signer scripts: break kernel parameters on spaces rather than word boundaries

The current kernel parameter parsing logic uses word boundaries (\b) to
keep from replacing parameters inside of other parameters (like "level=1"
mangling "loglevel=1" into "log"), but this fails when the last character
isn't a "word" character.  e.g. "\bconsole=\b" doesn't match "console=".

Change the \b to a space.  Since we're already using spaces as our split
marker, this shouldn't be a problem.

BRANCH=None
BUG=chrome-os-partner:12780
BUG=chromium-os:33868
TEST=ran `ensure_secure_kernelparams.sh` on an image with 'console=' and saw it work

Change-Id: Id69250179ea76aabfed9cd21c1c59483d78a215d
Reviewed-on: https://gerrit.chromium.org/gerrit/31356
Reviewed-by: David McMahon <djmm@chromium.org>
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>

scripts/image_signing/ensure_secure_kernelparams.sh

@@ -130,8 +130,12 @@ main() {
         echo "Expected: ${required_dmparams[@]}"
     fi
 
+    # A byte that should not appear in the command line to use as a sed
+    # marker when doing regular expression replacements.
+    M=$'\001'
+
     # Ensure all other required params are present.
-    for param in ${required_kparams[@]}; do
+    for param in "${required_kparams[@]}"; do
         if [[ "$kparams_nodm" != *$param* ]]; then
             echo "Kernel parameters missing required value: $param"
             testfail=1
@@ -139,25 +143,29 @@ main() {
             # Remove matched params as we go. If all goes well, kparams_nodm
             # will be nothing left but whitespace by the end.
             param=$(escape_regexmetas "$param")
-            kparams_nodm=$(echo "$kparams_nodm" | sed "s/\b$param\b//")
+            kparams_nodm=$(echo " ${kparams_nodm} " |
+                           sed "s${M} ${param} ${M} ${M}")
         fi
     done
 
     # Check-off each of the allowed-but-optional params that were present.
-    for param in ${optional_kparams[@]}; do
+    for param in "${optional_kparams[@]}"; do
         param=$(escape_regexmetas "$param")
-        kparams_nodm=$(echo "$kparams_nodm" | sed "s/\b$param\b//")
+        kparams_nodm=$(echo " ${kparams_nodm} " |
+                       sed "s${M} ${param} ${M} ${M}")
     done
 
     # Check-off each of the allowed-but-optional params that were present.
-    for param in ${optional_kparams_regex[@]}; do
+    for param in "${optional_kparams_regex[@]}"; do
-        kparams_nodm=$(echo "$kparams_nodm" | sed "s/\b$param\b//")
+        kparams_nodm=$(echo " ${kparams_nodm} " |
+                       sed "s${M} ${param} ${M} ${M}")
     done
 
     # This section enforces the default-deny for any unexpected params
     # not already processed by one of the above loops.
     if [[ ! -z ${kparams_nodm// /} ]]; then
-        echo "Unexpected kernel parameters found: $kparams_nodm"
+        echo "Unexpected kernel parameters found:"
+        echo " $(echo "${kparams_nodm}" | sed -r 's:  +: :g')"
         testfail=1
     fi