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;
 }