From cf4c024b908353fcc48309374d39e3399d67dfd1 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Thu, 10 Oct 2013 06:55:35 -0400 Subject: sunrpc: trim off EC bytes in GSSAPI v2 unwrap As Bruce points out in RFC 4121, section 4.2.3: "In Wrap tokens that provide for confidentiality, the first 16 octets of the Wrap token (the "header", as defined in section 4.2.6), SHALL be appended to the plaintext data before encryption. Filler octets MAY be inserted between the plaintext data and the "header."" ...and... "In Wrap tokens with confidentiality, the EC field SHALL be used to encode the number of octets in the filler..." It's possible for the client to stuff different data in that area on a retransmission, which could make the checksum come out wrong in the DRC code. After decrypting the blob, we should trim off any extra count bytes in addition to the checksum blob. Reported-by: "J. Bruce Fields" Signed-off-by: Jeff Layton Signed-off-by: J. Bruce Fields --- net/sunrpc/auth_gss/gss_krb5_wrap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'net/sunrpc/auth_gss') diff --git a/net/sunrpc/auth_gss/gss_krb5_wrap.c b/net/sunrpc/auth_gss/gss_krb5_wrap.c index 5040a46..42560e5 100644 --- a/net/sunrpc/auth_gss/gss_krb5_wrap.c +++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c @@ -576,8 +576,8 @@ gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf) buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip; buf->len -= GSS_KRB5_TOK_HDR_LEN + headskip; - /* Trim off the checksum blob */ - xdr_buf_trim(buf, GSS_KRB5_TOK_HDR_LEN + tailskip); + /* Trim off the trailing "extra count" and checksum blob */ + xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip); return GSS_S_COMPLETE; } -- cgit v1.1