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Subject: [PATCH 14/25] fsinfo: Support Smack superblock parameter retrieval
 [ver #13]
From:   David Howells <dhowells@redhat.com>
To:     viro@zeniv.linux.org.uk
Cc:     dhowells@redhat.com, raven@themaw.net, linux-api@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        mszeredi@redhat.com
Date:   Tue, 28 May 2019 16:13:00 +0100
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Add support to Smack for retrieval of the superblock parameters.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 security/smack/smack_lsm.c |   43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 0de725f88bed..0a1e88d50ad3 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -45,6 +45,7 @@
 #include <linux/parser.h>
 #include <linux/fs_context.h>
 #include <linux/fs_parser.h>
+#include <linux/fsinfo.h>
 #include "smack.h"
 
 #define TRANS_TRUE	"TRUE"
@@ -893,6 +894,45 @@ static int smack_sb_statfs(struct dentry *dentry)
 	return rc;
 }
 
+#ifdef CONFIG_FSINFO
+/*
+ * Retrieve the Smack filesystem information, including mount parameters.
+ */
+static int smack_sb_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+	struct superblock_smack *sp = path->dentry->d_sb->s_security;
+
+	switch (params->request) {
+	case FSINFO_ATTR_LSM_PARAMETERS: {
+		struct dentry *root = path->dentry->d_sb->s_root;
+		struct inode *inode = d_backing_inode(root);
+		struct inode_smack *isp = inode->i_security;
+
+		if (sp->smk_flags & SMK_SB_INITIALIZED)
+			return 0;
+		if (sp->smk_floor)
+			fsinfo_note_param(params, "fsfloor", sp->smk_floor->smk_known);
+		if (sp->smk_hat)
+			fsinfo_note_param(params, "fshat", sp->smk_hat->smk_known);
+		if (sp->smk_default)
+			fsinfo_note_param(params, "fsdefault", sp->smk_default->smk_known);
+
+		if (sp->smk_root) {
+			if (isp && isp->smk_flags & SMK_INODE_TRANSMUTE)
+				fsinfo_note_param(params, "fstransmute", sp->smk_root->smk_known);
+			else
+				fsinfo_note_param(params, "fsroot", sp->smk_root->smk_known);
+		}
+		return params->usage;
+	}
+
+	default:
+		return -ENODATA;
+	}
+	return 0;
+}
+#endif
+
 /*
  * BPRM hooks
  */
@@ -4606,6 +4646,9 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(sb_free_mnt_opts, smack_free_mnt_opts),
 	LSM_HOOK_INIT(sb_eat_lsm_opts, smack_sb_eat_lsm_opts),
 	LSM_HOOK_INIT(sb_statfs, smack_sb_statfs),
+#ifdef CONFIG_FSINFO
+	LSM_HOOK_INIT(sb_fsinfo, smack_sb_fsinfo),
+#endif
 	LSM_HOOK_INIT(sb_set_mnt_opts, smack_set_mnt_opts),
 
 	LSM_HOOK_INIT(bprm_set_creds, smack_bprm_set_creds),