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authorEric W. Biederman <ebiederm@xmission.com>2015-05-08 23:22:29 -0500
committerEric W. Biederman <ebiederm@xmission.com>2015-05-13 21:44:11 -0500
commit1b852bceb0d111e510d1a15826ecc4a19358d512 (patch)
treeb7a6b015d68f3ad25f79d7197690a29e08f0e21c /fs/namespace.c
parent7e96c1b0e0f495c5a7450dc4aa7c9a24ba4305bd (diff)
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mnt: Refactor the logic for mounting sysfs and proc in a user namespace
Fresh mounts of proc and sysfs are a very special case that works very much like a bind mount. Unfortunately the current structure can not preserve the MNT_LOCK... mount flags. Therefore refactor the logic into a form that can be modified to preserve those lock bits. Add a new filesystem flag FS_USERNS_VISIBLE that requires some mount of the filesystem be fully visible in the current mount namespace, before the filesystem may be mounted. Move the logic for calling fs_fully_visible from proc and sysfs into fs/namespace.c where it has greater access to mount namespace state. Cc: stable@vger.kernel.org Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'fs/namespace.c')
-rw-r--r--fs/namespace.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/fs/namespace.c b/fs/namespace.c
index 1b9e11167bae..8e7edaf60fe1 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2332,6 +2332,8 @@ unlock:
return err;
}
+static bool fs_fully_visible(struct file_system_type *fs_type);
+
/*
* create a new mount for userspace and request it to be added into the
* namespace's tree
@@ -2363,6 +2365,10 @@ static int do_new_mount(struct path *path, const char *fstype, int flags,
flags |= MS_NODEV;
mnt_flags |= MNT_NODEV | MNT_LOCK_NODEV;
}
+ if (type->fs_flags & FS_USERNS_VISIBLE) {
+ if (!fs_fully_visible(type))
+ return -EPERM;
+ }
}
mnt = vfs_kern_mount(type, flags, name, data);
@@ -3164,7 +3170,7 @@ bool current_chrooted(void)
return chrooted;
}
-bool fs_fully_visible(struct file_system_type *type)
+static bool fs_fully_visible(struct file_system_type *type)
{
struct mnt_namespace *ns = current->nsproxy->mnt_ns;
struct mount *mnt;