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authorBenjamin Coddington <bcodding@hammerspace.com>2026-02-25 07:51:36 -0500
committerChuck Lever <chuck.lever@oracle.com>2026-03-29 21:25:09 -0400
commit62346217fd722510c3551858ad7d0fcfab8cce7e (patch)
tree25bc45949eb65a157cec3cc0dd2fbbf8e7595b7f
parent116b6b7acdd82605ed530232cd7509d1b5282f5c (diff)
downloadlinux-next-history-62346217fd72.tar.gz
NFSD: Add a key for signing filehandles
A future patch will enable NFSD to sign filehandles by appending a Message Authentication Code(MAC). To do this, NFSD requires a secret 128-bit key that can persist across reboots. A persisted key allows the server to accept filehandles after a restart. Enable NFSD to be configured with this key via the netlink interface. Link: https://lore.kernel.org/linux-nfs/cover.1772022373.git.bcodding@hammerspace.com Signed-off-by: Benjamin Coddington <bcodding@hammerspace.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Diffstat
-rw-r--r--Documentation/netlink/specs/nfsd.yaml6
-rw-r--r--fs/nfsd/netlink.c5
-rw-r--r--fs/nfsd/netns.h1
-rw-r--r--fs/nfsd/nfsctl.c38
-rw-r--r--fs/nfsd/trace.h22
-rw-r--r--include/uapi/linux/nfsd_netlink.h1
6 files changed, 70 insertions, 3 deletions
diff --git a/Documentation/netlink/specs/nfsd.yaml b/Documentation/netlink/specs/nfsd.yaml
index f87b5a05e5e98..8ab43c8253b2e 100644
--- a/Documentation/netlink/specs/nfsd.yaml
+++ b/Documentation/netlink/specs/nfsd.yaml
@@ -81,6 +81,11 @@ attribute-sets:
-
name: min-threads
type: u32
+ -
+ name: fh-key
+ type: binary
+ checks:
+ exact-len: 16
-
name: version
attributes:
@@ -163,6 +168,7 @@ operations:
- leasetime
- scope
- min-threads
+ - fh-key
-
name: threads-get
doc: get the maximum number of running threads
diff --git a/fs/nfsd/netlink.c b/fs/nfsd/netlink.c
index 887525964451e..81c943345d13d 100644
--- a/fs/nfsd/netlink.c
+++ b/fs/nfsd/netlink.c
@@ -24,12 +24,13 @@ const struct nla_policy nfsd_version_nl_policy[NFSD_A_VERSION_ENABLED + 1] = {
};
/* NFSD_CMD_THREADS_SET - do */
-static const struct nla_policy nfsd_threads_set_nl_policy[NFSD_A_SERVER_MIN_THREADS + 1] = {
+static const struct nla_policy nfsd_threads_set_nl_policy[NFSD_A_SERVER_FH_KEY + 1] = {
[NFSD_A_SERVER_THREADS] = { .type = NLA_U32, },
[NFSD_A_SERVER_GRACETIME] = { .type = NLA_U32, },
[NFSD_A_SERVER_LEASETIME] = { .type = NLA_U32, },
[NFSD_A_SERVER_SCOPE] = { .type = NLA_NUL_STRING, },
[NFSD_A_SERVER_MIN_THREADS] = { .type = NLA_U32, },
+ [NFSD_A_SERVER_FH_KEY] = NLA_POLICY_EXACT_LEN(16),
};
/* NFSD_CMD_VERSION_SET - do */
@@ -58,7 +59,7 @@ static const struct genl_split_ops nfsd_nl_ops[] = {
.cmd = NFSD_CMD_THREADS_SET,
.doit = nfsd_nl_threads_set_doit,
.policy = nfsd_threads_set_nl_policy,
- .maxattr = NFSD_A_SERVER_MIN_THREADS,
+ .maxattr = NFSD_A_SERVER_FH_KEY,
.flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
},
{
diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
index 3a89d4708e8a9..6ad3fe5d7e124 100644
--- a/fs/nfsd/netns.h
+++ b/fs/nfsd/netns.h
@@ -227,6 +227,7 @@ struct nfsd_net {
spinlock_t local_clients_lock;
struct list_head local_clients;
#endif
+ siphash_key_t *fh_key;
};
/* Simple check to find out if a given net was properly initialized */
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 0bf01ae411c56..20ec00f323b49 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1582,6 +1582,32 @@ out_unlock:
}
/**
+ * nfsd_nl_fh_key_set - helper to copy fh_key from userspace
+ * @attr: nlattr NFSD_A_SERVER_FH_KEY
+ * @nn: nfsd_net
+ *
+ * Callers should hold nfsd_mutex, returns 0 on success or negative errno.
+ * Callers must ensure the server is shut down (sv_nrthreads == 0),
+ * userspace documentation asserts the key may only be set when the server
+ * is not running.
+ */
+static int nfsd_nl_fh_key_set(const struct nlattr *attr, struct nfsd_net *nn)
+{
+ siphash_key_t *fh_key = nn->fh_key;
+
+ if (!fh_key) {
+ fh_key = kmalloc(sizeof(siphash_key_t), GFP_KERNEL);
+ if (!fh_key)
+ return -ENOMEM;
+ nn->fh_key = fh_key;
+ }
+
+ fh_key->key[0] = get_unaligned_le64(nla_data(attr));
+ fh_key->key[1] = get_unaligned_le64(nla_data(attr) + 8);
+ return 0;
+}
+
+/**
* nfsd_nl_threads_set_doit - set the number of running threads
* @skb: reply buffer
* @info: netlink metadata and command arguments
@@ -1622,7 +1648,8 @@ int nfsd_nl_threads_set_doit(struct sk_buff *skb, struct genl_info *info)
if (info->attrs[NFSD_A_SERVER_GRACETIME] ||
info->attrs[NFSD_A_SERVER_LEASETIME] ||
- info->attrs[NFSD_A_SERVER_SCOPE]) {
+ info->attrs[NFSD_A_SERVER_SCOPE] ||
+ info->attrs[NFSD_A_SERVER_FH_KEY]) {
ret = -EBUSY;
if (nn->nfsd_serv && nn->nfsd_serv->sv_nrthreads)
goto out_unlock;
@@ -1651,6 +1678,14 @@ int nfsd_nl_threads_set_doit(struct sk_buff *skb, struct genl_info *info)
attr = info->attrs[NFSD_A_SERVER_SCOPE];
if (attr)
scope = nla_data(attr);
+
+ attr = info->attrs[NFSD_A_SERVER_FH_KEY];
+ if (attr) {
+ ret = nfsd_nl_fh_key_set(attr, nn);
+ trace_nfsd_ctl_fh_key_set((const char *)nn->fh_key, ret);
+ if (ret)
+ goto out_unlock;
+ }
}
attr = info->attrs[NFSD_A_SERVER_MIN_THREADS];
@@ -2237,6 +2272,7 @@ static __net_exit void nfsd_net_exit(struct net *net)
{
struct nfsd_net *nn = net_generic(net, nfsd_net_id);
+ kfree_sensitive(nn->fh_key);
nfsd_proc_stat_shutdown(net);
percpu_counter_destroy_many(nn->counter, NFSD_STATS_COUNTERS_NUM);
nfsd_idmap_shutdown(net);
diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
index d1d0b0dd05458..185a998996a03 100644
--- a/fs/nfsd/trace.h
+++ b/fs/nfsd/trace.h
@@ -2240,6 +2240,28 @@ TRACE_EVENT(nfsd_end_grace,
)
);
+TRACE_EVENT(nfsd_ctl_fh_key_set,
+ TP_PROTO(
+ const char *key,
+ int result
+ ),
+ TP_ARGS(key, result),
+ TP_STRUCT__entry(
+ __field(u32, key_hash)
+ __field(int, result)
+ ),
+ TP_fast_assign(
+ if (key)
+ __entry->key_hash = ~crc32_le(0xFFFFFFFF, key, 16);
+ else
+ __entry->key_hash = 0;
+ __entry->result = result;
+ ),
+ TP_printk("key=0x%08x result=%d",
+ __entry->key_hash, __entry->result
+ )
+);
+
DECLARE_EVENT_CLASS(nfsd_copy_class,
TP_PROTO(
const struct nfsd4_copy *copy
diff --git a/include/uapi/linux/nfsd_netlink.h b/include/uapi/linux/nfsd_netlink.h
index e9efbc9e63d83..97c7447f4d14d 100644
--- a/include/uapi/linux/nfsd_netlink.h
+++ b/include/uapi/linux/nfsd_netlink.h
@@ -36,6 +36,7 @@ enum {
NFSD_A_SERVER_LEASETIME,
NFSD_A_SERVER_SCOPE,
NFSD_A_SERVER_MIN_THREADS,
+ NFSD_A_SERVER_FH_KEY,
__NFSD_A_SERVER_MAX,
NFSD_A_SERVER_MAX = (__NFSD_A_SERVER_MAX - 1)
generated by cgit 1.3-korg (git 2.53.0) at 2026-06-01 06:45:03 +0000