From 29a517c232d21a717aecea29838aeb07131f6196 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Fri, 10 Jun 2016 13:03:05 -0500 Subject: [PATCH] kernfs: The cgroup filesystem also benefits from SB_I_NOEXEC The cgroup filesystem is in the same boat as sysfs. No one ever permits executables of any kind on the cgroup filesystem, and there is no reasonable future case to support executables in the future. Therefore move the setting of SB_I_NOEXEC which makes the code proof against future mistakes of accidentally creating executables from sysfs to kernfs itself. Making the code simpler and covering the sysfs, cgroup, and cgroup2 filesystems. Acked-by: Seth Forshee Signed-off-by: "Eric W. Biederman" --- fs/kernfs/mount.c | 2 ++ fs/sysfs/mount.c | 3 +-- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c index d90d574c15a2..1443df670260 100644 --- a/fs/kernfs/mount.c +++ b/fs/kernfs/mount.c @@ -152,6 +152,8 @@ static int kernfs_fill_super(struct super_block *sb, unsigned long magic) struct dentry *root; info->sb = sb; + /* Userspace would break if executables appear on sysfs */ + sb->s_iflags |= SB_I_NOEXEC; sb->s_blocksize = PAGE_SIZE; sb->s_blocksize_bits = PAGE_SHIFT; sb->s_magic = magic; diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c index f31e36994dfb..20b8f82e115b 100644 --- a/fs/sysfs/mount.c +++ b/fs/sysfs/mount.c @@ -41,8 +41,7 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type, if (IS_ERR(root) || !new_sb) kobj_ns_drop(KOBJ_NS_TYPE_NET, ns); else if (new_sb) - /* Userspace would break if executables appear on sysfs */ - root->d_sb->s_iflags |= SB_I_USERNS_VISIBLE | SB_I_NOEXEC; + root->d_sb->s_iflags |= SB_I_USERNS_VISIBLE; return root; }