| Message ID | 20171010124138.27342-1-nicolas.dichtel@6wind.com |
|---|---|
| State | Superseded, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | [net,v2] net: enable interface alias removal via rtnl | expand |
On 10/10/17 6:41 AM, Nicolas Dichtel wrote: > IFLA_IFALIAS is defined as NLA_STRING. It means that the minimal length of > the attribute is 1 ("\0"). However, to remove an alias, the attribute > length must be 0 (see dev_set_alias()). > > Let's define the type to NLA_BINARY, so that the alias can be removed. not to be pedantic, but we need to be clear that the type is changed only for policy validation. > > Example: > $ ip l s dummy0 alias foo > $ ip l l dev dummy0 > 5: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000 > link/ether ae:20:30:4f:a7:f3 brd ff:ff:ff:ff:ff:ff > alias foo > > Before the patch: > $ ip l s dummy0 alias "" > RTNETLINK answers: Numerical result out of range > > After the patch: > $ ip l s dummy0 alias "" > $ ip l l dev dummy0 > 5: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000 > link/ether ae:20:30:4f:a7:f3 brd ff:ff:ff:ff:ff:ff > > CC: Oliver Hartkopp <oliver@hartkopp.net> > CC: Stephen Hemminger <stephen@networkplumber.org> > Fixes: 96ca4a2cc145 ("net: remove ifalias on empty given alias") > Reported-by: Julien FLoret <julien.floret@6wind.com> > Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> > --- > > v1 -> v2: add the comment > > net/core/rtnetlink.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c > index d4bcdcc68e92..5343565d88b7 100644 > --- a/net/core/rtnetlink.c > +++ b/net/core/rtnetlink.c > @@ -1483,7 +1483,10 @@ static const struct nla_policy ifla_policy[IFLA_MAX+1] = { > [IFLA_LINKINFO] = { .type = NLA_NESTED }, > [IFLA_NET_NS_PID] = { .type = NLA_U32 }, > [IFLA_NET_NS_FD] = { .type = NLA_U32 }, > - [IFLA_IFALIAS] = { .type = NLA_STRING, .len = IFALIASZ-1 }, > + /* IFLA_IFALIAS is a string, but policy is set to NLA_BINARY to > + * allow 0-length string (needed to remove an alias). > + */ > + [IFLA_IFALIAS] = { .type = NLA_BINARY, .len = IFALIASZ - 1 }, > [IFLA_VFINFO_LIST] = {. type = NLA_NESTED }, > [IFLA_VF_PORTS] = { .type = NLA_NESTED }, > [IFLA_PORT_SELF] = { .type = NLA_NESTED }, > Seems like a reasonable solution. Acked-by: David Ahern <dsahern@gmail.com>
Le 10/10/2017 à 16:50, David Ahern a écrit : > On 10/10/17 6:41 AM, Nicolas Dichtel wrote: >> IFLA_IFALIAS is defined as NLA_STRING. It means that the minimal length of >> the attribute is 1 ("\0"). However, to remove an alias, the attribute >> length must be 0 (see dev_set_alias()). >> >> Let's define the type to NLA_BINARY, so that the alias can be removed. > > not to be pedantic, but we need to be clear that the type is changed > only for policy validation. With the comment in the code, it is clear, isn't it? Regards, Nicolas
On 10/11/17 6:29 AM, Nicolas Dichtel wrote: > Le 10/10/2017 à 16:50, David Ahern a écrit : >> On 10/10/17 6:41 AM, Nicolas Dichtel wrote: >>> IFLA_IFALIAS is defined as NLA_STRING. It means that the minimal length of >>> the attribute is 1 ("\0"). However, to remove an alias, the attribute >>> length must be 0 (see dev_set_alias()). >>> >>> Let's define the type to NLA_BINARY, so that the alias can be removed. >> >> not to be pedantic, but we need to be clear that the type is changed >> only for policy validation. > With the comment in the code, it is clear, isn't it? Code comment was fine; commit log -- line referenced above -- is open for interpretation.
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index d4bcdcc68e92..5343565d88b7 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -1483,7 +1483,10 @@ static const struct nla_policy ifla_policy[IFLA_MAX+1] = { [IFLA_LINKINFO] = { .type = NLA_NESTED }, [IFLA_NET_NS_PID] = { .type = NLA_U32 }, [IFLA_NET_NS_FD] = { .type = NLA_U32 }, - [IFLA_IFALIAS] = { .type = NLA_STRING, .len = IFALIASZ-1 }, + /* IFLA_IFALIAS is a string, but policy is set to NLA_BINARY to + * allow 0-length string (needed to remove an alias). + */ + [IFLA_IFALIAS] = { .type = NLA_BINARY, .len = IFALIASZ - 1 }, [IFLA_VFINFO_LIST] = {. type = NLA_NESTED }, [IFLA_VF_PORTS] = { .type = NLA_NESTED }, [IFLA_PORT_SELF] = { .type = NLA_NESTED },
IFLA_IFALIAS is defined as NLA_STRING. It means that the minimal length of the attribute is 1 ("\0"). However, to remove an alias, the attribute length must be 0 (see dev_set_alias()). Let's define the type to NLA_BINARY, so that the alias can be removed. Example: $ ip l s dummy0 alias foo $ ip l l dev dummy0 5: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000 link/ether ae:20:30:4f:a7:f3 brd ff:ff:ff:ff:ff:ff alias foo Before the patch: $ ip l s dummy0 alias "" RTNETLINK answers: Numerical result out of range After the patch: $ ip l s dummy0 alias "" $ ip l l dev dummy0 5: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000 link/ether ae:20:30:4f:a7:f3 brd ff:ff:ff:ff:ff:ff CC: Oliver Hartkopp <oliver@hartkopp.net> CC: Stephen Hemminger <stephen@networkplumber.org> Fixes: 96ca4a2cc145 ("net: remove ifalias on empty given alias") Reported-by: Julien FLoret <julien.floret@6wind.com> Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> --- v1 -> v2: add the comment net/core/rtnetlink.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)