[PATCH V3 02/10] capabilities: intuitive names for cap gain status

[Serge E. Hallyn]

On Fri, Sep 01, 2017 at 06:18:43AM -0400, Richard Guy Briggs wrote:
> On 2017-08-28 07:08, Richard Guy Briggs wrote:
> > On 2017-08-28 05:19, Richard Guy Briggs wrote:
> > > On 2017-08-24 12:06, Kees Cook wrote:
> > > > On Thu, Aug 24, 2017 at 9:37 AM, Serge E. Hallyn <serge at hallyn.com> wrote:
> > > > > Quoting Richard Guy Briggs (rgb at redhat.com):
> > > > >> On 2017-08-24 11:03, Serge E. Hallyn wrote:
> > > > >> > Quoting Richard Guy Briggs (rgb at redhat.com):
> > > > >> > > Introduce macros cap_gained, cap_grew, cap_full to make the use of the
> > > > >> > > negation of is_subset() easier to read and analyse.
> > > > >> > >
> > > > >> > > Signed-off-by: Richard Guy Briggs <rgb at redhat.com>
> > > > >> > > ---
> > > > >> > >  security/commoncap.c |   16 ++++++++++------
> > > > >> > >  1 files changed, 10 insertions(+), 6 deletions(-)
> > > > >> > >
> > > > >> > > diff --git a/security/commoncap.c b/security/commoncap.c
> > > > >> > > index b7fbf77..6f05ec0 100644
> > > > >> > > --- a/security/commoncap.c
> > > > >> > > +++ b/security/commoncap.c
> > > > >> > > @@ -513,6 +513,12 @@ void handle_privileged_root(struct linux_binprm *bprm, bool has_cap, bool *effec
> > > > >> > >           *effective = true;
> > > > >> > >  }
> > > > >> > >
> > > > >> >
> > > > >> > It's subjective and so might be just me, but I think I'd find it easier
> > > > >> > to read if it was cap_gained(source, target, field) and cap_grew(cred, source, target)
> > > > >>
> > > > >> In more than one place, I wanted to put the parameter that I was trying
> > > > >> to read aloud closest to the function name to make reading it flow
> > > > >> better, leaving the parameters less critical to comprehension towards
> > > > >> the end.
> > > > >
> > > > > And I see that in the final patch it looks nicer the way you have it.
> > > > >
> > > > >> > This looks correct though, so either way
> > > > >> >
> > > > >> > Reviewed-by: Serge Hallyn <serge at hallyn.com>
> > > > >>
> > > > >> Thanks.  Did you want to put this through, or send it through Paul's
> > > > >> audit tree?
> > > > >
> > > > > If Paul's around I'm happy to have it go through his tree.
> > > > 
> > > > Is this series based against -next with the changes that touch commoncap.c?
> > > 
> > > This series is against pcmoore's audit/next tree (I know I'm missing two
> > > commits but they pose no conflict.).
> > > 
> > > Which -next tree are you talking about?  I might guess
> > > linux-security/next or linux-next/master (I have at least a dozen "next"
> > > in my git repo config.)
> > > 
> > > I did eventually find your patches in sfr's tree and in your for-next/kspp branch.
> > > 
> > > I'll have a look at the commoncap.c changes including the elimination of cap_effective.
> > > 
> > > > Also, did you validate this with the existing LTP tests and selftests?
> > > > 
> > > > https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/commit/?h=for-next/secureexec&id=ee67ae7ef6ff499137292ac8a9dfe86096796283
> > > 
> > > No.  I will look into doing that.  Thanks for the suggestion.
> 
> Ok, I'm running the kernel self-test
> 
> 	make TARGETS="capabilities" kselftest
> 
> and getting a good way through it and then hit this on an unmodified kernel:
> 
> 	[RUN]   +++ Tests with uid != 0 +++
> 	[NOTE]  Using global UIDs for tests
> 	[OK]    Child succeeded
> 	test_execve: chdir to private tmpfs: Permission denied

Hm, just a hunch, anything in syslog?  The fact that you can mount the
private tmp but not chdir to it just sounds like selinux contexts.

Might run it under strace...

Boy, that's an interesting testcase.  

> 	[FAIL]  Child failed
> 	selftests:  test_execve [FAIL]
> 
> Is this a known limitation or have I got something weird in my runtime
> environment that is killing it at this part of the test?


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