Re: [REPOST PATCH] nfs: fix port value parsing

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On 30/6/22 08:41, Ian Kent wrote:

On 30/6/22 07:57, Trond Myklebust wrote:
On Thu, 2022-06-30 at 07:33 +0800, Ian Kent wrote:
On 29/6/22 23:33, Trond Myklebust wrote:
On Wed, 2022-06-29 at 09:02 +0800, Ian Kent wrote:
On 28/6/22 22:34, Trond Myklebust wrote:
On Tue, 2022-06-28 at 08:25 +0800, Ian Kent wrote:
The valid values of nfs options port and mountport are 0 to
USHRT_MAX.

The fs parser will return a fail for port values that are
negative
and the sloppy option handling then returns success.

But the sloppy option handling is meant to return success for
invalid
options not valid options with invalid values.

Parsing these values as s32 rather than u32 prevents the
parser
from
returning a parse fail allowing the later USHRT_MAX option
check
to
correctly return a fail in this case. The result check could
be
changed
to use the int_32 union variant as well but leaving it as a
uint_32
check avoids using two logical compares instead of one.

Signed-off-by: Ian Kent <raven@xxxxxxxxxx>
---
    fs/nfs/fs_context.c |    4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c
index 9a16897e8dc6..f4da1d2be616 100644
--- a/fs/nfs/fs_context.c
+++ b/fs/nfs/fs_context.c
@@ -156,14 +156,14 @@ static const struct fs_parameter_spec
nfs_fs_parameters[] = {
           fsparam_u32 ("minorversion",  Opt_minorversion),
           fsparam_string("mountaddr",     Opt_mountaddr),
           fsparam_string("mounthost",     Opt_mounthost),
-       fsparam_u32 ("mountport",     Opt_mountport),
+       fsparam_s32 ("mountport",     Opt_mountport),
           fsparam_string("mountproto",    Opt_mountproto),
           fsparam_u32 ("mountvers",     Opt_mountvers),
           fsparam_u32 ("namlen",        Opt_namelen),
           fsparam_u32 ("nconnect",      Opt_nconnect),
           fsparam_u32 ("max_connect",   Opt_max_connect),
           fsparam_string("nfsvers",       Opt_vers),
-       fsparam_u32   ("port",          Opt_port),
+       fsparam_s32   ("port",          Opt_port),
           fsparam_flag_no("posix",        Opt_posix),
           fsparam_string("proto",         Opt_proto),
           fsparam_flag_no("rdirplus",     Opt_rdirplus),


Why don't we just check for the ENOPARAM return value from
fs_parse()?
In this case I think the return will be EINVAL.
My point is that 'sloppy' is only supposed to work to suppress the
error in the case where an option is not found by the parser. That
corresponds to the error ENOPARAM.
Well, yes, and that's why ENOPARAM isn't returned and shouldn't be.

And if the sloppy option is given it doesn't get to check the value

of the option, it just returns success which isn't right.


I think that's a bit to general for this case.

This seemed like the most sensible way to fix it.

Your patch works around just one symptom of the problem instead of
addressing the root cause.

Ok, how do you recommend I fix this?

Maybe I'm missing something, but why not this?

8<--------------------------------
diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c
index 9a16897e8dc6..8f1f9b4af89d 100644
--- a/fs/nfs/fs_context.c
+++ b/fs/nfs/fs_context.c
@@ -484,7 +484,7 @@ static int nfs_fs_context_parse_param(struct
fs_context *fc,
        opt = fs_parse(fc, nfs_fs_parameters, param, &result);
      if (opt < 0)
-        return ctx->sloppy ? 1 : opt;
+        return (opt == -ENOPARAM && ctx->sloppy) ? 1 : opt;


Right but fs_parse() will return EINVAL in the case where a valid option

is used but its value is wrong such as where the value given is negative

but the param definition is unsigned (causing the EINVAL).

Of course this case is checked for and handled later in the NFS option

handling ...


Oh wait ... I think I've been too hasty and not understood what you

suggested ... let me ponder that a little ... and thanks for the suggestion.


Ian



There's also the question of option ordering which I haven't looked at

closely yet but might not be working properly.


Ian

        if (fc->security)
          ctx->has_sec_mnt_opts = 1;




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