perf symbols: Check kptr_restrict for root

If kptr_restrict is set to 2, even root is not allowed to see pointers.
This patch checks kptr_restrict even if euid == 0. For root, report
error if kptr_restrict is 2.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1464081688-167940-1-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 8 insertions, 8 deletions

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 20f9cb32b703..54c4ff2b1cee 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1933,17 +1933,17 @@ int setup_intlist(struct intlist **list, const char *list_str,
 static bool symbol__read_kptr_restrict(void)
 {
         bool value = false;
+        FILE *fp = fopen("/proc/sys/kernel/kptr_restrict", "r");
 
-        if (geteuid() != 0) {
-                FILE *fp = fopen("/proc/sys/kernel/kptr_restrict", "r");
-                if (fp != NULL) {
-                        char line[8];
+        if (fp != NULL) {
+                char line[8];
 
-                        if (fgets(line, sizeof(line), fp) != NULL)
-                                value = atoi(line) != 0;
+                if (fgets(line, sizeof(line), fp) != NULL)
+                        value = (geteuid() != 0) ?
+                                        (atoi(line) != 0) :
+                                        (atoi(line) == 2);
 
-                        fclose(fp);
-                }
+                fclose(fp);
         }
 
         return value;