From ff62a34210441103108d435ae8a00a777c4dcb99 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Marc-Andr=C3=A9=20Lureau?= Date: Wed, 31 Jan 2018 16:19:25 -0800 Subject: [PATCH] hugetlb: implement memfd sealing MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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. Link: http://lkml.kernel.org/r/20171107122800.25517-5-marcandre.lureau@redhat.com Signed-off-by: Marc-André Lureau Reviewed-by: Mike Kravetz Cc: Andrea Arcangeli Cc: Hugh Dickins Cc: Michal Hocko Cc: David Herrmann Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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 89e29574c1dc..8fe1b0aa2896 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); @@ -658,9 +673,16 @@ static int hugetlbfs_setattr(struct dentry *dentry, struct iattr *attr) return error; if (ia_valid & ATTR_SIZE) { - if (attr->ia_size & ~huge_page_mask(h)) + loff_t oldsize = inode->i_size; + loff_t newsize = attr->ia_size; + + 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; } @@ -712,6 +734,8 @@ 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, @@ -719,6 +743,7 @@ 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 d02301e3f232..944e6e8bd572 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -273,6 +273,7 @@ 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) -- 2.30.2