From 8235de189845986a535d676b1fd2c894b9c02e52 Mon Sep 17 00:00:00 2001 From: Niels de Vos Date: Thu, 20 Mar 2014 18:13:49 +0100 Subject: rpc: warn and truncate grouplist if RPC/AUTH can not hold everything The GlusterFS protocol currently uses AUTH_GLUSTERFS_V2 in the RPC/AUTH header. This header contains the uid, gid and auxiliary groups of the user/process that accesses the Gluster Volume. The AUTH_GLUSTERFS_V2 structure allows up to 65535 auxiliary groups to be passed on. Unfortunately, the RPC/AUTH header is limited to 400 bytes by the RPC specification: http://tools.ietf.org/html/rfc5531#section-8.2 In order to not cause complete failures on the client-side when trying to encode a AUTH_GLUSTERFS_V2 that would result in more than 400 bytes, we can calculate the expected size of the other elements: 1 | pid 1 | uid 1 | gid 1 | groups_len XX | groups_val (GF_MAX_AUX_GROUPS=65535) 1 | lk_owner_len YY | lk_owner_val (GF_MAX_LOCK_OWNER_LEN=1024) ----+------------------------------------------- 5 | total xdr-units one XDR-unit is defined as BYTES_PER_XDR_UNIT = 4 bytes MAX_AUTH_BYTES = 400 is the maximum, this is 100 xdr-units. XX + YY can be 95 to fill the 100 xdr-units. Note that the on-wire protocol has tighter requirements than the internal structures. It is possible for xlators to use more groups and a bigger lk_owner than that can be sent by a GlusterFS-client. This change prevents overflows when allocating the RPC/AUTH header. Two new macros are introduced to calculate the number of groups that fit in the RPC/AUTH header, when taking the size of the lk_owner in account. In case the list of groups exceeds the maximum possible, only the first groups are passed over the RPC/GlusterFS protocol to the bricks. A warning is added to the logs, so that most system administrators will get informed. The reducing of the number of groups is not a new inventions. The RPC/AUTH header (AUTH_SYS or AUTH_UNIX) that NFS uses has a limit of 16 groups. Most, if not all, NFS-clients will reduce any bigger number of groups to 16. (nfs.server-aux-gids can be used to workaround the limit of 16 groups, but the Gluster NFS-server will be limited to a maximum of 93 groups, or fewer in case the lk_owner structure contains more items.) Change-Id: I8410e59d0fd246d601b54b961d3ae9cb5a858c10 BUG: 1053579 Signed-off-by: Niels de Vos Reviewed-on: http://review.gluster.org/7202 Tested-by: Gluster Build System Reviewed-by: Harshavardhana Reviewed-by: Santosh Pradhan Reviewed-by: Vijay Bellur --- rpc/rpc-lib/src/xdr-common.h | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) (limited to 'rpc/rpc-lib/src/xdr-common.h') diff --git a/rpc/rpc-lib/src/xdr-common.h b/rpc/rpc-lib/src/xdr-common.h index 34dc9c6a2..f221192ad 100644 --- a/rpc/rpc-lib/src/xdr-common.h +++ b/rpc/rpc-lib/src/xdr-common.h @@ -18,6 +18,7 @@ #include #include +#include #include #include @@ -34,7 +35,34 @@ enum gf_dump_procnum { #define GLUSTER_DUMP_PROGRAM 123451501 /* Completely random */ #define GLUSTER_DUMP_VERSION 1 -#define GF_MAX_AUTH_BYTES 2048 +/* MAX_AUTH_BYTES is restricted to 400 bytes, see + * http://tools.ietf.org/html/rfc5531#section-8.2 */ +#define GF_MAX_AUTH_BYTES MAX_AUTH_BYTES + +/* The size of an AUTH_GLUSTERFS_V2 structure: + * + * 1 | pid + * 1 | uid + * 1 | gid + * 1 | groups_len + * XX | groups_val (GF_MAX_AUX_GROUPS=65535) + * 1 | lk_owner_len + * YY | lk_owner_val (GF_MAX_LOCK_OWNER_LEN=1024) + * ----+------------------------------------------- + * 5 | total xdr-units + * + * one XDR-unit is defined as BYTES_PER_XDR_UNIT = 4 bytes + * MAX_AUTH_BYTES = 400 is the maximum, this is 100 xdr-units. + * XX + YY can be 95 to fill the 100 xdr-units. + * + * Note that the on-wire protocol has tighter requirements than the internal + * structures. It is possible for xlators to use more groups and a bigger + * lk_owner than that can be sent by a GlusterFS-client. + */ +#define GF_AUTH_GLUSTERFS_MAX_GROUPS(lk_owner_len) \ + (95 - lk_owner_len) +#define GF_AUTH_GLUSTERFS_MAX_LKOWNER(groups_len) \ + (95 - groups_len) #if GF_DARWIN_HOST_OS #define xdr_u_quad_t xdr_u_int64_t -- cgit