From 24a9a9610ce3ba36fd87c1d2f2c9106de6b7e832 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Mon, 3 Aug 2015 07:44:53 -0400 Subject: [PATCH] sunrpc: increase UNX_MAXNODENAME from 32 to __NEW_UTS_LEN bytes The current limit of 32 bytes artificially limits the name string that we end up stuffing into NFSv4.x client ID blobs. If you have multiple hosts with long hostnames that only differ near the end, then this can cause NFSv4 client ID collisions. Linux nodenames are actually limited to __NEW_UTS_LEN bytes (64), so use that as the limit instead. Also, use XDR_QUADLEN to specify the slack length, just for clarity and in case someone in the future changes this to something not evenly divisible by 4. Reported-by: Michael Skralivetsky Signed-off-by: Jeff Layton Signed-off-by: Trond Myklebust --- include/linux/sunrpc/auth.h | 8 ++++++-- net/sunrpc/auth_unix.c | 2 +- 2 files changed, 7 insertions(+), 3 deletions(-) diff --git a/include/linux/sunrpc/auth.h b/include/linux/sunrpc/auth.h index a7cbb57..1ecf13e 100644 --- a/include/linux/sunrpc/auth.h +++ b/include/linux/sunrpc/auth.h @@ -18,9 +18,13 @@ #include #include #include +#include -/* size of the nodename buffer */ -#define UNX_MAXNODENAME 32 +/* + * Size of the nodename buffer. RFC1831 specifies a hard limit of 255 bytes, + * but Linux hostnames are actually limited to __NEW_UTS_LEN bytes. + */ +#define UNX_MAXNODENAME __NEW_UTS_LEN struct rpcsec_gss_info; diff --git a/net/sunrpc/auth_unix.c b/net/sunrpc/auth_unix.c index 4feda2d..548240d 100644 --- a/net/sunrpc/auth_unix.c +++ b/net/sunrpc/auth_unix.c @@ -23,7 +23,7 @@ struct unx_cred { }; #define uc_uid uc_base.cr_uid -#define UNX_WRITESLACK (21 + (UNX_MAXNODENAME >> 2)) +#define UNX_WRITESLACK (21 + XDR_QUADLEN(UNX_MAXNODENAME)) #if IS_ENABLED(CONFIG_SUNRPC_DEBUG) # define RPCDBG_FACILITY RPCDBG_AUTH -- 2.7.4