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fixes TOCTOU bug in bap log #937

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merged 4 commits into from
Apr 2, 2019
Merged

fixes TOCTOU bug in bap log #937

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32001ff
fixes TOCTOU bug in log
gitoleg Mar 28, 2019
8144128
protect mkdir too
gitoleg Mar 28, 2019
0f00f99
moved lock in tmp dir
gitoleg Mar 29, 2019
4747f8c
updated after review
gitoleg Mar 29, 2019
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23 changes: 20 additions & 3 deletions lib/bap/bap_log.ml
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Original file line number Diff line number Diff line change
Expand Up @@ -54,13 +54,30 @@ let print_message ppf msg =
| Error -> eprintf "%s@\n%!" msg.message
| _ -> ()

let lock_filename logdir =
let digest = Md5.digest_string logdir in
let name = sprintf "bap-%s.lock" (Md5.to_hex digest) in
Filename.get_temp_dir_name () / name

let lock file =
let lock = Unix.openfile file Unix.[O_RDWR; O_CREAT] 0o666 in
Unix.lockf lock Unix.F_LOCK 0;
lock

let unlock lock =
Unix.lockf lock Unix.F_ULOCK 0;
Unix.close lock

let open_log_channel user_dir =
try
let log_folder = log_folder user_dir in
mkdir log_folder;
let file = log_folder / "log" in
if Sys.file_exists file
then rotate max_logs file;
let lock = lock (lock_filename log_folder) in
protect ~f:(fun () ->
mkdir log_folder;
if Sys.file_exists file
then rotate max_logs file)
~finally:(fun () -> unlock lock);
let ch = Out_channel.create file in
formatter_of_out_channel ch
with exn ->
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