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Diffstat (limited to 'fs/nfs/super.c')
-rw-r--r--fs/nfs/super.c48
1 files changed, 41 insertions, 7 deletions
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 1bb071dca9ab..a366107a7331 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -1610,16 +1610,15 @@ out_security_failure:
/*
* Select a security flavor for this mount. The selected flavor
* is planted in args->auth_flavors[0].
+ *
+ * Returns 0 on success, -EACCES on failure.
*/
-static void nfs_select_flavor(struct nfs_parsed_mount_data *args,
+static int nfs_select_flavor(struct nfs_parsed_mount_data *args,
struct nfs_mount_request *request)
{
unsigned int i, count = *(request->auth_flav_len);
rpc_authflavor_t flavor;
- if (args->auth_flavors[0] != RPC_AUTH_MAXFLAVOR)
- goto out;
-
/*
* The NFSv2 MNT operation does not return a flavor list.
*/
@@ -1634,6 +1633,25 @@ static void nfs_select_flavor(struct nfs_parsed_mount_data *args,
goto out_default;
/*
+ * If the sec= mount option is used, the specified flavor or AUTH_NULL
+ * must be in the list returned by the server.
+ *
+ * AUTH_NULL has a special meaning when it's in the server list - it
+ * means that the server will ignore the rpc creds, so any flavor
+ * can be used.
+ */
+ if (args->auth_flavors[0] != RPC_AUTH_MAXFLAVOR) {
+ for (i = 0; i < count; i++) {
+ if (args->auth_flavors[0] == request->auth_flavs[i] ||
+ request->auth_flavs[i] == RPC_AUTH_NULL)
+ goto out;
+ }
+ dfprintk(MOUNT, "NFS: auth flavor %d not supported by server\n",
+ args->auth_flavors[0]);
+ goto out_err;
+ }
+
+ /*
* RFC 2623, section 2.7 suggests we SHOULD prefer the
* flavor listed first. However, some servers list
* AUTH_NULL first. Avoid ever choosing AUTH_NULL.
@@ -1653,12 +1671,29 @@ static void nfs_select_flavor(struct nfs_parsed_mount_data *args,
}
}
+ /*
+ * As a last chance, see if the server list contains AUTH_NULL -
+ * if it does, use the default flavor.
+ */
+ for (i = 0; i < count; i++) {
+ if (request->auth_flavs[i] == RPC_AUTH_NULL)
+ goto out_default;
+ }
+
+ dfprintk(MOUNT, "NFS: no auth flavors in common with server\n");
+ goto out_err;
+
out_default:
- flavor = RPC_AUTH_UNIX;
+ /* use default if flavor not already set */
+ flavor = (args->auth_flavors[0] == RPC_AUTH_MAXFLAVOR) ?
+ RPC_AUTH_UNIX : args->auth_flavors[0];
out_set:
args->auth_flavors[0] = flavor;
out:
dfprintk(MOUNT, "NFS: using auth flavor %d\n", args->auth_flavors[0]);
+ return 0;
+out_err:
+ return -EACCES;
}
/*
@@ -1721,8 +1756,7 @@ static int nfs_request_mount(struct nfs_parsed_mount_data *args,
return status;
}
- nfs_select_flavor(args, &request);
- return 0;
+ return nfs_select_flavor(args, &request);
}
struct dentry *nfs_try_mount(int flags, const char *dev_name,