[PATCH net] netdevsim: Fix hwstats debugfs file permissions

The hwstats debugfs files are only writeable, but they are created with
read and write permissions, causing certain selftests to fail [1].

Fix by creating the files with write permission only.

[1]
 # ./test_offload.py
 Test destruction of generic XDP...
 Traceback (most recent call last):
   File "/home/idosch/code/linux/tools/testing/selftests/bpf/./test_offload.py", line 810, in <module>
     simdev = NetdevSimDev()
 [...]
 Exception: Command failed: cat /sys/kernel/debug/netdevsim/netdevsim0//ports/0/dev/hwstats/l3/disable_ifindex

 cat: /sys/kernel/debug/netdevsim/netdevsim0//ports/0/dev/hwstats/l3/disable_ifindex: Invalid argument

Fixes: 1a6d7ae7d63c ("netdevsim: Introduce support for L3 offload xstats")
Reported-by: Jie2x Zhou <redacted>
Tested-by: Jie2x Zhou <redacted>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
---
 drivers/net/netdevsim/hwstats.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/netdevsim/hwstats.c b/drivers/net/netdevsim/hwstats.c
index 605a38e16db0..0e58aa7f0374 100644
--- a/drivers/net/netdevsim/hwstats.c
+++ b/drivers/net/netdevsim/hwstats.c

@@ -433,11 +433,11 @@ int nsim_dev_hwstats_init(struct nsim_dev *nsim_dev)
 		goto err_remove_hwstats_recursive;
 	}
 
-	debugfs_create_file("enable_ifindex", 0600, hwstats->l3_ddir, hwstats,
+	debugfs_create_file("enable_ifindex", 0200, hwstats->l3_ddir, hwstats,
 			    &nsim_dev_hwstats_l3_enable_fops.fops);
-	debugfs_create_file("disable_ifindex", 0600, hwstats->l3_ddir, hwstats,
+	debugfs_create_file("disable_ifindex", 0200, hwstats->l3_ddir, hwstats,
 			    &nsim_dev_hwstats_l3_disable_fops.fops);
-	debugfs_create_file("fail_next_enable", 0600, hwstats->l3_ddir, hwstats,
+	debugfs_create_file("fail_next_enable", 0200, hwstats->l3_ddir, hwstats,
 			    &nsim_dev_hwstats_l3_fail_fops.fops);
 
 	INIT_DELAYED_WORK(&hwstats->traffic_dw,

-- 
2.37.1

Ido Schimmel [off-list ref] writes:

The hwstats debugfs files are only writeable, but they are created with
read and write permissions, causing certain selftests to fail [1].

Fix by creating the files with write permission only.

[1]
 # ./test_offload.py
 Test destruction of generic XDP...
 Traceback (most recent call last):
   File "/home/idosch/code/linux/tools/testing/selftests/bpf/./test_offload.py", line 810, in <module>
     simdev = NetdevSimDev()
 [...]
 Exception: Command failed: cat /sys/kernel/debug/netdevsim/netdevsim0//ports/0/dev/hwstats/l3/disable_ifindex

 cat: /sys/kernel/debug/netdevsim/netdevsim0//ports/0/dev/hwstats/l3/disable_ifindex: Invalid argument

Fixes: 1a6d7ae7d63c ("netdevsim: Introduce support for L3 offload xstats")
Reported-by: Jie2x Zhou <redacted>
Tested-by: Jie2x Zhou <redacted>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>

Reviewed-by: Petr Machata <petrm@nvidia.com>

Hello:

This patch was applied to netdev/net.git (master)
by Jakub Kicinski [off-list ref]:

On Fri,  9 Sep 2022 18:38:30 +0300 you wrote:

The hwstats debugfs files are only writeable, but they are created with
read and write permissions, causing certain selftests to fail [1].

Fix by creating the files with write permission only.

[1]
 # ./test_offload.py
 Test destruction of generic XDP...
 Traceback (most recent call last):
   File "/home/idosch/code/linux/tools/testing/selftests/bpf/./test_offload.py", line 810, in <module>
     simdev = NetdevSimDev()
 [...]
 Exception: Command failed: cat /sys/kernel/debug/netdevsim/netdevsim0//ports/0/dev/hwstats/l3/disable_ifindex

[...]

Here is the summary with links:
  - [net] netdevsim: Fix hwstats debugfs file permissions
    https://git.kernel.org/netdev/net/c/34513ada53eb

You are awesome, thank you!
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