Re: [Qemu-devel] [PATCH] seccomp: report more useful errors from seccomp

[Eduardo Otubo]

On 25/03/2019 - 15:52:27, Daniel P. Berrange wrote:
> On Mon, Mar 25, 2019 at 04:25:19PM +0100, Marc-André Lureau wrote:
> > Hi
> > 
> > On Mon, Mar 25, 2019 at 3:07 PM Daniel P. Berrangé <address@hidden> wrote:
> > >
> > > Most of the seccomp functions return errnos as a negative return
> > > value. The code is currently ignoring these and reporting a generic
> > > error message for all seccomp failure scenarios making debugging
> > > painful. Report a more precise error from each failed call and include
> > > errno if it is available.
> > >
> > > Signed-off-by: Daniel P. Berrangé <address@hidden>
> > 
> > Is this for 4.0? Eligible imho.
> 
> I don't really mind either way.

Patch looks good.

Acked-by: Eduardo Otubo <address@hidden>

> 
> > 
> > Reviewed-by: Marc-André Lureau <address@hidden>
> > 
> > > ---
> > >  qemu-seccomp.c | 20 +++++++++++++-------
> > >  1 file changed, 13 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/qemu-seccomp.c b/qemu-seccomp.c
> > > index 36d5829831..8daa9e0528 100644
> > > --- a/qemu-seccomp.c
> > > +++ b/qemu-seccomp.c
> > > @@ -138,21 +138,23 @@ static uint32_t qemu_seccomp_get_kill_action(void)
> > >  }
> > >
> > >
> > > -static int seccomp_start(uint32_t seccomp_opts)
> > > +static int seccomp_start(uint32_t seccomp_opts, Error **errp)
> > >  {
> > > -    int rc = 0;
> > > +    int rc = -1;
> > >      unsigned int i = 0;
> > >      scmp_filter_ctx ctx;
> > >      uint32_t action = qemu_seccomp_get_kill_action();
> > >
> > >      ctx = seccomp_init(SCMP_ACT_ALLOW);
> > >      if (ctx == NULL) {
> > > -        rc = -1;
> > > +        error_setg(errp, "failed to initialize seccomp context");
> > >          goto seccomp_return;
> > >      }
> > >
> > >      rc = seccomp_attr_set(ctx, SCMP_FLTATR_CTL_TSYNC, 1);
> > >      if (rc != 0) {
> > > +        error_setg_errno(errp, -rc,
> > > +                         "failed to set seccomp thread synchronization");
> > >          goto seccomp_return;
> > >      }
> > >
> > > @@ -164,15 +166,21 @@ static int seccomp_start(uint32_t seccomp_opts)
> > >          rc = seccomp_rule_add_array(ctx, action, blacklist[i].num,
> > >                                      blacklist[i].narg, 
> > > blacklist[i].arg_cmp);
> > >          if (rc < 0) {
> > > +            error_setg_errno(errp, -rc,
> > > +                             "failed to add seccomp blacklist rules");
> > >              goto seccomp_return;
> > >          }
> > >      }
> > >
> > >      rc = seccomp_load(ctx);
> > > +    if (rc < 0) {
> > > +        error_setg_errno(errp, -rc,
> > > +                         "failed to load seccomp syscall filter in 
> > > kernel");
> > > +    }
> > >
> > >    seccomp_return:
> > >      seccomp_release(ctx);
> > > -    return rc;
> > > +    return rc < 0 ? -1 : 0;
> > >  }
> > >
> > >  #ifdef CONFIG_SECCOMP
> > > @@ -242,9 +250,7 @@ int parse_sandbox(void *opaque, QemuOpts *opts, Error 
> > > **errp)
> > >              }
> > >          }
> > >
> > > -        if (seccomp_start(seccomp_opts) < 0) {
> > > -            error_setg(errp, "failed to install seccomp syscall filter "
> > > -                       "in the kernel");
> > > +        if (seccomp_start(seccomp_opts, errp) < 0) {
> > >              return -1;
> > >          }
> > >      }
> > > --
> > > 2.20.1
> > >
> > >
> > 
> > 
> > -- 
> > Marc-André Lureau
> 
> Regards,
> Daniel
> -- 
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-- 
Eduardo Otubo

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