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shmem: add sealing support to hugetlb-backed memfd 

Adapt add_seals()/get_seals() to work with hugetbfs-backed memory.

Teach memfd_create() to allow sealing operations on MFD_HUGETLB.

Link: http://lkml.kernel.org/r/20171107122800.25517-6-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 16:19:29 -08:00 committed by Linus Torvalds
parent ff62a34210
commit 47b9012ecd
1 changed files with 28 additions and 19 deletions
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47
mm/shmem.c
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@ -2717,6 +2717,19 @@ continue_resched:
return error;
}
static unsigned int *memfd_file_seals_ptr(struct file *file)
{
if (file->f_op == &shmem_file_operations)
return &SHMEM_I(file_inode(file))->seals;
#ifdef CONFIG_HUGETLBFS
if (file->f_op == &hugetlbfs_file_operations)
return &HUGETLBFS_I(file_inode(file))->seals;
#endif
return NULL;
}
#define F_ALL_SEALS (F_SEAL_SEAL | \
F_SEAL_SHRINK | \
F_SEAL_GROW | \
@ -2725,7 +2738,7 @@ continue_resched:
static int memfd_add_seals(struct file *file, unsigned int seals)
{
struct inode *inode = file_inode(file);
struct shmem_inode_info *info = SHMEM_I(inode);
unsigned int *file_seals;
int error;
/*
@ -2758,8 +2771,6 @@ static int memfd_add_seals(struct file *file, unsigned int seals)
* other file types.
*/
if (file->f_op != &shmem_file_operations)
return -EINVAL;
if (!(file->f_mode & FMODE_WRITE))
return -EPERM;
if (seals & ~(unsigned int)F_ALL_SEALS)
@ -2767,12 +2778,18 @@ static int memfd_add_seals(struct file *file, unsigned int seals)
inode_lock(inode);
if (info->seals & F_SEAL_SEAL) {
file_seals = memfd_file_seals_ptr(file);
if (!file_seals) {
error = -EINVAL;
goto unlock;
}
if (*file_seals & F_SEAL_SEAL) {
error = -EPERM;
goto unlock;
}
if ((seals & F_SEAL_WRITE) && !(info->seals & F_SEAL_WRITE)) {
if ((seals & F_SEAL_WRITE) && !(*file_seals & F_SEAL_WRITE)) {
error = mapping_deny_writable(file->f_mapping);
if (error)
goto unlock;
@ -2784,7 +2801,7 @@ static int memfd_add_seals(struct file *file, unsigned int seals)
}
}
info->seals |= seals;
*file_seals |= seals;
error = 0;
unlock:
@ -2794,10 +2811,9 @@ unlock:
static int memfd_get_seals(struct file *file)
{
if (file->f_op != &shmem_file_operations)
return -EINVAL;
unsigned int *seals = memfd_file_seals_ptr(file);
return SHMEM_I(file_inode(file))->seals;
return seals ? *seals : -EINVAL;
}
long memfd_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
@ -3655,7 +3671,7 @@ SYSCALL_DEFINE2(memfd_create,
const char __user *, uname,
unsigned int, flags)
{
struct shmem_inode_info *info;
unsigned int *file_seals;
struct file *file;
int fd, error;
char *name;
@ -3665,9 +3681,6 @@ SYSCALL_DEFINE2(memfd_create,
if (flags & ~(unsigned int)MFD_ALL_FLAGS)
return -EINVAL;
} else {
/* Sealing not supported in hugetlbfs (MFD_HUGETLB) */
if (flags & MFD_ALLOW_SEALING)
return -EINVAL;
/* Allow huge page size encoding in flags. */
if (flags & ~(unsigned int)(MFD_ALL_FLAGS |
(MFD_HUGE_MASK << MFD_HUGE_SHIFT)))
@ -3720,12 +3733,8 @@ SYSCALL_DEFINE2(memfd_create,
file->f_flags |= O_RDWR | O_LARGEFILE;
if (flags & MFD_ALLOW_SEALING) {
/*
* flags check at beginning of function ensures
* this is not a hugetlbfs (MFD_HUGETLB) file.
*/
info = SHMEM_I(file_inode(file));
info->seals &= ~F_SEAL_SEAL;
file_seals = memfd_file_seals_ptr(file);
*file_seals &= ~F_SEAL_SEAL;
}
fd_install(fd, file);