[tip: irq/core] genirq/procfs: 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:     92f9d825b12fa3f6c14b42405489880d0694c96f
Gitweb:        https://git.kernel.org/tip/92f9d825b12fa3f6c14b42405489880d0694c96f
Author:        Jeff Xie <jeff.xie@xxxxxxxxx>
AuthorDate:    Sun, 25 Aug 2024 21:19:11 +08:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Tue, 27 Aug 2024 13:54:15 +02:00

genirq/procfs: 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 ]

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 | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index 8cccdf4..dcf8190 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -340,6 +340,7 @@ void register_irq_proc(unsigned int irq, struct irq_desc *desc)
 	static DEFINE_MUTEX(register_lock);
 	void __maybe_unused *irqp = (void *)(unsigned long) irq;
 	char name [MAX_NAMELEN];
+	umode_t umode = S_IRUGO;
 
 	if (!root_irq_dir || (desc->irq_data.chip == &no_irq_chip))
 		return;
@@ -362,8 +363,11 @@ void register_irq_proc(unsigned int irq, struct irq_desc *desc)
 		goto out_unlock;
 
 #ifdef CONFIG_SMP
+	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 +375,7 @@ 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,