Reject directory listing entries containing a path separator#6172
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aizu-m wants to merge 1 commit into
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Reject directory listing entries containing a path separator#6172aizu-m wants to merge 1 commit into
aizu-m wants to merge 1 commit into
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Entries from a remote directory listing are joined to a local path during recursive copy (cf-agent) and getdir (cf-net). A genuine dirent is a single path component; one carrying a separator escapes the destination once joined, so a hostile server can write outside it. ConsiderFile() already blocks ".", ".." and "..."; reject separator-bearing names there and in process_dir_recursive() too. Signed-off-by: aizu-m <aizumusheer2@gmail.com>
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Found while tracing cf-agent's recursive copy from a remote server. The
directory listing entries pass through ConsiderFile() and are then joined
to the local path by PathAppend(), which only concatenates:
ConsiderFile() already rejects ".", ".." and "..." (the last with a
CWE-32 note) but not a name that carries a separator. A genuine dirent is
one path component and never contains '/', so a listing entry that does
is a hostile server stepping outside the destination. cf-agent normally
runs as root, so that is an arbitrary file write.
cf-net "getdir" walks a remote listing the same way in
process_dir_recursive(); it skips "." and ".." and nothing else.
Both now reject an entry that contains a separator (IsFileSep). The unit
test fails before the change and passes after.