linux-kernel - [PATCH v2 13/25] smack: add hooks for fscaps operations

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Message-Id: <20240221-idmap-fscap-refactor-v2-13-3039364623bd@kernel.org>
Date: Wed, 21 Feb 2024 15:24:44 -0600
From: "Seth Forshee (DigitalOcean)" <sforshee@...nel.org>
To: Christian Brauner <brauner@...nel.org>, 
 Seth Forshee <sforshee@...nel.org>, Serge Hallyn <serge@...lyn.com>, 
 Paul Moore <paul@...l-moore.com>, Eric Paris <eparis@...hat.com>, 
 James Morris <jmorris@...ei.org>, Alexander Viro <viro@...iv.linux.org.uk>, 
 Jan Kara <jack@...e.cz>, Stephen Smalley <stephen.smalley.work@...il.com>, 
 Ondrej Mosnacek <omosnace@...hat.com>, 
 Casey Schaufler <casey@...aufler-ca.com>, Mimi Zohar <zohar@...ux.ibm.com>, 
 Roberto Sassu <roberto.sassu@...wei.com>, 
 Dmitry Kasatkin <dmitry.kasatkin@...il.com>, 
 Eric Snowberg <eric.snowberg@...cle.com>, 
 "Matthew Wilcox (Oracle)" <willy@...radead.org>, 
 Jonathan Corbet <corbet@....net>, Miklos Szeredi <miklos@...redi.hu>, 
 Amir Goldstein <amir73il@...il.com>
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, 
 linux-security-module@...r.kernel.org, audit@...r.kernel.org, 
 selinux@...r.kernel.org, linux-integrity@...r.kernel.org, 
 linux-doc@...r.kernel.org, linux-unionfs@...r.kernel.org
Subject: [PATCH v2 13/25] smack: add hooks for fscaps operations

Add hooks for set/get/remove fscaps operations which perform the same
checks as the xattr hooks would have done for XATTR_NAME_CAPS.

Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@...nel.org>
---
 security/smack/smack_lsm.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 0fdbf04cc258..1eaa89dede6b 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -1530,6 +1530,74 @@ static int smack_inode_remove_acl(struct mnt_idmap *idmap,
 	return rc;
 }
 
+/**
+ * smack_inode_set_fscaps - Smack check for setting file capabilities
+ * @mnt_userns: the userns attached to the source mnt for this request
+ * @detry: the object
+ * @caps: the file capabilities
+ * @flags: unused
+ *
+ * Returns 0 if the access is permitted, or an error code otherwise.
+ */
+static int smack_inode_set_fscaps(struct mnt_idmap *idmap,
+				  struct dentry *dentry,
+				  const struct vfs_caps *caps, int flags)
+{
+	struct smk_audit_info ad;
+	int rc;
+
+	smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_DENTRY);
+	smk_ad_setfield_u_fs_path_dentry(&ad, dentry);
+	rc = smk_curacc(smk_of_inode(d_backing_inode(dentry)), MAY_WRITE, &ad);
+	rc = smk_bu_inode(d_backing_inode(dentry), MAY_WRITE, rc);
+	return rc;
+}
+
+/**
+ * smack_inode_get_fscaps - Smack check for getting file capabilities
+ * @dentry: the object
+ *
+ * Returns 0 if access is permitted, an error code otherwise
+ */
+static int smack_inode_get_fscaps(struct mnt_idmap *idmap,
+				  struct dentry *dentry)
+{
+	struct smk_audit_info ad;
+	int rc;
+
+	smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_DENTRY);
+	smk_ad_setfield_u_fs_path_dentry(&ad, dentry);
+
+	rc = smk_curacc(smk_of_inode(d_backing_inode(dentry)), MAY_READ, &ad);
+	rc = smk_bu_inode(d_backing_inode(dentry), MAY_READ, rc);
+	return rc;
+}
+
+/**
+ * smack_inode_remove_acl - Smack check for removing file capabilities
+ * @idmap: idmap of the mnt this request came from
+ * @dentry: the object
+ *
+ * Returns 0 if access is permitted, an error code otherwise
+ */
+static int smack_inode_remove_fscaps(struct mnt_idmap *idmap,
+				     struct dentry *dentry)
+{
+	struct smk_audit_info ad;
+	int rc;
+
+	rc = cap_inode_removexattr(idmap, dentry, XATTR_NAME_CAPS);
+	if (rc != 0)
+		return rc;
+
+	smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_DENTRY);
+	smk_ad_setfield_u_fs_path_dentry(&ad, dentry);
+
+	rc = smk_curacc(smk_of_inode(d_backing_inode(dentry)), MAY_WRITE, &ad);
+	rc = smk_bu_inode(d_backing_inode(dentry), MAY_WRITE, rc);
+	return rc;
+}
+
 /**
  * smack_inode_getsecurity - get smack xattrs
  * @idmap: idmap of the mount
@@ -5045,6 +5113,9 @@ static struct security_hook_list smack_hooks[] __ro_after_init = {
 	LSM_HOOK_INIT(inode_set_acl, smack_inode_set_acl),
 	LSM_HOOK_INIT(inode_get_acl, smack_inode_get_acl),
 	LSM_HOOK_INIT(inode_remove_acl, smack_inode_remove_acl),
+	LSM_HOOK_INIT(inode_set_fscaps, smack_inode_set_fscaps),
+	LSM_HOOK_INIT(inode_get_fscaps, smack_inode_get_fscaps),
+	LSM_HOOK_INIT(inode_remove_fscaps, smack_inode_remove_fscaps),
 	LSM_HOOK_INIT(inode_getsecurity, smack_inode_getsecurity),
 	LSM_HOOK_INIT(inode_setsecurity, smack_inode_setsecurity),
 	LSM_HOOK_INIT(inode_listsecurity, smack_inode_listsecurity),

-- 
2.43.0