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authorPaul Burton <paul.burton@mips.com>2018-11-01 17:51:34 +0000
committerTrond Myklebust <trond.myklebust@hammerspace.com>2018-11-01 13:55:24 -0400
commitc3be6577d82a9f0163eb1e2c37a477414d12a209 (patch)
treed6cee7e555354f3f81f10b35b284b93fecc68ade /net
parent86bbd7422ae6a33735df6846fd685e46686da714 (diff)
downloadlinux-c3be6577d82a9f0163eb1e2c37a477414d12a209.tar.gz
SUNRPC: Use atomic(64)_t for seq_send(64)
The seq_send & seq_send64 fields in struct krb5_ctx are used as atomically incrementing counters. This is implemented using cmpxchg() & cmpxchg64() to implement what amount to custom versions of atomic_fetch_inc() & atomic64_fetch_inc(). Besides the duplication, using cmpxchg64() has another major drawback in that some 32 bit architectures don't provide it. As such commit 571ed1fd2390 ("SUNRPC: Replace krb5_seq_lock with a lockless scheme") resulted in build failures for some architectures. Change seq_send to be an atomic_t and seq_send64 to be an atomic64_t, then use atomic(64)_* functions to manipulate the values. The atomic64_t type & associated functions are provided even on architectures which lack real 64 bit atomic memory access via CONFIG_GENERIC_ATOMIC64 which uses spinlocks to serialize access. This fixes the build failures for architectures lacking cmpxchg64(). A potential alternative that was raised would be to provide cmpxchg64() on the 32 bit architectures that currently lack it, using spinlocks. However this would provide a version of cmpxchg64() with semantics a little different to the implementations on architectures with real 64 bit atomics - the spinlock-based implementation would only work if all access to the memory used with cmpxchg64() is *always* performed using cmpxchg64(). That is not currently a requirement for users of cmpxchg64(), and making it one seems questionable. As such avoiding cmpxchg64() outside of architecture-specific code seems best, particularly in cases where atomic64_t seems like a better fit anyway. The CONFIG_GENERIC_ATOMIC64 implementation of atomic64_* functions will use spinlocks & so faces the same issue, but with the key difference that the memory backing an atomic64_t ought to always be accessed via the atomic64_* functions anyway making the issue moot. Signed-off-by: Paul Burton <paul.burton@mips.com> Fixes: 571ed1fd2390 ("SUNRPC: Replace krb5_seq_lock with a lockless scheme") Cc: Trond Myklebust <trond.myklebust@hammerspace.com> Cc: Anna Schumaker <anna.schumaker@netapp.com> Cc: J. Bruce Fields <bfields@fieldses.org> Cc: Jeff Layton <jlayton@kernel.org> Cc: David S. Miller <davem@davemloft.net> Cc: linux-nfs@vger.kernel.org Cc: netdev@vger.kernel.org Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Diffstat (limited to 'net')
-rw-r--r--net/sunrpc/auth_gss/gss_krb5_mech.c16
-rw-r--r--net/sunrpc/auth_gss/gss_krb5_seal.c28
-rw-r--r--net/sunrpc/auth_gss/gss_krb5_wrap.c4
3 files changed, 14 insertions, 34 deletions
diff --git a/net/sunrpc/auth_gss/gss_krb5_mech.c b/net/sunrpc/auth_gss/gss_krb5_mech.c
index 7bb2514aadd9..71cb29dc86c2 100644
--- a/net/sunrpc/auth_gss/gss_krb5_mech.c
+++ b/net/sunrpc/auth_gss/gss_krb5_mech.c
@@ -275,6 +275,7 @@ out_err:
static int
gss_import_v1_context(const void *p, const void *end, struct krb5_ctx *ctx)
{
+ u32 seq_send;
int tmp;
p = simple_get_bytes(p, end, &ctx->initiate, sizeof(ctx->initiate));
@@ -316,9 +317,10 @@ gss_import_v1_context(const void *p, const void *end, struct krb5_ctx *ctx)
p = simple_get_bytes(p, end, &ctx->endtime, sizeof(ctx->endtime));
if (IS_ERR(p))
goto out_err;
- p = simple_get_bytes(p, end, &ctx->seq_send, sizeof(ctx->seq_send));
+ p = simple_get_bytes(p, end, &seq_send, sizeof(seq_send));
if (IS_ERR(p))
goto out_err;
+ atomic_set(&ctx->seq_send, seq_send);
p = simple_get_netobj(p, end, &ctx->mech_used);
if (IS_ERR(p))
goto out_err;
@@ -610,6 +612,7 @@ static int
gss_import_v2_context(const void *p, const void *end, struct krb5_ctx *ctx,
gfp_t gfp_mask)
{
+ u64 seq_send64;
int keylen;
p = simple_get_bytes(p, end, &ctx->flags, sizeof(ctx->flags));
@@ -620,14 +623,15 @@ gss_import_v2_context(const void *p, const void *end, struct krb5_ctx *ctx,
p = simple_get_bytes(p, end, &ctx->endtime, sizeof(ctx->endtime));
if (IS_ERR(p))
goto out_err;
- p = simple_get_bytes(p, end, &ctx->seq_send64, sizeof(ctx->seq_send64));
+ p = simple_get_bytes(p, end, &seq_send64, sizeof(seq_send64));
if (IS_ERR(p))
goto out_err;
+ atomic64_set(&ctx->seq_send64, seq_send64);
/* set seq_send for use by "older" enctypes */
- ctx->seq_send = ctx->seq_send64;
- if (ctx->seq_send64 != ctx->seq_send) {
- dprintk("%s: seq_send64 %lx, seq_send %x overflow?\n", __func__,
- (unsigned long)ctx->seq_send64, ctx->seq_send);
+ atomic_set(&ctx->seq_send, seq_send64);
+ if (seq_send64 != atomic_read(&ctx->seq_send)) {
+ dprintk("%s: seq_send64 %llx, seq_send %x overflow?\n", __func__,
+ seq_send64, atomic_read(&ctx->seq_send));
p = ERR_PTR(-EINVAL);
goto out_err;
}
diff --git a/net/sunrpc/auth_gss/gss_krb5_seal.c b/net/sunrpc/auth_gss/gss_krb5_seal.c
index b4adeb06660b..48fe4a591b54 100644
--- a/net/sunrpc/auth_gss/gss_krb5_seal.c
+++ b/net/sunrpc/auth_gss/gss_krb5_seal.c
@@ -123,30 +123,6 @@ 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 = cmpxchg64(&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)
@@ -177,7 +153,7 @@ gss_get_mic_v1(struct krb5_ctx *ctx, struct xdr_buf *text,
memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len);
- seq_send = gss_seq_send_fetch_and_inc(ctx);
+ seq_send = atomic_fetch_inc(&ctx->seq_send);
if (krb5_make_seq_num(ctx, ctx->seq, ctx->initiate ? 0 : 0xff,
seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8))
@@ -205,7 +181,7 @@ 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 */
- seq_send_be64 = cpu_to_be64(gss_seq_send64_fetch_and_inc(ctx));
+ seq_send_be64 = cpu_to_be64(atomic64_fetch_inc(&ctx->seq_send64));
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 41cb294cd071..6af6f119d9c1 100644
--- a/net/sunrpc/auth_gss/gss_krb5_wrap.c
+++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c
@@ -228,7 +228,7 @@ gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset,
memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len);
- seq_send = gss_seq_send_fetch_and_inc(kctx);
+ seq_send = atomic_fetch_inc(&kctx->seq_send);
/* XXX would probably be more efficient to compute checksum
* and encrypt at the same time: */
@@ -475,7 +475,7 @@ gss_wrap_kerberos_v2(struct krb5_ctx *kctx, u32 offset,
*be16ptr++ = 0;
be64ptr = (__be64 *)be16ptr;
- *be64ptr = cpu_to_be64(gss_seq_send64_fetch_and_inc(kctx));
+ *be64ptr = cpu_to_be64(atomic64_fetch_inc(&kctx->seq_send64));
err = (*kctx->gk5e->encrypt_v2)(kctx, offset, buf, pages);
if (err)