On 10/31/2017 11:40 AM, Marc-André Lureau wrote:
> Implements memfd sealing, similar to shmem:
> - WRITE: deny fallocate(PUNCH_HOLE). mmap() write is denied in
> memfd_add_seals(). write() doesn't exist for hugetlbfs.
> - SHRINK: added similar check as shmem_setattr()
> - GROW: added similar check as shmem_setattr() & shmem_fallocate()
>
> Except write() operation that doesn't exist with hugetlbfs, that
> should make sealing as close as it can be to shmem support.
>
> Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
Looks fine to me,
Reviewed-by: Mike Kravetz <mike.krav...@oracle.com>
--
Mike Kravetz
> ---
> fs/hugetlbfs/inode.c | 29 +++++++++++++++++++++++++++--
> include/linux/hugetlb.h | 1 +
> 2 files changed, 28 insertions(+), 2 deletions(-)
>
> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
> index ea7b10357ac4..62d70b1b1ab9 100644
> --- a/fs/hugetlbfs/inode.c
> +++ b/fs/hugetlbfs/inode.c
> @@ -510,8 +510,16 @@ static long hugetlbfs_punch_hole(struct inode *inode,
> loff_t offset, loff_t len)
>
> if (hole_end > hole_start) {
> struct address_space *mapping = inode->i_mapping;
> + struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
>
> inode_lock(inode);
> +
> + /* protected by i_mutex */
> + if (info->seals & F_SEAL_WRITE) {
> + inode_unlock(inode);
> + return -EPERM;
> + }
> +
> i_mmap_lock_write(mapping);
> if (!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))
> hugetlb_vmdelete_list(&mapping->i_mmap,
> @@ -529,6 +537,7 @@ static long hugetlbfs_fallocate(struct file *file, int
> mode, loff_t offset,
> loff_t len)
> {
> struct inode *inode = file_inode(file);
> + struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
> struct address_space *mapping = inode->i_mapping;
> struct hstate *h = hstate_inode(inode);
> struct vm_area_struct pseudo_vma;
> @@ -560,6 +569,11 @@ static long hugetlbfs_fallocate(struct file *file, int
> mode, loff_t offset,
> if (error)
> goto out;
>
> + if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
> + error = -EPERM;
> + goto out;
> + }
> +
> /*
> * Initialize a pseudo vma as this is required by the huge page
> * allocation routines. If NUMA is configured, use page index
> @@ -650,6 +664,7 @@ static int hugetlbfs_setattr(struct dentry *dentry,
> struct iattr *attr)
> struct hstate *h = hstate_inode(inode);
> int error;
> unsigned int ia_valid = attr->ia_valid;
> + struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
>
> BUG_ON(!inode);
>
> @@ -658,10 +673,17 @@ static int hugetlbfs_setattr(struct dentry *dentry,
> struct iattr *attr)
> return error;
>
> if (ia_valid & ATTR_SIZE) {
> + loff_t oldsize = inode->i_size;
> + loff_t newsize = attr->ia_size;
> +
> error = -EINVAL;
> - if (attr->ia_size & ~huge_page_mask(h))
> + if (newsize & ~huge_page_mask(h))
> return -EINVAL;
> - error = hugetlb_vmtruncate(inode, attr->ia_size);
> + /* protected by i_mutex */
> + if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
> + (newsize > oldsize && (info->seals & F_SEAL_GROW)))
> + return -EPERM;
> + error = hugetlb_vmtruncate(inode, newsize);
> if (error)
> return error;
> }
> @@ -713,6 +735,8 @@ static struct inode *hugetlbfs_get_inode(struct
> super_block *sb,
>
> inode = new_inode(sb);
> if (inode) {
> + struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
> +
> inode->i_ino = get_next_ino();
> inode_init_owner(inode, dir, mode);
> lockdep_set_class(&inode->i_mapping->i_mmap_rwsem,
> @@ -720,6 +744,7 @@ static struct inode *hugetlbfs_get_inode(struct
> super_block *sb,
> inode->i_mapping->a_ops = &hugetlbfs_aops;
> inode->i_atime = inode->i_mtime = inode->i_ctime =
> current_time(inode);
> inode->i_mapping->private_data = resv_map;
> + info->seals = F_SEAL_SEAL;
> switch (mode & S_IFMT) {
> default:
> init_special_inode(inode, mode, dev);
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index f78daf54897d..128ef10902f3 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -281,6 +281,7 @@ static inline struct hugetlbfs_sb_info
> *HUGETLBFS_SB(struct super_block *sb)
> struct hugetlbfs_inode_info {
> struct shared_policy policy;
> struct inode vfs_inode;
> + unsigned int seals;
> };
>
> static inline struct hugetlbfs_inode_info *HUGETLBFS_I(struct inode *inode)
>
