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Subject: [PATCH 12/38] vfs: Pass key and value into LSM and FS and provide a
 helper parser [ver #10]
From:   David Howells <dhowells@redhat.com>
To:     viro@zeniv.linux.org.uk
Cc:     torvalds@linux-foundation.org, dhowells@redhat.com,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Fri, 27 Jul 2018 18:32:44 +0100
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Note: I've put some test code in the AFS filesystem that needs taking back
out.
---

 security/apparmor/lsm.c |   33 +++++++++++++++++++++++++++++----
 1 file changed, 29 insertions(+), 4 deletions(-)

diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 9a5915dffbdc..c52a87b0447d 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -553,15 +553,35 @@ static void apparmor_fs_context_free(struct fs_context *fc)
  * to pass them to the DFA evaluator *after* mount point parameters, which
  * means deferring the entire check to the sb_mountpoint hook.
  */
-static int apparmor_fs_context_parse_option(struct fs_context *fc, char *opt, size_t len)
+static int apparmor_fs_context_parse_option(struct fs_context *fc, const char *key,
+					    enum fs_value_type v_type,
+					    void *value, size_t v_len)
 {
 	struct apparmor_fs_context *afc = fc->security;
-	size_t space = 0;
+	size_t space = 0, k_len = strlen(key), len = k_len;
 	char *p, *q;
 
 	if (afc->saved_size > 0)
 		space = 1;
 
+	switch (v_type) {
+	case fs_value_is_string:
+		len += 1 + v_len;
+		break;
+	case fs_value_is_path:
+	case fs_value_is_path_empty: {
+		struct filename *f = value;
+		value = (char *)f->name;
+		v_len = strlen(f->name);
+		len += 1 + v_len;
+		break;
+	}
+	default:
+		value = NULL;
+		v_len = 0;
+		break;
+	}
+
 	p = krealloc(afc->saved_options, afc->saved_size + space + len + 1, GFP_KERNEL);
 	if (!p)
 		return -ENOMEM;
@@ -569,8 +589,13 @@ static int apparmor_fs_context_parse_option(struct fs_context *fc, char *opt, si
 	q = p + afc->saved_size;
 	if (q != p)
 		*q++ = ' ';
-	memcpy(q, opt, len);
-	q += len;
+	memcpy(q, key, k_len);
+	q += k_len;
+	if (value) {
+		*q++ = '=';
+		memcpy(q, value, v_len);
+		q += v_len;
+	}
 	*q = 0;
 
 	afc->saved_options = p;