For compatibility reason, MAY_CHROOT is always set with MAY_CHDIR.
However, this new flag enable to differentiate a chdir form a chroot.
This is needed for the Landlock LSM to be able to evaluate a new root
directory.
Signed-off-by: Mickaël Salaün <m...@digikod.net>
Cc: Alexander Viro <v...@zeniv.linux.org.uk>
Cc: Casey Schaufler <ca...@schaufler-ca.com>
Cc: James Morris <jmor...@namei.org>
Cc: John Johansen <john.johan...@canonical.com>
Cc: Kees Cook <keesc...@chromium.org>
Cc: Paul Moore <p...@paul-moore.com>
Cc: "Serge E. Hallyn" <se...@hallyn.com>
Cc: Stephen Smalley <s...@tycho.nsa.gov>
Cc: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp>
Cc: linux-fsde...@vger.kernel.org
---
fs/open.c | 3 ++-
include/linux/fs.h | 1 +
2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/open.c b/fs/open.c
index 7ea118471dce..084d147c0e96 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -489,7 +489,8 @@ SYSCALL_DEFINE1(chroot, const char __user *, filename)
if (error)
goto out;
- error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
+ error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR |
+ MAY_CHROOT);
if (error)
goto dput_and_out;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 2a815560fda0..67c62374446c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -90,6 +90,7 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
#define MAY_CHDIR 0x00000040
/* called from RCU mode, don't block */
#define MAY_NOT_BLOCK 0x00000080
+#define MAY_CHROOT 0x00000100
/*
* flags in file.f_mode. Note that FMODE_READ and FMODE_WRITE must correspond
--
2.16.2
