[PATCH v1] env: add w flags for net config in explicit write mode

[PATCH v1] env: add w flags for net config in explicit write mode

[Heiko Schocher]

From: Adrian Freihofer <adrian.freihofer@siemens.com>

In explicit write access mode (CONFIG_ENV_WRITEABLE_LIST) the
environment variables listed in NET_FLAGS and NET6_FLAGS are
probably intended to be writeable. Therefore add the 'w' flag
to these variables.

Signed-off-by: Adrian Freihofer <adrian.freihofer@siemens.com>
Signed-off-by: Heiko Schocher <hs@nabladev.com>
---

 include/env_flags.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

Azure build (patch is in a bunch of siemens patches sending
now to mainline):
https://dev.azure.com/hs0298/hs/_build/results?buildId=202&view=results

diff --git a/include/env_flags.h b/include/env_flags.h
index 0c48874690f..fc65dcaba21 100644
--- a/include/env_flags.h
+++ b/include/env_flags.h
@@ -56,6 +56,16 @@ enum env_flags_varaccess {
 #define ETHADDR_FLAGS "eth" ETHADDR_WILDCARD "addr:mo,"
 #endif
 #endif
+#ifdef CONFIG_ENV_WRITEABLE_LIST
+#define NET_FLAGS \
+	"ipaddr:iw," \
+	"gatewayip:iw," \
+	"netmask:iw," \
+	"serverip:iw," \
+	"nvlan:dw," \
+	"vlan:dw," \
+	"dnsip:iw,"
+#else
 #define NET_FLAGS \
 	"ipaddr:i," \
 	"gatewayip:i," \
@@ -64,16 +74,24 @@ enum env_flags_varaccess {
 	"nvlan:d," \
 	"vlan:d," \
 	"dnsip:i,"
+#endif
 #else
 #define ETHADDR_FLAGS
 #define NET_FLAGS
 #endif
 
 #ifdef CONFIG_IPV6
+#ifdef CONFIG_ENV_WRITEABLE_LIST
+#define NET6_FLAGS \
+	"ip6addr:sw," \
+	"serverip6:sw," \
+	"gatewayip6:sw,"
+#else
 #define NET6_FLAGS \
 	"ip6addr:s," \
 	"serverip6:s," \
 	"gatewayip6:s,"
+#endif
 #else
 #define NET6_FLAGS
 #endif
-- 
2.20.1

base-commit: 6b2d05748cf3cd6ba417a96c00602b0122e10af6

Re: [PATCH v1] env: add w flags for net config in explicit write mode

[Benjamin ROBIN]

Hello,

On Saturday, January 24, 2026 at 6:40 AM, Heiko Schocher wrote:
> From: Adrian Freihofer <adrian.freihofer@siemens.com>
> 
> In explicit write access mode (CONFIG_ENV_WRITEABLE_LIST) the
> environment variables listed in NET_FLAGS and NET6_FLAGS are
> probably intended to be writeable. Therefore add the 'w' flag
> to these variables.

Users who enable CONFIG_ENV_WRITEABLE_LIST typically want full control over 
which environment variables are writable. The new default behavior introduced 
by your patch might not align with what all users expect or want.

Would overriding the flags using CFG_ENV_FLAGS_LIST_STATIC not work in this 
case?

> diff --git a/include/env_flags.h b/include/env_flags.h
> index 0c48874690f..fc65dcaba21 100644
> --- a/include/env_flags.h
> +++ b/include/env_flags.h
> @@ -56,6 +56,16 @@ enum env_flags_varaccess {
>  #define ETHADDR_FLAGS "eth" ETHADDR_WILDCARD "addr:mo,"
>  #endif
>  #endif
> +#ifdef CONFIG_ENV_WRITEABLE_LIST
> +#define NET_FLAGS \
> +	"ipaddr:iw," \
> +	"gatewayip:iw," \
> +	"netmask:iw," \
> +	"serverip:iw," \
> +	"nvlan:dw," \
> +	"vlan:dw," \
> +	"dnsip:iw,"
> +#else
>  #define NET_FLAGS \
>  	"ipaddr:i," \
>  	"gatewayip:i," \
> @@ -64,16 +74,24 @@ enum env_flags_varaccess {
>  	"nvlan:d," \
>  	"vlan:d," \
>  	"dnsip:i,"
> +#endif
>  #else
>  #define ETHADDR_FLAGS
>  #define NET_FLAGS
>  #endif
> 
>  #ifdef CONFIG_IPV6
> +#ifdef CONFIG_ENV_WRITEABLE_LIST
> +#define NET6_FLAGS \
> +	"ip6addr:sw," \
> +	"serverip6:sw," \
> +	"gatewayip6:sw,"
> +#else
>  #define NET6_FLAGS \
>  	"ip6addr:s," \
>  	"serverip6:s," \
>  	"gatewayip6:s,"
> +#endif
>  #else
>  #define NET6_FLAGS
>  #endif

Best regards,
-- 
Benjamin Robin, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v1] env: add w flags for net config in explicit write mode

[Heiko Schocher]

Hello Benjamin,

On 24.01.26 12:35, Benjamin ROBIN wrote:
> Hello,
> 
> On Saturday, January 24, 2026 at 6:40 AM, Heiko Schocher wrote:
>> From: Adrian Freihofer <adrian.freihofer@siemens.com>
>>
>> In explicit write access mode (CONFIG_ENV_WRITEABLE_LIST) the
>> environment variables listed in NET_FLAGS and NET6_FLAGS are
>> probably intended to be writeable. Therefore add the 'w' flag
>> to these variables.
> 
> Users who enable CONFIG_ENV_WRITEABLE_LIST typically want full control over
> which environment variables are writable. The new default behavior introduced
> by your patch might not align with what all users expect or want.
> 
> Would overriding the flags using CFG_ENV_FLAGS_LIST_STATIC not work in this
> case?

Good question, I have to test... or may Adrian has already done
such tests...

But looking into code.. if we add this variables in ENV_WRITEABLE_LIST
the results would be, that this variables are twice in ENV_FLAGS_LIST_STATIC

include/env_flags.h
  87 #define ENV_FLAGS_LIST_STATIC \
  88         ETHADDR_FLAGS \
  89         NET_FLAGS \
  90         NET6_FLAGS \
  91         SERIAL_FLAGS \
  92         CFG_ENV_FLAGS_LIST_STATIC

once through NET_FLAGS and once through CFG_ENV_FLAGS_LIST_STATIC

So, that is not good, and I think, code will find the first
entry, and parse it -> so it will not work.

Should we instead in case CONFIG_ENV_WRITEABLE_LIST is enabled
only set/allow CFG_ENV_FLAGS_LIST_STATIC in ENV_FLAGS_LIST_STATIC ?

bye,
Heiko
-- 
Nabla Software Engineering
HRB 40522 Augsburg
Phone: +49 821 45592596
E-Mail: office@nabladev.com
Geschäftsführer : Stefano Babic

Re: [PATCH v1] env: add w flags for net config in explicit write mode

[Benjamin ROBIN]

Hello Heiko,

On Sunday, January 25, 2026 at 2:03 PM, Heiko Schocher wrote:
> > Users who enable CONFIG_ENV_WRITEABLE_LIST typically want full control
> > over
> > which environment variables are writable. The new default behavior
> > introduced by your patch might not align with what all users expect or
> > want.
> > 
> > Would overriding the flags using CFG_ENV_FLAGS_LIST_STATIC not work in
> > this
> > case?
> 
> Good question, I have to test... or may Adrian has already done
> such tests...

Please test.

> But looking into code.. if we add this variables in ENV_WRITEABLE_LIST
> the results would be, that this variables are twice in ENV_FLAGS_LIST_STATIC
>
> include/env_flags.h
>   87 #define ENV_FLAGS_LIST_STATIC \
>   88         ETHADDR_FLAGS \
>   89         NET_FLAGS \
>   90         NET6_FLAGS \
>   91         SERIAL_FLAGS \
>   92         CFG_ENV_FLAGS_LIST_STATIC
> 
> once through NET_FLAGS and once through CFG_ENV_FLAGS_LIST_STATIC

Yes, the variables with the flags would be declared twice.
 
> So, that is not good, and I think, code will find the first
> entry, and parse it -> so it will not work.

What leads you to this assumption?

If you examine the code, you'll notice that:
 - The env_attr_lookup() function returns the last entry.
 - When iterating over the flags using env_attr_walk(), any previous attribute
   flags are overridden by subsequent flag declarations.

> Should we instead in case CONFIG_ENV_WRITEABLE_LIST is enabled
> only set/allow CFG_ENV_FLAGS_LIST_STATIC in ENV_FLAGS_LIST_STATIC ?

I haven't tested this myself, as I currently don't have a test environment 
available. Please test it, and if it doesn't work, the correct fix would be to 
ensure that any future flag declaration overrides previous ones.

-- 
Benjamin Robin, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v1] env: add w flags for net config in explicit write mode

[Heiko Schocher]

Hello Benjamin,

On 25.01.26 14:33, Benjamin ROBIN wrote:
> Hello Heiko,
> 
> On Sunday, January 25, 2026 at 2:03 PM, Heiko Schocher wrote:
>>> Users who enable CONFIG_ENV_WRITEABLE_LIST typically want full control
>>> over
>>> which environment variables are writable. The new default behavior
>>> introduced by your patch might not align with what all users expect or
>>> want.
>>>
>>> Would overriding the flags using CFG_ENV_FLAGS_LIST_STATIC not work in
>>> this
>>> case?
>>
>> Good question, I have to test... or may Adrian has already done
>> such tests...
> 
> Please test.

We will do.

> 
>> But looking into code.. if we add this variables in ENV_WRITEABLE_LIST
>> the results would be, that this variables are twice in ENV_FLAGS_LIST_STATIC
>>
>> include/env_flags.h
>>    87 #define ENV_FLAGS_LIST_STATIC \
>>    88         ETHADDR_FLAGS \
>>    89         NET_FLAGS \
>>    90         NET6_FLAGS \
>>    91         SERIAL_FLAGS \
>>    92         CFG_ENV_FLAGS_LIST_STATIC
>>
>> once through NET_FLAGS and once through CFG_ENV_FLAGS_LIST_STATIC
> 
> Yes, the variables with the flags would be declared twice.
>   
>> So, that is not good, and I think, code will find the first
>> entry, and parse it -> so it will not work.
> 
> What leads you to this assumption?
> 
> If you examine the code, you'll notice that:
>   - The env_attr_lookup() function returns the last entry.
>   - When iterating over the flags using env_attr_walk(), any previous attribute
>     flags are overridden by subsequent flag declarations.

Ah, thats the trick! If this is the case, I aggree, and we can
simply drop this patch!

> 
>> Should we instead in case CONFIG_ENV_WRITEABLE_LIST is enabled
>> only set/allow CFG_ENV_FLAGS_LIST_STATIC in ENV_FLAGS_LIST_STATIC ?
> 
> I haven't tested this myself, as I currently don't have a test environment
> available. Please test it, and if it doesn't work, the correct fix would be to
> ensure that any future flag declaration overrides previous ones.

We will test, thanks!

bye,
Heiko
-- 
Nabla Software Engineering
HRB 40522 Augsburg
Phone: +49 821 45592596
E-Mail: office@nabladev.com
Geschäftsführer : Stefano Babic

Re: [PATCH v1] env: add w flags for net config in explicit write mode

[Heiko Schocher]

Hello Benjamin

On 25.01.26 14:40, Heiko Schocher wrote:
> Hello Benjamin,
> 
> On 25.01.26 14:33, Benjamin ROBIN wrote:
>> Hello Heiko,
>>
>> On Sunday, January 25, 2026 at 2:03 PM, Heiko Schocher wrote:
>>>> Users who enable CONFIG_ENV_WRITEABLE_LIST typically want full control
>>>> over
>>>> which environment variables are writable. The new default behavior
>>>> introduced by your patch might not align with what all users expect or
>>>> want.
>>>>
>>>> Would overriding the flags using CFG_ENV_FLAGS_LIST_STATIC not work in
>>>> this
>>>> case?
>>>
>>> Good question, I have to test... or may Adrian has already done
>>> such tests...
>>
>> Please test.
> 
> We will do.
> 
>>
>>> But looking into code.. if we add this variables in ENV_WRITEABLE_LIST
>>> the results would be, that this variables are twice in ENV_FLAGS_LIST_STATIC
>>>
>>> include/env_flags.h
>>>    87 #define ENV_FLAGS_LIST_STATIC \
>>>    88         ETHADDR_FLAGS \
>>>    89         NET_FLAGS \
>>>    90         NET6_FLAGS \
>>>    91         SERIAL_FLAGS \
>>>    92         CFG_ENV_FLAGS_LIST_STATIC
>>>
>>> once through NET_FLAGS and once through CFG_ENV_FLAGS_LIST_STATIC
>>
>> Yes, the variables with the flags would be declared twice.
>>> So, that is not good, and I think, code will find the first
>>> entry, and parse it -> so it will not work.
>>
>> What leads you to this assumption?
>>
>> If you examine the code, you'll notice that:
>>   - The env_attr_lookup() function returns the last entry.
>>   - When iterating over the flags using env_attr_walk(), any previous attribute
>>     flags are overridden by subsequent flag declarations.
> 
> Ah, thats the trick! If this is the case, I aggree, and we can
> simply drop this patch!
> 
>>
>>> Should we instead in case CONFIG_ENV_WRITEABLE_LIST is enabled
>>> only set/allow CFG_ENV_FLAGS_LIST_STATIC in ENV_FLAGS_LIST_STATIC ?
>>
>> I haven't tested this myself, as I currently don't have a test environment
>> available. Please test it, and if it doesn't work, the correct fix would be to
>> ensure that any future flag declaration overrides previous ones.
> 
> We will test, thanks!

Thanks for this hint, we tested your suggestion and it works!

So this patch can be ignored, I already changed the state in
patchwork to superseded!

Thanks!

bye,
Heiko
> 
> bye,
> Heiko

-- 
Nabla Software Engineering
HRB 40522 Augsburg
Phone: +49 821 45592596
E-Mail: office@nabladev.com
Geschäftsführer : Stefano Babic