From 1110201eddb377e0b900f6f9f8de93fcddfde1a3 Mon Sep 17 00:00:00 2001
From: Jonas Smedegaard <dr@jones.dk>
Date: Sat, 9 Mar 2013 17:21:43 +0100
Subject: Preserve (instead of collapse) arguments in su_monkeysphere_user().
It is a healthy coding practice to keep each argument separate when
executing system calls, i.e. quote each variable separately instead of
relying on whitespace to indicate argument separation.
Quoting shell-inside-shell is tricky to do right, but not impossible:
Bourne-derived shells treat single-quoting literally, which means that
shell command arguments (i.e. an array of strings) should be safe to
serialize (dual-quote) using these simple rules:
b) each single-quote inside each string is escaped as '\''
a) each string is surrounded by single-quotes
This patch applies above single-quote serialization for
su_monkeysphere_user().
This appears to break for commands that start with variable
assignment, like:
PAGER=cat git diff
So as long as we do not use that form, su_monkeysphere_user() should
not treat its variables any worse than previous non-quoting.
---
src/share/common | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
(limited to 'src')
diff --git a/src/share/common b/src/share/common
index 508b064..78fb04e 100755
--- a/src/share/common
+++ b/src/share/common
@@ -101,15 +101,19 @@ su_monkeysphere_user() {
# introduce an extra dependency just for this. This may be a
# candidate for re-factoring if we switch implementation languages.
+ # singlequote-escape strings - like this bashism:
+ # printf -v CMDLINE "%q " "$@"
+ local CMDLINE="$(perl -0 -e "foreach (@ARGV) {s/'/'\\\\''/g; print \"'\$_' \"}" "$@")"
+
case $(id -un) in
# if monkeysphere user, run the command under bash
"$MONKEYSPHERE_USER")
- bash -c "$*"
+ bash -c "$CMDLINE"
;;
# if root, su command as monkeysphere user
'root')
- su "$MONKEYSPHERE_USER" -c "$*"
+ su "$MONKEYSPHERE_USER" -c "$CMDLINE"
;;
# otherwise, fail
--
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