Quoting Mimi Zohar (zohar@xxxxxxxxxxxxxxxxxx): > Files on FUSE can change at any point in time without IMA being able > to detect it. The file data read for the file signature verification > could be totally different from what is subsequently read, making the > signature verification useless. > > FUSE can be mounted by unprivileged users either today with fusermount > installed with setuid, or soon with the upcoming patches to allow FUSE > mounts in a non-init user namespace. > > This patch sets the SB_I_IMA_UNVERIFIABLE_SIGNATURE flag and when > appropriate sets the SB_I_UNTRUSTED_MOUNTER flag. > > Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx> > Cc: Miklos Szeredi <miklos@xxxxxxxxxx> > Cc: Seth Forshee <seth.forshee@xxxxxxxxxxxxx> > Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx> > Cc: Dongsu Park <dongsu@xxxxxxxxxx> > Cc: Alban Crequy <alban@xxxxxxxxxx> > Cc: "Serge E. Hallyn" <serge@xxxxxxxxxx> Acked-by: Serge Hallyn <serge@xxxxxxxxxx> Of course when IMA namespacing hits, you'll want to compare the sb->s_user_ns to the (~handwaving~) user_ns owning the ima ns right? > --- > fs/fuse/inode.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c > index 624f18bbfd2b..ef309958e060 100644 > --- a/fs/fuse/inode.c > +++ b/fs/fuse/inode.c > @@ -1080,6 +1080,9 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent) > sb->s_maxbytes = MAX_LFS_FILESIZE; > sb->s_time_gran = 1; > sb->s_export_op = &fuse_export_operations; > + sb->s_iflags |= SB_I_IMA_UNVERIFIABLE_SIGNATURE; > + if (sb->s_user_ns != &init_user_ns) > + sb->s_iflags |= SB_I_UNTRUSTED_MOUNTER; > > file = fget(d.fd); > err = -EINVAL; > -- > 2.7.5
