From ccebad103f3466d5e8fc2b60f6127af618adf8d2 Mon Sep 17 00:00:00 2001

From: David Lutterkort <lutter@watzmann.net>

Date: Mon, 4 Jun 2018 10:45:19 -0700

Subject: [PATCH] Grub: tolerate some invalid entries

Refusing to parse an entire file because of invalid entries is too

harsh. Try to make the behavior a little friendlier by simply mapping invalid

entries to '#error' nodes but still parsing the rest of the file.

Also remove del_to_eol, that would delete anything up to eol; it was only

used in kw_pres, but should have never been used there. kw_pres should only

match the keyword and eol. A line like 'quiet foo bar baz' should not be

accepted by (kw_pres "quiet").

---

 lenses/grub.aug            | 58 ++++++++++++++++++++++++++++++++------

 lenses/tests/test_grub.aug | 25 ++++++++++++++++

 2 files changed, 75 insertions(+), 8 deletions(-)

diff --git a/lenses/grub.aug b/lenses/grub.aug

index 9866f3f7..f99a3a92 100644

--- a/lenses/grub.aug

+++ b/lenses/grub.aug

@@ -29,9 +29,6 @@ module Grub =

     (* View: eol *)

     let eol = Util.eol

-    (* View: del_to_eol *)

-    let del_to_eol = del /[^ \t\n]*/ ""

-

     (* View: spc *)

     let spc = Util.del_ws_spc

@@ -92,7 +89,22 @@ module Grub =

       eol ]

     (* View: kw_pres *)

-    let kw_pres (kw:string) = [ opt_ws . key kw . del_to_eol . eol ]

+    let kw_pres (kw:string) = [ opt_ws . key kw . eol ]

+

+    (* View: error

+     *   Parse a line that looks almost like a valid setting, but isn't,

+     *   into an '#error' node. Any line that starts with letters, but not

+     *   anything matching kw, is considered an error line.

+     *

+     *   Parameters:

+     *     kw:regexp - the valid keywords that are _not_ considered an

+     *                 error

+     *)

+    let error (kw:regexp) =

+      let not_kw = /[a-zA-Z]+/ - kw in

+      [ label "#error" . Util.del_opt_ws "\t"

+        . store (not_kw . /([^a-zA-Z\n].*[^ \t\n])?/) . eol ]

+

 (************************************************************************

  * Group:                 BOOT ENTRIES

@@ -138,8 +150,8 @@ module Grub =

         spc . [ label "from" . store Rx.no_spaces ] )? .

       eol ]

-    (* View: menu_setting *)

-    let menu_setting = kw_menu_arg "default"

+    (* View: menu_entry *)

+    let menu_entry = kw_menu_arg "default"

                      | kw_menu_arg "fallback"

                      | kw_pres "hiddenmenu"

                      | kw_menu_arg "timeout"

@@ -156,6 +168,21 @@ module Grub =

                      | device

                      | setkey

+    (* View: menu_error

+     *   Accept lines not matching menu_entry and stuff them into

+     *   '#error' nodes

+     *)

+    let menu_error =

+      let kw = /default|fallback|hiddenmenu|timeout|splashimage|gfxmenu/

+             |/foreground|background|verbose|boot|password|title/

+             |/serial|setkey|terminal|color|device/ in

+      error kw

+

+    (* View: menu_setting

+     *   a valid menu setting or a line that looks like one but is an #error

+     *)

+    let menu_setting = menu_entry | menu_error

+

     (* View: title *)

     let title = del /title[ \t=]+/ "title " . value_to_eol . eol

@@ -206,9 +233,9 @@ module Grub =

     let configfile =

       [ command "configfile" "\t" . spc . store Rx.no_spaces . eol ]

-    (* View: boot_setting

+    (* View: boot_entry

         <boot> entries *)

-    let boot_setting =

+    let boot_entry =

           let boot_arg_re = "root" | "initrd" | "rootnoverify" | "uuid"

                           | "findroot" | "bootfs" (* Solaris extensions *)

        in kw_boot_arg boot_arg_re

@@ -223,6 +250,21 @@ module Grub =

         | kw_pres "makeactive"

         | password_arg

+    (* View: boot_error

+     *   Accept lines not matching boot_entry and stuff them into

+     *   '#error' nodes

+     *)

+    let boot_error =

+      let kw = /lock|uuid|password|root|initrd|rootnoverify|findroot|bootfs/

+             |/configfile|chainloader|title|boot|quiet|kernel|module/

+             |/makeactive|savedefault|map/ in

+      error kw

+

+    (* View: boot_setting

+     *   a valid boot setting or a line that looks like one but is an #error

+     *)

+    let boot_setting = boot_entry | boot_error

+

     (* View: boot *)

     let boot =

       let line = ((boot_setting|comment)* . boot_setting)? in

diff --git a/lenses/tests/test_grub.aug b/lenses/tests/test_grub.aug

index 8a0d9f4a..75657203 100644

--- a/lenses/tests/test_grub.aug

+++ b/lenses/tests/test_grub.aug

@@ -257,3 +257,28 @@ password --encrypted ^9^32kwzzX./3WISQ0C /boot/grub/custom.lst

     { "password" = "secret"

       { "md5" }

     } }

+

+  (* Test parsing of invalid entries via menu_error *)

+  test Grub.lns get "default=0\ncrud=no\n" =

+  { "default" = "0" }

+  { "#error" = "crud=no" }

+

+  (* We handle some pretty bizarre bad syntax *)

+  test Grub.lns get "default=0

+crud no

+valid:nope

+nonsense  =   yes

+bad arg1 arg2 arg3=v\n" =

+  { "default" = "0" }

+  { "#error" = "crud no" }

+  { "#error" = "valid:nope" }

+  { "#error" = "nonsense  =   yes" }

+  { "#error" = "bad arg1 arg2 arg3=v" }

+

+  (* Test parsing of invalid entries via boot_error *)

+  test Grub.lns get "title test

+    root (hd0,0)

+    crud foo\n" =

+  { "title" = "test"

+    { "root" = "(hd0,0)" }

+    { "#error" = "crud foo" } }

-- 

2.17.2