This merges up the security fix from v2.17.5.
Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>

This merges up the security fix from v2.17.5.
Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>

This merges up the security fix from v2.17.5.
Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>

This merges up the security fix from v2.17.5.
Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>

This merges up the security fix from v2.17.5.
Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>

This merges up the security fix from v2.17.5.
Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>

This merges up the security fix from v2.17.5.
Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>

This merges up the security fix from v2.17.5.
Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>

Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>

Git's URL parser interprets

	https:///example.com/repo.git

to have no host and a path of "example.com/repo.git".  Curl, on the
other hand, internally redirects it to https://example.com/repo.git.  As
a result, until "credential: parse URL without host as empty host, not
unset", tricking a user into fetching from such a URL would cause Git to
send credentials for another host to example.com.

Teach fsck to block and detect .gitmodules files using such a URL to
prevent sharing them with Git versions that are not yet protected.

A relative URL in a .gitmodules file could also be used to trigger this.
The relative URL resolver used for .gitmodules does not normalize
sequences of slashes and can follow ".." components out of the path part
and to the host part of a URL, meaning that such a relative URL can be
used to traverse from a https://foo.example.com/innocent superproject to
a https:///attacker.example.com/exploit submodule. Fortunately,
redundant extra slashes in .gitmodules are rare, so we can catch this by
detecting one after a leading sequence of "./" and "../" components.
Helped-by: NJeff King <peff@peff.net>
Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>
Reviewed-by: NJeff King <peff@peff.net>

Until "credential: refuse to operate when missing host or protocol",
Git's credential handling code interpreted URLs with empty scheme to
mean "give me credentials matching this host for any protocol".

Luckily libcurl does not recognize such URLs (it tries to look for a
protocol named "" and fails). Just in case that changes, let's reject
them within Git as well. This way, credential_from_url is guaranteed to
always produce a "struct credential" with protocol and host set.
Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>

libcurl permits making requests without a URL scheme specified.  In
this case, it guesses the URL from the hostname, so I can run

	git ls-remote http::ftp.example.com/path/to/repo

and it would make an FTP request.

Any user intentionally using such a URL is likely to have made a typo.
Unfortunately, credential_from_url is not able to determine the host and
protocol in order to determine appropriate credentials to send, and
until "credential: refuse to operate when missing host or protocol",
this resulted in another host's credentials being leaked to the named
host.

Teach credential_from_url_gently to consider such a URL to be invalid
so that fsck can detect and block gitmodules files with such URLs,
allowing server operators to avoid serving them to downstream users
running older versions of Git.

This also means that when such URLs are passed on the command line, Git
will print a clearer error so affected users can switch to the simpler
URL that explicitly specifies the host and protocol they intend.

One subtlety: .gitmodules files can contain relative URLs, representing
a URL relative to the URL they were cloned from.  The relative URL
resolver used for .gitmodules can follow ".." components out of the path
part and past the host part of a URL, meaning that such a relative URL
can be used to traverse from a https://foo.example.com/innocent
superproject to a https::attacker.example.com/exploit submodule.
Fortunately a leading ':' in the first path component after a series of
leading './' and '../' components is unlikely to show up in other
contexts, so we can catch this by detecting that pattern.
Reported-by: NJeff King <peff@peff.net>
Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>
Reviewed-by: NJeff King <peff@peff.net>

When we try to initialize credential loading by URL and find that the
URL is invalid, we set all fields to NULL in order to avoid acting on
malicious input. Later when we request credentials, we diagonse the
erroneous input:

	fatal: refusing to work with credential missing host field

This is problematic in two ways:

- The message doesn't tell the user *why* we are missing the host
  field, so they can't tell from this message alone how to recover.
  There can be intervening messages after the original warning of
  bad input, so the user may not have the context to put two and two
  together.

- The error only occurs when we actually need to get a credential.  If
  the URL permits anonymous access, the only encouragement the user gets
  to correct their bogus URL is a quiet warning.

  This is inconsistent with the check we perform in fsck, where any use
  of such a URL as a submodule is an error.

When we see such a bogus URL, let's not try to be nice and continue
without helpers. Instead, die() immediately. This is simpler and
obviously safe. And there's very little chance of disrupting a normal
workflow.

It's _possible_ that somebody has a legitimate URL with a raw newline in
it. It already wouldn't work with credential helpers, so this patch
steps that up from an inconvenience to "we will refuse to work with it
at all". If such a case does exist, we should figure out a way to work
with it (especially if the newline is only in the path component, which
we normally don't even pass to helpers). But until we see a real report,
we're better off being defensive.
Reported-by: NCarlo Arenas <carenas@gmail.com>
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>

In 07259e74 (fsck: detect gitmodules URLs with embedded newlines,
2020-03-11), git fsck learned to check whether URLs in .gitmodules could
be understood by the credential machinery when they are handled by
git-remote-curl.

However, the check is overbroad: it checks all URLs instead of only
URLs that would be passed to git-remote-curl. In principle a git:// or
file:/// URL does not need to follow the same conventions as an http://
URL; in particular, git:// and file:// protocols are not succeptible to
issues in the credential API because they do not support attaching
credentials.

In the HTTP case, the URL in .gitmodules does not always match the URL
that would be passed to git-remote-curl and the credential machinery:
Git's URL syntax allows specifying a remote helper followed by a "::"
delimiter and a URL to be passed to it, so that

	git ls-remote http::https://example.com/repo.git

invokes git-remote-http with https://example.com/repo.git as its URL
argument. With today's checks, that distinction does not make a
difference, but for a check we are about to introduce (for empty URL
schemes) it will matter.

.gitmodules files also support relative URLs. To ensure coverage for the
https based embedded-newline attack, urldecode and check them directly
for embedded newlines.
Helped-by: NJeff King <peff@peff.net>
Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>
Reviewed-by: NJeff King <peff@peff.net>

The credential helper protocol was designed to be very flexible: the
fields it takes as input are treated as a pattern, and any missing
fields are taken as wildcards. This allows unusual things like:

  echo protocol=https | git credential reject

to delete all stored https credentials (assuming the helpers themselves
treat the input that way). But when helpers are invoked automatically by
Git, this flexibility works against us. If for whatever reason we don't
have a "host" field, then we'd match _any_ host. When you're filling a
credential to send to a remote server, this is almost certainly not what
you want.

Prevent this at the layer that writes to the credential helper. Add a
check to the credential API that the host and protocol are always passed
in, and add an assertion to the credential_write function that speaks
credential helper protocol to be doubly sure.

There are a few ways this can be triggered in practice:

  - the "git credential" command passes along arbitrary credential
    parameters it reads from stdin.

  - until the previous patch, when the host field of a URL is empty, we
    would leave it unset (rather than setting it to the empty string)

  - a URL like "example.com/foo.git" is treated by curl as if "http://"
    was present, but our parser sees it as a non-URL and leaves all
    fields unset

  - the recent fix for URLs with embedded newlines blanks the URL but
    otherwise continues. Rather than having the desired effect of
    looking up no credential at all, many helpers will return _any_
    credential

Our earlier test for an embedded newline didn't catch this because it
only checked that the credential was cleared, but didn't configure an
actual helper. Configuring the "verbatim" helper in the test would show
that it is invoked (it's obviously a silly helper which doesn't look at
its input, but the point is that it shouldn't be run at all). Since
we're switching this case to die(), we don't need to bother with a
helper. We can see the new behavior just by checking that the operation
fails.

We'll add new tests covering partial input as well (these can be
triggered through various means with url-parsing, but it's simpler to
just check them directly, as we know we are covered even if the url
parser changes behavior in the future).

[jn: changed to die() instead of logging and showing a manual
 username/password prompt]
Reported-by: NCarlo Arenas <carenas@gmail.com>
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>

We may feed a URL like "cert:///path/to/cert.pem" into the credential
machinery to get the key for a client-side certificate. That
credential has no hostname field, which is about to be disallowed (to
avoid confusion with protocols where a helper _would_ expect a
hostname).

This means as of the next patch, credential helpers won't work for
unlocking certs. Let's fix that by doing two things:

  - when we parse a url with an empty host, set the host field to the
    empty string (asking only to match stored entries with an empty
    host) rather than NULL (asking to match _any_ host).

  - when we build a cert:// credential by hand, similarly assign an
    empty string

It's the latter that is more likely to impact real users in practice,
since it's what's used for http connections. But we don't have good
infrastructure to test it.

The url-parsing version will help anybody using git-credential in a
script, and is easy to test.
Signed-off-by: NJeff King <peff@peff.net>
Reviewed-by: NTaylor Blau <me@ttaylorr.com>
Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>

Many of the tests in t0300 give partial inputs to git-credential,
omitting a protocol or hostname. We're checking only high-level things
like whether and how helpers are invoked at all, and we don't care about
specific hosts. However, in preparation for tightening up the rules
about when we're willing to run a helper, let's start using input that's
a bit more realistic: pretend as if http://example.com is being
examined.

This shouldn't change the point of any of the tests, but do note we have
to adjust the expected output to accommodate this (filling a credential
will repeat back the protocol/host fields to stdout, and the helper
debug messages and askpass prompt will change on stderr).
Signed-off-by: NJeff King <peff@peff.net>
Reviewed-by: NTaylor Blau <me@ttaylorr.com>
Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>

We test a toy credential helper that writes "quit=1" and confirms that
we stop running other helpers. However, that helper is unrealistic in
that it does not bother to read its stdin at all.

For now we don't send any input to it, because we feed git-credential a
blank credential. But that will change in the next patch, which will
cause this test to racily fail, as git-credential will get SIGPIPE
writing to the helper rather than exiting because it was asked to.

Let's make this one-off helper more like our other sample helpers, and
have it source the "dump" script. That will read stdin, fixing the
SIGPIPE problem. But it will also write what it sees to stderr. We can
make the test more robust by checking that output, which confirms that
we do run the quit helper, don't run any other helpers, and exit for the
reason we expected.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJonathan Nieder <jrnieder@gmail.com>

Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Now that Unicode 13.0 has been announced[0], update the character
width tables to the new version.

[0] https://home.unicode.org/announcing-the-unicode-standard-version-13-0/Signed-off-by: NBeat Bolli <dev+git@drbeat.li>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Updates to the CI settings.

* js/ci-windows-update:
  Azure Pipeline: switch to the latest agent pools
  ci: prevent `perforce` from being quarantined
  t/lib-httpd: avoid using macOS' sed

Code style cleanup.

* jk/run-command-formatfix:
  run-command.h: fix mis-indented struct member

Docfix.

* jk/doc-credential-helper:
  doc: move credential helper info into gitcredentials(7)

Dev support.

* js/mingw-open-in-gdb:
  mingw: add a helper function to attach GDB to the current process

Test updates.

* js/test-unc-fetch:
  t5580: test cloning without file://, test fetching via UNC paths

Testfix.

* js/test-write-junit-xml-fix:
  tests: fix --write-junit-xml with subshells

Code simplification.

* en/simplify-check-updates-in-unpack-trees:
  unpack-trees: exit check_updates() early if updates are not wanted

Both "git ls-remote -h" and "git grep -h" give short usage help,
like any other Git subcommand, but it is not unreasonable to expect
that the former would behave the same as "git ls-remote --head"
(there is no other sensible behaviour for the latter).  The
documentation has been updated in an attempt to clarify this.

* jc/doc-single-h-is-for-help:
  Documentation: clarify that `-h` alone stands for `help`

"git show" and others gave an object name in raw format in its
error output, which has been corrected to give it in hex.

* hd/show-one-mergetag-fix:
  show_one_mergetag: print non-parent in hex form.

MinGW's poll() emulation has been improved.

* am/mingw-poll-fix:
  mingw: workaround for hangs when sending STDIN

"git merge signed-tag" while lacking the public key started to say
"No signature", which was utterly wrong.  This regression has been
reverted.

* hi/gpg-use-check-signature:
  Revert "gpg-interface: prefer check_signature() for GPG verification"

Fix for a bug revealed by a recent change to make the protocol v2
the default.

* ds/partial-clone-fixes:
  partial-clone: avoid fetching when looking for objects
  partial-clone: demonstrate bugs in partial fetch

The merge-recursive machinery failed to refresh the cache entry for
a merge result in a couple of places, resulting in an unnecessary
merge failure, which has been fixed.

* en/t3433-rebase-stat-dirty-failure:
  merge-recursive: fix the refresh logic in update_file_flags
  t3433: new rebase testcase documenting a stat-dirty-like failure

"git check-ignore" did not work when the given path is explicitly
marked as not ignored with a negative entry in the .gitignore file.

* en/check-ignore:
  check-ignore: fix documentation and implementation to match

Doc markup fix.

* jk/push-option-doc-markup-fix:
  doc/config/push: use longer "--" line for preformatted example

Update to doc-diff.

* jk/doc-diff-parallel:
  doc-diff: use single-colon rule in rendering Makefile

The code to automatically shrink the fan-out in the notes tree had
an off-by-one bug, which has been killed.

* jh/notes-fanout-fix:
  notes.c: fix off-by-one error when decreasing notes fanout
  t3305: check notes fanout more carefully and robustly

The index-pack code now diagnoses a bad input packstream that
records the same object twice when it is used as delta base; the
code used to declare a software bug when encountering such an
input, but it is an input error.

* jk/index-pack-dupfix:
  index-pack: downgrade twice-resolved REF_DELTA to die()

"git rebase -i" identifies existing commits in its todo file with
their abbreviated object name, which could become ambigous as it
goes to create new commits, and has a mechanism to avoid ambiguity
in the main part of its execution.  A few other cases however were
not covered by the protection against ambiguity, which has been
corrected.

* js/rebase-i-with-colliding-hash:
  rebase -i: also avoid SHA-1 collisions with missingCommitsCheck
  rebase -i: re-fix short SHA-1 collision
  parse_insn_line(): improve error message when parsing failed