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From:   Christian Brauner <christian.brauner@ubuntu.com>
To:     =?UTF-8?q?St=C3=A9phane=20Graber?= <stgraber@ubuntu.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
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Cc:     smbarber@chromium.org, Seth Forshee <seth.forshee@canonical.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Serge Hallyn <serge@hallyn.com>,
        James Morris <jmorris@namei.org>,
        Kees Cook <keescook@chromium.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Phil Estes <estesp@gmail.com>, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org,
        containers@lists.linux-foundation.org,
        linux-security-module@vger.kernel.org, linux-api@vger.kernel.org,
        Christian Brauner <christian.brauner@ubuntu.com>
Subject: [PATCH v2 24/28] commoncap: cap_task_fix_setuid(): handle fsid mappings
Date:   Fri, 14 Feb 2020 19:35:50 +0100
Message-Id: <20200214183554.1133805-25-christian.brauner@ubuntu.com>
In-Reply-To: <20200214183554.1133805-1-christian.brauner@ubuntu.com>
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Switch cap_task_fix_setuid() to lookup fsids in the fsid mappings. If no fsid
mappings are setup the behavior is unchanged, i.e. fsids are looked up in the
id mappings.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
/* v2 */
unchanged
---
 security/commoncap.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/security/commoncap.c b/security/commoncap.c
index 9641695d8383..0581c6aa8bdc 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -24,6 +24,7 @@
 #include <linux/user_namespace.h>
 #include <linux/binfmts.h>
 #include <linux/personality.h>
+#include <linux/fsuidgid.h>
 
 /*
  * If a non-root user executes a setuid-root binary in
@@ -1061,7 +1062,7 @@ int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags)
 		 *          if not, we might be a bit too harsh here.
 		 */
 		if (!issecure(SECURE_NO_SETUID_FIXUP)) {
-			kuid_t root_uid = make_kuid(old->user_ns, 0);
+			kuid_t root_uid = make_kfsuid(old->user_ns, 0);
 			if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid))
 				new->cap_effective =
 					cap_drop_fs_set(new->cap_effective);
-- 
2.25.0