Thanks for reviewing these patches!
"Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> writes:
On Fri, Mar 31, 2023 at 11:50:39PM +0000, Ackerley Tng wrote:
...
+static int restrictedmem_create_on_user_mount(int mount_fd)
+{
+ int ret;
+ struct fd f;
+ struct vfsmount *mnt;
+
+ f = fdget_raw(mount_fd);
+ if (!f.file)
+ return -EBADF;
+
+ ret = -EINVAL;
+ if (!is_mount_root(f.file))
+ goto out;
+
+ mnt = f.file->f_path.mnt;
+ if (!is_shmem_mount(mnt))
+ goto out;
+
+ ret = file_permission(f.file, MAY_WRITE | MAY_EXEC);
Why MAY_EXEC?
Christian pointed out that this check does not make sense, I'll be
removing the entire check in the next revision.
+ if (ret)
+ goto out;
+
+ ret = mnt_want_write(mnt);
+ if (unlikely(ret))
+ goto out;
+
+ ret = restrictedmem_create(mnt);
+
+ mnt_drop_write(mnt);
+out:
+ fdput(f);
+
+ return ret;
+}
We need review from fs folks. Look mostly sensible, but I have no
experience in fs.
+
+SYSCALL_DEFINE2(memfd_restricted, unsigned int, flags, int, mount_fd)
+{
+ if (flags & ~RMFD_USERMNT)
+ return -EINVAL;
+
+ if (flags == RMFD_USERMNT) {
+ if (mount_fd < 0)
+ return -EINVAL;
+
+ return restrictedmem_create_on_user_mount(mount_fd);
+ } else {
+ return restrictedmem_create(NULL);
+ }
Maybe restructure with single restrictedmem_create() call?
struct vfsmount *mnt = NULL;
if (flags == RMFD_USERMNT) {
...
mnt = ...();
}
return restrictedmem_create(mnt);
Will do so in the next revision.
+}
+
int restrictedmem_bind(struct file *file, pgoff_t start, pgoff_t end,
struct restrictedmem_notifier *notifier, bool exclusive)
{
--
2.40.0.348.gf938b09366-goog
