Re: [Libguestfs] [PATCH 2/2] builder: use a disposable GPG keyring for every Sigchecker

Create a temporary directory and tell gpg to use it as homedir, so imported keys do not get into the user's keyring. This also avoid importing the default key when a different one is needed to check the signature. The only exception is when a non-default fingerprint is used: in this case, that key is read from the user's keyring, since it is where it is.

diff --git a/builder/sigchecker.ml b/builder/sigchecker.ml index b20a186..10e342e 100644 --- a/builder/sigchecker.ml +++ b/builder/sigchecker.ml @@ -95,21 +95,38 @@ ZvXkQ3FVJwZoLmHw47vvlVpLD/4gi1SuHWieRvZ+UdDq00E348pm =neBW -----END PGP PUBLIC KEY BLOCK----- " -let key_imported = ref false type t = { debug : bool; gpg : string; fingerprint : string; check_signature : bool; + gpghome : string; + mutable key_imported : bool; } let create ~debug ~gpg ~fingerprint ~check_signature = + (* Create a temporary directory for gnupg. *) + let tmpdir = Mkdtemp.mkdtemp (Filename.temp_dir_name // "vb.gpghome.XXXXXX") in + rmdir_on_exit tmpdir; + (* Run gpg once, so it can setup its own home directory, failing + * if it cannot. + *) + let cmd = sprintf "%s --homedir %s --list-keys%s" + gpg tmpdir (if debug then "" else " >/dev/null 2>&1") in + if debug then eprintf "%s\n%!" cmd; + let r = Sys.command cmd in + if r <> 0 then ( + eprintf (f_"virt-builder: error: GPG failure: could not run GPG the first time\nUse the '-v' option and look for earlier error messages.\n"); + exit 1 + ); { debug = debug; gpg = gpg; fingerprint = fingerprint; check_signature = check_signature; + gpghome = tmpdir; + key_imported = false; } (* Compare two strings of hex digits ignoring whitespace and case. *) @@ -159,8 +176,9 @@ and do_verify t args = let status_file = Filename.temp_file "vbstat" ".txt" in unlink_on_exit status_file; let cmd = - sprintf "%s --verify%s --status-file %s %s" - t.gpg (if t.debug then "" else " -q --logger-file /dev/null") + sprintf "%s --homedir %s --verify%s --status-file %s %s" + t.gpg t.gpghome + (if t.debug then "" else " -q --logger-file /dev/null") (quote status_file) args in if t.debug then eprintf "%s\n%!" cmd; let r = Sys.command cmd in @@ -188,23 +206,40 @@ and do_verify t args = exit 1 ) -(* Import the default public key. *) +(* Import the requested public key. *) and import_key t = - if not !key_imported then ( - let filename, chan = Filename.open_temp_file "vbpubkey" ".asc" in - unlink_on_exit filename; - output_string chan default_pubkey; - close_out chan; - - let cmd = sprintf "%s --import %s%s" - t.gpg (quote filename) + if not t.key_imported then ( + let keyfile = ref "" in + if equal_fingerprints default_fingerprint t.fingerprint then ( + let filename, chan = Filename.open_temp_file "vbpubkey" ".asc" in + unlink_on_exit filename; + output_string chan default_pubkey; + close_out chan; + keyfile := filename + ) else ( + let filename = Filename.temp_file "vbpubkey" ".asc" in + unlink_on_exit filename; + let cmd = sprintf "%s --yes --armor --output %s --export %s%s" + t.gpg (quote filename) (quote t.fingerprint) + (if t.debug then "" else " >/dev/null 2>&1") in + if t.debug then eprintf "%s\n%!" cmd; + let r = Sys.command cmd in + if r <> 0 then ( + eprintf (f_"virt-builder: error: could not export public key\nUse the '-v' option and look for earlier error messages.\n"); + exit 1 + ); + keyfile := filename + ); + + let cmd = sprintf "%s --homedir %s --import %s%s" + t.gpg t.gpghome (quote !keyfile) (if t.debug then "" else " >/dev/null 2>&1") in let r = Sys.command cmd in if r <> 0 then ( eprintf (f_"virt-builder: error: could not import public key\nUse the '-v' option and look for earlier error messages.\n"); exit 1 ); - key_imported := true + t.key_imported <- true ) type csum_t = SHA512 of string