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>
---
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)
--
2.15.0.rc0.40.gaefcc5f6f
