On Sat, 2007-06-30 at 10:39 +0100, Christoph Hellwig wrote:
> On Mon, Jun 25, 2007 at 08:19:52AM -0700, Dave Hansen wrote:
> > > Should we just take the calls outside the switch statement?
> >
> > Yeah, that's much better. I assume we don't care whether we're getting
> > -EROFS or -EPERM/-EINVAL for the S_IFDIR and default cases?
>
> We need to keep the exact error returns, so you'll have to add some
> special case checks before the r/o check. It's probably still cleaner,
> though.
How does this (untested) patch look?
--
This takes care of all of the direct callers of vfs_mknod().
Since a few of these cases also handle normal file creation
as well, this also covers some calls to vfs_create().
So that we don't have to make three mnt_want/drop_write()
calls inside of the switch statement, we move some of its
logic outside of the switch.
One thing I noticed: do we actually _need_ the first
S_ISDIR() check at the top of the function?
Signed-off-by: Dave Hansen <haveblue@xxxxxxxxxx>
---
lxc-dave/fs/namei.c | 29 ++++++++++++++++++++---------
lxc-dave/fs/nfsd/vfs.c | 8 ++++++--
lxc-dave/net/unix/af_unix.c | 4 ++++
3 files changed, 30 insertions(+), 11 deletions(-)
diff -puN fs/namei.c~18-24-sys-mknodat-elevate-write-count-for-vfs-mknod-create fs/namei.c
--- lxc/fs/namei.c~18-24-sys-mknodat-elevate-write-count-for-vfs-mknod-create 2007-07-05 15:40:18.000000000 -0700
+++ lxc-dave/fs/namei.c 2007-07-05 15:40:26.000000000 -0700
@@ -1911,13 +1911,27 @@ asmlinkage long sys_mknodat(int dfd, con
error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd);
if (error)
goto out;
+
dentry = lookup_create(&nd, 0);
error = PTR_ERR(dentry);
+ if (error)
+ goto out_unlock;
if (!IS_POSIXACL(nd.dentry->d_inode))
mode &= ~current->fs->umask;
- if (!IS_ERR(dentry)) {
- switch (mode & S_IFMT) {
+ if (S_ISDIR(mode)) {
+ error = -EPERM;
+ goto out_dput;
+ }
+ if (!S_ISREG(mode) && !S_ISCHR(mode) && !S_ISBLK(mode) &&
+ !S_ISFIFO(mode) && !S_ISSOCK(mode) && (mode != 0)) {
+ error = -EINVAL;
+ goto out_dput;
+ }
+ error = mnt_want_write(nd.mnt);
+ if (error)
+ goto out_dput;
+ switch (mode & S_IFMT) {
case 0: case S_IFREG:
error = vfs_create(nd.dentry->d_inode,dentry,mode,&nd);
break;
@@ -1928,14 +1942,11 @@ asmlinkage long sys_mknodat(int dfd, con
case S_IFIFO: case S_IFSOCK:
error = vfs_mknod(nd.dentry->d_inode,dentry,mode,0);
break;
- case S_IFDIR:
- error = -EPERM;
- break;
- default:
- error = -EINVAL;
- }
- dput(dentry);
}
+ mnt_drop_write(nd.mnt);
+out_dput:
+ dput(dentry);
+out_unlock:
mutex_unlock(&nd.dentry->d_inode->i_mutex);
path_release(&nd);
out:
diff -puN fs/nfsd/vfs.c~18-24-sys-mknodat-elevate-write-count-for-vfs-mknod-create fs/nfsd/vfs.c
--- lxc/fs/nfsd/vfs.c~18-24-sys-mknodat-elevate-write-count-for-vfs-mknod-create 2007-07-05 15:40:18.000000000 -0700
+++ lxc-dave/fs/nfsd/vfs.c 2007-07-05 15:40:18.000000000 -0700
@@ -1199,7 +1199,11 @@ nfsd_create(struct svc_rqst *rqstp, stru
case S_IFBLK:
case S_IFIFO:
case S_IFSOCK:
+ host_err = mnt_want_write(fhp->fh_export->ex_mnt);
+ if (host_err)
+ break;
host_err = vfs_mknod(dirp, dchild, iap->ia_mode, rdev);
+ mnt_drop_write(fhp->fh_export->ex_mnt);
break;
default:
printk("nfsd: bad file type %o in nfsd_create\n", type);
@@ -1810,7 +1814,7 @@ nfsd_permission(struct svc_export *exp,
inode->i_mode,
IS_IMMUTABLE(inode)? " immut" : "",
IS_APPEND(inode)? " append" : "",
- __mnt_is_readonly(exp->mnt)? " ro" : "");
+ __mnt_is_readonly(exp->ex_mnt)? " ro" : "");
dprintk(" owner %d/%d user %d/%d\n",
inode->i_uid, inode->i_gid, current->fsuid, current->fsgid);
#endif
@@ -1821,7 +1825,7 @@ nfsd_permission(struct svc_export *exp,
*/
if (!(acc & MAY_LOCAL_ACCESS))
if (acc & (MAY_WRITE | MAY_SATTR | MAY_TRUNC)) {
- if (EX_RDONLY(exp) || __mnt_is_readonly(exp->mnt))
+ if (EX_RDONLY(exp) || __mnt_is_readonly(exp->ex_mnt))
return nfserr_rofs;
if (/* (acc & MAY_WRITE) && */ IS_IMMUTABLE(inode))
return nfserr_perm;
diff -puN net/unix/af_unix.c~18-24-sys-mknodat-elevate-write-count-for-vfs-mknod-create net/unix/af_unix.c
--- lxc/net/unix/af_unix.c~18-24-sys-mknodat-elevate-write-count-for-vfs-mknod-create 2007-07-05 15:40:18.000000000 -0700
+++ lxc-dave/net/unix/af_unix.c 2007-07-05 15:40:18.000000000 -0700
@@ -815,7 +815,11 @@ static int unix_bind(struct socket *sock
*/
mode = S_IFSOCK |
(SOCK_INODE(sock)->i_mode & ~current->fs->umask);
+ err = mnt_want_write(nd.mnt);
+ if (err)
+ goto out_mknod_dput;
err = vfs_mknod(nd.dentry->d_inode, dentry, mode, 0);
+ mnt_drop_write(nd.mnt);
if (err)
goto out_mknod_dput;
mutex_unlock(&nd.dentry->d_inode->i_mutex);
_
-
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