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From: Christian Brauner <christian.brauner@ubuntu.com>
To: "Stéphane Graber" <stgraber@ubuntu.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	"Aleksa Sarai" <cyphar@cyphar.com>,
	"Jann Horn" <jannh@google.com>
Cc: smbarber@chromium.org, 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>,
	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 15/24] commoncap:cap_bprm_set_creds(): handle fsid mappings
Date: Tue, 11 Feb 2020 17:57:44 +0100	[thread overview]
Message-ID: <20200211165753.356508-16-christian.brauner@ubuntu.com> (raw)
In-Reply-To: <20200211165753.356508-1-christian.brauner@ubuntu.com>

During exec the kfsids are currently reset to the effective kids. To retain the
same semantics with the introduction of fsid mappings, we lookup the userspace
effective id in the id mappings and translate the effective id into the
corresponding kfsid in the fsidmapping. This means, the behavior is unchanged
when no fsid mappings are setup and the semantics stay the same even when fsid
mappings are setup.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
 security/commoncap.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/security/commoncap.c b/security/commoncap.c
index ecfa0d0c250e..8d1a81e98610 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -811,7 +811,10 @@ int cap_bprm_set_creds(struct linux_binprm *bprm)
 	struct cred *new = bprm->cred;
 	bool effective = false, has_fcap = false, is_setid;
 	int ret;
-	kuid_t root_uid;
+	kuid_t root_uid, kfsuid;
+	kgid_t kfsgid;
+	uid_t fsuid;
+	gid_t fsgid;
 
 	if (WARN_ON(!cap_ambient_invariant_ok(old)))
 		return -EPERM;
@@ -848,8 +851,15 @@ int cap_bprm_set_creds(struct linux_binprm *bprm)
 						   old->cap_permitted);
 	}
 
-	new->suid = new->fsuid = new->euid;
-	new->sgid = new->fsgid = new->egid;
+	fsuid = from_kuid_munged(new->user_ns, new->euid);
+	kfsuid = make_kfsuid(new->user_ns, fsuid);
+	new->suid = new->euid;
+	new->fsuid = kfsuid;
+
+	fsgid = from_kgid_munged(new->user_ns, new->egid);
+	kfsgid = make_kfsgid(new->user_ns, fsgid);
+	new->sgid = new->egid;
+	new->fsgid = kfsgid;
 
 	/* File caps or setid cancels ambient. */
 	if (has_fcap || is_setid)
-- 
2.25.0


  parent reply	other threads:[~2020-02-11 16:59 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-11 16:57 [PATCH 00/24] user_namespace: introduce " Christian Brauner
2020-02-11 16:57 ` [PATCH 01/24] user_namespace: introduce fsid mappings infrastructure Christian Brauner
2020-02-11 17:26   ` Randy Dunlap
2020-02-11 16:57 ` [PATCH 02/24] proc: add /proc/<pid>/fsuid_map Christian Brauner
2020-02-11 16:57 ` [PATCH 03/24] proc: add /proc/<pid>/fsgid_map Christian Brauner
2020-02-11 16:57 ` [PATCH 04/24] fsuidgid: add fsid mapping helpers Christian Brauner
2020-02-11 16:57 ` [PATCH 05/24] proc: task_state(): use from_kfs{g,u}id_munged Christian Brauner
2020-02-11 16:57 ` [PATCH 06/24] fs: add is_userns_visible() helper Christian Brauner
2020-02-11 16:57 ` [PATCH 07/24] namei: may_{o_}create(): handle fsid mappings Christian Brauner
2020-02-11 16:57 ` [PATCH 08/24] inode: inode_owner_or_capable(): " Christian Brauner
2020-02-11 16:57 ` [PATCH 09/24] capability: privileged_wrt_inode_uidgid(): " Christian Brauner
2020-02-11 16:57 ` [PATCH 10/24] stat: " Christian Brauner
2020-02-11 16:57 ` [PATCH 11/24] open: chown_common(): " Christian Brauner
2020-02-11 16:57 ` [PATCH 12/24] posix_acl: " Christian Brauner
2020-02-11 16:57 ` [PATCH 13/24] attr: notify_change(): " Christian Brauner
2020-02-11 16:57 ` [PATCH 14/24] commoncap: cap_task_fix_setuid(): " Christian Brauner
2020-02-11 16:57 ` Christian Brauner [this message]
2020-02-11 16:57 ` [PATCH 16/24] sys: __sys_setfsuid(): " Christian Brauner
2020-02-11 16:57 ` [PATCH 17/24] sys: __sys_setfsgid(): " Christian Brauner
2020-02-11 16:57 ` [PATCH 18/24] sys:__sys_setuid(): " Christian Brauner
2020-02-11 16:57 ` [PATCH 19/24] sys:__sys_setgid(): " Christian Brauner
2020-02-11 16:57 ` [PATCH 20/24] sys:__sys_setreuid(): " Christian Brauner
2020-02-11 16:57 ` [PATCH 21/24] sys:__sys_setregid(): " Christian Brauner
2020-02-11 16:57 ` [PATCH 22/24] sys:__sys_setresuid(): " Christian Brauner
2020-02-11 16:57 ` [PATCH 23/24] sys:__sys_setresgid(): " Christian Brauner
2020-02-11 16:57 ` [PATCH 24/24] devpts: " Christian Brauner
2020-02-11 20:55 ` [PATCH 00/24] user_namespace: introduce " Jann Horn
2020-02-12 14:51   ` Christian Brauner
2020-02-12 18:53     ` Jann Horn

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