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gerrit.openbmc.org / openbmc / bmcweb / 0260d9d6b252d5fef81a51d4797e27a6893827f4
commit0260d9d6b252d5fef81a51d4797e27a6893827f4[log] [tgz]
authorEd Tanous <ed@tanous.net>Sun Feb 07 19:31:07 2021 +0000
committerEd Tanous <ed@tanous.net>Fri Feb 19 20:40:24 2021 +0000
treefbaaae47d3a1ad2997f26b52a6760e1dac5f2eef
parent71f52d96b51bda2a2f00374237f368e980396692 [diff]
Fix compile issue on DISABLE_XSS_PREVENTION

Fixes #178

Every few months, this option breaks because of some combination of
compiler options.  I'm hoping that this is a more permenant fix, and
will keep it working forever.

Functionally, this commit changes a couple things.
1.  It fixes the regression that snuck into this option, by making the
req variable optional using the c++17 [[maybe_unused]] syntax.
2. It promotes the BMCWEB_INSECURE_DISABLE_XSS_PREVENTION into the
config.h file, and a constexpr variable rather than a #define.  This has
the benefit that both the code paths in question will compiled
regardless of whether or not they're used, thus ensuring they stay
buildable forever.  The optimization path will still delete the code
later, but we won't have so many one-off build options breaking.  We
should move all the other feature driven #ifdefs to this pattern in the
future.
3. As a mechnaical change to #2, this adds a config.h.in, which delcares
the various variables as their respective constexpr types.  This allows
the constants to be used in a cleaner way.

As an aside, at some point, DISABLE_XSS_PREVENTION should really move to
a non-persistent runtime option rather than a compile time option.  Too
many people get hung up on having to recompile their BMC, and moving it
to runtime under admin credentials is no more a security risk.

As another aside, we should move all the other #ifdef style options to
this pattern.  It seems like it would help with keeping all options
buildable, and is definitely more modern than #ifdefs for features,
especially if they don't require #include changes or linker changes.

Tested:
enabled meson option insecure-disable-xss, and verified code builds and
works again.

Change-Id: Id03faa17cffdbabaf4e5b0d46b24bb58b7f44669
Signed-off-by: Ed Tanous <edtanous@google.com>
6 files changed
tree: fbaaae47d3a1ad2997f26b52a6760e1dac5f2eef
  1. .github/
  2. http/
  3. include/
  4. redfish-core/
  5. scripts/
  6. src/
  7. static/
  8. subprojects/
  9. .clang-format
  10. .clang-ignore
  11. .clang-tidy
  12. .dockerignore
  13. .gitignore
  14. .shellcheck
  15. bmcweb.service.in
  16. bmcweb.socket
  17. build_x86.sh
  18. build_x86_docker.sh
  19. COMMON_ERRORS.md
  20. config.h.in
  21. DEVELOPING.md
  22. Dockerfile
  23. Dockerfile.base
  24. LICENCE
  25. MAINTAINERS
  26. meson.build
  27. meson_options.txt
  28. OEM_SCHEMAS.md
  29. OWNERS
  30. pam-webserver
  31. README.md
  32. Redfish.md
README.md

OpenBMC webserver

This component attempts to be a "do everything" embedded webserver for openbmc.

Capabilities

At this time, the webserver implements a few interfaces:

  • Authentication middleware that supports cookie and token based authentication, as well as CSRF prevention backed by linux PAM authentication credentials.
  • An (incomplete) attempt at replicating phosphor-dbus-rest interfaces in C++. Right now, a few of the endpoint definitions work as expected, but there is still a lot of work to be done. The portions of the interface that are functional are designed to work correctly for phosphor-webui, but may not yet be complete.
  • Replication of the rest-dbus backend interfaces to allow bmc debug to logged in users.
  • An initial attempt at a read-only redfish interface. Currently the redfish interface targets ServiceRoot, SessionService, AccountService, Roles, and ManagersService. Some functionality here has been shimmed to make development possible. For example, there exists only a single user role.
  • SSL key generation at runtime. See the configuration section for details.
  • Static file hosting. Currently, static files are hosted from the fixed location at /usr/share/www. This is intended to allow loose coupling with yocto projects, and allow overriding static files at build time.
  • Dbus-monitor over websocket. A generic endpoint that allows UIs to open a websocket and register for notification of events to avoid polling in single page applications. (this interface may be modified in the future due to security concerns.

Configuration

BMCWeb is configured by setting -D flags that correspond to options in bmcweb/meson_options.txt and then compiling. For example, meson <builddir> -Dkvm=disabled ... followed by ninja in build directory. The option names become C++ preprocessor symbols that control which code is compiled into the program.

Compile bmcweb with default options:

meson builddir
ninja -C builddir

Compile bmcweb with yocto defaults:

meson builddir -Dbuildtype=minsize -Db_lto=true -Dtests=disabled
ninja -C buildir

If any of the dependencies are not found on the host system during configuration, meson automatically gets them via its wrap dependencies mentioned in bmcweb/subprojects.

Enable/Disable meson wrap feature

meson builddir -Dwrap_mode=nofallback
ninja -C builddir

Generate test coverage report:

meson builddir -Db_coverage=true -Dtests=enabled
ninja coverage -C builddir test

When BMCWeb starts running, it reads persistent configuration data (such as UUID and session data) from a local file. If this is not usable, it generates a new configuration.

When BMCWeb SSL support is enabled and a usable certificate is not found, it will generate a self-sign a certificate before launching the server. The keys are generated by the secp384r1 algorithm. The certificate

  • is issued by C=US, O=OpenBMC, CN=testhost,
  • is valid for 10 years,
  • has a random serial number, and
  • is signed using the SHA-256 algorithm.