[PATCH v3 4/6] setpriv: dump ambient capabilities

[Patrick Steinhardt]

As with the previous commit, this commit introduces the ability to dump
the set of ambient capabilities.

function                                             old     new   delta
setpriv_main                                         982    1129    +147
.rodata                                           146148  146198     +50

Signed-off-by: Patrick Steinhardt <ps at pks.im>
---
 util-linux/setpriv.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/util-linux/setpriv.c b/util-linux/setpriv.c
index a958e9a95..161ad3451 100644
--- a/util-linux/setpriv.c
+++ b/util-linux/setpriv.c
@@ -94,6 +94,11 @@
 #define PR_GET_NO_NEW_PRIVS 39
 #endif
 
+#ifndef PR_CAP_AMBIENT
+#define PR_CAP_AMBIENT 47
+#define PR_CAP_AMBIENT_IS_SET 1
+#endif
+
 enum {
 	IF_FEATURE_SETPRIV_DUMP(OPTBIT_DUMP,)
 	OPTBIT_NNP,
@@ -265,6 +270,24 @@ static int dump(void)
 	if (!n)
 		printf("[none]");
 
+	printf("\nAmbient capabilities: ");
+	fmt = ",%s" + 1;
+	for (n = 0, i = 0; cap_valid(i); i++) {
+		int ret = prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, (unsigned long) i, 0UL, 0UL);
+		if (ret < 0)
+			bb_simple_perror_msg_and_die("prctl: CAP_AMBIENT_IS_SET");
+
+		if (ret) {
+			printf(fmt, getcapname(buf, sizeof(buf), i));
+			n++;
+			fmt = ",%s";
+		}
+	}
+	if (!n && !i)
+		printf("[unsupported]");
+	else if (!n)
+		printf("[none]");
+
 	printf("\nCapability bounding set: ");
 	fmt = ",%s" + 1;
 	for (n = 0, i = 0; cap_valid(i); i++) {
-- 
2.13.2