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hugetlb: implement memfd sealing 

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 <marcandre.lureau@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Marc-André Lureau 2018-01-31 16:19:25 -08:00 committed by Linus Torvalds
parent da14c1e524
commit ff62a34210
2 changed files with 28 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
fs/hugetlbfs/inode.c
View File

@ -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);

1
include/linux/hugetlb.h
View File

@ -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)