[PATCH 16/18] crypto: add --try-decrypt=nostash to avoid stashing session keys
Daniel Kahn Gillmor
dkg at fifthhorseman.net
Tue Oct 24 23:52:01 PDT 2017
Here's the configuration choice for people who want a cleartext index,
but don't want stashed session keys.
Interestingly, this "nostash" decryption policy is actually the same
policy that should be used by "notmuch show" and "notmuch reply",
since they never modify the index or database when they are invoked
with --decrypt.
We take advantage of this parallel to tune the behavior of those
programs so that we're not requesting session keys from GnuPG during
"show" and "reply" that we would then otherwise just throw away.
---
completion/notmuch-completion.bash | 6 +++---
doc/man1/notmuch-config.rst | 10 ++++++++--
doc/man1/notmuch-insert.rst | 11 +++++++----
doc/man1/notmuch-new.rst | 11 +++++++----
doc/man1/notmuch-reindex.rst | 11 +++++++----
lib/indexopts.c | 2 ++
lib/notmuch.h | 1 +
notmuch-reply.c | 2 +-
notmuch-show.c | 3 ++-
notmuch.c | 1 +
test/T357-index-decryption.sh | 26 ++++++++++++++++++++++++++
util/crypto.c | 4 ++--
12 files changed, 67 insertions(+), 21 deletions(-)
diff --git a/completion/notmuch-completion.bash b/completion/notmuch-completion.bash
index 53d7380b..29256210 100644
--- a/completion/notmuch-completion.bash
+++ b/completion/notmuch-completion.bash
@@ -288,7 +288,7 @@ _notmuch_insert()
return
;;
--try-decrypt)
- COMPREPLY=( $( compgen -W "true false auto" -- "${cur}" ) )
+ COMPREPLY=( $( compgen -W "true false auto nostash" -- "${cur}" ) )
return
;;
esac
@@ -320,7 +320,7 @@ _notmuch_new()
$split &&
case "${prev}" in
--try-decrypt)
- COMPREPLY=( $( compgen -W "true false auto" -- "${cur}" ) )
+ COMPREPLY=( $( compgen -W "true false auto nostash" -- "${cur}" ) )
return
;;
esac
@@ -442,7 +442,7 @@ _notmuch_reindex()
$split &&
case "${prev}" in
--try-decrypt)
- COMPREPLY=( $( compgen -W "true false auto" -- "${cur}" ) )
+ COMPREPLY=( $( compgen -W "true false auto nostash" -- "${cur}" ) )
return
;;
esac
diff --git a/doc/man1/notmuch-config.rst b/doc/man1/notmuch-config.rst
index 5adde070..d9e22653 100644
--- a/doc/man1/notmuch-config.rst
+++ b/doc/man1/notmuch-config.rst
@@ -141,6 +141,9 @@ The available configuration items are described below.
**index.try_decrypt**
**[STORED IN DATABASE]**
+
+ One of ``false``, ``auto``, ``nostash``, or ``true``.
+
When indexing an encrypted e-mail message, if this variable is
set to ``true``, notmuch will try to decrypt the message and
index the cleartext, stashing a copy of any discovered session
@@ -150,11 +153,14 @@ The available configuration items are described below.
secret keys. Use ``false`` to avoid decrypting even when a
stashed session key is already present.
+ ``nostash`` is the same as ``true`` except that it will not
+ stash newly-discovered session keys in the database.
+
Be aware that the notmuch index is likely sufficient to
reconstruct the cleartext of the message itself, so please
ensure that the notmuch message index is adequately protected.
- DO NOT USE ``index.try_decrypt=true`` without considering the
- security of your index.
+ DO NOT USE ``index.try_decrypt=true`` or ``index-only``
+ without considering the security of your index.
Default: ``auto``.
diff --git a/doc/man1/notmuch-insert.rst b/doc/man1/notmuch-insert.rst
index 3e6f538d..bf659a3d 100644
--- a/doc/man1/notmuch-insert.rst
+++ b/doc/man1/notmuch-insert.rst
@@ -50,10 +50,10 @@ Supported options for **insert** include
``--no-hooks``
Prevent hooks from being run.
- ``--try-decrypt=(true|auto|false)``
+ ``--try-decrypt=(true|nostash|auto|false)``
If ``true`` and the message is encrypted, try to decrypt the
- message while indexing, storing any session keys discovered.
+ message while indexing, stashing any session keys discovered.
If ``auto``, and notmuch already knows about a session key for
the message, it will try decrypting using that session key but
will not try to access the user's secret keys. If decryption
@@ -61,11 +61,14 @@ Supported options for **insert** include
message is always stored to disk in its original form
(ciphertext).
+ ``nostash`` is the same as ``true`` except that it will not
+ stash newly-discovered session keys in the database.
+
Be aware that the index is likely sufficient to reconstruct
the cleartext of the message itself, so please ensure that the
notmuch message index is adequately protected. DO NOT USE
- ``--try-decrypt=true`` without considering the security of
- your index.
+ ``--try-decrypt=true`` or ``nostash`` without considering
+ the security of your index.
See also ``index.try_decrypt`` in **notmuch-config(1)**.
diff --git a/doc/man1/notmuch-new.rst b/doc/man1/notmuch-new.rst
index 351b7591..2660988d 100644
--- a/doc/man1/notmuch-new.rst
+++ b/doc/man1/notmuch-new.rst
@@ -43,20 +43,23 @@ Supported options for **new** include
``--quiet``
Do not print progress or results.
- ``--try-decrypt=(true|auto|false)``
+ ``--try-decrypt=(true|nostash|auto|false)``
If ``true``, when encountering an encrypted message, try to
- decrypt it while indexing, and store any discovered session
+ decrypt it while indexing, and stash any discovered session
keys. If ``auto``, try to use any session key already known
to belong to this message, but do not attempt to use the
user's secret keys. If decryption is successful, index the
cleartext of the message.
+ ``nostash`` is the same as ``true`` except that it will not
+ stash newly-discovered session keys in the database.
+
Be aware that the index is likely sufficient to reconstruct
the cleartext of the message itself, so please ensure that the
notmuch message index is adequately protected. DO NOT USE
- ``--try-decrypt=true`` without considering the security of
- your index.
+ ``--try-decrypt=true`` or ``nostash`` without considering
+ the security of your index.
See also ``index.try_decrypt`` in **notmuch-config(1)**.
diff --git a/doc/man1/notmuch-reindex.rst b/doc/man1/notmuch-reindex.rst
index 3b99b934..7883e0cb 100644
--- a/doc/man1/notmuch-reindex.rst
+++ b/doc/man1/notmuch-reindex.rst
@@ -21,23 +21,26 @@ messages using the supplied options.
Supported options for **reindex** include
- ``--try-decrypt=(true|auto|false)``
+ ``--try-decrypt=(true|nostash|auto|false)``
If ``true``, when encountering an encrypted message, try to
- decrypt it while reindexing, storing any session keys
+ decrypt it while reindexing, stashing any session keys
discovered. If ``auto``, and notmuch already knows about a
session key for the message, it will try decrypting using that
session key but will not try to access the user's secret keys.
If decryption is successful, index the cleartext itself.
+ ``nostash`` is the same as ``true`` except that it will not
+ stash newly-discovered session keys in the database.
+
If ``false``, notmuch reindex will also delete any stashed
session keys for all messages matching the search terms.
Be aware that the index is likely sufficient to reconstruct
the cleartext of the message itself, so please ensure that the
notmuch message index is adequately protected. DO NOT USE
- ``--try-decrypt=true`` without considering the security of
- your index.
+ ``--try-decrypt=true`` or ``nostash`` without considering
+ the security of your index.
See also ``index.try_decrypt`` in **notmuch-config(1)**.
diff --git a/lib/indexopts.c b/lib/indexopts.c
index a61d6420..e698dcea 100644
--- a/lib/indexopts.c
+++ b/lib/indexopts.c
@@ -42,6 +42,8 @@ notmuch_database_get_default_indexopts (notmuch_database_t *db)
(!(strcasecmp(try_decrypt, "no"))) ||
(!(strcasecmp(try_decrypt, "0"))))
notmuch_indexopts_set_try_decrypt (ret, NOTMUCH_DECRYPT_FALSE);
+ else if (!strcasecmp(try_decrypt, "nostash"))
+ notmuch_indexopts_set_try_decrypt (ret, NOTMUCH_DECRYPT_NOSTASH);
}
free (try_decrypt);
diff --git a/lib/notmuch.h b/lib/notmuch.h
index 7b1c61ad..103a7091 100644
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -2242,6 +2242,7 @@ typedef enum {
NOTMUCH_DECRYPT_FALSE,
NOTMUCH_DECRYPT_TRUE,
NOTMUCH_DECRYPT_AUTO,
+ NOTMUCH_DECRYPT_NOSTASH,
} notmuch_decryption_policy_t;
/**
diff --git a/notmuch-reply.c b/notmuch-reply.c
index fd990a9a..5cdf642b 100644
--- a/notmuch-reply.c
+++ b/notmuch-reply.c
@@ -730,7 +730,7 @@ notmuch_reply_command (notmuch_config_t *config, int argc, char *argv[])
notmuch_process_shared_options (argv[0]);
if (decrypt_set)
- params.crypto.decrypt = decrypt ? NOTMUCH_DECRYPT_TRUE : NOTMUCH_DECRYPT_FALSE;
+ params.crypto.decrypt = decrypt ? NOTMUCH_DECRYPT_NOSTASH : NOTMUCH_DECRYPT_FALSE;
notmuch_exit_if_unsupported_format ();
diff --git a/notmuch-show.c b/notmuch-show.c
index c8f5a48f..4e22424b 100644
--- a/notmuch-show.c
+++ b/notmuch-show.c
@@ -1121,7 +1121,8 @@ notmuch_show_command (notmuch_config_t *config, int argc, char *argv[])
if (decrypt_set) {
if (decrypt) {
- params.crypto.decrypt = NOTMUCH_DECRYPT_TRUE;
+ /* we do not need or want to ask for session keys */
+ params.crypto.decrypt = NOTMUCH_DECRYPT_NOSTASH;
/* decryption implies verification */
params.crypto.verify = true;
} else {
diff --git a/notmuch.c b/notmuch.c
index 62706748..2f43ad28 100644
--- a/notmuch.c
+++ b/notmuch.c
@@ -104,6 +104,7 @@ const notmuch_opt_desc_t notmuch_shared_indexing_options [] = {
(notmuch_keyword_t []){ { "false", NOTMUCH_DECRYPT_FALSE },
{ "true", NOTMUCH_DECRYPT_TRUE },
{ "auto", NOTMUCH_DECRYPT_AUTO },
+ { "nostash", NOTMUCH_DECRYPT_NOSTASH },
{ 0, 0 } },
.name = "try-decrypt" },
{ }
diff --git a/test/T357-index-decryption.sh b/test/T357-index-decryption.sh
index 3ac8c43e..8aef4354 100755
--- a/test/T357-index-decryption.sh
+++ b/test/T357-index-decryption.sh
@@ -182,6 +182,32 @@ test_expect_equal \
"$output" \
"$expected"
+test_begin_subtest "index cleartext without keeping session keys"
+test_expect_success "notmuch reindex --try-decrypt=nostash tag:blarney"
+
+test_begin_subtest "Ensure that the indexed terms are present"
+output=$(notmuch search wumpus)
+test_expect_equal \
+ "$output" \
+ "$expected"
+
+test_begin_subtest "show one of the messages with --decrypt"
+output=$(notmuch show --decrypt thread:0000000000000001 | awk '/^\014part}/{ f=0 }; { if (f) { print $0 } } /^\014part{ ID: 3/{ f=1 }')
+expected='This is a test encrypted message with a wumpus.'
+test_expect_equal \
+ "$output" \
+ "$expected"
+
+test_begin_subtest "Ensure that we cannot show the message without --decrypt"
+output=$(notmuch show thread:0000000000000001 | awk '/^\014part}/{ f=0 }; { if (f) { print $0 } } /^\014part{ ID: 3/{ f=1 }')
+expected='Non-text part: application/octet-stream'
+test_expect_equal \
+ "$output" \
+ "$expected"
+
+
+
+
add_email_corpus crypto
test_begin_subtest "indexing message fails when secret key not available"
diff --git a/util/crypto.c b/util/crypto.c
index ba9bfa7b..ac018005 100644
--- a/util/crypto.c
+++ b/util/crypto.c
@@ -190,7 +190,7 @@ _notmuch_crypto_decrypt (bool *attempted,
#if (GMIME_MAJOR_VERSION < 3)
#if (GMIME_MAJOR_VERSION == 2 && GMIME_MINOR_VERSION == 6 && GMIME_MICRO_VERSION >= 21)
gboolean oldgetsk = g_mime_crypto_context_get_retrieve_session_key (crypto_ctx);
- gboolean newgetsk = (decrypt_result);
+ gboolean newgetsk = (decrypt == NOTMUCH_DECRYPT_TRUE && decrypt_result);
if (newgetsk != oldgetsk)
/* This could return an error, but we can't do anything about it, so ignore it */
g_mime_crypto_context_set_retrieve_session_key (crypto_ctx, newgetsk, NULL);
@@ -203,7 +203,7 @@ _notmuch_crypto_decrypt (bool *attempted,
#endif
#else
GMimeDecryptFlags flags = GMIME_DECRYPT_NONE;
- if (decrypt_result)
+ if (decrypt == NOTMUCH_DECRYPT_TRUE && decrypt_result)
flags |= GMIME_DECRYPT_EXPORT_SESSION_KEY;
ret = g_mime_multipart_encrypted_decrypt(part, flags, NULL,
decrypt_result, err);
--
2.14.2
More information about the notmuch
mailing list