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Introduce fips build tag (#14495)
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Unlike fips_140_3, fips will be a (FIPS) version-agnostic build tag.
The listener support will remain in 140-3 only, but the IsFIPS() check
should apply regardless of FIPS version.

We add two FIPS-only build files which validate the constraints of FIPS
builds here: fips must be specified with either fips_140_2 or fips_140_3
build tags, and fips and cgo must also be specified together.
Additionally, using only a version-specific FIPS build tag without the
version-agnostic FIPS tag should be a failure.

Signed-off-by: Alexander Scheel <[email protected]>
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cipherboy authored Mar 15, 2022
1 parent f4292d8 commit a915c9d
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2 changes: 1 addition & 1 deletion helper/constants/fips.go
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@@ -1,4 +1,4 @@
//go:build !fips_140_3
//go:build !fips

package constants

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38 changes: 38 additions & 0 deletions helper/constants/fips_build_check.go
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@@ -0,0 +1,38 @@
//go:build (!fips && (fips_140_2 || fips_140_3)) || (fips && !fips_140_2 && !fips_140_3) || (fips_140_2 && fips_140_3)

package constants

import "C"

// This function is the equivalent of an external (CGo) function definition,
// without implementation in any imported or built library. This results in
// a linker err if the above build constraints are satisfied:
//
// /home/cipherboy/GitHub/cipherboy/vault-enterprise/helper/constants/fips_build_check.go:10: undefined reference to `github.com/hashicorp/vault/helper/constants.VaultFIPSBuildRequiresVersionAgnosticTagAndOneVersionTag'
//
// This indicates that a build error has occurred due to mismatched tags.
//
// In particular, we use this to enforce the following restrictions on build
// tags:
//
// - If a versioned fips_140_* tag is specified, the unversioned tag must
// also be.
// - If the unversioned tag is specified, a versioned tag must be.
// - Both versioned flags cannot be specified at the same time.
//
// In the unlikely event that a FFI implementation for this function exists
// in the future, it should be renamed to a new function which does not
// exist.
//
// This approach was chosen above the other implementation in fips_cgo_check.go
// because this version does not break static analysis tools: most tools do not
// cross the CGo boundary and thus do not know that the below function is
// missing an implementation. However, in the other file, the function call is
// not marked as CGo (in part large because the lack of a cgo build tag
// prohibits us from using the same technique) and thus it must be a Go
// declaration, that is missing.
func VaultFIPSBuildRequiresVersionAgnosticTagAndOneVersionTag()

func init() {
VaultFIPSBuildRequiresVersionAgnosticTagAndOneVersionTag()
}
18 changes: 18 additions & 0 deletions helper/constants/fips_cgo_check.go
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@@ -0,0 +1,18 @@
//go:build (fips || fips_140_2 || fips_140_3) && !cgo

package constants

func init() {
// See note in fips_build_check.go.
//
// This function call is missing a declaration, causing the build to
// fail on improper tags (fips specified but cgo not specified). This
// ensures Vault fails to build if a FIPS build is requested but CGo
// support is not enabled.
//
// Note that this could confuse static analysis tools as this function
// should not ever be defined. If this function is defined in the future,
// the below reference should be renamed to a new name that is not
// defined to ensure we get a build failure.
VaultFIPSBuildTagMustEnableCGo()
}

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