[RFC PATCH 2/9] smb: client: support security.xfstests over EAs

Before checking file capabilities, generic/093 calls _require_attrs
security. This helper runs "setfattr -n security.xfstests" to check the
security xattr namespace. The security handler supports only
security.capability, so this command returns "Operation not supported".

Add security.xfstests as another exact security EA name. Keep this name
unchanged in EA lists. Continue to reject other security xattrs.

Signed-off-by: Ze Tan <[email protected]>
---
 fs/smb/client/smb2ops.c | 4 ++++
 fs/smb/client/xattr.c   | 7 ++++---
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index d58185f676a4..bfa089511b9b 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -1050,6 +1050,10 @@ static bool cifs_passthrough(const char *name, size_t name_len)
 	    !memcmp(name, XATTR_NAME_CAPS, name_len))
 		return true;
 
+	if (name_len == sizeof(XATTR_SECURITY_PREFIX "xfstests") - 1 &&
+	    !memcmp(name, XATTR_SECURITY_PREFIX "xfstests", name_len))
+		return true;
+
 	return false;
 }
 
diff --git a/fs/smb/client/xattr.c b/fs/smb/client/xattr.c
index 8fa40593bc93..42db6920901e 100644
--- a/fs/smb/client/xattr.c
+++ b/fs/smb/client/xattr.c
@@ -49,10 +49,11 @@ static int cifs_build_ea_name(int xattr_flag, const char *name, char *ea_name,
 	switch (xattr_flag) {
 	case XATTR_SECURITY:
 		/*
-		 * Only security.capability has native Linux security xattr
-		 * semantics on POSIX-capable servers.
+		 * Only security.capability and the xfstests security namespace
+		 * probe are supported on POSIX-capable servers.
 		 */
-		if (strcmp(name, XATTR_CAPS_SUFFIX))
+		if (strcmp(name, XATTR_CAPS_SUFFIX) &&
+		    strcmp(name, "xfstests"))
 			return -EOPNOTSUPP;
 		name_len = strlen(name);
 		if (ea_name_size <= XATTR_SECURITY_PREFIX_LEN ||
-- 
2.43.0