From 571ed1fd2390f74e4c1f46994f753fb0d29285e4 Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trond.myklebust@hammerspace.com>
Date: Sat, 29 Sep 2018 16:00:43 -0400
Subject: [PATCH] SUNRPC: Replace krb5_seq_lock with a lockless scheme
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
include/linux/sunrpc/gss_krb5.h | 3 ++-
net/sunrpc/auth_gss/gss_krb5_seal.c | 37 ++++++++++++++++++++---------
net/sunrpc/auth_gss/gss_krb5_wrap.c | 8 ++-----
3 files changed, 30 insertions(+), 18 deletions(-)
diff --git a/include/linux/sunrpc/gss_krb5.h b/include/linux/sunrpc/gss_krb5.h
index 7df625d41e35..69f749afa617 100644
--- a/include/linux/sunrpc/gss_krb5.h
+++ b/include/linux/sunrpc/gss_krb5.h
@@ -118,7 +118,8 @@ struct krb5_ctx {
u8 acceptor_integ[GSS_KRB5_MAX_KEYLEN];
};
-extern spinlock_t krb5_seq_lock;
+extern u32 gss_seq_send_fetch_and_inc(struct krb5_ctx *ctx);
+extern u64 gss_seq_send64_fetch_and_inc(struct krb5_ctx *ctx);
/* The length of the Kerberos GSS token header */
#define GSS_KRB5_TOK_HDR_LEN (16)
diff --git a/net/sunrpc/auth_gss/gss_krb5_seal.c b/net/sunrpc/auth_gss/gss_krb5_seal.c
index eaad9bc7a0bd..0ffb797b92e5 100644
--- a/net/sunrpc/auth_gss/gss_krb5_seal.c
+++ b/net/sunrpc/auth_gss/gss_krb5_seal.c
@@ -68,8 +68,6 @@
# define RPCDBG_FACILITY RPCDBG_AUTH
#endif
-DEFINE_SPINLOCK(krb5_seq_lock);
-
static void *
setup_token(struct krb5_ctx *ctx, struct xdr_netobj *token)
{
@@ -124,6 +122,30 @@ setup_token_v2(struct krb5_ctx *ctx, struct xdr_netobj *token)
return krb5_hdr;
}
+u32
+gss_seq_send_fetch_and_inc(struct krb5_ctx *ctx)
+{
+ u32 old, seq_send = READ_ONCE(ctx->seq_send);
+
+ do {
+ old = seq_send;
+ seq_send = cmpxchg(&ctx->seq_send, old, old + 1);
+ } while (old != seq_send);
+ return seq_send;
+}
+
+u64
+gss_seq_send64_fetch_and_inc(struct krb5_ctx *ctx)
+{
+ u64 old, seq_send = READ_ONCE(ctx->seq_send);
+
+ do {
+ old = seq_send;
+ seq_send = cmpxchg(&ctx->seq_send64, old, old + 1);
+ } while (old != seq_send);
+ return seq_send;
+}
+
static u32
gss_get_mic_v1(struct krb5_ctx *ctx, struct xdr_buf *text,
struct xdr_netobj *token)
@@ -154,9 +176,7 @@ gss_get_mic_v1(struct krb5_ctx *ctx, struct xdr_buf *text,
memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len);
- spin_lock(&krb5_seq_lock);
- seq_send = ctx->seq_send++;
- spin_unlock(&krb5_seq_lock);
+ seq_send = gss_seq_send_fetch_and_inc(ctx);
if (krb5_make_seq_num(ctx, ctx->seq, ctx->initiate ? 0 : 0xff,
seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8))
@@ -174,7 +194,6 @@ gss_get_mic_v2(struct krb5_ctx *ctx, struct xdr_buf *text,
.data = cksumdata};
void *krb5_hdr;
s32 now;
- u64 seq_send;
u8 *cksumkey;
unsigned int cksum_usage;
__be64 seq_send_be64;
@@ -185,11 +204,7 @@ gss_get_mic_v2(struct krb5_ctx *ctx, struct xdr_buf *text,
/* Set up the sequence number. Now 64-bits in clear
* text and w/o direction indicator */
- spin_lock(&krb5_seq_lock);
- seq_send = ctx->seq_send64++;
- spin_unlock(&krb5_seq_lock);
-
- seq_send_be64 = cpu_to_be64(seq_send);
+ seq_send_be64 = cpu_to_be64(gss_seq_send64_fetch_and_inc(ctx));
memcpy(krb5_hdr + 8, (char *) &seq_send_be64, 8);
if (ctx->initiate) {
diff --git a/net/sunrpc/auth_gss/gss_krb5_wrap.c b/net/sunrpc/auth_gss/gss_krb5_wrap.c
index 39a2e672900b..41cb294cd071 100644
--- a/net/sunrpc/auth_gss/gss_krb5_wrap.c
+++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c
@@ -228,9 +228,7 @@ gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset,
memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len);
- spin_lock(&krb5_seq_lock);
- seq_send = kctx->seq_send++;
- spin_unlock(&krb5_seq_lock);
+ seq_send = gss_seq_send_fetch_and_inc(kctx);
/* XXX would probably be more efficient to compute checksum
* and encrypt at the same time: */
@@ -477,9 +475,7 @@ gss_wrap_kerberos_v2(struct krb5_ctx *kctx, u32 offset,
*be16ptr++ = 0;
be64ptr = (__be64 *)be16ptr;
- spin_lock(&krb5_seq_lock);
- *be64ptr = cpu_to_be64(kctx->seq_send64++);
- spin_unlock(&krb5_seq_lock);
+ *be64ptr = cpu_to_be64(gss_seq_send64_fetch_and_inc(kctx));
err = (*kctx->gk5e->encrypt_v2)(kctx, offset, buf, pages);
if (err)