS systems only.

And yet it also enables fallback access with usedforsecurity=False for
any missing (historical, disallowed or missing certified
implementation) algorithms (i.e. blake2, md5, shake/sha3) depending on
the runtime configuration of OpenSSL.
@picnixz picnixz added type-security A security issue extension-modules C modules in the Modules dir topic-SSL labels Nov 27, 2024
@picnixz
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picnixz commented Nov 27, 2024

Yes, I think that's the issue I had in mind. Good to know it's not a duplicate.

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