linux-kernel - [PATCH v1 1/2] landlock: Handle weird files

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Message-ID: <20250110153918.241810-1-mic@digikod.net>
Date: Fri, 10 Jan 2025 16:39:13 +0100
From: Mickaël Salaün <mic@...ikod.net>
To: Günther Noack <gnoack@...gle.com>
Cc: Mickaël Salaün <mic@...ikod.net>,
	linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	Paul Moore <paul@...l-moore.com>,
	Dave Chinner <david@...morbit.com>,
	Kent Overstreet <kent.overstreet@...ux.dev>,
	syzbot+34b68f850391452207df@...kaller.appspotmail.com,
	syzbot+360866a59e3c80510a62@...kaller.appspotmail.com,
	Ubisectech Sirius <bugreport@...sectech.com>
Subject: [PATCH v1 1/2] landlock: Handle weird files

A corrupted filesystem (e.g. bcachefs) might return weird files.
Instead of throwing a warning and allowing access to such file, treat
them as regular files.

Cc: Dave Chinner <david@...morbit.com>
Cc: Günther Noack <gnoack@...gle.com>
Cc: Kent Overstreet <kent.overstreet@...ux.dev>
Cc: Paul Moore <paul@...l-moore.com>
Reported-by: syzbot+34b68f850391452207df@...kaller.appspotmail.com
Closes: https://lore.kernel.org/r/000000000000a65b35061cffca61@google.com
Reported-by: syzbot+360866a59e3c80510a62@...kaller.appspotmail.com
Closes: https://lore.kernel.org/r/67379b3f.050a0220.85a0.0001.GAE@google.com
Reported-by: Ubisectech Sirius <bugreport@...sectech.com>
Closes: https://lore.kernel.org/r/c426821d-8380-46c4-a494-7008bbd7dd13.bugreport@ubisectech.com
Fixes: cb2c7d1a1776 ("landlock: Support filesystem access-control")
Signed-off-by: Mickaël Salaün <mic@...ikod.net>
---
 security/landlock/fs.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index e31b97a9f175..7adb25150488 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -937,10 +937,6 @@ static access_mask_t get_mode_access(const umode_t mode)
 	switch (mode & S_IFMT) {
 	case S_IFLNK:
 		return LANDLOCK_ACCESS_FS_MAKE_SYM;
-	case 0:
-		/* A zero mode translates to S_IFREG. */
-	case S_IFREG:
-		return LANDLOCK_ACCESS_FS_MAKE_REG;
 	case S_IFDIR:
 		return LANDLOCK_ACCESS_FS_MAKE_DIR;
 	case S_IFCHR:
@@ -951,9 +947,12 @@ static access_mask_t get_mode_access(const umode_t mode)
 		return LANDLOCK_ACCESS_FS_MAKE_FIFO;
 	case S_IFSOCK:
 		return LANDLOCK_ACCESS_FS_MAKE_SOCK;
+	case S_IFREG:
+	case 0:
+		/* A zero mode translates to S_IFREG. */
 	default:
-		WARN_ON_ONCE(1);
-		return 0;
+		/* Treats weird files as regular files. */
+		return LANDLOCK_ACCESS_FS_MAKE_REG;
 	}
 }
 
-- 
2.47.1