| From | Kamal Mostafa <> | Subject | [PATCH 4.2.y-ckt 135/206] sunrpc: fix stripping of padded MIC tokens | Date | Thu, 9 Jun 2016 14:15:44 -0700 |
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4.2.8-ckt12 -stable review patch. If anyone has any objections, please let me know.
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From: =?UTF-8?q?Tom=C3=A1=C5=A1=20Trnka?= <ttrnka@mail.muni.cz>
commit c0cb8bf3a8e4bd82e640862cdd8891400405cb89 upstream.
The length of the GSS MIC token need not be a multiple of four bytes. It is then padded by XDR to a multiple of 4 B, but unwrap_integ_data() would previously only trim mic.len + 4 B. The remaining up to three bytes would then trigger a check in nfs4svc_decode_compoundargs(), leading to a "garbage args" error and mount failure:
nfs4svc_decode_compoundargs: compound not properly padded! nfsd: failed to decode arguments!
This would prevent older clients using the pre-RFC 4121 MIC format (37-byte MIC including a 9-byte OID) from mounting exports from v3.9+ servers using krb5i.
The trimming was introduced by commit 4c190e2f913f ("sunrpc: trim off trailing checksum before returning decrypted or integrity authenticated buffer").
Fixes: 4c190e2f913f "unrpc: trim off trailing checksum..." Signed-off-by: Tomáš Trnka <ttrnka@mail.muni.cz> Acked-by: Jeff Layton <jlayton@poochiereds.net> Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- net/sunrpc/auth_gss/svcauth_gss.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c index 1095be9..4605dc7 100644 --- a/net/sunrpc/auth_gss/svcauth_gss.c +++ b/net/sunrpc/auth_gss/svcauth_gss.c @@ -857,8 +857,8 @@ unwrap_integ_data(struct svc_rqst *rqstp, struct xdr_buf *buf, u32 seq, struct g goto out; if (svc_getnl(&buf->head[0]) != seq) goto out; - /* trim off the mic at the end before returning */ - xdr_buf_trim(buf, mic.len + 4); + /* trim off the mic and padding at the end before returning */ + xdr_buf_trim(buf, round_up_to_quad(mic.len) + 4); stat = 0; out: kfree(mic.data); -- 2.7.4
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