From: Christian Brauner <brauner@kernel.org>
Date: Fri, 30 Sep 2022 13:02:52 +0000 (+0200)
Subject: namespace-util: add in_same_namespace()
X-Git-Tag: v252-rc1~13^2~2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2fe299a320757bf5a3e0362a00e570d3bf713eab;p=thirdparty%2Fsystemd.git

namespace-util: add in_same_namespace()

Add a helper for the canonical way to determine whether two namespaces
are identical.
---

diff --git a/src/basic/namespace-util.c b/src/basic/namespace-util.c
index b330e2a11d1..a87a875943c 100644
--- a/src/basic/namespace-util.c
+++ b/src/basic/namespace-util.c
@@ -236,3 +236,27 @@ int userns_acquire(const char *uid_map, const char *gid_map) {
         return TAKE_FD(userns_fd);
 
 }
+
+int in_same_namespace(pid_t pid1, pid_t pid2, NamespaceType type) {
+        const char *ns_path;
+        struct stat ns_st1, ns_st2;
+
+        if (pid1 == 0)
+                pid1 = getpid_cached();
+
+        if (pid2 == 0)
+                pid2 = getpid_cached();
+
+        if (pid1 == pid2)
+                return 1;
+
+        ns_path = pid_namespace_path(pid1, type);
+        if (stat(ns_path, &ns_st1) < 0)
+                return -errno;
+
+        ns_path = pid_namespace_path(pid2, type);
+        if (stat(ns_path, &ns_st2) < 0)
+                return -errno;
+
+        return stat_inode_same(&ns_st1, &ns_st2);
+}
diff --git a/src/basic/namespace-util.h b/src/basic/namespace-util.h
index 5c1912985d8..be5b2281d3c 100644
--- a/src/basic/namespace-util.h
+++ b/src/basic/namespace-util.h
@@ -45,3 +45,4 @@ static inline bool userns_shift_range_valid(uid_t shift, uid_t range) {
 }
 
 int userns_acquire(const char *uid_map, const char *gid_map);
+int in_same_namespace(pid_t pid1, pid_t pid2, NamespaceType type);