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[RFC,v2,2/2] kernel/ksysfs.c: Add capabilities attribute.

Message ID 20220117141254.46278-3-flaniel@linux.microsoft.com (mailing list archive)
State New, archived
Headers show
Series Add capabilities file to sysfs | expand

Commit Message

Francis Laniel Jan. 17, 2022, 2:12 p.m. UTC 
This new read-only attribute prints the capabilities values with their names:
0       CAP_CHOWN
1       CAP_DAC_OVERRIDE
...
39      CAP_BPF

Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
---
 kernel/ksysfs.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
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Patch

diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index 35859da8bd4f..7d39794a55bc 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -182,6 +182,23 @@  static ssize_t rcu_normal_store(struct kobject *kobj,
 KERNEL_ATTR_RW(rcu_normal);
 #endif /* #ifndef CONFIG_TINY_RCU */
 
+static ssize_t capabilities_show(struct kobject *unused0,
+				struct kobj_attribute *unused1, char *buf)
+{
+	int at = 0;
+	int i;
+
+	for (i = 0; i < CAP_LAST_CAP; i++) {
+		if (at >= PAGE_SIZE)
+			return at;
+
+		at += sysfs_emit_at(buf, at, "%d\t%s\n", i, cap_strings[i]);
+	}
+
+	return at;
+}
+KERNEL_ATTR_RO(capabilities);
+
 /*
  * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
  */
@@ -229,6 +246,7 @@  static struct attribute * kernel_attrs[] = {
 	&rcu_expedited_attr.attr,
 	&rcu_normal_attr.attr,
 #endif
+	&capabilities_attr.attr,
 	NULL
 };