lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Fri, 11 Sep 2020 15:15:58 +0200
From:   Jiri Olsa <>
To:     Alexei Starovoitov <>
Cc:     Jiri Olsa <>, Alexei Starovoitov <>,
        Daniel Borkmann <>,
        Andrii Nakryiko <>,
        Network Development <>,
        bpf <>, Martin KaFai Lau <>,
        Song Liu <>, Yonghong Song <>,
        John Fastabend <>,
        KP Singh <>
Subject: Re: [PATCH bpf-next] selftests/bpf: Check trampoline execution in
 d_path test

On Thu, Sep 10, 2020 at 05:46:21PM -0700, Alexei Starovoitov wrote:
> On Thu, Sep 10, 2020 at 5:22 AM Jiri Olsa <> wrote:
> >
> > Some kernels builds might inline vfs_getattr call within
> > fstat syscall code path, so fentry/vfs_getattr trampoline
> > is not called.
> >
> > I'm not sure how to handle this in some generic way other
> > than use some other function, but that might get inlined at
> > some point as well.
> It's great that we had the test and it failed.
> Doing the test skipping will only hide the problem.
> Please don't do it here and in the future.
> Instead let's figure out the real solution.
> Assuming that vfs_getattr was added to btf_allowlist_d_path
> for a reason we have to make this introspection place
> reliable regardless of compiler inlining decisions.
> We can mark it as 'noinline', but that's undesirable.
> I suggest we remove it from the allowlist and replace it with
> security_inode_getattr.
> I think that is a better long term fix.

in my case vfs_getattr got inlined in vfs_statx_fd and both
of them are defined in fs/stat.c 

so the idea is that inlining will not happen if the function
is defined in another object? or less likely..?

we should be safe when it's called from module

> While at it I would apply the same critical thinking to other
> functions in the allowlist. They might suffer the same issue.
> So s/vfs_truncate/security_path_truncate/ and so on?
> Things won't work when CONFIG_SECURITY is off, but that is a rare kernel config?
> Or add both security_* and vfs_* variants and switch tests to use security_* ?
> but it feels fragile to allow inline-able funcs in allowlist.

hm, what's the difference between vfs_getattr and security_inode_getattr
in this regard? I'd expect compiler could inline it same way as for vfs_getattr


Powered by blists - more mailing lists