LU-17015 gss: support large kerberos token on client side

If the current Kerberos setup is using large token, like
when MS-PAC feature is enabled, client can crash.

Instead of asserting, return E2BIG to avoid the crash
and increase the default buffer size to 4kB instead of 1kB.
This will only increase the SEC_CTX_INIT RPC size accordingly
as the buffer is shrunk before being sent over the wire.

Up to 2kB security token will be properly handled by Lustre.
But, above that size, a different issue will happen on
server side that will require an other patch.

Test-Parameters: kerberos=true testlist=sanity-krb5
Signed-off-by: Aurelien Degremont <adegremont@nvidia.com>
Change-Id: I9ce30ee7f8c95bfe41525c49986ffac45ffac97c

diff --git a/lustre/ptlrpc/gss/gss_cli_upcall.c b/lustre/ptlrpc/gss/gss_cli_upcall.c
index 94be1ed..18dabd6 100644 (file)
--- a/lustre/ptlrpc/gss/gss_cli_upcall.c
+++ b/lustre/ptlrpc/gss/gss_cli_upcall.c
@@ -65,12 +65,13 @@ int ctx_init_pack_request(struct obd_import *imp,
                          long token_size,
                          char __user *token)
 {
-       struct lustre_msg       *msg = req->rq_reqbuf;
-       struct gss_sec          *gsec;
-       struct gss_header       *ghdr;
+       struct lustre_msg *msg = req->rq_reqbuf;
+       struct gss_sec *gsec;
+       struct gss_header *ghdr;
        struct ptlrpc_user_desc *pud;
-       __u32                   *p, size, offset = 2;
-       rawobj_t                 obj;
+       __u32 total_size;
+       __u32 *p, size, offset = 2;
+       rawobj_t obj;
 
        LASSERT(msg->lm_bufcount <= 4);
        LASSERT(req->rq_cli_ctx);
@@ -127,16 +128,23 @@ int ctx_init_pack_request(struct obd_import *imp,
                LBUG();
 
        /* 4. now the token */
-       LASSERT(size >= (sizeof(__u32) + token_size));
+       total_size = sizeof(__u32) + token_size;
+       if (size < total_size) {
+               CERROR("%s: security token is too large (%d > %d): rc = %d\n",
+                      imp->imp_obd->obd_name, total_size, size, -E2BIG);
+               return -E2BIG;
+       }
        *p++ = cpu_to_le32(((__u32) token_size));
        if (copy_from_user(p, token, token_size)) {
                CERROR("can't copy token\n");
                return -EFAULT;
        }
-       size -= sizeof(__u32) + round_up(token_size, 4);
 
-       req->rq_reqdata_len = lustre_shrink_msg(req->rq_reqbuf, offset,
+       if (size > sizeof(__u32) + round_up(token_size, 4)) {
+               size -= sizeof(__u32) + round_up(token_size, 4);
+               req->rq_reqdata_len = lustre_shrink_msg(req->rq_reqbuf, offset,
                                             msg->lm_buflens[offset] - size, 0);
+       }
        return 0;
 }
 

diff --git a/lustre/ptlrpc/gss/gss_internal.h b/lustre/ptlrpc/gss/gss_internal.h
index f27779f..8fc39e8 100644 (file)
--- a/lustre/ptlrpc/gss/gss_internal.h
+++ b/lustre/ptlrpc/gss/gss_internal.h
@@ -281,7 +281,7 @@ static inline struct gss_sec_keyring *sec2gsec_keyring(struct ptlrpc_sec *sec)
 # define cache_read_unlock(cdetail) read_unlock(&((cdetail)->hash_lock))
 #endif
 
-#define GSS_CTX_INIT_MAX_LEN            (1024)
+#define GSS_CTX_INIT_MAX_LEN            (4096)
 
 /*
  * This only guaranteed be enough for current krb5 des-cbc-crc . We might