linux-kernel - [PATCH RFC 3/4] device_cgroup: wrapper for bpf cgroup device guard

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Message-Id: <20230814-devcg_guard-v1-3-654971ab88b1@aisec.fraunhofer.de>
Date:   Mon, 14 Aug 2023 16:26:11 +0200
From:   Michael Weiß <michael.weiss@...ec.fraunhofer.de>
To:     Alexander Mikhalitsyn <alexander@...alicyn.com>,
        Christian Brauner <brauner@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
        Quentin Monnet <quentin@...valent.com>,
        Alexander Viro <viro@...iv.linux.org.uk>
Cc:     bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, gyroidos@...ec.fraunhofer.de,
        Michael Weiß <michael.weiss@...ec.fraunhofer.de>
Subject: [PATCH RFC 3/4] device_cgroup: wrapper for bpf cgroup device guard

Export the bpf based cgroup guard through device_cgroup to others.
Thus, devcgroup_task_is_guarded() could be used by subsystems
which already make use of device_cgroup features, such as fs/namei.

Signed-off-by: Michael Weiß <michael.weiss@...ec.fraunhofer.de>
---
 include/linux/device_cgroup.h |  7 +++++++
 security/device_cgroup.c      | 10 ++++++++++
 2 files changed, 17 insertions(+)

diff --git a/include/linux/device_cgroup.h b/include/linux/device_cgroup.h
index d02f32b7514e..00c0748b6a8d 100644
--- a/include/linux/device_cgroup.h
+++ b/include/linux/device_cgroup.h
@@ -65,3 +65,10 @@ static inline int devcgroup_inode_permission(struct inode *inode, int mask)
 static inline int devcgroup_inode_mknod(int mode, dev_t dev)
 { return 0; }
 #endif
+
+#ifdef CONFIG_CGROUP_BPF
+bool devcgroup_task_is_guarded(struct task_struct *task);
+#else
+static inline bool devcgroup_task_is_guarded(struct task_struct *task)
+{ return false; }
+#endif /* CONFIG_CGROUP_BPF */
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index dc4df7475081..95200a3d0b63 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -874,3 +874,13 @@ int devcgroup_check_permission(short type, u32 major, u32 minor, short access)
 }
 EXPORT_SYMBOL(devcgroup_check_permission);
 #endif /* defined(CONFIG_CGROUP_DEVICE) || defined(CONFIG_CGROUP_BPF) */
+
+#ifdef CONFIG_CGROUP_BPF
+
+bool devcgroup_task_is_guarded(struct task_struct *task)
+{
+	return (cgroup_bpf_enabled(CGROUP_DEVICE) &&
+		cgroup_bpf_device_guard_enabled(task));
+}
+EXPORT_SYMBOL(devcgroup_task_is_guarded);
+#endif /* CONFIG_CGROUP_BPF */

-- 
2.30.2