nilfs2: allow future expansion of metadata read out via get info ioctl
Nilfs has some ioctl commands to read out metadata from meta data
files:
- NILFS_IOCTL_GET_CPINFO for checkpoint file,
- NILFS_IOCTL_GET_SUINFO for segment usage file, and
- NILFS_IOCTL_GET_VINFO for Disk Address Transalation (DAT) file,
respectively.
Every routine on these metadata files is implemented so that it allows
future expansion of on-disk format. But, the above ioctl commands do
not support expansion even though nilfs_argv structure can handle
arbitrary size for data exchanged via ioctl.
This allows future expansion of the following structures which give
basic format of the "get information" ioctls:
- struct nilfs_cpinfo
- struct nilfs_suinfo
- struct nilfs_vinfo
So, this introduces forward compatility of such ioctl commands.
In this patch, a sanity check in nilfs_ioctl_get_info() function is
changed to accept larger data structure [1], and metadata read
routines are rewritten so that they become compatible for larger
structures; the routines will just ignore the remaining fields which
the current version of nilfs doesn't know.
[1] The ioctl function already has another upper limit (PAGE_SIZE
against a structure, which appears in nilfs_ioctl_wrap_copy
function), and this will not cause security problem.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index bdad7e4..6ea5f87 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -152,7 +152,7 @@
down_read(&nilfs->ns_segctor_sem);
ret = nilfs_cpfile_get_cpinfo(nilfs->ns_cpfile, posp, flags, buf,
- nmembs);
+ size, nmembs);
up_read(&nilfs->ns_segctor_sem);
return ret;
}
@@ -182,7 +182,8 @@
int ret;
down_read(&nilfs->ns_segctor_sem);
- ret = nilfs_sufile_get_suinfo(nilfs->ns_sufile, *posp, buf, nmembs);
+ ret = nilfs_sufile_get_suinfo(nilfs->ns_sufile, *posp, buf, size,
+ nmembs);
up_read(&nilfs->ns_segctor_sem);
return ret;
}
@@ -212,7 +213,7 @@
int ret;
down_read(&nilfs->ns_segctor_sem);
- ret = nilfs_dat_get_vinfo(nilfs_dat_inode(nilfs), buf, nmembs);
+ ret = nilfs_dat_get_vinfo(nilfs_dat_inode(nilfs), buf, size, nmembs);
up_read(&nilfs->ns_segctor_sem);
return ret;
}
@@ -589,7 +590,7 @@
if (copy_from_user(&argv, argp, sizeof(argv)))
return -EFAULT;
- if (argv.v_size != membsz)
+ if (argv.v_size < membsz)
return -EINVAL;
ret = nilfs_ioctl_wrap_copy(nilfs, &argv, _IOC_DIR(cmd), dofunc);