On Tue, 5 Jan 2016, Ian Lepore wrote:
Log: Use the more proper -f. Leave /bin/rm in place since that's what other rc scripts have, though it isn't strictly necessary.
"proper -f" is hard to parse. I think you mean: Use 'rm -f' to turn off -i in case rm is broken and is an alias which has -i (and perhaps actually even something resembling rm) in it. More precisely, use 'rm -f /usr/bin' to partly defend against the same bug in /bin/rm (where it would be larger). Keep using /usr/rm instead of restoring the use of plain rm since that is what other rc scripts have. The previous change to use /bin/rm instead of plain rm was neither necessary nor sufficient for fixing the bug. Neither is this one, but it gets closer. It is a little-known bug in aliases that even absolute pathnames can be aliased. So /bin/rm might be aliased to 'rm -ri /'. Appending -f would accidentally help for that too, by turning it into a syntax error, instead of accidentally making it more forceful by turning -ri into -rf. Hopefully this is all FUD. Non-interactive scripts shouldn't source any files that are not mentioned in the script. /etc/rc depends on a secure environment being set up by init and probably gets it since init doesn't set up much. sh(1) documents closing the security hole of sourcing the script in $ENV for non-interactive shells, but was never a problem for /etc/rc since init must be trusted to not put security holes in $ENV. But users could put security holes in a sourced config file like /etc/rc.conf.local.
Modified: head/etc/rc ===================================================================== ========= --- head/etc/rc Tue Jan 5 21:20:46 2016 (r293226) +++ head/etc/rc Tue Jan 5 21:20:47 2016 (r293227) @@ -132,9 +132,9 @@ done # Remove the firstboot sentinel, and reboot if it was requested. if [ -e ${firstboot_sentinel} ]; then [ ${root_rw_mount} = "yes" ] || mount -uw / - /bin/rm ${firstboot_sentinel} + /bin/rm -f ${firstboot_sentinel} if [ -e ${firstboot_sentinel}-reboot ]; then - /bin/rm ${firstboot_sentinel}-reboot + /bin/rm -f ${firstboot_sentinel}-reboot [ ${root_rw_mount} = "yes" ] || mount -ur / kill -INT 1 fiUsing rm -f to suppress an error message seems like a bad idea here -- if the sentinel file can't be removed that implies it's going to do firstboot behavior every time it boots, and that's the sort of error that should be in-your-face. Especially on the reboot one because you're going to be stuck in a reboot loop with no error message.
Er, -f on rm only turns off -i and supresses the warning message for failing to remove nonexistent files. But we just tested that the file exists, and in the impossible even of a race making it not exist by the time that it runs, we have more problems than the failure of rm since we use the file's existence as a control for other things. So the only effect of this -f is to turn off -i, which can only be set if the FUD was justified. The correct fix seems to be 'unalias -a'. Bruce _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
