From 31c9590ae468478fe47dc0f5f0d3562b2f69450e Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Sat, 18 Apr 2020 21:06:23 -0400 Subject: SUNRPC: Add "@len" parameter to gss_unwrap() Refactor: This is a pre-requisite to fixing the client-side ralign computation in gss_unwrap_resp_priv(). The length value is passed in explicitly rather that as the value of buf->len. This will subsequently allow gss_unwrap_kerberos_v1() to compute a slack and align value, instead of computing it in gss_unwrap_resp_priv(). Fixes: 35e77d21baa0 ("SUNRPC: Add rpc_auth::au_ralign field") Signed-off-by: Chuck Lever --- include/linux/sunrpc/gss_api.h | 2 ++ include/linux/sunrpc/gss_krb5.h | 6 +++--- 2 files changed, 5 insertions(+), 3 deletions(-) (limited to 'include') diff --git a/include/linux/sunrpc/gss_api.h b/include/linux/sunrpc/gss_api.h index 48c1b1674cbf..e9a79518d652 100644 --- a/include/linux/sunrpc/gss_api.h +++ b/include/linux/sunrpc/gss_api.h @@ -66,6 +66,7 @@ u32 gss_wrap( u32 gss_unwrap( struct gss_ctx *ctx_id, int offset, + int len, struct xdr_buf *inbuf); u32 gss_delete_sec_context( struct gss_ctx **ctx_id); @@ -126,6 +127,7 @@ struct gss_api_ops { u32 (*gss_unwrap)( struct gss_ctx *ctx_id, int offset, + int len, struct xdr_buf *buf); void (*gss_delete_sec_context)( void *internal_ctx_id); diff --git a/include/linux/sunrpc/gss_krb5.h b/include/linux/sunrpc/gss_krb5.h index c1d77dd8ed41..e8f8ffe7448b 100644 --- a/include/linux/sunrpc/gss_krb5.h +++ b/include/linux/sunrpc/gss_krb5.h @@ -83,7 +83,7 @@ struct gss_krb5_enctype { u32 (*encrypt_v2) (struct krb5_ctx *kctx, u32 offset, struct xdr_buf *buf, struct page **pages); /* v2 encryption function */ - u32 (*decrypt_v2) (struct krb5_ctx *kctx, u32 offset, + u32 (*decrypt_v2) (struct krb5_ctx *kctx, u32 offset, u32 len, struct xdr_buf *buf, u32 *headskip, u32 *tailskip); /* v2 decryption function */ }; @@ -255,7 +255,7 @@ gss_wrap_kerberos(struct gss_ctx *ctx_id, int offset, struct xdr_buf *outbuf, struct page **pages); u32 -gss_unwrap_kerberos(struct gss_ctx *ctx_id, int offset, +gss_unwrap_kerberos(struct gss_ctx *ctx_id, int offset, int len, struct xdr_buf *buf); @@ -312,7 +312,7 @@ gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset, struct page **pages); u32 -gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, +gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, u32 len, struct xdr_buf *buf, u32 *plainoffset, u32 *plainlen); -- cgit v1.2.3 From a7e429a6fa6d612d1dacde96c885dc1bb4a9f400 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Sat, 18 Apr 2020 14:38:19 -0400 Subject: SUNRPC: Fix GSS privacy computation of auth->au_ralign When the au_ralign field was added to gss_unwrap_resp_priv, the wrong calculation was used. Setting au_rslack == au_ralign is probably correct for kerberos_v1 privacy, but kerberos_v2 privacy adds additional GSS data after the clear text RPC message. au_ralign needs to be smaller than au_rslack in that fairly common case. When xdr_buf_trim() is restored to gss_unwrap_kerberos_v2(), it does exactly what I feared it would: it trims off part of the clear text RPC message. However, that's because rpc_prepare_reply_pages() does not set up the rq_rcv_buf's tail correctly because au_ralign is too large. Fixing the au_ralign computation also corrects the alignment of rq_rcv_buf->pages so that the client does not have to shift reply data payloads after they are received. Fixes: 35e77d21baa0 ("SUNRPC: Add rpc_auth::au_ralign field") Signed-off-by: Chuck Lever --- include/linux/sunrpc/gss_api.h | 1 + net/sunrpc/auth_gss/auth_gss.c | 8 +++----- net/sunrpc/auth_gss/gss_krb5_wrap.c | 19 +++++++++++++++---- 3 files changed, 19 insertions(+), 9 deletions(-) (limited to 'include') diff --git a/include/linux/sunrpc/gss_api.h b/include/linux/sunrpc/gss_api.h index e9a79518d652..bc07e51f20d1 100644 --- a/include/linux/sunrpc/gss_api.h +++ b/include/linux/sunrpc/gss_api.h @@ -21,6 +21,7 @@ struct gss_ctx { struct gss_api_mech *mech_type; void *internal_ctx_id; + unsigned int slack, align; }; #define GSS_C_NO_BUFFER ((struct xdr_netobj) 0) diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c index 7885f37e3688..ac5cac0dd24b 100644 --- a/net/sunrpc/auth_gss/auth_gss.c +++ b/net/sunrpc/auth_gss/auth_gss.c @@ -2032,7 +2032,6 @@ gss_unwrap_resp_priv(struct rpc_task *task, struct rpc_cred *cred, struct xdr_buf *rcv_buf = &rqstp->rq_rcv_buf; struct kvec *head = rqstp->rq_rcv_buf.head; struct rpc_auth *auth = cred->cr_auth; - unsigned int savedlen = rcv_buf->len; u32 offset, opaque_len, maj_stat; __be32 *p; @@ -2059,10 +2058,9 @@ gss_unwrap_resp_priv(struct rpc_task *task, struct rpc_cred *cred, */ xdr_init_decode(xdr, rcv_buf, p, rqstp); - auth->au_rslack = auth->au_verfsize + 2 + - XDR_QUADLEN(savedlen - rcv_buf->len); - auth->au_ralign = auth->au_verfsize + 2 + - XDR_QUADLEN(savedlen - rcv_buf->len); + auth->au_rslack = auth->au_verfsize + 2 + ctx->gc_gss_ctx->slack; + auth->au_ralign = auth->au_verfsize + 2 + ctx->gc_gss_ctx->align; + return 0; unwrap_failed: trace_rpcgss_unwrap_failed(task); diff --git a/net/sunrpc/auth_gss/gss_krb5_wrap.c b/net/sunrpc/auth_gss/gss_krb5_wrap.c index c7589e35d5d9..4905652e7567 100644 --- a/net/sunrpc/auth_gss/gss_krb5_wrap.c +++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c @@ -262,7 +262,8 @@ gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset, static u32 gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, int len, - struct xdr_buf *buf) + struct xdr_buf *buf, unsigned int *slack, + unsigned int *align) { int signalg; int sealalg; @@ -280,6 +281,7 @@ gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, int len, u32 conflen = kctx->gk5e->conflen; int crypt_offset; u8 *cksumkey; + unsigned int saved_len = buf->len; dprintk("RPC: gss_unwrap_kerberos\n"); @@ -383,6 +385,10 @@ gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, int len, if (gss_krb5_remove_padding(buf, blocksize)) return GSS_S_DEFECTIVE_TOKEN; + /* slack must include room for krb5 padding */ + *slack = XDR_QUADLEN(saved_len - buf->len); + /* The GSS blob always precedes the RPC message payload */ + *align = *slack; return GSS_S_COMPLETE; } @@ -489,7 +495,8 @@ gss_wrap_kerberos_v2(struct krb5_ctx *kctx, u32 offset, static u32 gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, int len, - struct xdr_buf *buf) + struct xdr_buf *buf, unsigned int *slack, + unsigned int *align) { time64_t now; u8 *ptr; @@ -583,6 +590,8 @@ gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, int len, /* Trim off the trailing "extra count" and checksum blob */ buf->len -= ec + GSS_KRB5_TOK_HDR_LEN + tailskip; + *align = XDR_QUADLEN(GSS_KRB5_TOK_HDR_LEN + headskip); + *slack = *align + XDR_QUADLEN(ec + GSS_KRB5_TOK_HDR_LEN + tailskip); return GSS_S_COMPLETE; } @@ -617,9 +626,11 @@ gss_unwrap_kerberos(struct gss_ctx *gctx, int offset, case ENCTYPE_DES_CBC_RAW: case ENCTYPE_DES3_CBC_RAW: case ENCTYPE_ARCFOUR_HMAC: - return gss_unwrap_kerberos_v1(kctx, offset, len, buf); + return gss_unwrap_kerberos_v1(kctx, offset, len, buf, + &gctx->slack, &gctx->align); case ENCTYPE_AES128_CTS_HMAC_SHA1_96: case ENCTYPE_AES256_CTS_HMAC_SHA1_96: - return gss_unwrap_kerberos_v2(kctx, offset, len, buf); + return gss_unwrap_kerberos_v2(kctx, offset, len, buf, + &gctx->slack, &gctx->align); } } -- cgit v1.2.3 From 0a8e7b7d08466b5fc52f8e96070acc116d82a8bb Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Wed, 15 Apr 2020 17:36:22 -0400 Subject: SUNRPC: Revert 241b1f419f0e ("SUNRPC: Remove xdr_buf_trim()") I've noticed that when krb5i or krb5p security is in use, retransmitted requests are missing the server's duplicate reply cache. The computed checksum on the retransmitted request does not match the cached checksum, resulting in the server performing the retransmitted request again instead of returning the cached reply. The assumptions made when removing xdr_buf_trim() were not correct. In the send paths, the upper layer has already set the segment lengths correctly, and shorting the buffer's content is simply a matter of reducing buf->len. xdr_buf_trim() is the right answer in the receive/unwrap path on both the client and the server. The buffer segment lengths have to be shortened one-by-one. On the server side in particular, head.iov_len needs to be updated correctly to enable nfsd_cache_csum() to work correctly. The simple buf->len computation doesn't do that, and that results in checksumming stale data in the buffer. The problem isn't noticed until there's significant instability of the RPC transport. At that point, the reliability of retransmit detection on the server becomes crucial. Fixes: 241b1f419f0e ("SUNRPC: Remove xdr_buf_trim()") Signed-off-by: Chuck Lever --- include/linux/sunrpc/xdr.h | 1 + net/sunrpc/auth_gss/gss_krb5_wrap.c | 7 +++---- net/sunrpc/auth_gss/svcauth_gss.c | 2 +- net/sunrpc/xdr.c | 41 +++++++++++++++++++++++++++++++++++++ 4 files changed, 46 insertions(+), 5 deletions(-) (limited to 'include') diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h index 01bb41908c93..22c207b2425f 100644 --- a/include/linux/sunrpc/xdr.h +++ b/include/linux/sunrpc/xdr.h @@ -184,6 +184,7 @@ xdr_adjust_iovec(struct kvec *iov, __be32 *p) extern void xdr_shift_buf(struct xdr_buf *, size_t); extern void xdr_buf_from_iov(struct kvec *, struct xdr_buf *); extern int xdr_buf_subsegment(struct xdr_buf *, struct xdr_buf *, unsigned int, unsigned int); +extern void xdr_buf_trim(struct xdr_buf *, unsigned int); extern int read_bytes_from_xdr_buf(struct xdr_buf *, unsigned int, void *, unsigned int); extern int write_bytes_to_xdr_buf(struct xdr_buf *, unsigned int, void *, unsigned int); diff --git a/net/sunrpc/auth_gss/gss_krb5_wrap.c b/net/sunrpc/auth_gss/gss_krb5_wrap.c index 4905652e7567..cf0fd170ac18 100644 --- a/net/sunrpc/auth_gss/gss_krb5_wrap.c +++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c @@ -580,15 +580,14 @@ gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, int len, */ movelen = min_t(unsigned int, buf->head[0].iov_len, len); movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip; - if (offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen > - buf->head[0].iov_len) - return GSS_S_FAILURE; + BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen > + buf->head[0].iov_len); memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen); buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip; buf->len = len - GSS_KRB5_TOK_HDR_LEN + headskip; /* Trim off the trailing "extra count" and checksum blob */ - buf->len -= ec + GSS_KRB5_TOK_HDR_LEN + tailskip; + xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip); *align = XDR_QUADLEN(GSS_KRB5_TOK_HDR_LEN + headskip); *slack = *align + XDR_QUADLEN(ec + GSS_KRB5_TOK_HDR_LEN + tailskip); diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c index d0a2f084e5a4..50d93c49ef1a 100644 --- a/net/sunrpc/auth_gss/svcauth_gss.c +++ b/net/sunrpc/auth_gss/svcauth_gss.c @@ -906,7 +906,7 @@ unwrap_integ_data(struct svc_rqst *rqstp, struct xdr_buf *buf, u32 seq, struct g if (svc_getnl(&buf->head[0]) != seq) goto out; /* trim off the mic and padding at the end before returning */ - buf->len -= 4 + round_up_to_quad(mic.len); + xdr_buf_trim(buf, round_up_to_quad(mic.len) + 4); stat = 0; out: kfree(mic.data); diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c index 15b58c5144f9..6f7d82fb1eb0 100644 --- a/net/sunrpc/xdr.c +++ b/net/sunrpc/xdr.c @@ -1150,6 +1150,47 @@ xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf, } EXPORT_SYMBOL_GPL(xdr_buf_subsegment); +/** + * xdr_buf_trim - lop at most "len" bytes off the end of "buf" + * @buf: buf to be trimmed + * @len: number of bytes to reduce "buf" by + * + * Trim an xdr_buf by the given number of bytes by fixing up the lengths. Note + * that it's possible that we'll trim less than that amount if the xdr_buf is + * too small, or if (for instance) it's all in the head and the parser has + * already read too far into it. + */ +void xdr_buf_trim(struct xdr_buf *buf, unsigned int len) +{ + size_t cur; + unsigned int trim = len; + + if (buf->tail[0].iov_len) { + cur = min_t(size_t, buf->tail[0].iov_len, trim); + buf->tail[0].iov_len -= cur; + trim -= cur; + if (!trim) + goto fix_len; + } + + if (buf->page_len) { + cur = min_t(unsigned int, buf->page_len, trim); + buf->page_len -= cur; + trim -= cur; + if (!trim) + goto fix_len; + } + + if (buf->head[0].iov_len) { + cur = min_t(size_t, buf->head[0].iov_len, trim); + buf->head[0].iov_len -= cur; + trim -= cur; + } +fix_len: + buf->len -= (len - trim); +} +EXPORT_SYMBOL_GPL(xdr_buf_trim); + static void __read_bytes_from_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len) { unsigned int this_len; -- cgit v1.2.3