[tip: irq/core] genirq/proc: Correctly set file permissions for affinity control files

[tip-bot2 for Jeff Xie]

The following commit has been merged into the irq/core branch of tip:

Commit-ID:     c7718e5c76d49b5bb394265383ae51f766d5dd3a
Gitweb:        https://git.kernel.org/tip/c7718e5c76d49b5bb394265383ae51f766d5dd3a
Author:        Jeff Xie <jeff.xie@xxxxxxxxx>
AuthorDate:    Sun, 25 Aug 2024 21:19:11 +08:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Thu, 29 Aug 2024 16:41:42 +02:00

genirq/proc: Correctly set file permissions for affinity control files

The kernel already knows at the time of interrupt allocation whether
affinity of an interrupt can be controlled by userspace or not.

It still creates all related procfs control files with read/write
permissions. That's inconsistent and non-intuitive for system
administrators and tools.

Therefore set the file permissions to read-only for such interrupts.

[ tglx: Massage change log, fixed UP build ]

Signed-off-by: Jeff Xie <jeff.xie@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/all/20240825131911.107119-1-jeff.xie@xxxxxxxxx
---
 kernel/irq/proc.c |  9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index 8cccdf4..9b3b12a 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -362,8 +362,13 @@ void register_irq_proc(unsigned int irq, struct irq_desc *desc)
 		goto out_unlock;
 
 #ifdef CONFIG_SMP
+	umode_t umode = S_IRUGO;
+
+	if (irq_can_set_affinity_usr(desc->irq_data.irq))
+		umode |= S_IWUSR;
+
 	/* create /proc/irq/<irq>/smp_affinity */
-	proc_create_data("smp_affinity", 0644, desc->dir,
+	proc_create_data("smp_affinity", umode, desc->dir,
 			 &irq_affinity_proc_ops, irqp);
 
 	/* create /proc/irq/<irq>/affinity_hint */
@@ -371,7 +376,7 @@ void register_irq_proc(unsigned int irq, struct irq_desc *desc)
 			irq_affinity_hint_proc_show, irqp);
 
 	/* create /proc/irq/<irq>/smp_affinity_list */
-	proc_create_data("smp_affinity_list", 0644, desc->dir,
+	proc_create_data("smp_affinity_list", umode, desc->dir,
 			 &irq_affinity_list_proc_ops, irqp);
 
 	proc_create_single_data("node", 0444, desc->dir, irq_node_proc_show,