This is shorter and should make the function easier to
follow. But more importantly, it removes the possibility of
any deadlocks based on reading or writing to gpg.
It's not clear if such a deadlock is possible in practice.
We do write the whole payload before reading anything, so we
could deadlock there. However, in practice gpg will need to
read our whole input to verify the signature, so it will
drain our payload first. It could write an error to stderr
before reading, but it's unlikely that such an error
wouldn't be followed by it immediately exiting, or that the
error would actually be larger than a pipe buffer.
On the writing side, we drain stderr (with the
human-readable output) in its entirety before reading stdout
(with the status-fd data). Running strace on "gpg --verify"
does show interleaved output on the two descriptors:
write(2, "gpg: ", 5) = 5
write(2, "Signature made Thu 16 Jun 2016 0"..., 73) = 73
write(1, "[GNUPG:] SIG_ID tQw8KGcs9rBfLvAj"..., 66) = 66
write(1, "[GNUPG:] GOODSIG 69808639F9430ED"..., 60) = 60
write(2, "gpg: ", 5) = 5
write(2, "Good signature from \"Jeff King <"..., 47) = 47
write(2, "\n", 1) = 1
write(2, "gpg: ", 5) = 5
write(2, " aka \"Jeff King <"..., 49) = 49
write(2, "\n", 1) = 1
write(1, "[GNUPG:] VALIDSIG C49CE24156AF08"..., 135) = 135
write(1, "[GNUPG:] TRUST_ULTIMATE\n", 24) = 24
The second line written to stdout there contains the
signer's UID, which can be arbitrarily long. If it fills the
pipe buffer, then gpg would block writing to its stdout,
while we are blocked trying to read its stderr.
In practice, GPG seems to limit UIDs to 2048 bytes, so
unless your pipe buffer size is quite small, or unless gpg
does not enforce the limit under some conditions, this seems
unlikely in practice.
Still, it is not hard for us to be cautious and just use
pipe_command.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We use git_mkstemp to create a temporary file, and try to
clean it up in all exit paths from the function. But that
misses any cases where we die by signal, or by calling die()
in a sub-function. In addition, we missed one of the exit
paths.
Let's convert to using a tempfile object, which handles the
hard cases for us, and add the missing cleanup call. Note
that we would not simply want to rely on program exit to
catch our missed cleanup, as this function may be called
many times in a single program (for the same reason, we use
a static tempfile instead of heap-allocating a new one; that
gives an upper bound on our memory usage).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If our caller gave us a non-NULL gpg_status parameter, we
write the gpg status into their strbuf. If they didn't, then
we write it to a temporary local strbuf (since we still need
to look at it). The variable "pbuf" adds an extra layer of
indirection so that the rest of the function can just access
whichever is appropriate.
However, the name "pbuf" isn't very descriptive, and it's
easy to get confused about what is supposed to be in it
(especially because we are reading both "status" and
"output" from gpg).
Rather than give it a more descriptive name, we can just use
gpg_status as our indirection pointer. Either it points to
the caller's input, or we can point it directly to our
temporary buffer.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Our argv allocations are relatively straightforward, but
this avoids us having to manually keep the count up to date
(or create new to-be-replaced slots in the declaration) when
we add new arguments.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The code for warning_errno/die_errno has been refactored and a new
error_errno() reporting helper is introduced.
* nd/error-errno: (41 commits)
wrapper.c: use warning_errno()
vcs-svn: use error_errno()
upload-pack.c: use error_errno()
unpack-trees.c: use error_errno()
transport-helper.c: use error_errno()
sha1_file.c: use {error,die,warning}_errno()
server-info.c: use error_errno()
sequencer.c: use error_errno()
run-command.c: use error_errno()
rerere.c: use error_errno() and warning_errno()
reachable.c: use error_errno()
mailmap.c: use error_errno()
ident.c: use warning_errno()
http.c: use error_errno() and warning_errno()
grep.c: use error_errno()
gpg-interface.c: use error_errno()
fast-import.c: use error_errno()
entry.c: use error_errno()
editor.c: use error_errno()
diff-no-index.c: use error_errno()
...
The verify_signed_buffer() function may trigger a SIGPIPE when the
GPG child process terminates early (due to a bad keyid, for example)
and Git tries to write to it afterwards. Previously, ignoring
SIGPIPE was done in builtin/verify-tag.c to avoid this issue.
However, any other caller who wants to call verify_signed_buffer()
would have to do the same.
Use sigchain_push(SIGPIPE, SIG_IGN) in verify_signed_buffer(),
pretty much like in sign_buffer(), so that any caller is not
required to perform this task.
This will avoid possible mistakes by further developers using
verify_signed_buffer().
Signed-off-by: Santiago Torres <santiago@nyu.edu>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
verify-commit by default displays human-readable output on standard
error. However, it can also be useful to get access to the raw gpg
status information, which is machine-readable, allowing automated
implementation of signing policy. Add a --raw option to make
verify-commit produce the gpg status information on standard error
instead of the human-readable format.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The code to handle printing of signature data from a struct
signature_check is very similar between verify-commit and verify-tag.
Place this in a single function. verify-tag retains its special case
behavior of printing the tag even when no valid signature is found.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
verify-commit and verify-tag both share a central codepath for verifying
commits: check_signature. However, verify-tag exited successfully for
untrusted signature, while verify-commit exited unsuccessfully.
Centralize this signature check and make verify-commit adopt the older
verify-tag behavior. This behavior is more logical anyway, as the
signature is in fact valid, whether or not there's a path of trust to
the author.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
verify-tag was executing an entirely different codepath than
verify-commit, except for the underlying verify_signed_buffer. Move
much of the code from check_commit_signature to a generic
check_signature function and adjust both codepaths to call it.
Update verify-tag to explicitly output the signature text, as we now
call verify_signed_buffer with strbufs to catch the output, which
prevents it from being printed automatically.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Allow "git push" request to be signed, so that it can be verified and
audited, using the GPG signature of the person who pushed, that the
tips of branches at a public repository really point the commits
the pusher wanted to, without having to "trust" the server.
* jc/push-cert: (24 commits)
receive-pack::hmac_sha1(): copy the entire SHA-1 hash out
signed push: allow stale nonce in stateless mode
signed push: teach smart-HTTP to pass "git push --signed" around
signed push: fortify against replay attacks
signed push: add "pushee" header to push certificate
signed push: remove duplicated protocol info
send-pack: send feature request on push-cert packet
receive-pack: GPG-validate push certificates
push: the beginning of "git push --signed"
pack-protocol doc: typofix for PKT-LINE
gpg-interface: move parse_signature() to where it should be
gpg-interface: move parse_gpg_output() to where it should be
send-pack: clarify that cmds_sent is a boolean
send-pack: refactor inspecting and resetting status and sending commands
send-pack: rename "new_refs" to "need_pack_data"
receive-pack: factor out capability string generation
send-pack: factor out capability string generation
send-pack: always send capabilities
send-pack: refactor decision to send update per ref
send-pack: move REF_STATUS_REJECT_NODELETE logic a bit higher
...
Our signed-tag objects set the standard format used by Git to store
GPG-signed payload (i.e. the payload followed by its detached
signature) [*1*], and it made sense to have a helper to find the
boundary between the payload and its signature in tag.c back then.
Newer code added later to parse other kinds of objects that learned
to use the same format to store GPG-signed payload (e.g. signed
commits), however, kept using the helper from the same location.
Move it to gpg-interface; the helper is no longer about signed tag,
but it is how our code and data interact with GPG.
[Reference]
*1* http://thread.gmane.org/gmane.linux.kernel/297998/focus=1383
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Earlier, ffb6d7d5 (Move commit GPG signature verification to
commit.c, 2013-03-31) moved this helper that used to be in pretty.c
(i.e. the output code path) to commit.c for better reusability.
It was a good first step in the right direction, but still suffers
from a myopic view that commits will be the only thing we would ever
want to sign---we would actually want to be able to reuse it even
wider.
The function interprets what GPG said; gpg-interface is obviously a
better place. Move it there.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Most struct child_process variables are cleared using memset first after
declaration. Provide a macro, CHILD_PROCESS_INIT, that can be used to
initialize them statically instead. That's shorter, doesn't require a
function call and is slightly more readable (especially given that we
already have STRBUF_INIT, ARGV_ARRAY_INIT etc.).
Helped-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In contrast to tag signatures, commit signatures are put into the
header, that is between the other header parts and commit messages.
Provide access to the commit content sans the signature, which is the
payload that is actually signed. Commit signature verification does the
parsing anyways, and callers may wish to act on or display the commit
object sans the signature.
Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The struct has been growing members whose malloced memory needs to be
freed. Do this with one helper function so that no malloced memory shall
be left unfreed.
Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Call "gpg" using the right API when validating the signature on
tags.
* mg/gpg-interface-using-status:
pretty: make %GK output the signing key for signed commits
pretty: parse the gpg status lines rather than the output
gpg_interface: allow to request status return
log-tree: rely upon the check in the gpg_interface
gpg-interface: check good signature in a reliable way
Currently, verify_signed_buffer() returns the user facing output only.
Allow callers to request the status output also.
Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Currently, verify_signed_buffer() only checks the return code of gpg,
and some callers implement additional unreliable checks for "Good
signature" in the gpg output meant for the user.
Use the status output instead and parse for a line beinning with
"[GNUPG:] GOODSIG ". This is the only reliable way of checking for a
good gpg signature.
If needed we can change this easily to "[GNUPG:] VALIDSIG " if we want
to take into account the trust model.
Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We forgot to close the file descriptor reading from "gpg" output,
killing "git log --show-signature" on a long history.
* sb/gpg-plug-fd-leak:
gpg: close stderr once finished with it in verify_signed_buffer()
We forgot to close the file descriptor reading from "gpg" output,
killing "git log --show-signature" on a long history.
* sb/gpg-plug-fd-leak:
gpg: close stderr once finished with it in verify_signed_buffer()
Failing to close the stderr pipe in verify_signed_buffer() causes
git to run out of file descriptors if there are many calls to
verify_signed_buffer(). An easy way to trigger this is to run
git log --show-signature --merges | grep "key"
on the linux kernel git repo. Eventually it will fail with
error: cannot create pipe for gpg: Too many open files
error: could not run gpg.
Close the stderr pipe so that this can't happen.
Suggested-by: Jeff King <peff@peff.net>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Mark these strings for translation so that error messages are
printed in the user's language of choice.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Callers who ask for ERROR_ON_NO_NAME are not so much
concerned that the name will be blank (because, after all,
we will fall back to using the username), but rather it is a
check to make sure that low-quality identities do not end up
in things like commit messages or emails (whereas it is OK
for them to end up in things like reflogs).
When future commits add more quality checks on the identity,
each of these callers would want to use those checks, too.
Rather than modify each of them later to add a new flag,
let's refactor the flag.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The function used to take an integer flag to specify where the output
should go, but these days we supply a strbuf to receive it.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This mostly moves existing code from builtin/tag.c (for signing)
and builtin/verify-tag.c (for verifying) to a new gpg-interface.c
file to provide a more generic library interface.
- sign_buffer() takes a payload strbuf, a signature strbuf, and a signing
key, runs "gpg" to produce a detached signature for the payload, and
appends it to the signature strbuf. The contents of a signed tag that
concatenates the payload and the detached signature can be produced by
giving the same strbuf as payload and signature strbuf.
- verify_signed_buffer() takes a payload and a detached signature as
<ptr, len> pairs, and runs "gpg --verify" to see if the payload matches
the signature. It can optionally capture the output from GPG to allow
the callers to pretty-print it in a way more suitable for their
contexts.
"verify-tag" (aka "tag -v") used to save the whole tag contents as if it
is a detached signature, and fed gpg the payload part of the tag. It
relied on gpg to fail when the given tag is not signed but just is
annotated. The updated run_gpg_verify() function detects the lack of
detached signature in the input, and errors out without bothering "gpg".
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Jeff King
Junio C Hamano
Nguyễn Thái Ngọc Duy
Santiago Torres
brian m. carlson
René Scharfe
Michael J Gruber
Stephen Boyd