Re: [PATCH v3 4/9] bugreport: add config values from whitelist

[Emily Shaffer <emilyshaffer@google.com>]

On Mon, Oct 28, 2019 at 03:14:35PM +0100, Johannes Schindelin wrote:
> Hi Emily,

Sorry for the delay in replying. This work has been backburnered and
this mail slipped through the cracks.

> 
> On Thu, 24 Oct 2019, Emily Shaffer wrote:
> 
> > Teach bugreport to gather the values of config options which are present
> > in 'git-bugreport-config-whitelist'.
> >
> > Many config options are sensitive, and many Git add-ons use config
> > options which git-core does not know about; it is better only to gather
> > config options which we know to be safe, rather than excluding options
> > which we know to be unsafe.
> 
> Should we still have the `// bugreport-exclude` comments, then?

They were optional (useless) before too. I can remove them if you want;
I suppose I like the idea of having precedent if someone wants to build
their own internal version with opt-out configs rather than opt-in. I
can remove them if we want; it doesn't matter very much to me either
way.

> 
> >
> > Reading the whitelist into memory and sorting it saves us time -
> > since git_config_bugreport() is called for every option the user has
> > configured, limiting the file IO to one open/read/close and performing
> > option lookup in sublinear time is a useful optimization.
> 
> Maybe we even want a hashmap? That would reduce the time complexity even
> further.

Sure, we can do it. I'll make that change.

> 
> > diff --git a/bugreport.c b/bugreport.c
> > index ada54fe583..afa4836ab1 100644
> > --- a/bugreport.c
> > +++ b/bugreport.c
> > @@ -1,10 +1,24 @@
> >  #include "cache.h"
> >
> >  #include "bugreport.h"
> > +#include "config.h"
> > +#include "exec-cmd.h"
> >  #include "help.h"
> >  #include "run-command.h"
> >  #include "version.h"
> >
> > +/**
> > + * A sorted list of config options which we will add to the bugreport. Managed
> > + * by 'gather_whitelist(...)'.
> > + */
> > +struct string_list whitelist = STRING_LIST_INIT_DUP;
> > +struct strbuf configs_and_values = STRBUF_INIT;
> > +
> > +// git version --build-options
> > +// uname -a
> > +// curl-config --version
> > +// ldd --version
> > +// echo $SHELL
> 
> These comments probably want to move to a single, C style comment, and
> they probably want to be introduced together with `get_system_info()`.

Yeah, it's stale and has been removed now. It was less commentary and
more todo list for author ;)

> 
> I also have to admit that I might have missed where `$SHELL` was added
> to the output...

I skipped it entirely since bugreport doesn't run in shell anymore. If
you have advice for gathering the user's shell I can try to add it; is
there such a difference between, say, a Debian user using bash and a
Debian user using zsh? I suppose it could be useful if someone has an
issue with GIT_PS1, or with autocompletion. I'll look into gathering it.

> 
> >  void get_system_info(struct strbuf *sys_info)
> >  {
> >  	struct child_process cp = CHILD_PROCESS_INIT;
> > @@ -53,3 +67,39 @@ void get_system_info(struct strbuf *sys_info)
> >  	argv_array_clear(&cp.args);
> >  	strbuf_reset(&std_out);
> >  }
> > +
> > +void gather_whitelist(struct strbuf *path)
> > +{
> > +	struct strbuf tmp = STRBUF_INIT;
> > +	strbuf_read_file(&tmp, path->buf, 0);
> > +	string_list_init(&whitelist, 1);
> > +	string_list_split(&whitelist, tmp.buf, '\n', -1);
> > +	string_list_sort(&whitelist);
> > +}
> > +
> > +int git_config_bugreport(const char *var, const char *value, void *cb)
> > +{
> > +	if (string_list_has_string(&whitelist, var)) {
> > +		strbuf_addf(&configs_and_values,
> > +			    "%s : %s\n",
> > +			    var, value);
> 
> A quite useful piece of information would be the config source. Not sure
> whether we can do that outside of `config.c` yet...

It's possible. I can add it.

> 
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +void get_whitelisted_config(struct strbuf *config_info)
> > +{
> > +	struct strbuf path = STRBUF_INIT;
> > +
> > +	strbuf_addstr(&path, git_exec_path());
> > +	strbuf_addstr(&path, "/git-bugreport-config-whitelist");
> 
> Hmm. I would have expected this patch to come directly after the patch
> 2/9 that generates that white-list, and I would also have expected that
> to be pre-sorted, and compiled in.
> 
> Do you want users to _edit_ the file in the exec path? In general, that
> path will be write-protected, though. A better alternative would
> probably be to compile in a hard-coded list, and to allow including more
> values e.g. by offering command-line options to specify config setting
> patterns. But if we allow patterns, we might actually want to have those
> exclusions to prevent sensitive data from being included.

Hm, interesting. Do we have precedent for compiling in a header
generated during the build process? I think I saw one when I was adding
this script - I'll take a look.

> 
> > +
> > +	gather_whitelist(&path);
> > +	strbuf_init(&configs_and_values, whitelist.nr);
> > +
> > +	git_config(git_config_bugreport, NULL);
> > +
> > +	strbuf_reset(config_info);
> > +	strbuf_addbuf(config_info, &configs_and_values);
> > +}
> > diff --git a/bugreport.h b/bugreport.h
> > index ba216acf3f..7413e7e1be 100644
> > --- a/bugreport.h
> > +++ b/bugreport.h
> > @@ -5,3 +5,10 @@
> >   * The previous contents of sys_info will be discarded.
> >   */
> >  void get_system_info(struct strbuf *sys_info);
> > +
> > +/**
> 
> I also frequently use JavaDoc-style `/**`, but I am not sure that this
> is actually desired in Git's source code ;-)
> 
> > + * Adds the values of the config items listed in
> > + * 'git-bugreport-config-whitelist' to config_info. The previous contents of
> > + * config_info will be discarded.
> > + */
> > +void get_whitelisted_config(struct strbuf *sys_info);
> > diff --git a/builtin/bugreport.c b/builtin/bugreport.c
> > index 7232d31be7..70fe0d2b85 100644
> > --- a/builtin/bugreport.c
> > +++ b/builtin/bugreport.c
> > @@ -56,6 +56,10 @@ int cmd_bugreport(int argc, const char **argv, const char *prefix)
> >  	get_system_info(&buffer);
> >  	strbuf_write(&buffer, report);
> >
> > +	add_header(report, "Whitelisted Config");
> 
> Quite honestly, I would like to avoid the term "whitelist" for good. How
> about "Selected config settings" instead?

Will do - thanks for the callout.

> 
> Thanks,
> Dscho
> 
> > +	get_whitelisted_config(&buffer);
> > +	strbuf_write(&buffer, report);
> > +
> >  	fclose(report);
> >
> >  	launch_editor(report_path.buf, NULL, NULL);
> > --
> > 2.24.0.rc0.303.g954a862665-goog
> >
> >