@@ -11,6 +11,7 @@
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*/
+#include <linux/debugfs.h> /* debugfs_create_u32() */
#include <linux/mm_types.h> /* mm_struct, vma, etc... */
#include <linux/pkeys.h> /* PKEY_* */
#include <uapi/asm-generic/mman-common.h>
@@ -159,3 +160,68 @@ void copy_init_pkru_to_fpregs(void)
*/
write_pkru(init_pkru_value_snapshot);
}
+
+static ssize_t init_pkru_read_file(struct file *file, char __user *user_buf,
+ size_t count, loff_t *ppos)
+{
+ char buf[32];
+ unsigned int len;
+
+ len = sprintf(buf, "0x%x\n", init_pkru_value);
+ return simple_read_from_buffer(user_buf, count, ppos, buf, len);
+}
+
+static ssize_t init_pkru_write_file(struct file *file,
+ const char __user *user_buf, size_t count, loff_t *ppos)
+{
+ char buf[32];
+ ssize_t len;
+ u32 new_init_pkru;
+
+ len = min(count, sizeof(buf) - 1);
+ if (copy_from_user(buf, user_buf, len))
+ return -EFAULT;
+
+ /* Make the buffer a valid string that we can not overrun */
+ buf[len] = '\0';
+ if (kstrtouint(buf, 0, &new_init_pkru))
+ return -EINVAL;
+
+ /*
+ * Don't allow insane settings that will blow the system
+ * up immediately if someone attempts to disable access
+ * or writes to pkey 0.
+ */
+ if (new_init_pkru & (PKRU_AD_BIT|PKRU_WD_BIT))
+ return -EINVAL;
+
+ WRITE_ONCE(init_pkru_value, new_init_pkru);
+ return count;
+}
+
+static const struct file_operations fops_init_pkru = {
+ .read = init_pkru_read_file,
+ .write = init_pkru_write_file,
+ .llseek = default_llseek,
+};
+
+static int __init create_init_pkru_value(void)
+{
+ debugfs_create_file("init_pkru", S_IRUSR | S_IWUSR,
+ arch_debugfs_dir, NULL, &fops_init_pkru);
+ return 0;
+}
+late_initcall(create_init_pkru_value);
+
+static __init int setup_init_pkru(char *opt)
+{
+ u32 new_init_pkru;
+
+ if (kstrtouint(opt, 0, &new_init_pkru))
+ return 1;
+
+ WRITE_ONCE(init_pkru_value, new_init_pkru);
+
+ return 1;
+}
+__setup("init_pkru=", setup_init_pkru);