Re: [PATCH Version 2 1/1] NFS NFS test SECINFO RPC_AUTH_GSS pseudoflavors for support

["Adamson, Andy" <William.Adamson@netapp.com>]

On Jun 16, 2014, at 1:56 PM, Trond Myklebust <trond.myklebust@primarydata.com> wrote:

> On Thu, 2014-06-12 at 15:02 -0400, andros@netapp.com wrote:
>> From: Andy Adamson <andros@netapp.com>
>> 
>> Fix nfs4_negotiate_security to create an rpc_clnt used to test each SECINFO
>> returned pseudoflavor. Check credential creation  (and gss_context creation)
>> which is important for RPC_AUTH_GSS pseudoflavors which can fail for multiple
>> reasons including mis-configuration.
>> 
>> Don't call nfs4_negotiate in nfs4_submount as it was just called by
>> nfs4_proc_lookup_mountpoint (nfs4_proc_lookup_common)
>> 
>> Signed-off-by: Andy Adamson <andros@netapp.com>
>> 
>> Conflicts:
>> 	fs/nfs/nfs4namespace.c
> 
> Queued for 3.17, but I had to fix a couple of issues with
> nfs_find_best_sec() first. See below:

Thanks for the fixes which look good.

> 
> 
>> ---
>> fs/nfs/nfs4_fs.h       |   2 +-
>> fs/nfs/nfs4namespace.c | 103 ++++++++++++++++++++++++++++---------------------
>> fs/nfs/nfs4proc.c      |   2 +-
>> net/sunrpc/auth.c      |   1 +
>> 4 files changed, 61 insertions(+), 47 deletions(-)
>> 
>> diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
>> index f63cb87..ba2affa 100644
>> --- a/fs/nfs/nfs4_fs.h
>> +++ b/fs/nfs/nfs4_fs.h
>> @@ -230,7 +230,7 @@ int nfs_atomic_open(struct inode *, struct dentry *, struct file *,
>> extern struct file_system_type nfs4_fs_type;
>> 
>> /* nfs4namespace.c */
>> -struct rpc_clnt *nfs4_create_sec_client(struct rpc_clnt *, struct inode *, struct qstr *);
>> +struct rpc_clnt *nfs4_negotiate_security(struct rpc_clnt *, struct inode *, struct qstr *);
>> struct vfsmount *nfs4_submount(struct nfs_server *, struct dentry *,
>> 			       struct nfs_fh *, struct nfs_fattr *);
>> int nfs4_replace_transport(struct nfs_server *server,
>> diff --git a/fs/nfs/nfs4namespace.c b/fs/nfs/nfs4namespace.c
>> index 3d5dbf8..5517f02 100644
>> --- a/fs/nfs/nfs4namespace.c
>> +++ b/fs/nfs/nfs4namespace.c
>> @@ -139,19 +139,28 @@ static size_t nfs_parse_server_name(char *string, size_t len,
>>  * @server: NFS server struct
>>  * @flavors: List of security tuples returned by SECINFO procedure
>>  *
>> - * Return the pseudoflavor of the first security mechanism in
>> - * "flavors" that is locally supported.  Return RPC_AUTH_UNIX if
>> - * no matching flavor is found in the array.  The "flavors" array
>> + * Return an rpc client that uses the first security mechanism in
>> + * "flavors" that is locally supported.  The "flavors" array
>>  * is searched in the order returned from the server, per RFC 3530
>> - * recommendation.
>> + * recommendation and each flavor is checked for membership in the
>> + * sec= mount option list if it exists.
>> + *
>> + * Return -EPERM if no matching flavor is found in the array.
>> + *
>> + * Please call rpc_shutdown_client() when you are done with this rpc client.
>> + *
>>  */
>> -static rpc_authflavor_t nfs_find_best_sec(struct nfs_server *server,
>> +static struct rpc_clnt *nfs_find_best_sec(struct rpc_clnt *clnt,
>> +					  struct nfs_server *server,
>> 					  struct nfs4_secinfo_flavors *flavors)
>> {
>> -	rpc_authflavor_t pseudoflavor;
>> +	rpc_authflavor_t pflavor;
>> 	struct nfs4_secinfo4 *secinfo;
>> +	struct rpc_clnt *new;
>> 	unsigned int i;
>> +	struct rpc_cred *cred;
>> 
>> +	new = ERR_PTR(-EPERM);
>> 	for (i = 0; i < flavors->num_flavors; i++) {
>> 		secinfo = &flavors->flavors[i];
>> 
>> @@ -159,62 +168,71 @@ static rpc_authflavor_t nfs_find_best_sec(struct nfs_server *server,
>> 		case RPC_AUTH_NULL:
>> 		case RPC_AUTH_UNIX:
>> 		case RPC_AUTH_GSS:
>> -			pseudoflavor = rpcauth_get_pseudoflavor(secinfo->flavor,
>> +			pflavor = rpcauth_get_pseudoflavor(secinfo->flavor,
>> 							&secinfo->flavor_info);
>> -			/* make sure pseudoflavor matches sec= mount opt */
>> -			if (pseudoflavor != RPC_AUTH_MAXFLAVOR &&
>> -			    nfs_auth_info_match(&server->auth_info,
>> -						pseudoflavor))
>> -				return pseudoflavor;
>> -			break;
>> +			/* does the pseudoflavor match a sec= mount opt? */
>> +			if (pflavor != RPC_AUTH_MAXFLAVOR &&
>> +			    nfs_auth_info_match(&server->auth_info, pflavor)) {
>> +
>> +				/* Cloning creates an rpc_auth for the flavor */
>> +				new = rpc_clone_client_set_auth(clnt, pflavor);
>> +				if (IS_ERR(new))
>> +					continue;
> 
> If IS_ERR(new), we can end up returning an error which is not EPERM.
> 
>> +				/**
>> +				* Check that the user actually can use the
>> +				* flavor. This is mostly for RPC_AUTH_GSS
>> +				* where cr_init obtains a gss context
>> +				*/
>> +				cred = rpcauth_lookupcred(new->cl_auth, 0);
>> +				if (IS_ERR(cred)) {
>> +					rpc_shutdown_client(new);
>> +					continue;
>> +				}
>> +				put_rpccred(cred);
>> +				break;
> 
> If IS_ERR(cred), we can end up freeing 'new', and then returning the
> pointer to the freed client.

ugg. Should have caught this one…

Thanks

—>Andy

> 
>> +			}
>> 		}
>> 	}
>> -
>> -	/* if there were any sec= options then nothing matched */
>> -	if (server->auth_info.flavor_len > 0)
>> -		return -EPERM;
>> -
>> -	return RPC_AUTH_UNIX;
>> +	return new;
>> }
>> 
>> -static rpc_authflavor_t nfs4_negotiate_security(struct inode *inode, struct qstr *name)
>> +/**
>> + * nfs4_negotiate_security - in response to an NFS4ERR_WRONGSEC on lookup,
>> + * return an rpc_clnt that uses the best available security flavor with
>> + * respect to the secinfo flavor list and the sec= mount options.
>> + *
>> + * @clnt: RPC client to clone
>> + * @inode: directory inode
>> + * @name: lookup name
>> + *
>> + * Please call rpc_shutdown_client() when you are done with this rpc client.
>> + */
>> +struct rpc_clnt *
>> +nfs4_negotiate_security(struct rpc_clnt *clnt, struct inode *inode,
>> +					struct qstr *name)
>> {
>> 	struct page *page;
>> 	struct nfs4_secinfo_flavors *flavors;
>> -	rpc_authflavor_t flavor;
>> +	struct rpc_clnt *new = ERR_PTR(-ENOMEM);
>> 	int err;
>> 
>> 	page = alloc_page(GFP_KERNEL);
>> 	if (!page)
>> -		return -ENOMEM;
>> +		return new;
>> +
>> 	flavors = page_address(page);
>> 
>> 	err = nfs4_proc_secinfo(inode, name, flavors);
>> 	if (err < 0) {
>> -		flavor = err;
>> +		new = ERR_PTR(err);;
>> 		goto out;
>> 	}
>> 
>> -	flavor = nfs_find_best_sec(NFS_SERVER(inode), flavors);
>> +	new = nfs_find_best_sec(clnt, NFS_SERVER(inode), flavors);
>> 
>> out:
>> 	put_page(page);
>> -	return flavor;
>> -}
>> -
>> -/*
>> - * Please call rpc_shutdown_client() when you are done with this client.
>> - */
>> -struct rpc_clnt *nfs4_create_sec_client(struct rpc_clnt *clnt, struct inode *inode,
>> -					struct qstr *name)
>> -{
>> -	rpc_authflavor_t flavor;
>> -
>> -	flavor = nfs4_negotiate_security(inode, name);
>> -	if ((int)flavor < 0)
>> -		return ERR_PTR((int)flavor);
>> -
>> -	return rpc_clone_client_set_auth(clnt, flavor);
>> +	return new;
>> }
>> 
>> static struct vfsmount *try_location(struct nfs_clone_mount *mountdata,
>> @@ -397,11 +415,6 @@ struct vfsmount *nfs4_submount(struct nfs_server *server, struct dentry *dentry,
>> 
>> 	if (client->cl_auth->au_flavor != flavor)
>> 		flavor = client->cl_auth->au_flavor;
>> -	else {
>> -		rpc_authflavor_t new = nfs4_negotiate_security(dir, name);
>> -		if ((int)new >= 0)
>> -			flavor = new;
>> -	}
>> 	mnt = nfs_do_submount(dentry, fh, fattr, flavor);
>> out:
>> 	rpc_shutdown_client(client);
>> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
>> index 68dd81e..fe14063 100644
>> --- a/fs/nfs/nfs4proc.c
>> +++ b/fs/nfs/nfs4proc.c
>> @@ -3247,7 +3247,7 @@ static int nfs4_proc_lookup_common(struct rpc_clnt **clnt, struct inode *dir,
>> 			err = -EPERM;
>> 			if (client != *clnt)
>> 				goto out;
>> -			client = nfs4_create_sec_client(client, dir, name);
>> +			client = nfs4_negotiate_security(client, dir, name);
>> 			if (IS_ERR(client))
>> 				return PTR_ERR(client);
>> 
>> diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
>> index 5285ead..1d97e19 100644
>> --- a/net/sunrpc/auth.c
>> +++ b/net/sunrpc/auth.c
>> @@ -592,6 +592,7 @@ rpcauth_lookupcred(struct rpc_auth *auth, int flags)
>> 	put_group_info(acred.group_info);
>> 	return ret;
>> }
>> +EXPORT_SYMBOL_GPL(rpcauth_lookupcred);
>> 
>> void
>> rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,
> 
> -- 
> Trond Myklebust
> Linux NFS client maintainer, PrimaryData
> trond.myklebust@primarydata.com