netdevice.7 SIOCGIFFLAGS/SIOCSIFFLAGS

netdevice.7 SIOCGIFFLAGS/SIOCSIFFLAGS

[Erik Flodin]

Hi,

The documentation for SIOCGIFFLAGS/SIOCSIFFLAGS in netdevice.7 lists
IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO, but those can't be set in
ifr_flags as it is only a short and the flags start at 1<<16.

See also https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=746e6ad23cd6fec2edce056e014a0eabeffa838c

Thanks,
// Erik

Re: netdevice.7 SIOCGIFFLAGS/SIOCSIFFLAGS

[Alejandro Colomar (man-pages)]

[CC += Fredrik, John, David S., Steven, Oliver, Urs]

Hi,

On 3/17/21 3:12 PM, Erik Flodin wrote:
> Hi,
> 
> The documentation for SIOCGIFFLAGS/SIOCSIFFLAGS in netdevice.7 lists
> IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO, but those can't be set in
> ifr_flags as it is only a short and the flags start at 1<<16.
> 
> See also https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=746e6ad23cd6fec2edce056e014a0eabeffa838c
> 

I don't know what's the history of that.
I researched a bit, and while the struct member is indeed a 'short' [1],
the flags were added to the kernel for some reason.
I added a few people to the thread that may know better what to do.Let's
see if they can comment.

Links to relevant commits:

<https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=746e6ad23cd6fec2edce056e014a0eabeffa838c>
<https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b00055aacdb172c05067612278ba27265fcd05ce>
<https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=cd05acfe65ed2cf2db683fa9a6adb8d35635263b>
<https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit/?id=6ecda4d14604d250d385346f4fe9de707f281759>

Thanks,

Alex

[1]:

.../linux$ sed -n '/struct ifreq {/,/};/p' include/uapi/linux/if.h
struct ifreq {
#define IFHWADDRLEN	6
	union
	{
		char	ifrn_name[IFNAMSIZ];		/* if name, e.g. "en0" */
	} ifr_ifrn;
	
	union {
		struct	sockaddr ifru_addr;
		struct	sockaddr ifru_dstaddr;
		struct	sockaddr ifru_broadaddr;
		struct	sockaddr ifru_netmask;
		struct  sockaddr ifru_hwaddr;
		short	ifru_flags;
		int	ifru_ivalue;
		int	ifru_mtu;
		struct  ifmap ifru_map;
		char	ifru_slave[IFNAMSIZ];	/* Just fits the size */
		char	ifru_newname[IFNAMSIZ];
		void __user *	ifru_data;
		struct	if_settings ifru_settings;
	} ifr_ifru;
};
.../linux$ grep 'define\sifr_flags' include/uapi/linux/if.h
#define	ifr_flags	ifr_ifru.ifru_flags	/* flags		*/
.../linux$
	
-- 
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/

Re: Fwd: netdevice.7 SIOCGIFFLAGS/SIOCSIFFLAGS

[Oliver Hartkopp]

Hi Alejandro,

we added IFF_ECHO these days on suggestion of Dave Miller - and the 
IFF_LOWER_UP/IFF_DORMANT were already there at that time.

I don't know if there ioctls are still used for retrieving these flags 
as I assume this is done via netlink interface today.

At least there is enough space (in the union) in the ioctl structure for 
longer data structures:

https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/if.h#L265

https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/if.h#L247

https://elixir.bootlin.com/linux/latest/source/net/core/dev_ioctl.c#L114

If you continue discussing about this topic, please remove the 
Volkswagen mail addresses from Urs and me.

I'm still maintaining the CAN subsystem in the Linux kernel - but with a 
private mail address.

And you should better add the netdev ML to your recipients 
netdev@vger.kernel.org where all the netdev guys (including Dave Miller) 
hang out.

Best,
Oliver


> 
> ------------------------------------------------------------------------
> *Von:* Alejandro Colomar (man-pages) <alx.manpages@gmail.com>
> *Gesendet:* Freitag, März 19, 2021 9:00 PM
> *An:* Erik Flodin; mtk.manpages@gmail.com
> *Cc:* linux-man@vger.kernel.org; Stefan Rompf; David S. Miller; Fredrik 
> Arnerup; John Dykstra; David S. Miller; Hartkopp, Oliver, Dr. (EESC/3); 
> Thuermann, Urs, Dr. (K-AERD/M)
> *Betreff:* Re: netdevice.7 SIOCGIFFLAGS/SIOCSIFFLAGS
> [CC += Fredrik, John, David S., Steven, Oliver, Urs]
> 
> Hi,
> 
> On 3/17/21 3:12 PM, Erik Flodin wrote:
>> Hi,
>> 
>> The documentation for SIOCGIFFLAGS/SIOCSIFFLAGS in netdevice.7 lists
>> IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO, but those can't be set in
>> ifr_flags as it is only a short and the flags start at 1<<16.
>> 
>> See also https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=746e6ad23cd6fec2edce056e014a0eabeffa838c 
> <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=746e6ad23cd6fec2edce056e014a0eabeffa838c>
>> 
> 
> I don't know what's the history of that.
> I researched a bit, and while the struct member is indeed a 'short' [1],
> the flags were added to the kernel for some reason.
> I added a few people to the thread that may know better what to do.Let's
> see if they can comment.
> 
> Links to relevant commits:
> 
> <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=746e6ad23cd6fec2edce056e014a0eabeffa838c 
> <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=746e6ad23cd6fec2edce056e014a0eabeffa838c>>
> <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b00055aacdb172c05067612278ba27265fcd05ce 
> <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b00055aacdb172c05067612278ba27265fcd05ce>>
> <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=cd05acfe65ed2cf2db683fa9a6adb8d35635263b 
> <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=cd05acfe65ed2cf2db683fa9a6adb8d35635263b>>
> <https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit/?id=6ecda4d14604d250d385346f4fe9de707f281759 
> <https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit/?id=6ecda4d14604d250d385346f4fe9de707f281759>>
> 
> Thanks,
> 
> Alex
> 
> [1]:
> 
> .../linux$ sed -n '/struct ifreq {/,/};/p' include/uapi/linux/if.h
> struct ifreq {
> #define IFHWADDRLEN     6
>          union
>          {
>                  char    ifrn_name[IFNAMSIZ];            /* if name, 
> e.g. "en0" */
>          } ifr_ifrn;
> 
>          union {
>                  struct  sockaddr ifru_addr;
>                  struct  sockaddr ifru_dstaddr;
>                  struct  sockaddr ifru_broadaddr;
>                  struct  sockaddr ifru_netmask;
>                  struct  sockaddr ifru_hwaddr;
>                  short   ifru_flags;
>                  int     ifru_ivalue;
>                  int     ifru_mtu;
>                  struct  ifmap ifru_map;
>                  char    ifru_slave[IFNAMSIZ];   /* Just fits the size */
>                  char    ifru_newname[IFNAMSIZ];
>                  void __user *   ifru_data;
>                  struct  if_settings ifru_settings;
>          } ifr_ifru;
> };
> .../linux$ grep 'define\sifr_flags' include/uapi/linux/if.h
> #define ifr_flags       ifr_ifru.ifru_flags     /* flags                */
> .../linux$
> 
> -- 
> Alejandro Colomar
> Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/ 
> <https://www.kernel.org/doc/man-pages/>
> http://www.alejandro-colomar.es/ <http://www.alejandro-colomar.es/>

Re: netdevice.7 SIOCGIFFLAGS/SIOCSIFFLAGS

[Erik Flodin]

Hi,

On Fri, 19 Mar 2021 at 20:53, Alejandro Colomar (man-pages)
<alx.manpages@gmail.com> wrote:
> On 3/17/21 3:12 PM, Erik Flodin wrote:
> > The documentation for SIOCGIFFLAGS/SIOCSIFFLAGS in netdevice.7 lists
> > IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO, but those can't be set in
> > ifr_flags as it is only a short and the flags start at 1<<16.
> >
> > See also https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=746e6ad23cd6fec2edce056e014a0eabeffa838c
> >
>
> I don't know what's the history of that.

Judging from commit message in the commit linked above it was added by
mistake. As noted the flags are accessible via netlink, just not via
SIOCGIFFLAGS.

// Erik

Re: netdevice.7 SIOCGIFFLAGS/SIOCSIFFLAGS

[Alejandro Colomar (man-pages)]

[CC += netdev]

Hi Erik,

On 4/14/21 8:52 PM, Erik Flodin wrote:
> Hi,
> 
> On Fri, 19 Mar 2021 at 20:53, Alejandro Colomar (man-pages)
> <alx.manpages@gmail.com> wrote:
>> On 3/17/21 3:12 PM, Erik Flodin wrote:
>>> The documentation for SIOCGIFFLAGS/SIOCSIFFLAGS in netdevice.7 lists
>>> IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO, but those can't be set in
>>> ifr_flags as it is only a short and the flags start at 1<<16.
>>>
>>> See also https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=746e6ad23cd6fec2edce056e014a0eabeffa838c
>>>
>>
>> I don't know what's the history of that.
> 
> Judging from commit message in the commit linked above it was added by
> mistake. As noted the flags are accessible via netlink, just not via
> SIOCGIFFLAGS.
> 
> // Erik
> 

I should have CCd netdev@ before.  Thanks for the update.  Let's see if 
anyone there can comment.

Thanks,

Alex


-- 
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/

Re: netdevice.7 SIOCGIFFLAGS/SIOCSIFFLAGS

[Erik Flodin]

Hi again,

Have there been any updates on this one?

// Erik

On Wed, 14 Apr 2021 at 21:56, Alejandro Colomar (man-pages)
<alx.manpages@gmail.com> wrote:
>
> [CC += netdev]
>
> Hi Erik,
>
> On 4/14/21 8:52 PM, Erik Flodin wrote:
> > Hi,
> >
> > On Fri, 19 Mar 2021 at 20:53, Alejandro Colomar (man-pages)
> > <alx.manpages@gmail.com> wrote:
> >> On 3/17/21 3:12 PM, Erik Flodin wrote:
> >>> The documentation for SIOCGIFFLAGS/SIOCSIFFLAGS in netdevice.7 lists
> >>> IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO, but those can't be set in
> >>> ifr_flags as it is only a short and the flags start at 1<<16.
> >>>
> >>> See also https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=746e6ad23cd6fec2edce056e014a0eabeffa838c
> >>>
> >>
> >> I don't know what's the history of that.
> >
> > Judging from commit message in the commit linked above it was added by
> > mistake. As noted the flags are accessible via netlink, just not via
> > SIOCGIFFLAGS.
> >
> > // Erik
> >
>
> I should have CCd netdev@ before.  Thanks for the update.  Let's see if
> anyone there can comment.
>
> Thanks,
>
> Alex
>
>
> --
> Alejandro Colomar
> Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
> http://www.alejandro-colomar.es/

Re: netdevice.7 SIOCGIFFLAGS/SIOCSIFFLAGS

[Alejandro Colomar (man-pages)]

[PING mtk, netdev@]
[CC += linux-kernel]

Hi Erik,

On 4/29/21 9:45 PM, Erik Flodin wrote:
> On Wed, 14 Apr 2021 at 21:56, Alejandro Colomar (man-pages)
> <alx.manpages@gmail.com> wrote:
>>
>> [CC += netdev]
>>
>> Hi Erik,
>>
>> On 4/14/21 8:52 PM, Erik Flodin wrote:
>>> Hi,
>>>
>>> On Fri, 19 Mar 2021 at 20:53, Alejandro Colomar (man-pages)
>>> <alx.manpages@gmail.com> wrote:
>>>> On 3/17/21 3:12 PM, Erik Flodin wrote:
>>>>> The documentation for SIOCGIFFLAGS/SIOCSIFFLAGS in netdevice.7 lists
>>>>> IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO, but those can't be set in
>>>>> ifr_flags as it is only a short and the flags start at 1<<16.
>>>>>
>>>>> See also https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=746e6ad23cd6fec2edce056e014a0eabeffa838c
>>>>>
>>>>
>>>> I don't know what's the history of that.
>>>
>>> Judging from commit message in the commit linked above it was added by
>>> mistake. As noted the flags are accessible via netlink, just not via
>>> SIOCGIFFLAGS.
>>>
>>> // Erik
>>>
>>
>> I should have CCd netdev@ before.  Thanks for the update.  Let's see if
>> anyone there can comment.
>>
>> Thanks,
>>
>> Alex
>>

> Hi again,
> 
> Have there been any updates on this one?

No, Noone from the kernel answered.  And I'm sorry, but I'm not sure
what is going on in the code, so I don't want to close this here by just
removing those flags from the manual page, because I worry that the
actual code may be wrong or something.  So I prefer that when Michael
has some time he can maybe review this and say something.  Ideally,
someone from the kernel would also respond, but they haven't.  I've CCd
the LKML; let's see if someone reads this and can help.

Thanks,

Alex

P.S.:  Please, if we haven't responded in a month from now, ping us
again.  Thanks again.

> 
> // Erik
> 
>>
>> --
>> Alejandro Colomar
>> Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
>> http://www.alejandro-colomar.es/

-- 
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/

Re: netdevice.7 SIOCGIFFLAGS/SIOCSIFFLAGS

[Alejandro Colomar (man-pages)]

Hi Erik,

On 10/2/21 18:35, Erik Flodin wrote:
> A bit more than a month has passed so here's a ping :)
> 
> // Erik

Thanks for the ping.

alarm(3600 * 24 * 30);  // :)

> 
> On Fri, 30 Apr 2021 at 21:32, Alejandro Colomar (man-pages) 
> <alx.manpages@gmail.com <mailto:alx.manpages@gmail.com>> wrote:
> 
>     [PING mtk, netdev@]
>     [CC += linux-kernel]
> 
>     Hi Erik,
> 
>     On 4/29/21 9:45 PM, Erik Flodin wrote:
>      > On Wed, 14 Apr 2021 at 21:56, Alejandro Colomar (man-pages)
>      > <alx.manpages@gmail.com <mailto:alx.manpages@gmail.com>> wrote:
>      >>
>      >> [CC += netdev]
>      >>
>      >> Hi Erik,
>      >>
>      >> On 4/14/21 8:52 PM, Erik Flodin wrote:
>      >>> Hi,
>      >>>
>      >>> On Fri, 19 Mar 2021 at 20:53, Alejandro Colomar (man-pages)
>      >>> <alx.manpages@gmail.com <mailto:alx.manpages@gmail.com>> wrote:
>      >>>> On 3/17/21 3:12 PM, Erik Flodin wrote:
>      >>>>> The documentation for SIOCGIFFLAGS/SIOCSIFFLAGS in
>     netdevice.7 lists
>      >>>>> IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO, but those can't be set in
>      >>>>> ifr_flags as it is only a short and the flags start at 1<<16.
>      >>>>>
>      >>>>> See also
>     https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=746e6ad23cd6fec2edce056e014a0eabeffa838c
>     <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=746e6ad23cd6fec2edce056e014a0eabeffa838c>
>      >>>>>
>      >>>>
>      >>>> I don't know what's the history of that.
>      >>>
>      >>> Judging from commit message in the commit linked above it was
>     added by
>      >>> mistake. As noted the flags are accessible via netlink, just
>     not via
>      >>> SIOCGIFFLAGS.
>      >>>
>      >>> // Erik
>      >>>
>      >>
>      >> I should have CCd netdev@ before.  Thanks for the update.  Let's
>     see if
>      >> anyone there can comment.
>      >>
>      >> Thanks,
>      >>
>      >> Alex
>      >>
> 
>      > Hi again,
>      >
>      > Have there been any updates on this one?
> 
>     No, Noone from the kernel answered.  And I'm sorry, but I'm not sure
>     what is going on in the code, so I don't want to close this here by just
>     removing those flags from the manual page, because I worry that the
>     actual code may be wrong or something.  So I prefer that when Michael
>     has some time he can maybe review this and say something.  Ideally,
>     someone from the kernel would also respond, but they haven't.  I've CCd
>     the LKML; let's see if someone reads this and can help.
> 
>     Thanks,
> 
>     Alex
> 
>     P.S.:  Please, if we haven't responded in a month from now, ping us
>     again.  Thanks again.
> 
>      >
>      > // Erik
>      >
>      >>
>      >> --
>      >> Alejandro Colomar
>      >> Linux man-pages comaintainer;
>     https://www.kernel.org/doc/man-pages/
>     <https://www.kernel.org/doc/man-pages/>
>      >> http://www.alejandro-colomar.es/ <http://www.alejandro-colomar.es/>
> 
>     -- 
>     Alejandro Colomar
>     Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
>     <https://www.kernel.org/doc/man-pages/>
>     http://www.alejandro-colomar.es/ <http://www.alejandro-colomar.es/>
> 

-- 
Alejandro Colomar
Linux man-pages comaintainer; http://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/