From: Al Viro <[email protected]> This is a seriously simplified patch from Eric Sandeen; copy of rationale follows: === mounting stacked ecryptfs on ecryptfs has been shown to lead to bugs in testing. For crypto info in xattr, there is no mechanism for handling this at all, and for normal file headers, we run into other trouble:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 IP: [<ffffffffa015b0b3>] ecryptfs_d_revalidate+0x43/0xa0 [ecryptfs] ... There doesn't seem to be any good usecase for this, so I'd suggest just disallowing the configuration. Based on a patch originally, I believe, from Mike Halcrow. === Signed-off-by: Al Viro <[email protected]> (cherry picked from commit 4403158ba295c8e36f6736b1bb12d0f7e1923dac) Signed-off-by: Tim Gardner <[email protected]> --- fs/ecryptfs/main.c | 8 ++++++++ 1 files changed, 8 insertions(+), 0 deletions(-) diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c index c6ac85d..f6ccb4f 100644 --- a/fs/ecryptfs/main.c +++ b/fs/ecryptfs/main.c @@ -487,6 +487,7 @@ out: } struct kmem_cache *ecryptfs_sb_info_cache; +static struct file_system_type ecryptfs_fs_type; /** * ecryptfs_fill_super @@ -561,6 +562,13 @@ static int ecryptfs_read_super(struct super_block *sb, const char *dev_name) ecryptfs_printk(KERN_WARNING, "path_lookup() failed\n"); goto out; } + if (path.dentry->d_sb->s_type == &ecryptfs_fs_type) { + rc = -EINVAL; + printk(KERN_ERR "Mount on filesystem of type " + "eCryptfs explicitly disallowed due to " + "known incompatibilities\n"); + goto out_free; + } ecryptfs_set_superblock_lower(sb, path.dentry->d_sb); sb->s_maxbytes = path.dentry->d_sb->s_maxbytes; sb->s_blocksize = path.dentry->d_sb->s_blocksize; -- 1.7.9 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
