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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 <michael.skralivetsky@primarydata.com>
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
hifive-unleashed-5.1
Jeff Layton 2015-08-03 07:44:53 -04:00 committed by Trond Myklebust
parent c8ad8894e9
commit 24a9a9610c
2 changed files with 7 additions and 3 deletions
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8
include/linux/sunrpc/auth.h
View File

@ -18,9 +18,13 @@
#include <linux/atomic.h>
#include <linux/rcupdate.h>
#include <linux/uidgid.h>
#include <linux/utsname.h>
/* 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;

2
net/sunrpc/auth_unix.c
View File

@ -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