diff options
| -rw-r--r-- | README.rst | 4 | ||||
| -rwxr-xr-x | tmpoverlay | 30 |
2 files changed, 20 insertions, 14 deletions
@@ -7,7 +7,7 @@ overlayfs mounts. Features -------- -- minimal requirements (sh, mount, getopt, stat) +- minimal requirements (sh, mount, getopt) Benefits over manually calling ``mkdir /tmp/x; mount ...`` @@ -39,7 +39,5 @@ POSIX-only shells: - ``mount -t overlay`` is obviously required - ``getopt --`` is required for proper handling of options containing spaces -- ``stat -c`` is required to obtain upperdir owner and permissions, because - parsing ls -l is ridiculous. - ``getfattr`` is used for xattr copying but in case of failure, the system is assumed to not support xattrs and setfattr is skipped. @@ -202,23 +202,31 @@ try_ovl_opt() { ovl_opts="$new_ovl_opts" } try_ovl_opt index on -# redirect_dir/metacopy are unsafe with untrusted non-bottom layers +# redirect_dir and metacopy are unsafe with untrusted non-bottom layers +# nfs_export conflicts with metacopy [ "${lowerdir#*:}" = "$lowerdir" ] && \ ! chk_ovl_opt userxattr on && \ try_ovl_opt redirect_dir on && \ { chk_ovl_opt nfs_export on || try_ovl_opt metacopy on; } try_ovl_opt volatile -# try to match perms/attrs. this is not race-free but it's impossible without -# atomic (CAS) chown/chmod/setfattr. chown --from is not atomic, not portable, -# and also doesn't cover chmod/setfattr. +logv 'copying lowerdir owner/perms to upperdir' lastlowerdir=${lowerdir##*:} -logv 'copying lowerdir owner to upperdir' -owner=$(stat -c %u:%g "$lastlowerdir") || die -chown "$owner" "$upperdir" || die -logv 'copying lowerdir perms to upperdir' -mode=$(stat -c %a "$lastlowerdir") || die -chmod "$mode" "$upperdir" || die +# stat -c isn't posix -.- +ls=$(ls -dn "$lastlowerdir/.") || die +tmp=${ls#* * } +owner=${tmp%% *} +tmp=${tmp#* } +group=${tmp%% *} +chown "$owner:$group" "$upperdir" || die +mode=${ls%% *} +[ "${#mode}" = 10 ] || die "bad ls permission format" +mode=${mode#?} +umode=${mode%??????} +ugmode=${mode%???} +gmode=${ugmode#???} +omode=${mode#??????} +chmod "u=$umode,g=$gmode,o=$omode" "$upperdir" || die # -m - covers ACLs (system.posix_acl_access) and file caps # (security.capability). theoretically someone might have get/setcap and/or # get/setfacl but not get/setxattr, but this is unlikely since libcap/acl @@ -229,7 +237,7 @@ if attrs=$(cd "$lastlowerdir" && getfattr -d -m - . 2>/dev/null); then printf '%s\n' "$attrs" | (cd "$upperdir"; setfattr --restore=-) || die fi else - log 'getfattr not found or failed, skipping xattrs' + log 'getfattr failed, skipping xattrs' fi logv 'mounting overlay' |