1 files changed, 47 insertions, 2 deletions

diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 127e7cfafa55..51b49ed452e4 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -480,6 +480,7 @@ struct kallsym_iter {
 	char name[KSYM_NAME_LEN];
 	char module_name[MODULE_NAME_LEN];
 	int exported;
+	int show_value;
 };
 
 static int get_ksymbol_mod(struct kallsym_iter *iter)
@@ -580,14 +581,23 @@ static void s_stop(struct seq_file *m, void *p)
 {
 }
 
+#ifndef CONFIG_64BIT
+# define KALLSYM_FMT "%08lx"
+#else
+# define KALLSYM_FMT "%016lx"
+#endif
+
 static int s_show(struct seq_file *m, void *p)
 {
+	unsigned long value;
 	struct kallsym_iter *iter = m->private;
 
 	/* Some debugging symbols have no name.  Ignore them. */
 	if (!iter->name[0])
 		return 0;
 
+	value = iter->show_value ? iter->value : 0;
+
 	if (iter->module_name[0]) {
 		char type;
 
@@ -597,10 +607,10 @@ static int s_show(struct seq_file *m, void *p)
 		 */
 		type = iter->exported ? toupper(iter->type) :
 					tolower(iter->type);
-		seq_printf(m, "%pK %c %s\t[%s]\n", (void *)iter->value,
+		seq_printf(m, KALLSYM_FMT " %c %s\t[%s]\n", value,
 			   type, iter->name, iter->module_name);
 	} else
-		seq_printf(m, "%pK %c %s\n", (void *)iter->value,
+		seq_printf(m, KALLSYM_FMT " %c %s\n", value,
 			   iter->type, iter->name);
 	return 0;
 }
@@ -612,6 +622,40 @@ static const struct seq_operations kallsyms_op = {
 	.show = s_show
 };
 
+static inline int kallsyms_for_perf(void)
+{
+#ifdef CONFIG_PERF_EVENTS
+	extern int sysctl_perf_event_paranoid;
+	if (sysctl_perf_event_paranoid <= 1)
+		return 1;
+#endif
+	return 0;
+}
+
+/*
+ * We show kallsyms information even to normal users if we've enabled
+ * kernel profiling and are explicitly not paranoid (so kptr_restrict
+ * is clear, and sysctl_perf_event_paranoid isn't set).
+ *
+ * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to
+ * block even that).
+ */
+static int kallsyms_show_value(void)
+{
+	switch (kptr_restrict) {
+	case 0:
+		if (kallsyms_for_perf())
+			return 1;
+	/* fallthrough */
+	case 1:
+		if (has_capability_noaudit(current, CAP_SYSLOG))
+			return 1;
+	/* fallthrough */
+	default:
+		return 0;
+	}
+}
+
 static int kallsyms_open(struct inode *inode, struct file *file)
 {
 	/*
@@ -625,6 +669,7 @@ static int kallsyms_open(struct inode *inode, struct file *file)
 		return -ENOMEM;
 	reset_iter(iter, 0);
 
+	iter->show_value = kallsyms_show_value();
 	return 0;
 }