From a1a237775ec8fd2694b9f8e451821fd168e730d8 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Thu, 16 Aug 2018 12:05:54 -0400 Subject: [PATCH] sunrpc: Enable the kernel to specify the hostname part of service principals A multi-homed NFS server may have more than one "nfs" key in its keytab. Enable the kernel to pick the key it wants as a machine credential when establishing a GSS context. This is useful for GSS-protected NFSv4.0 callbacks, which are required by RFC 7530 S3.3.3 to use the same principal as the service principal the client used when establishing its lease. A complementary modification to rpc.gssd is required to fully enable this feature. Signed-off-by: Chuck Lever Signed-off-by: J. Bruce Fields --- net/sunrpc/auth_gss/auth_gss.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c index be8f103d22fd..1943e1198804 100644 --- a/net/sunrpc/auth_gss/auth_gss.c +++ b/net/sunrpc/auth_gss/auth_gss.c @@ -284,7 +284,12 @@ gss_fill_context(const void *p, const void *end, struct gss_cl_ctx *ctx, struct return p; } -#define UPCALL_BUF_LEN 128 +/* XXX: Need some documentation about why UPCALL_BUF_LEN is so small. + * Is user space expecting no more than UPCALL_BUF_LEN bytes? + * Note that there are now _two_ NI_MAXHOST sized data items + * being passed in this string. + */ +#define UPCALL_BUF_LEN 256 struct gss_upcall_msg { refcount_t count; @@ -462,8 +467,17 @@ static int gss_encode_v1_msg(struct gss_upcall_msg *gss_msg, p += len; gss_msg->msg.len += len; } - if (service_name != NULL) { - len = scnprintf(p, buflen, "service=%s ", service_name); + if (service_name) { + char *c = strchr(service_name, '@'); + + if (!c) + len = scnprintf(p, buflen, "service=%s ", + service_name); + else + len = scnprintf(p, buflen, + "service=%.*s srchost=%s ", + (int)(c - service_name), + service_name, c + 1); buflen -= len; p += len; gss_msg->msg.len += len; -- GitLab