Commit c10e6cf85e7d ("net: genetlink: push attrbuf allocation and parsing
to a separate function") moved attribute buffer allocation and attribute
parsing from genl_family_rcv_msg_doit() into a separate function
genl_family_rcv_msg_attrs_parse() which, unlike the previous code, calls
__nlmsg_parse() even if family->maxattr is 0 (i.e. the family does its own
parsing). The parser error is ignored and does not propagate out of
genl_family_rcv_msg_attrs_parse() but an error message ("Unknown attribute
type") is set in extack and if further processing generates no error or
warning, it stays there and is interpreted as a warning by userspace.
Dumpit requests are not affected as genl_family_rcv_msg_dumpit() bypasses
the call of genl_family_rcv_msg_doit() if family->maxattr is zero. Do the
same also in genl_family_rcv_msg_doit().
Fixes: c10e6cf85e7d ("net: genetlink: push attrbuf allocation and parsing to a separate function")
Signed-off-by: Michal Kubecek <[email protected]>
---
net/netlink/genetlink.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index ecc2bd3e73e4..1f14e55ad3ad 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -639,21 +639,23 @@ static int genl_family_rcv_msg_doit(const struct genl_family *family,
const struct genl_ops *ops,
int hdrlen, struct net *net)
{
- struct nlattr **attrbuf;
+ struct nlattr **attrbuf = NULL;
struct genl_info info;
int err;
if (!ops->doit)
return -EOPNOTSUPP;
+ if (!family->maxattr)
+ goto no_attrs;
attrbuf = genl_family_rcv_msg_attrs_parse(family, nlh, extack,
ops, hdrlen,
GENL_DONT_VALIDATE_STRICT,
- family->maxattr &&
family->parallel_ops);
if (IS_ERR(attrbuf))
return PTR_ERR(attrbuf);
+no_attrs:
info.snd_seq = nlh->nlmsg_seq;
info.snd_portid = NETLINK_CB(skb).portid;
info.nlhdr = nlh;
@@ -676,8 +678,7 @@ static int genl_family_rcv_msg_doit(const struct genl_family *family,
family->post_doit(ops, skb, &info);
out:
- genl_family_rcv_msg_attrs_free(family, attrbuf,
- family->maxattr && family->parallel_ops);
+ genl_family_rcv_msg_attrs_free(family, attrbuf, family->parallel_ops);
return err;
}
--
2.23.0
Thu, Oct 10, 2019 at 12:34:02PM CEST, [email protected] wrote:
>Commit c10e6cf85e7d ("net: genetlink: push attrbuf allocation and parsing
>to a separate function") moved attribute buffer allocation and attribute
>parsing from genl_family_rcv_msg_doit() into a separate function
>genl_family_rcv_msg_attrs_parse() which, unlike the previous code, calls
>__nlmsg_parse() even if family->maxattr is 0 (i.e. the family does its own
>parsing). The parser error is ignored and does not propagate out of
>genl_family_rcv_msg_attrs_parse() but an error message ("Unknown attribute
>type") is set in extack and if further processing generates no error or
>warning, it stays there and is interpreted as a warning by userspace.
>
>Dumpit requests are not affected as genl_family_rcv_msg_dumpit() bypasses
>the call of genl_family_rcv_msg_doit() if family->maxattr is zero. Do the
>same also in genl_family_rcv_msg_doit().
>
>Fixes: c10e6cf85e7d ("net: genetlink: push attrbuf allocation and parsing to a separate function")
>Signed-off-by: Michal Kubecek <[email protected]>
Acked-by: Jiri Pirko <[email protected]>
Thanks!
On Thu, 10 Oct 2019 12:34:02 +0200 (CEST), Michal Kubecek wrote:
> Commit c10e6cf85e7d ("net: genetlink: push attrbuf allocation and parsing
> to a separate function") moved attribute buffer allocation and attribute
> parsing from genl_family_rcv_msg_doit() into a separate function
> genl_family_rcv_msg_attrs_parse() which, unlike the previous code, calls
> __nlmsg_parse() even if family->maxattr is 0 (i.e. the family does its own
> parsing). The parser error is ignored and does not propagate out of
> genl_family_rcv_msg_attrs_parse() but an error message ("Unknown attribute
> type") is set in extack and if further processing generates no error or
> warning, it stays there and is interpreted as a warning by userspace.
>
> Dumpit requests are not affected as genl_family_rcv_msg_dumpit() bypasses
> the call of genl_family_rcv_msg_doit() if family->maxattr is zero. Do the
> same also in genl_family_rcv_msg_doit().
>
> Fixes: c10e6cf85e7d ("net: genetlink: push attrbuf allocation and parsing to a separate function")
> Signed-off-by: Michal Kubecek <[email protected]>
> ---
> net/netlink/genetlink.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
> index ecc2bd3e73e4..1f14e55ad3ad 100644
> --- a/net/netlink/genetlink.c
> +++ b/net/netlink/genetlink.c
> @@ -639,21 +639,23 @@ static int genl_family_rcv_msg_doit(const struct genl_family *family,
> const struct genl_ops *ops,
> int hdrlen, struct net *net)
> {
> - struct nlattr **attrbuf;
> + struct nlattr **attrbuf = NULL;
> struct genl_info info;
> int err;
>
> if (!ops->doit)
> return -EOPNOTSUPP;
>
> + if (!family->maxattr)
> + goto no_attrs;
> attrbuf = genl_family_rcv_msg_attrs_parse(family, nlh, extack,
> ops, hdrlen,
> GENL_DONT_VALIDATE_STRICT,
> - family->maxattr &&
> family->parallel_ops);
> if (IS_ERR(attrbuf))
> return PTR_ERR(attrbuf);
>
> +no_attrs:
The use of a goto statement as a replacement for an if is making me
uncomfortable.
Looks like both callers of genl_family_rcv_msg_attrs_parse() jump
around it if !family->maxattr and then check the result with IS_ERR().
Would it not make more sense to have genl_family_rcv_msg_attrs_parse()
return NULL if !family->maxattr?
Just wondering, if you guys prefer this version I can apply..
> info.snd_seq = nlh->nlmsg_seq;
> info.snd_portid = NETLINK_CB(skb).portid;
> info.nlhdr = nlh;
> @@ -676,8 +678,7 @@ static int genl_family_rcv_msg_doit(const struct genl_family *family,
> family->post_doit(ops, skb, &info);
>
> out:
> - genl_family_rcv_msg_attrs_free(family, attrbuf,
> - family->maxattr && family->parallel_ops);
> + genl_family_rcv_msg_attrs_free(family, attrbuf, family->parallel_ops);
>
> return err;
> }
On Thu, Oct 10, 2019 at 10:21:02AM -0700, Jakub Kicinski wrote:
> On Thu, 10 Oct 2019 12:34:02 +0200 (CEST), Michal Kubecek wrote:
> > Commit c10e6cf85e7d ("net: genetlink: push attrbuf allocation and parsing
> > to a separate function") moved attribute buffer allocation and attribute
> > parsing from genl_family_rcv_msg_doit() into a separate function
> > genl_family_rcv_msg_attrs_parse() which, unlike the previous code, calls
> > __nlmsg_parse() even if family->maxattr is 0 (i.e. the family does its own
> > parsing). The parser error is ignored and does not propagate out of
> > genl_family_rcv_msg_attrs_parse() but an error message ("Unknown attribute
> > type") is set in extack and if further processing generates no error or
> > warning, it stays there and is interpreted as a warning by userspace.
> >
> > Dumpit requests are not affected as genl_family_rcv_msg_dumpit() bypasses
> > the call of genl_family_rcv_msg_doit() if family->maxattr is zero. Do the
> > same also in genl_family_rcv_msg_doit().
> >
> > Fixes: c10e6cf85e7d ("net: genetlink: push attrbuf allocation and parsing to a separate function")
> > Signed-off-by: Michal Kubecek <[email protected]>
> > ---
> > net/netlink/genetlink.c | 9 +++++----
> > 1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
> > index ecc2bd3e73e4..1f14e55ad3ad 100644
> > --- a/net/netlink/genetlink.c
> > +++ b/net/netlink/genetlink.c
> > @@ -639,21 +639,23 @@ static int genl_family_rcv_msg_doit(const struct genl_family *family,
> > const struct genl_ops *ops,
> > int hdrlen, struct net *net)
> > {
> > - struct nlattr **attrbuf;
> > + struct nlattr **attrbuf = NULL;
> > struct genl_info info;
> > int err;
> >
> > if (!ops->doit)
> > return -EOPNOTSUPP;
> >
> > + if (!family->maxattr)
> > + goto no_attrs;
> > attrbuf = genl_family_rcv_msg_attrs_parse(family, nlh, extack,
> > ops, hdrlen,
> > GENL_DONT_VALIDATE_STRICT,
> > - family->maxattr &&
> > family->parallel_ops);
> > if (IS_ERR(attrbuf))
> > return PTR_ERR(attrbuf);
> >
> > +no_attrs:
>
> The use of a goto statement as a replacement for an if is making me
> uncomfortable.
I used instead of a simple if because (1) it's what the dumpit code does
and (2) the function call arguments are already quite pressed to the
80-character barrier.
> Looks like both callers of genl_family_rcv_msg_attrs_parse() jump
> around it if !family->maxattr and then check the result with IS_ERR().
>
> Would it not make more sense to have genl_family_rcv_msg_attrs_parse()
> return NULL if !family->maxattr?
This sounds like a good solution. I'll check again in the morning and
send v3.
Michal
Thu, Oct 10, 2019 at 07:21:02PM CEST, [email protected] wrote:
>On Thu, 10 Oct 2019 12:34:02 +0200 (CEST), Michal Kubecek wrote:
>> Commit c10e6cf85e7d ("net: genetlink: push attrbuf allocation and parsing
>> to a separate function") moved attribute buffer allocation and attribute
>> parsing from genl_family_rcv_msg_doit() into a separate function
>> genl_family_rcv_msg_attrs_parse() which, unlike the previous code, calls
>> __nlmsg_parse() even if family->maxattr is 0 (i.e. the family does its own
>> parsing). The parser error is ignored and does not propagate out of
>> genl_family_rcv_msg_attrs_parse() but an error message ("Unknown attribute
>> type") is set in extack and if further processing generates no error or
>> warning, it stays there and is interpreted as a warning by userspace.
>>
>> Dumpit requests are not affected as genl_family_rcv_msg_dumpit() bypasses
>> the call of genl_family_rcv_msg_doit() if family->maxattr is zero. Do the
>> same also in genl_family_rcv_msg_doit().
>>
>> Fixes: c10e6cf85e7d ("net: genetlink: push attrbuf allocation and parsing to a separate function")
>> Signed-off-by: Michal Kubecek <[email protected]>
>> ---
>> net/netlink/genetlink.c | 9 +++++----
>> 1 file changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
>> index ecc2bd3e73e4..1f14e55ad3ad 100644
>> --- a/net/netlink/genetlink.c
>> +++ b/net/netlink/genetlink.c
>> @@ -639,21 +639,23 @@ static int genl_family_rcv_msg_doit(const struct genl_family *family,
>> const struct genl_ops *ops,
>> int hdrlen, struct net *net)
>> {
>> - struct nlattr **attrbuf;
>> + struct nlattr **attrbuf = NULL;
>> struct genl_info info;
>> int err;
>>
>> if (!ops->doit)
>> return -EOPNOTSUPP;
>>
>> + if (!family->maxattr)
>> + goto no_attrs;
>> attrbuf = genl_family_rcv_msg_attrs_parse(family, nlh, extack,
>> ops, hdrlen,
>> GENL_DONT_VALIDATE_STRICT,
>> - family->maxattr &&
>> family->parallel_ops);
>> if (IS_ERR(attrbuf))
>> return PTR_ERR(attrbuf);
>>
>> +no_attrs:
>
>The use of a goto statement as a replacement for an if is making me
>uncomfortable.
>
>Looks like both callers of genl_family_rcv_msg_attrs_parse() jump
>around it if !family->maxattr and then check the result with IS_ERR().
>
>Would it not make more sense to have genl_family_rcv_msg_attrs_parse()
>return NULL if !family->maxattr?
Okay. Sounds fine to me.
>
>Just wondering, if you guys prefer this version I can apply..
>
>> info.snd_seq = nlh->nlmsg_seq;
>> info.snd_portid = NETLINK_CB(skb).portid;
>> info.nlhdr = nlh;
>> @@ -676,8 +678,7 @@ static int genl_family_rcv_msg_doit(const struct genl_family *family,
>> family->post_doit(ops, skb, &info);
>>
>> out:
>> - genl_family_rcv_msg_attrs_free(family, attrbuf,
>> - family->maxattr && family->parallel_ops);
>> + genl_family_rcv_msg_attrs_free(family, attrbuf, family->parallel_ops);
>>
>> return err;
>> }