From patchwork Wed Dec 18 04:47:07 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 13913014 X-Patchwork-Delegate: bpf@iogearbox.net Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5EFE535974; Wed, 18 Dec 2024 04:47:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734497258; cv=none; b=bLRnztc/1VFjgCERbfA8GzeCu+76DezmAI9oV0p1pG2KLxhIqS4LsOiyMeXf7oIJp+Cz/UZVrOpGaW5lc72k0uOXCvftNt1eb70+jQ1U9JnlWH+BE8ORvpe9VgVMRgIAhA70ZOjeRMjJPSKVtWge6BNqD1NW+ezDk1jHEIHJsdU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734497258; c=relaxed/simple; bh=IJFC1v25WWLbFn6yORvMGUMUMr97ljm73SJMJjYoIY8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Jk9CfaiG2+BJW2YLruaJlKHruJlhfPCAd8FkbuCRBliSKiPMsXq7mPCD1+NIN9RYDFL1DpOgtVtThuu48tajHgyOBozMed/3BjWcif9gN3mp7/dgBw9bPrqj6DKLw3r3pshfWMKp4nEBfx4u+Eilp6AD2awiV5D0uGu9UYYeogg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=SnZ0wKBA; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="SnZ0wKBA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7D488C4CECE; Wed, 18 Dec 2024 04:47:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1734497258; bh=IJFC1v25WWLbFn6yORvMGUMUMr97ljm73SJMJjYoIY8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SnZ0wKBA1IKlymLA+JwjVn5H8Q8hnhn6ZHMIZm8tmv/MLvJTPqlU4ELYMOMzf8L/i 2mJy6Lif+DkFMYQJlCKwFZIzWEFiodbRcZHV7tdnIhqVjl1/rN12S1M+Scose5G5Uo QFKhBVcA4MqmMvtz1mdgEHFcLoq4ZfekPm2N/99ocuBuq5mnoW6cPwKqx5+n5nhX3+ IQrsja1WRGHomHU/KhJrCjvAdGIvfT6gBpWhbuuHSFDCx1bDsjW4KIWhZf7O05E/V9 Kd2SoU9569NmrKUrql64tIQFWAiOvmUCLY7fihXr6LZ7QoxO5KtN5b5Jo4V7eKxTrR XWWE8Ymuwnr1g== From: Song Liu To: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org Cc: kernel-team@meta.com, andrii@kernel.org, ast@kernel.org, daniel@iogearbox.net, martin.lau@linux.dev, kpsingh@kernel.org, mattbobrowski@google.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, memxor@gmail.com, Song Liu , Christian Brauner Subject: [PATCH v5 bpf-next 1/5] fs/xattr: bpf: Introduce security.bpf. xattr name prefix Date: Tue, 17 Dec 2024 20:47:07 -0800 Message-ID: <20241218044711.1723221-2-song@kernel.org> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20241218044711.1723221-1-song@kernel.org> References: <20241218044711.1723221-1-song@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net Introduct new xattr name prefix security.bpf., and enable reading these xattrs from bpf kfuncs bpf_get_[file|dentry]_xattr(). As we are on it, correct the comments for return value of bpf_get_[file|dentry]_xattr(), i.e. return length the xattr value on success. Signed-off-by: Song Liu Acked-by: Christian Brauner --- fs/bpf_fs_kfuncs.c | 19 ++++++++++++++----- include/uapi/linux/xattr.h | 4 ++++ 2 files changed, 18 insertions(+), 5 deletions(-) diff --git a/fs/bpf_fs_kfuncs.c b/fs/bpf_fs_kfuncs.c index 3fe9f59ef867..8a65184c8c2c 100644 --- a/fs/bpf_fs_kfuncs.c +++ b/fs/bpf_fs_kfuncs.c @@ -93,6 +93,11 @@ __bpf_kfunc int bpf_path_d_path(struct path *path, char *buf, size_t buf__sz) return len; } +static bool match_security_bpf_prefix(const char *name__str) +{ + return !strncmp(name__str, XATTR_NAME_BPF_LSM, XATTR_NAME_BPF_LSM_LEN); +} + /** * bpf_get_dentry_xattr - get xattr of a dentry * @dentry: dentry to get xattr from @@ -101,9 +106,10 @@ __bpf_kfunc int bpf_path_d_path(struct path *path, char *buf, size_t buf__sz) * * Get xattr *name__str* of *dentry* and store the output in *value_ptr*. * - * For security reasons, only *name__str* with prefix "user." is allowed. + * For security reasons, only *name__str* with prefix "user." or + * "security.bpf." is allowed. * - * Return: 0 on success, a negative value on error. + * Return: length of the xattr value on success, a negative value on error. */ __bpf_kfunc int bpf_get_dentry_xattr(struct dentry *dentry, const char *name__str, struct bpf_dynptr *value_p) @@ -117,7 +123,9 @@ __bpf_kfunc int bpf_get_dentry_xattr(struct dentry *dentry, const char *name__st if (WARN_ON(!inode)) return -EINVAL; - if (strncmp(name__str, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) + /* Allow reading xattr with user. and security.bpf. prefix */ + if (strncmp(name__str, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN) && + !match_security_bpf_prefix(name__str)) return -EPERM; value_len = __bpf_dynptr_size(value_ptr); @@ -139,9 +147,10 @@ __bpf_kfunc int bpf_get_dentry_xattr(struct dentry *dentry, const char *name__st * * Get xattr *name__str* of *file* and store the output in *value_ptr*. * - * For security reasons, only *name__str* with prefix "user." is allowed. + * For security reasons, only *name__str* with prefix "user." or + * "security.bpf." is allowed. * - * Return: 0 on success, a negative value on error. + * Return: length of the xattr value on success, a negative value on error. */ __bpf_kfunc int bpf_get_file_xattr(struct file *file, const char *name__str, struct bpf_dynptr *value_p) diff --git a/include/uapi/linux/xattr.h b/include/uapi/linux/xattr.h index 9854f9cff3c6..c7c85bb504ba 100644 --- a/include/uapi/linux/xattr.h +++ b/include/uapi/linux/xattr.h @@ -83,6 +83,10 @@ struct xattr_args { #define XATTR_CAPS_SUFFIX "capability" #define XATTR_NAME_CAPS XATTR_SECURITY_PREFIX XATTR_CAPS_SUFFIX +#define XATTR_BPF_LSM_SUFFIX "bpf." +#define XATTR_NAME_BPF_LSM (XATTR_SECURITY_PREFIX XATTR_BPF_LSM_SUFFIX) +#define XATTR_NAME_BPF_LSM_LEN (sizeof(XATTR_NAME_BPF_LSM) - 1) + #define XATTR_POSIX_ACL_ACCESS "posix_acl_access" #define XATTR_NAME_POSIX_ACL_ACCESS XATTR_SYSTEM_PREFIX XATTR_POSIX_ACL_ACCESS #define XATTR_POSIX_ACL_DEFAULT "posix_acl_default"