lkml.org 
[lkml]   [2019]   [Jun]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 08/16] nfsd: escape high characters in binary data
    On Wed, Jun 26, 2019 at 12:21:49PM -0400, J. Bruce Fields wrote:
    > On Mon, Jun 24, 2019 at 05:05:12PM -0400, J. Bruce Fields wrote:
    > > On Sat, Jun 22, 2019 at 01:22:56PM -0700, Kees Cook wrote:
    > > > On Sat, Jun 22, 2019 at 03:00:58PM -0400, J. Bruce Fields wrote:
    > > > > The logic around ESCAPE_NP and the "only" string is really confusing. I
    > > > > started assuming I could just add an ESCAPE_NONASCII flag and stick "
    > > > > and \ into the "only" string, but it doesn't work that way.
    > > >
    > > > Yeah, if ESCAPE_NP isn't specified, the "only" characters are passed
    > > > through. It'd be nice to have an "add" or a clearer way to do actual
    > > > ctype subsets, etc. If there isn't an obviously clear way to refactor
    > > > it, just skip it for now and I'm happy to ack your original patch. :)
    > >
    > > There may well be some simplification possible here.... There aren't
    > > really many users of "only", for example. I'll look into it some more.
    >
    > The printk users are kind of mysterious to me. I did a grep for
    >
    > git grep '%[0-9.*]pE'
    >
    > which got 75 hits. All of them for pE. I couldn't find any of the
    > other pE[achnops] variants. pE is equivalent to ESCAPE_ANY|ESCAPE_NP.
    > Confusingly, ESCAPE_NP doesn't mean "escape non-printable", it means
    > "don't escape printable". So things like carriage returns aren't
    > escaped.

    No, I was confused: "\n" is non-printable according to isprint(), so
    ESCAPE_ANY_NP *will* escape it. So this isn't quite so bad. SSIDs are
    usually printed as '%*pE', so arguably we should be escaping the single
    quote character too, but at least we're not allowing line breaks
    through. I don't know about non-ascii.

    > One of the hits outside wireless code was in drm_dp_cec_adap_status,
    > which was printing some device ID into a debugfs file with "ID: %*pE\n".
    > If the ID actually needs escaping, then I suspect the meant to escape \n
    > too to prevent misparsing that output.

    And same here, this is OK.

    --b.

    \
     
     \ /
      Last update: 2019-06-27 22:22    [W:2.779 / U:0.028 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site