Hacking NSS

From Libreswan
Revision as of 21:48, 26 October 2021 by Andrew Cagney (talk | contribs) (updates)
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Using NSS from Pluto

use lsw_nss_error*() to report errors

It includes both the error symbol name and the error message (the former is really useful when reading the code^D^D^D^D documentation when tracking down why the error was returned).

Debugging NSS

Linking libreswan against a custom NSS build

Building and Installing a Custom NSS RPMs

Below are notes on building the latest Fedora RPM on the build machine.

Build Custom NSS RPM

... using fedpkg local and the build machine

on the build machine:

$ ./kvm sh build

pick somewhere to build (here I'm using /pool aka KVM_POOLDIR, but /testing and /root should all work), then get fedpkg and use that to download:

# cd /pool
# dnf install -y fedpkg
# fedpkg clone --anonymous nss
# cd nss

In theory, all that's left is install the dependencies and kick off the build. Unfortunately, not so easy:

  1. disable tests (so --without tests isn't needed)
  2. fix %[expr] which seems to be new
  3. tone down optimization
  4. screw around with compiler flags
  5. ignore xmlto's exit code

here's a diff:

diff --git a/nss.spec b/nss.spec
index e373644..230f794 100644
--- a/nss.spec
+++ b/nss.spec
@@ -9,3 +9,3 @@
 # release number between nss and nspr are different.
-%global nspr_release %[%baserelease+2]
+%global nspr_release 3
 # only need to update this as we added new
@@ -19,3 +19,3 @@
 
-%bcond_without tests
+%bcond_with tests
 %bcond_with dbm
@@ -347,3 +347,3 @@ done
 for m in nspr-config.xml; do
-  xmlto man ${m}
+  xmlto man ${m} || true
 done
@@ -370,7 +370,7 @@ export NSS_FORCE_FIPS=1
 # Enable compiler optimizations and disable debugging code
-export BUILD_OPT=1
+export BUILD_OPT=0
 
-# Uncomment to disable optimizations
-#RPM_OPT_FLAGS=`echo $RPM_OPT_FLAGS | sed -e 's/-O2/-O0/g'`
-#export RPM_OPT_FLAGS
+# Tone down optimization to make debugging more meaningful
+RPM_OPT_FLAGS=`echo $RPM_OPT_FLAGS | sed -e 's/-O2/-O1/g'`
+export RPM_OPT_FLAGS
 
@@ -386,3 +386,3 @@ export XCFLAGS="$XCFLAGS -Wno-error=maybe-uninitialized"
 # Similarly, but for gcc-11
-export XCFLAGS="$XCFLAGS -Wno-array-parameter"
+# export XCFLAGS="$XCFLAGS -Wno-array-parameter"
 
@@ -528,3 +528,3 @@ done
 for m in %{configFiles}  %{dbfiles}; do
-  xmlto man ${m}.xml
+  xmlto man ${m}.xml || true
 done
@@ -552,3 +552,3 @@ export FREEBL_NO_DEPEND=1
 
-export BUILD_OPT=1
+export BUILD_OPT=0
 export NSS_DISABLE_PPC_GHASH=1

continuing, pull in the dependencies and build (something better?):

# dnf builddep nss
# fedpkg local --without tests:

(or fedpkg prep --without tests; fedpkg compile --short-circuit --without tests).

... using fedpkg mock and the Fedora host

Hmm, something goes here!

fedpkg mock-config
fedpkg mockbuild

Making the Custom NSS RPs Stick

Distribute Custom NSS RPMs

For legal reasons, tar up both the .rpm and .srpm files into a single archive and make that available - it forces whoever is using the RPMs to also download the sources.