libcutils: qtaguid: support socket untagging, return errors.

  - Enable and rename qtaguid_tagSocket()
  - Add qtaguid_untagSocket()
  - Return kernel errors to caller

Change-Id: I8e33c8832b7f6b24ed9081f36ce1ea9ae6b099c0
Signed-off-by: Ashish Sharma <ashishsharma@google.com>

2 files changed, 42 insertions, 14 deletions

diff --git a/include/cutils/qtaguid.h b/include/cutils/qtaguid.h
index 8aa34ea35..e6d61e639 100644
--- a/include/cutils/qtaguid.h
+++ b/include/cutils/qtaguid.h
@@ -28,7 +28,12 @@ extern "C" {
 /*
  * Set tags (and owning UIDs) for network sockets.
 */
-extern int set_qtaguid(int sockfd, int tag, uid_t uid);
+extern int qtaguid_tagSocket(int sockfd, int tag, uid_t uid);
+
+/*
+ * Untag a network socket before closing.
+*/
+extern int qtaguid_untagSocket(int sockfd);
 
 #ifdef __cplusplus
 }
diff --git a/libcutils/qtaguid.c b/libcutils/qtaguid.c
index 517e78422..218a21f13 100644
--- a/libcutils/qtaguid.c
+++ b/libcutils/qtaguid.c
@@ -19,26 +19,49 @@
 
 #include <cutils/qtaguid.h>
 #include <cutils/log.h>
+#include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>
 
-extern int set_qtaguid(int sockfd, int tag, uid_t uid) {
+extern int qtaguid_tagSocket(int sockfd, int tag, uid_t uid) {
     char lineBuf[128];
-    int fd, cnt = 0;
+    int fd, cnt = 0, res = 0;
     uint64_t kTag = (uint64_t)tag << 32;
     snprintf(lineBuf, sizeof(lineBuf), "t %d %llu %d", sockfd, kTag, uid);
 
-    LOGV("Tagging Socket with command %s\n", lineBuf);
-    /* TODO: Enable after the kernel module is fixed.
-       fd = open("/proc/net/xt_qtaguid/ctrl", O_WRONLY);
-       if (fd < 0) {
-           return -1;
-       }
-
-       cnt = write(fd, lineBuf, strlen(lineBuf));
-       close(fd);
-    */
-    return (cnt>0?0:-1);
+    LOGI("Tagging socket %d with tag %llx(%d) for uid %d", sockfd, kTag, tag, uid);
+    fd = open("/proc/net/xt_qtaguid/ctrl", O_WRONLY);
+    if (fd < 0) {
+        return -errno;
+    }
+
+    cnt = write(fd, lineBuf, strlen(lineBuf));
+    if (cnt < 0) {
+        res = -errno;
+    }
+
+    close(fd);
+    return res;
+}
+
+extern int qtaguid_untagSocket(int sockfd) {
+    char lineBuf[128];
+    int fd, cnt = 0, res = 0;
+    snprintf(lineBuf, sizeof(lineBuf), "u %d", sockfd);
+
+    LOGI("Untagging socket %d", sockfd);
+    fd = open("/proc/net/xt_qtaguid/ctrl", O_WRONLY);
+    if (fd < 0) {
+        return -errno;
+    }
+
+    cnt = write(fd, lineBuf, strlen(lineBuf));
+    if (cnt < 0) {
+        res = -errno;
+    }
+
+    close(fd);
+    return res;
 }