On Nov 26, 2012, at 5:15 PM, "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote:
> On Mon, Nov 26, 2012 at 05:05:22PM -0500, Chuck Lever wrote:
>>
>> On Nov 26, 2012, at 5:03 PM, "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote:
>>
>>> From: "J. Bruce Fields" <bfields@xxxxxxxxxx>
>>>
>>> This reverts commit 485f7a21e1649797f29317b865cbb094c1f6a71d. The
>>> failures handled there could be any sort of name resolution failure, not
>>> just an allocation, and failing to downcall (hence leaving the client
>>> hanging) is not the correct thing to do in those cases.
>>
>> The problem is in the kernel, then: a downcall should be allowed to fail, IMO.
>
> In this case, after a revert, a failure here will result in the downcall
> passing down a client named "DEFAULT". Presumably that won't be
> permitted access to the export, so the client will end up getting an
> error.
"A failure here" can mean either malloc() returned NULL in client_resolve() or client_compose(), or . . . ?
> But I may not understand your objection.
The main problem is I don't understand your patch description. :-)
I don't seem to have commit 485f7a21 in my nfs-utils git tree (it's helpful to include the short description for such a case).
What exactly is the problem with the current code?
client_resolve() can return a NULL in some cases. Why is it OK to pass a NULL "ai" to client_compose() ? Looks like that can result in a mountd segfault. The kernel won't get any downcall reply in that case! Is that what you are trying to fix?
WRT my original objection: In general I don't see how to make it impossible for mountd to fail. Thus the kernel needs to be better about recovering when mountd suddenly disappears.
>
> --b.
>
>>
>>> Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
>>> ---
>>> utils/mountd/cache.c | 12 +++---------
>>> 1 file changed, 3 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/utils/mountd/cache.c b/utils/mountd/cache.c
>>> index 8f14032..6710eca 100644
>>> --- a/utils/mountd/cache.c
>>> +++ b/utils/mountd/cache.c
>>> @@ -84,6 +84,7 @@ static void auth_unix_ip(FILE *f)
>>> char ipaddr[INET6_ADDRSTRLEN];
>>> char *client = NULL;
>>> struct addrinfo *tmp = NULL;
>>> + struct addrinfo *ai = NULL;
>>> if (readline(fileno(f), &lbuf, &lbuflen) != 1)
>>> return;
>>>
>>> @@ -106,16 +107,12 @@ static void auth_unix_ip(FILE *f)
>>>
>>> /* addr is a valid, interesting address, find the domain name... */
>>> if (!use_ipaddr) {
>>> - struct addrinfo *ai = NULL;
>>> -
>>> ai = client_resolve(tmp->ai_addr);
>>> - if (ai == NULL)
>>> - goto out;
>>> client = client_compose(ai);
>>> freeaddrinfo(ai);
>>> - if (!client)
>>> - goto out;
>>> }
>>> + freeaddrinfo(tmp);
>>> +
>>> qword_print(f, "nfsd");
>>> qword_print(f, ipaddr);
>>> qword_printuint(f, time(0) + DEFAULT_TTL);
>>> @@ -127,9 +124,6 @@ static void auth_unix_ip(FILE *f)
>>> xlog(D_CALL, "auth_unix_ip: client %p '%s'", client, client?client: "DEFAULT");
>>>
>>> free(client);
>>> -out:
>>> - freeaddrinfo(tmp);
>>> -
>>> }
>>>
>>> static void auth_unix_gid(FILE *f)
>>> --
>>> 1.7.11.7
>>>
>>> --
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>>
>> --
>> Chuck Lever
>> chuck[dot]lever[at]oracle[dot]com
>>
>>
>>
--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com
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