nfs: only show Posix ACLs in listxattr if actually present

The big ACL switched nfs to use generic_listxattr, which calls all existing
->list handlers.  Add a custom .listxattr implementation that only lists
the ACLs if they actually are present on the given inode.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Philippe Troin <phil@fifi.org>
Tested-by: Philippe Troin <phil@fifi.org>
Fixes: 013cdf1088d7 (nfs: use generic posix ACL infrastructure ...)
Cc: stable@vger.kernel.org # 3.14+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

2 files changed, 45 insertions, 2 deletions

diff --git a/fs/nfs/nfs3acl.c b/fs/nfs/nfs3acl.c
index 871d6eda8dba..8f854dde4150 100644
--- a/fs/nfs/nfs3acl.c
+++ b/fs/nfs/nfs3acl.c
@@ -247,3 +247,46 @@ const struct xattr_handler *nfs3_xattr_handlers[] = {
         &posix_acl_default_xattr_handler,
         NULL,
 };
+
+static int
+nfs3_list_one_acl(struct inode *inode, int type, const char *name, void *data,
+                size_t size, ssize_t *result)
+{
+        struct posix_acl *acl;
+        char *p = data + *result;
+
+        acl = get_acl(inode, type);
+        if (!acl)
+                return 0;
+
+        posix_acl_release(acl);
+
+        *result += strlen(name);
+        *result += 1;
+        if (!size)
+                return 0;
+        if (*result > size)
+                return -ERANGE;
+
+        strcpy(p, name);
+        return 0;
+}
+
+ssize_t
+nfs3_listxattr(struct dentry *dentry, char *data, size_t size)
+{
+        struct inode *inode = dentry->d_inode;
+        ssize_t result = 0;
+        int error;
+
+        error = nfs3_list_one_acl(inode, ACL_TYPE_ACCESS,
+                        POSIX_ACL_XATTR_ACCESS, data, size, &result);
+        if (error)
+                return error;
+
+        error = nfs3_list_one_acl(inode, ACL_TYPE_DEFAULT,
+                        POSIX_ACL_XATTR_DEFAULT, data, size, &result);
+        if (error)
+                return error;
+        return result;
+}
diff --git a/fs/nfs/nfs3proc.c b/fs/nfs/nfs3proc.c
index e7daa42bbc86..f0afa291fd58 100644
--- a/fs/nfs/nfs3proc.c
+++ b/fs/nfs/nfs3proc.c
@@ -885,7 +885,7 @@ static const struct inode_operations nfs3_dir_inode_operations = {
         .getattr        = nfs_getattr,
         .setattr        = nfs_setattr,
 #ifdef CONFIG_NFS_V3_ACL
-        .listxattr      = generic_listxattr,
+        .listxattr      = nfs3_listxattr,
         .getxattr       = generic_getxattr,
         .setxattr       = generic_setxattr,
         .removexattr    = generic_removexattr,
@@ -899,7 +899,7 @@ static const struct inode_operations nfs3_file_inode_operations = {
         .getattr        = nfs_getattr,
         .setattr        = nfs_setattr,
 #ifdef CONFIG_NFS_V3_ACL
-        .listxattr      = generic_listxattr,
+        .listxattr      = nfs3_listxattr,
         .getxattr       = generic_getxattr,
         .setxattr       = generic_setxattr,
         .removexattr    = generic_removexattr,