[PATCH 1/1] NFS: fix error handling on access_ok in compat_sys_nfsservctl

From: Lin Feng Shen
Date: Thu May 11 2006 - 02:25:00 EST

From: Lin Feng Shen <shenlinf@xxxxxxxxxx>

Functions compat_nfs_svc_trans, compat_nfs_clnt_trans, compat_nfs_exp_trans,
compat_nfs_getfd_trans and compat_nfs_getfs_trans, which are called by
compat_sys_nfsservctl(fs/compat.c), don't handle the return value of
access_ok properly. access_ok return 1 when the addr is valid, and 0
when it's not, but these functions have the reversed understanding. When the
address is valid, they always return -EFAULT to compat_sys_nfsservctl.

An example is to run /usr/sbin/rpc.nfsd(32bit program on Power5). It doesn't
function as expected. strace showes that nfsservctl returns -EFAULT.

The patch fixes this by correcting the error handling on the return value of
access_ok in the five functions. It is created against linux-2.6.17-rc3-git16.

Signed-off-by: Lin Feng Shen <shenlinf@xxxxxxxxxx>
---

--- linux-2.6.17-rc3-git16/fs/compat.c.orig 2006-05-09 09:07:38.000000000 -0500
+++ linux-2.6.17-rc3-git16/fs/compat.c 2006-05-09 09:21:00.000000000 -0500
@@ -2032,101 +2032,96 @@ union compat_nfsctl_res {

static int compat_nfs_svc_trans(struct nfsctl_arg *karg, struct compat_nfsctl_arg __user *arg)
{
- int err;
-
- err = access_ok(VERIFY_READ, &arg->ca32_svc, sizeof(arg->ca32_svc));
- err |= get_user(karg->ca_version, &arg->ca32_version);
- err |= __get_user(karg->ca_svc.svc_port, &arg->ca32_svc.svc32_port);
- err |= __get_user(karg->ca_svc.svc_nthreads, &arg->ca32_svc.svc32_nthreads);
- return (err) ? -EFAULT : 0;
+ if(!access_ok(VERIFY_READ, &arg->ca32_svc, sizeof(arg->ca32_svc)) ||
+ get_user(karg->ca_version, &arg->ca32_version) ||
+ __get_user(karg->ca_svc.svc_port, &arg->ca32_svc.svc32_port) ||
+ __get_user(karg->ca_svc.svc_nthreads, &arg->ca32_svc.svc32_nthreads))
+ return -EFAULT;
+ return 0;
}

static int compat_nfs_clnt_trans(struct nfsctl_arg *karg, struct compat_nfsctl_arg __user *arg)
{
- int err;
-
- err = access_ok(VERIFY_READ, &arg->ca32_client, sizeof(arg->ca32_client));
- err |= get_user(karg->ca_version, &arg->ca32_version);
- err |= __copy_from_user(&karg->ca_client.cl_ident[0],
+ if(!access_ok(VERIFY_READ, &arg->ca32_client, sizeof(arg->ca32_client)) ||
+ get_user(karg->ca_version, &arg->ca32_version) ||
+ __copy_from_user(&karg->ca_client.cl_ident[0],
&arg->ca32_client.cl32_ident[0],
- NFSCLNT_IDMAX);
- err |= __get_user(karg->ca_client.cl_naddr, &arg->ca32_client.cl32_naddr);
- err |= __copy_from_user(&karg->ca_client.cl_addrlist[0],
+ NFSCLNT_IDMAX) ||
+ __get_user(karg->ca_client.cl_naddr, &arg->ca32_client.cl32_naddr) ||
+ __copy_from_user(&karg->ca_client.cl_addrlist[0],
&arg->ca32_client.cl32_addrlist[0],
- (sizeof(struct in_addr) * NFSCLNT_ADDRMAX));
- err |= __get_user(karg->ca_client.cl_fhkeytype,
- &arg->ca32_client.cl32_fhkeytype);
- err |= __get_user(karg->ca_client.cl_fhkeylen,
- &arg->ca32_client.cl32_fhkeylen);
- err |= __copy_from_user(&karg->ca_client.cl_fhkey[0],
+ (sizeof(struct in_addr) * NFSCLNT_ADDRMAX)) ||
+ __get_user(karg->ca_client.cl_fhkeytype,
+ &arg->ca32_client.cl32_fhkeytype) ||
+ __get_user(karg->ca_client.cl_fhkeylen,
+ &arg->ca32_client.cl32_fhkeylen) ||
+ __copy_from_user(&karg->ca_client.cl_fhkey[0],
&arg->ca32_client.cl32_fhkey[0],
- NFSCLNT_KEYMAX);
+ NFSCLNT_KEYMAX))
+ return -EFAULT;

- return (err) ? -EFAULT : 0;
+ return 0;
}

static int compat_nfs_exp_trans(struct nfsctl_arg *karg, struct compat_nfsctl_arg __user *arg)
{
- int err;
-
- err = access_ok(VERIFY_READ, &arg->ca32_export, sizeof(arg->ca32_export));
- err |= get_user(karg->ca_version, &arg->ca32_version);
- err |= __copy_from_user(&karg->ca_export.ex_client[0],
+ if(!access_ok(VERIFY_READ, &arg->ca32_export, sizeof(arg->ca32_export)) ||
+ get_user(karg->ca_version, &arg->ca32_version) ||
+ __copy_from_user(&karg->ca_export.ex_client[0],
&arg->ca32_export.ex32_client[0],
- NFSCLNT_IDMAX);
- err |= __copy_from_user(&karg->ca_export.ex_path[0],
+ NFSCLNT_IDMAX) ||
+ __copy_from_user(&karg->ca_export.ex_path[0],
&arg->ca32_export.ex32_path[0],
- NFS_MAXPATHLEN);
- err |= __get_user(karg->ca_export.ex_dev,
- &arg->ca32_export.ex32_dev);
- err |= __get_user(karg->ca_export.ex_ino,
- &arg->ca32_export.ex32_ino);
- err |= __get_user(karg->ca_export.ex_flags,
- &arg->ca32_export.ex32_flags);
- err |= __get_user(karg->ca_export.ex_anon_uid,
- &arg->ca32_export.ex32_anon_uid);
- err |= __get_user(karg->ca_export.ex_anon_gid,
- &arg->ca32_export.ex32_anon_gid);
+ NFS_MAXPATHLEN) ||
+ __get_user(karg->ca_export.ex_dev,
+ &arg->ca32_export.ex32_dev) ||
+ __get_user(karg->ca_export.ex_ino,
+ &arg->ca32_export.ex32_ino) ||
+ __get_user(karg->ca_export.ex_flags,
+ &arg->ca32_export.ex32_flags) ||
+ __get_user(karg->ca_export.ex_anon_uid,
+ &arg->ca32_export.ex32_anon_uid) ||
+ __get_user(karg->ca_export.ex_anon_gid,
+ &arg->ca32_export.ex32_anon_gid))
+ return -EFAULT;
SET_UID(karg->ca_export.ex_anon_uid, karg->ca_export.ex_anon_uid);
SET_GID(karg->ca_export.ex_anon_gid, karg->ca_export.ex_anon_gid);

- return (err) ? -EFAULT : 0;
+ return 0;
}

static int compat_nfs_getfd_trans(struct nfsctl_arg *karg, struct compat_nfsctl_arg __user *arg)
{
- int err;
-
- err = access_ok(VERIFY_READ, &arg->ca32_getfd, sizeof(arg->ca32_getfd));
- err |= get_user(karg->ca_version, &arg->ca32_version);
- err |= __copy_from_user(&karg->ca_getfd.gd_addr,
+ if(!access_ok(VERIFY_READ, &arg->ca32_getfd, sizeof(arg->ca32_getfd)) ||
+ get_user(karg->ca_version, &arg->ca32_version) ||
+ __copy_from_user(&karg->ca_getfd.gd_addr,
&arg->ca32_getfd.gd32_addr,
- (sizeof(struct sockaddr)));
- err |= __copy_from_user(&karg->ca_getfd.gd_path,
+ (sizeof(struct sockaddr))) ||
+ __copy_from_user(&karg->ca_getfd.gd_path,
&arg->ca32_getfd.gd32_path,
- (NFS_MAXPATHLEN+1));
- err |= __get_user(karg->ca_getfd.gd_version,
- &arg->ca32_getfd.gd32_version);
+ (NFS_MAXPATHLEN+1)) ||
+ __get_user(karg->ca_getfd.gd_version,
+ &arg->ca32_getfd.gd32_version))
+ return -EFAULT;

- return (err) ? -EFAULT : 0;
+ return 0;
}

static int compat_nfs_getfs_trans(struct nfsctl_arg *karg, struct compat_nfsctl_arg __user *arg)
{
- int err;
-
- err = access_ok(VERIFY_READ, &arg->ca32_getfs, sizeof(arg->ca32_getfs));
- err |= get_user(karg->ca_version, &arg->ca32_version);
- err |= __copy_from_user(&karg->ca_getfs.gd_addr,
+ if(!access_ok(VERIFY_READ, &arg->ca32_getfs, sizeof(arg->ca32_getfs)) ||
+ get_user(karg->ca_version, &arg->ca32_version) ||
+ __copy_from_user(&karg->ca_getfs.gd_addr,
&arg->ca32_getfs.gd32_addr,
- (sizeof(struct sockaddr)));
- err |= __copy_from_user(&karg->ca_getfs.gd_path,
+ (sizeof(struct sockaddr))) ||
+ __copy_from_user(&karg->ca_getfs.gd_path,
&arg->ca32_getfs.gd32_path,
- (NFS_MAXPATHLEN+1));
- err |= __get_user(karg->ca_getfs.gd_maxlen,
- &arg->ca32_getfs.gd32_maxlen);
+ (NFS_MAXPATHLEN+1)) ||
+ __get_user(karg->ca_getfs.gd_maxlen,
+ &arg->ca32_getfs.gd32_maxlen))
+ return -EFAULT;

- return (err) ? -EFAULT : 0;
+ return 0;
}

/* This really doesn't need translations, we are only passing

-
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