On Nov 20, 2008, at Nov 20, 2008, 2:27 PM, Trond Myklebust wrote:
On Wed, 2008-11-05 at 15:25 -0500, Chuck Lever wrote:The standard default security setting for NFS is AUTH_SYS. An NFS client connects to NFS servers via a privileged source port and a fixed standard destination port (2049). The client sends raw uid and gid numbers to identify users making NFS requests, and the server assumes an appropriate authority on the client has vetted these values because the source port is privileged. On Linux, by default in-kernel RPC services use a privileged port in the range between 650 and 1023 to avoid using source ports of well- known IP services. Using such a small range limits the number of NFS mount points and the number of unique NFS servers to which a client can connect concurrently.An NFS client can use unprivileged source ports to expand the range ofsource port numbers, allowing more concurrent server connections and more NFS mount points. Servers must explicitly allow NFS connections from unprivileged ports for this to work. In the past, bumping the value of the sunrpc.max_resvport sysctl on the client would permit the NFS client to use unprivileged ports. Bumping this setting also changes the maximum port number used by other in-kernel RPC services, some of which still required a port number less than 1023. This is exacerbated by the way source port numbers are chosen by the Linux RPC client, which starts at the top of the range and works downwards. It means that bumping the maximum means all RPC services requesting a source port will likely get an unprivileged port instead of a privileged one. Changing this setting effects all NFS mount points on a client. A sysadmin could not selectively choose which mount points would use non-privileged ports and which could not. Lastly, this mechanism of expanding the limit on the number of NFS mount points was entirely undocumented. To address the need for the NFS client to use a large range of source ports without interfering with the activity of other in-kernel RPCservices, we introduce a new NFS mount option. This option explicitlytells only the NFS client to use a non-privileged source port when communicating with the NFS server for one specific mount point.This new mount option is called "resvport," like the similar NFS mountoption on FreeBSD and Mac OS X. A sister patch for nfs-utils will be submitted that documents this new option in nfs(5). The default setting for this new mount option requires the NFS client to use a privileged port, as before. Explicitly specifying the"noresvport" mount option allows the NFS client to use an unprivilegedsource port for this mount point when connecting to the NFS server port. This mount option is supported only for text-based NFS mounts. [ Sidebar: it is widely known that security mechanisms based on the use of privileged source ports are ineffective. However, the NFS client can combine the use of unprivileged ports with the use of secure authentication mechanisms, such as Kerberos. This allows a large number of connections and mount points while ensuring a useful level of security. Eventually we may change the default setting for this option depending on the security flavor used for the mount. For example, if the mount is using only AUTH_SYS, then the default setting will be "resvport;" if the mount is using a strong security flavor such as krb5, the default setting will be "noresvport." ] Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> --- fs/nfs/client.c | 9 ++++++--- fs/nfs/super.c | 12 +++++++++++- include/linux/nfs_mount.h | 3 ++- 3 files changed, 19 insertions(+), 5 deletions(-) diff --git a/fs/nfs/client.c b/fs/nfs/client.c index 2719033..cd4a174 100644 --- a/fs/nfs/client.c +++ b/fs/nfs/client.c@@ -627,7 +627,8 @@ static int nfs_init_client(struct nfs_client *clp,* Create a client RPC handle for doing FSSTAT with UNIX auth only * - RFC 2623, sec 2.3.2 */ - error = nfs_create_rpc_client(clp, timeparms, RPC_AUTH_UNIX, 0, 0); + error = nfs_create_rpc_client(clp, timeparms, RPC_AUTH_UNIX, + 0, data->flags & NFS_MOUNT_NORESVPORT); if (error < 0) goto error; nfs_mark_client_ready(clp, NFS_CS_READY); @@ -969,6 +970,7 @@ error: static int nfs4_init_client(struct nfs_client *clp, const struct rpc_timeout *timeparms, const char *ip_addr, + const int flags, rpc_authflavor_t authflavour)^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^{ int error;@@ -983,7 +985,7 @@ static int nfs4_init_client(struct nfs_client *clp,clp->rpc_ops = &nfs_v4_clientops; error = nfs_create_rpc_client(clp, timeparms, authflavour, - 1, 0); + 1, flags & NFS_MOUNT_NORESVPORT); if (error < 0) goto error; memcpy(clp->cl_ipaddr, ip_addr, sizeof(clp->cl_ipaddr));@@ -1034,7 +1036,8 @@ static int nfs4_set_client(struct nfs_server *server,error = PTR_ERR(clp); goto error; } - error = nfs4_init_client(clp, timeparms, ip_addr, authflavour); + error = nfs4_init_client(clp, timeparms, ip_addr, authflavour, + server->flags);^^^^^^^^^^^^^^^ Hmm... You didn't ever actually test an NFSv4 mount with this patch applied, did you?
Perhaps not with the most recent version of this patch, but I do expect the compiler to identify problems like this. Unfortunately not the case for simple integer types.
Do you want another version of this patch, or can you fix this yourself?
if (error < 0) goto error_put; diff --git a/fs/nfs/super.c b/fs/nfs/super.c index 735ff2b..773594f 100644 --- a/fs/nfs/super.c +++ b/fs/nfs/super.c @@ -76,6 +76,7 @@ enum { Opt_acl, Opt_noacl, Opt_rdirplus, Opt_nordirplus, Opt_sharecache, Opt_nosharecache, + Opt_resvport, Opt_noresvport, /* Mount options that take integer arguments */ Opt_port,@@ -130,6 +131,8 @@ static const match_table_t nfs_mount_option_tokens = {{ Opt_nordirplus, "nordirplus" }, { Opt_sharecache, "sharecache" }, { Opt_nosharecache, "nosharecache" }, + { Opt_resvport, "resvport" }, + { Opt_noresvport, "noresvport" }, { Opt_port, "port=%u" }, { Opt_rsize, "rsize=%u" },@@ -515,7 +518,8 @@ static void nfs_show_mount_options(struct seq_file *m, struct nfs_server *nfss,{ NFS_MOUNT_NONLM, ",nolock", "" }, { NFS_MOUNT_NOACL, ",noacl", "" }, { NFS_MOUNT_NORDIRPLUS, ",nordirplus", "" }, - { NFS_MOUNT_UNSHARED, ",nosharecache", ""}, + { NFS_MOUNT_UNSHARED, ",nosharecache", "" }, + { NFS_MOUNT_NORESVPORT, ",noresvport", "" }, { 0, NULL, NULL } }; const struct proc_nfs_info *nfs_infop; @@ -916,6 +920,12 @@ static int nfs_parse_mount_options(char *raw, case Opt_nosharecache: mnt->flags |= NFS_MOUNT_UNSHARED; break; + case Opt_resvport: + mnt->flags &= ~NFS_MOUNT_NORESVPORT; + break; + case Opt_noresvport: + mnt->flags |= NFS_MOUNT_NORESVPORT; + break; /* * options that take numeric values diff --git a/include/linux/nfs_mount.h b/include/linux/nfs_mount.h index 6549a06..4499016 100644 --- a/include/linux/nfs_mount.h +++ b/include/linux/nfs_mount.h @@ -45,7 +45,7 @@ struct nfs_mount_data { char context[NFS_MAX_CONTEXT_LEN + 1]; /* 6 */ }; -/* bits in the flags field */ +/* bits in the flags field visible to user space */ #define NFS_MOUNT_SOFT 0x0001 /* 1 */ #define NFS_MOUNT_INTR 0x0002 /* 1 */ /* now unused, but ABI */ @@ -68,5 +68,6 @@ struct nfs_mount_data { /* The following are for internal use only */ #define NFS_MOUNT_LOOKUP_CACHE_NONEG 0x10000 #define NFS_MOUNT_LOOKUP_CACHE_NONE 0x20000 +#define NFS_MOUNT_NORESVPORT 0x40000 #endif-- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@xxxxxxxxxx www.netapp.com --To unsubscribe from this list: send the line "unsubscribe linux-nfs" inthe body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
-- Chuck Lever chuck[dot]lever[at]oracle[dot]com -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
