From: Christian Brauner <christian.brauner@ubuntu.com>
Date: Sun, 9 Sep 2018 10:46:00 +0000 (+0200)
Subject: utils: improve get_ns_uid() and add get_ns_gid()
X-Git-Tag: lxc-3.1.0~115^2~6
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b962868f4ca36b80dcc7bc4681586da0178eae0d;p=thirdparty%2Flxc.git

utils: improve get_ns_uid() and add get_ns_gid()

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---

diff --git a/src/lxc/cgroups/cgfsng.c b/src/lxc/cgroups/cgfsng.c
index 1fe561498..c37456b92 100644
--- a/src/lxc/cgroups/cgfsng.c
+++ b/src/lxc/cgroups/cgfsng.c
@@ -1388,6 +1388,8 @@ static int chown_cgroup_wrapper(void *data)
 	}
 
 	destuid = get_ns_uid(arg->origuid);
+	if (destuid == LXC_INVALID_UID)
+		destuid = 0;
 
 	for (i = 0; arg->hierarchies[i]; i++) {
 		char *fullpath;
diff --git a/src/lxc/macro.h b/src/lxc/macro.h
index d44e2f9b1..c0a50371d 100644
--- a/src/lxc/macro.h
+++ b/src/lxc/macro.h
@@ -340,4 +340,7 @@ extern int __build_bug_on_failed;
 #define PTR_TO_INTMAX(p) ((intmax_t)((intptr_t)(p)))
 #define INTMAX_TO_PTR(u) ((void *)((intptr_t)(u)))
 
+#define LXC_INVALID_UID ((uid_t)-1)
+#define LXC_INVALID_GID ((gid_t)-1)
+
 #endif /* __LXC_MACRO_H */
diff --git a/src/lxc/utils.c b/src/lxc/utils.c
index 9795b51b6..b85383a42 100644
--- a/src/lxc/utils.c
+++ b/src/lxc/utils.c
@@ -544,7 +544,34 @@ uid_t get_ns_uid(uid_t orig)
 		}
 	}
 
-	nsid = 0;
+	nsid = LXC_INVALID_UID;
+
+found:
+	fclose(f);
+	free(line);
+	return nsid;
+}
+
+gid_t get_ns_gid(gid_t orig)
+{
+	char *line = NULL;
+	size_t sz = 0;
+	gid_t nsid, hostid, range;
+	FILE *f = fopen("/proc/self/gid_map", "r");
+	if (!f)
+		return 0;
+
+	while (getline(&line, &sz, f) != -1) {
+		if (sscanf(line, "%u %u %u", &nsid, &hostid, &range) != 3)
+			continue;
+
+		if (hostid <= orig && hostid + range > orig) {
+			nsid += orig - hostid;
+			goto found;
+		}
+	}
+
+	nsid = LXC_INVALID_GID;
 
 found:
 	fclose(f);
diff --git a/src/lxc/utils.h b/src/lxc/utils.h
index f2d802991..51cfe4c85 100644
--- a/src/lxc/utils.h
+++ b/src/lxc/utils.h
@@ -328,6 +328,10 @@ inline static bool am_host_unpriv(void)
  * parse /proc/self/uid_map to find what @orig maps to
  */
 extern uid_t get_ns_uid(uid_t orig);
+/*
+ * parse /proc/self/gid_map to find what @orig maps to
+ */
+extern gid_t get_ns_gid(gid_t orig);
 
 extern bool dir_exists(const char *path);