[PATCH v2] block: grant IOPRIO_CLASS_RT to CAP_SYS_NICE

[PATCH v2] block: grant IOPRIO_CLASS_RT to CAP_SYS_NICE

[Khazhismel Kumykov]

CAP_SYS_ADMIN is too broad, and ionice fits into CAP_SYS_NICE's grouping.

Retain CAP_SYS_ADMIN permission for backwards compatibility.

Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
---
 block/ioprio.c                  | 2 +-
 include/uapi/linux/capability.h | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

v2: fix embarrassing logic mistake
diff --git a/block/ioprio.c b/block/ioprio.c
index 77bcab11dce5..276496246fe9 100644
--- a/block/ioprio.c
+++ b/block/ioprio.c
@@ -69,7 +69,7 @@ int ioprio_check_cap(int ioprio)
 
 	switch (class) {
 		case IOPRIO_CLASS_RT:
-			if (!capable(CAP_SYS_ADMIN))
+			if (!capable(CAP_SYS_NICE) && !capable(CAP_SYS_ADMIN))
 				return -EPERM;
 			/* fall through */
 			/* rt has prio field too */
diff --git a/include/uapi/linux/capability.h b/include/uapi/linux/capability.h
index 395dd0df8d08..c6ca33034147 100644
--- a/include/uapi/linux/capability.h
+++ b/include/uapi/linux/capability.h
@@ -288,6 +288,8 @@ struct vfs_ns_cap_data {
    processes and setting the scheduling algorithm used by another
    process. */
 /* Allow setting cpu affinity on other processes */
+/* Allow setting realtime ioprio class */
+/* Allow setting ioprio class on other processes */
 
 #define CAP_SYS_NICE         23
 
-- 
2.28.0.297.g1956fa8f8d-goog

Re: [PATCH v2] block: grant IOPRIO_CLASS_RT to CAP_SYS_NICE

[Serge E. Hallyn]

On Mon, Aug 24, 2020 at 03:10:34PM -0700, Khazhismel Kumykov wrote:
> CAP_SYS_ADMIN is too broad, and ionice fits into CAP_SYS_NICE's grouping.
> 
> Retain CAP_SYS_ADMIN permission for backwards compatibility.
> 
> Signed-off-by: Khazhismel Kumykov <khazhy@google.com>

Acked-by: Serge Hallyn <serge@hallyn.com>

> ---
>  block/ioprio.c                  | 2 +-
>  include/uapi/linux/capability.h | 2 ++
>  2 files changed, 3 insertions(+), 1 deletion(-)
> 
> v2: fix embarrassing logic mistake
> diff --git a/block/ioprio.c b/block/ioprio.c
> index 77bcab11dce5..276496246fe9 100644
> --- a/block/ioprio.c
> +++ b/block/ioprio.c
> @@ -69,7 +69,7 @@ int ioprio_check_cap(int ioprio)
>  
>  	switch (class) {
>  		case IOPRIO_CLASS_RT:
> -			if (!capable(CAP_SYS_ADMIN))
> +			if (!capable(CAP_SYS_NICE) && !capable(CAP_SYS_ADMIN))
>  				return -EPERM;
>  			/* fall through */
>  			/* rt has prio field too */
> diff --git a/include/uapi/linux/capability.h b/include/uapi/linux/capability.h
> index 395dd0df8d08..c6ca33034147 100644
> --- a/include/uapi/linux/capability.h
> +++ b/include/uapi/linux/capability.h
> @@ -288,6 +288,8 @@ struct vfs_ns_cap_data {
>     processes and setting the scheduling algorithm used by another
>     process. */
>  /* Allow setting cpu affinity on other processes */
> +/* Allow setting realtime ioprio class */
> +/* Allow setting ioprio class on other processes */
>  
>  #define CAP_SYS_NICE         23
>  
> -- 
> 2.28.0.297.g1956fa8f8d-goog

Re: [PATCH v2] block: grant IOPRIO_CLASS_RT to CAP_SYS_NICE

[Bart Van Assche]

On 2020-08-24 15:10, Khazhismel Kumykov wrote:
> CAP_SYS_ADMIN is too broad, and ionice fits into CAP_SYS_NICE's grouping.
> 
> Retain CAP_SYS_ADMIN permission for backwards compatibility.
> 
> Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
> ---
>  block/ioprio.c                  | 2 +-
>  include/uapi/linux/capability.h | 2 ++
>  2 files changed, 3 insertions(+), 1 deletion(-)
> 
> v2: fix embarrassing logic mistake
> diff --git a/block/ioprio.c b/block/ioprio.c
> index 77bcab11dce5..276496246fe9 100644
> --- a/block/ioprio.c
> +++ b/block/ioprio.c
> @@ -69,7 +69,7 @@ int ioprio_check_cap(int ioprio)
>  
>  	switch (class) {
>  		case IOPRIO_CLASS_RT:
> -			if (!capable(CAP_SYS_ADMIN))
> +			if (!capable(CAP_SYS_NICE) && !capable(CAP_SYS_ADMIN))
>  				return -EPERM;
>  			/* fall through */
>  			/* rt has prio field too */
> diff --git a/include/uapi/linux/capability.h b/include/uapi/linux/capability.h
> index 395dd0df8d08..c6ca33034147 100644
> --- a/include/uapi/linux/capability.h
> +++ b/include/uapi/linux/capability.h
> @@ -288,6 +288,8 @@ struct vfs_ns_cap_data {
>     processes and setting the scheduling algorithm used by another
>     process. */
>  /* Allow setting cpu affinity on other processes */
> +/* Allow setting realtime ioprio class */
> +/* Allow setting ioprio class on other processes */
>  
>  #define CAP_SYS_NICE         23

From https://www.kernel.org/doc/man-pages/linux-api-ml.html:
"all Linux kernel patches that change userspace interfaces should be CCed
to linux-api@vger.kernel.org"

So I have added the linux-api mailing list to the Cc-list. Anyway:

Reviewed-by: Bart Van Assche <bvanassche@acm.org>

Re: [PATCH v2] block: grant IOPRIO_CLASS_RT to CAP_SYS_NICE

[Khazhismel Kumykov]

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On Sat, Aug 29, 2020 at 6:00 PM Bart Van Assche <bvanassche@acm.org> wrote:
>
> From https://www.kernel.org/doc/man-pages/linux-api-ml.html:
> "all Linux kernel patches that change userspace interfaces should be CCed
> to linux-api@vger.kernel.org"
>
> So I have added the linux-api mailing list to the Cc-list. Anyway:
Thanks, sorry for missing that!
>
> Reviewed-by: Bart Van Assche <bvanassche@acm.org>

Jens, does this change look good?

khazhy

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Re: [PATCH v2] block: grant IOPRIO_CLASS_RT to CAP_SYS_NICE

[Jens Axboe]

On 9/1/20 4:49 PM, Khazhismel Kumykov wrote:
> On Sat, Aug 29, 2020 at 6:00 PM Bart Van Assche <bvanassche@acm.org> wrote:
>>
>> From https://www.kernel.org/doc/man-pages/linux-api-ml.html:
>> "all Linux kernel patches that change userspace interfaces should be CCed
>> to linux-api@vger.kernel.org"
>>
>> So I have added the linux-api mailing list to the Cc-list. Anyway:
> Thanks, sorry for missing that!
>>
>> Reviewed-by: Bart Van Assche <bvanassche@acm.org>
> 
> Jens, does this change look good?

Yes, I'll queue it up for 5.10.

-- 
Jens Axboe