nfsd: let nfsd_symlink assume null-terminated data

Currently nfsd_symlink has a weird hack to serve callers who don't
null-terminate symlink data: it looks ahead at the next byte to see if
it's zero, and copies it to a new buffer to null-terminate if not.

That means callers don't have to null-terminate, but they *do* have to
ensure that the byte following the end of the data is theirs to read.

That's a bit subtle, and the NFSv4 code actually got this wrong.

So let's just throw out that code and let callers pass null-terminated
strings; we've already fixed them to do that.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

5 files changed, 7 insertions, 18 deletions

diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index 61ef42c7b0a6..19ba233cf006 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -282,7 +282,7 @@ nfsd3_proc_symlink(struct svc_rqst *rqstp, struct nfsd3_symlinkargs *argp,
         fh_copy(&resp->dirfh, &argp->ffh);
         fh_init(&resp->fh, NFS3_FHSIZE);
         nfserr = nfsd_symlink(rqstp, &resp->dirfh, argp->fname, argp->flen,
-                                                   argp->tname, argp->tlen,
+                                                   argp->tname,
                                                    &resp->fh, &argp->attrs);
         RETURN_STATUS(nfserr);
 }
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 2b3795a135e8..7aa83bf34fa9 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -623,7 +623,7 @@ nfsd4_create(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
         case NF4LNK:
                 status = nfsd_symlink(rqstp, &cstate->current_fh,
                                       create->cr_name, create->cr_namelen,
-                                      create->cr_linkname, create->cr_linklen,
+                                      create->cr_linkname,
                                       &resfh, &create->cr_iattr);
                 break;
 
diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
index aebe23c45cbe..583ed03877e4 100644
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -409,7 +409,7 @@ nfsd_proc_symlink(struct svc_rqst *rqstp, struct nfsd_symlinkargs *argp,
          */
         argp->tname[argp->tlen] = '\0';
         nfserr = nfsd_symlink(rqstp, &argp->ffh, argp->fname, argp->flen,
-                                                 argp->tname, argp->tlen,
+                                                 argp->tname,
                                                  &newfh, &argp->attrs);
 
 
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 6ffaa70300ed..7518c65f9a5a 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1504,7 +1504,7 @@ out_nfserr:
 __be32
 nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
                                 char *fname, int flen,
-                                char *path,  int plen,
+                                char *path,
                                 struct svc_fh *resfhp,
                                 struct iattr *iap)
 {
@@ -1513,7 +1513,7 @@ nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
         int             host_err;
 
         err = nfserr_noent;
-        if (!flen || !plen)
+        if (!flen || path[0] == '\0')
                 goto out;
         err = nfserr_exist;
         if (isdotent(fname, flen))
@@ -1534,18 +1534,7 @@ nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
         if (IS_ERR(dnew))
                 goto out_nfserr;
 
-        if (unlikely(path[plen] != 0)) {
-                char *path_alloced = kmalloc(plen+1, GFP_KERNEL);
-                if (path_alloced == NULL)
-                        host_err = -ENOMEM;
-                else {
-                        strncpy(path_alloced, path, plen);
-                        path_alloced[plen] = 0;
-                        host_err = vfs_symlink(dentry->d_inode, dnew, path_alloced);
-                        kfree(path_alloced);
-                }
-        } else
-                host_err = vfs_symlink(dentry->d_inode, dnew, path);
+        host_err = vfs_symlink(dentry->d_inode, dnew, path);
         err = nfserrno(host_err);
         if (!err)
                 err = nfserrno(commit_metadata(fhp));
diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
index b84aef50f55d..20e4b6679e46 100644
--- a/fs/nfsd/vfs.h
+++ b/fs/nfsd/vfs.h
@@ -85,7 +85,7 @@ __be32 		nfsd_write(struct svc_rqst *, struct svc_fh *,struct file *,
 __be32          nfsd_readlink(struct svc_rqst *, struct svc_fh *,
                                 char *, int *);
 __be32          nfsd_symlink(struct svc_rqst *, struct svc_fh *,
-                                char *name, int len, char *path, int plen,
+                                char *name, int len, char *path,
                                 struct svc_fh *res, struct iattr *);
 __be32          nfsd_link(struct svc_rqst *, struct svc_fh *,
                                 char *, int, struct svc_fh *);