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Transport with dumb http can be fooled into following foreign URLs
that the end user does not intend to, especially with the server
side redirects and http-alternates mechanism, which can lead to
security issues. Tighten the redirection and make it more obvious
to the end user when it happens.
* jk/http-walker-limit-redirect-2.9:
http: treat http-alternates like redirects
http: make redirects more obvious
remote-curl: rename shadowed options variable
http: always update the base URL for redirects
http: simplify update_url_from_redirect
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The previous commit made HTTP redirects more obvious and
tightened up the default behavior. However, there's another
way for a server to ask a git client to fetch arbitrary
content: by having an http-alternates file (or a regular
alternates file, which is used as a backup).
Similar to the HTTP redirect case, a malicious server can
claim to have refs pointing at object X, return a 404 when
the client asks for X, but point to some other URL via
http-alternates, which the client will transparently fetch.
The end result is that it looks from the user's perspective
like the objects came from the malicious server, as the
other URL is not mentioned at all.
Worse, because we feed the new URL to curl ourselves, the
usual protocol restrictions do not kick in (neither curl's
default of disallowing file://, nor the protocol
whitelisting in f4113cac0 (http: limit redirection to
protocol-whitelist, 2015-09-22).
Let's apply the same rules here as we do for HTTP redirects.
Namely:
- unless http.followRedirects is set to "always", we will
not follow remote redirects from http-alternates (or
alternates) at all
- set CURLOPT_PROTOCOLS alongside CURLOPT_REDIR_PROTOCOLS
restrict ourselves to a known-safe set and respect any
user-provided whitelist.
- mention alternate object stores on stderr so that the
user is aware another source of objects may be involved
The first item may prove to be too restrictive. The most
common use of alternates is to point to another path on the
same server. While it's possible for a single-server
redirect to be an attack, it takes a fairly obscure setup
(victim and evil repository on the same host, host speaks
dumb http, and evil repository has access to edit its own
http-alternates file).
So we could make the checks more specific, and only cover
cross-server redirects. But that means parsing the URLs
ourselves, rather than letting curl handle them. This patch
goes for the simpler approach. Given that they are only used
with dumb http, http-alternates are probably pretty rare.
And there's an escape hatch: the user can allow redirects on
a specific server by setting http.<url>.followRedirects to
"always".
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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We instruct curl to always follow HTTP redirects. This is
convenient, but it creates opportunities for malicious
servers to create confusing situations. For instance,
imagine Alice is a git user with access to a private
repository on Bob's server. Mallory runs her own server and
wants to access objects from Bob's repository.
Mallory may try a few tricks that involve asking Alice to
clone from her, build on top, and then push the result:
1. Mallory may simply redirect all fetch requests to Bob's
server. Git will transparently follow those redirects
and fetch Bob's history, which Alice may believe she
got from Mallory. The subsequent push seems like it is
just feeding Mallory back her own objects, but is
actually leaking Bob's objects. There is nothing in
git's output to indicate that Bob's repository was
involved at all.
The downside (for Mallory) of this attack is that Alice
will have received Bob's entire repository, and is
likely to notice that when building on top of it.
2. If Mallory happens to know the sha1 of some object X in
Bob's repository, she can instead build her own history
that references that object. She then runs a dumb http
server, and Alice's client will fetch each object
individually. When it asks for X, Mallory redirects her
to Bob's server. The end result is that Alice obtains
objects from Bob, but they may be buried deep in
history. Alice is less likely to notice.
Both of these attacks are fairly hard to pull off. There's a
social component in getting Mallory to convince Alice to
work with her. Alice may be prompted for credentials in
accessing Bob's repository (but not always, if she is using
a credential helper that caches). Attack (1) requires a
certain amount of obliviousness on Alice's part while making
a new commit. Attack (2) requires that Mallory knows a sha1
in Bob's repository, that Bob's server supports dumb http,
and that the object in question is loose on Bob's server.
But we can probably make things a bit more obvious without
any loss of functionality. This patch does two things to
that end.
First, when we encounter a whole-repo redirect during the
initial ref discovery, we now inform the user on stderr,
making attack (1) much more obvious.
Second, the decision to follow redirects is now
configurable. The truly paranoid can set the new
http.followRedirects to false to avoid any redirection
entirely. But for a more practical default, we will disallow
redirects only after the initial ref discovery. This is
enough to thwart attacks similar to (2), while still
allowing the common use of redirects at the repository
level. Since c93c92f30 (http: update base URLs when we see
redirects, 2013-09-28) we re-root all further requests from
the redirect destination, which should generally mean that
no further redirection is necessary.
As an escape hatch, in case there really is a server that
needs to redirect individual requests, the user can set
http.followRedirects to "true" (and this can be done on a
per-server basis via http.*.followRedirects config).
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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"git fetch http::/site/path" did not die correctly and segfaulted
instead.
* jk/fix-remote-curl-url-wo-proto:
remote-curl: handle URLs without protocol
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Generally remote-curl would never see a URL that did not
have "proto:" at the beginning, as that is what tells git to
run the "git-remote-proto" helper (and git-remote-http, etc,
are aliases for git-remote-curl).
However, the special syntax "proto::something" will run
git-remote-proto with only "something" as the URL. So a
malformed URL like:
http::/example.com/repo.git
will feed the URL "/example.com/repo.git" to
git-remote-http. The resulting URL has no protocol, but the
code added by 372370f (http: use credential API to handle
proxy authentication, 2016-01-26) does not handle this case
and segfaults.
For the purposes of this code, we don't really care what the
exact protocol; only whether or not it is https. So let's
just assume that a missing protocol is not, and curl will
handle the real error (which is that the URL is nonsense).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Use the new GIT_TRACE_CURL environment variable instead
of the deprecated GIT_CURL_VERBOSE.
Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Before 14111fc (git: submodule honor -c credential.* from
command line, 2016-02-29), it was sufficient for code which
spawned a process in a submodule to just set the child
process's "env" field to "local_repo_env" to clear the
environment of any repo-specific variables.
That commit introduced a more complicated procedure, in
which we clear most variables but allow through sanitized
config. For C code, we used that procedure only for cloning,
but not for any of the programs spawned by submodule.c. As a
result, things like "git fetch --recurse-submodules" behave
differently than "git clone --recursive"; the former will
not pass through the sanitized config.
We can fix this by using prepare_submodule_repo_env()
everywhere in submodule.c.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Commit 14111fc (git: submodule honor -c credential.* from
command line, 2016-02-29) taught git-submodule.sh to save
the sanitized value of $GIT_CONFIG_PARAMETERS when clearing
the environment for a submodule. However, it failed to
export the result, meaning that it had no effect for any
sub-programs.
We didn't catch this in our initial tests because we checked
only the "clone" case, which does not go through the shell
script at all. Provoking "git submodule update" to do a
fetch demonstrates the bug.
Noticed-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Right now we test only the cloning case, but there are other
interesting cases (e.g., fetching). Let's pull the setup
bits into their own test, which will make things flow more
logically once we start adding more tests which use the
setup.
Let's also introduce some whitespace to the clone-test to
split the two parts: making sure it fails without our
cmdline config, and that it succeeds with it.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Commit 14111fc (git: submodule honor -c credential.* from
command line, 2016-02-29) accidentally wrote $HTTP_URL. It
happened to work because we ended up with "credential..helper",
which we treat the same as "credential.helper", applying it
to all URLs.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Due to the way that the git-submodule code works, it clears all local
git environment variables before entering submodules. This is normally
a good thing since we want to clear settings such as GIT_WORKTREE and
other variables which would affect the operation of submodule commands.
However, GIT_CONFIG_PARAMETERS is special, and we actually do want to
preserve these settings. However, we do not want to preserve all
configuration as many things should be left specific to the parent
project.
Add a git submodule--helper function, sanitize-config, which shall be
used to sanitize GIT_CONFIG_PARAMETERS, removing all key/value pairs
except a small subset that are known to be safe and necessary.
Replace all the calls to clear_local_git_env with a wrapped function
that filters GIT_CONFIG_PARAMETERS using the new helper and then
restores it to the filtered subset after clearing the rest of the
environment.
Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The Git CodingGuidelines prefer the $(...) construct for command
substitution instead of using the backquotes `...`.
The backquoted form is the traditional method for command
substitution, and is supported by POSIX. However, all but the
simplest uses become complicated quickly. In particular, embedded
command substitutions and/or the use of double quotes require
careful escaping with the backslash character.
The patch was generated by:
for _f in $(find . -name "*.sh")
do
perl -i -pe 'BEGIN{undef $/;} s/`(.+?)`/\$(\1)/smg' "${_f}"
done
and then carefully proof-read.
Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Test clean-up.
* jk/skip-http-tests-under-no-curl:
tests: skip dav http-push tests under NO_EXPAT=NoThanks
t/lib-httpd.sh: skip tests if NO_CURL is defined
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If we built git without curl, we can't actually test against
an http server. In fact, all of the test scripts which
include lib-httpd.sh already perform this check, with one
exception: t5540. For those scripts, this is a noop, and for
t5540, this is a bugfix (it used to fail when built with
NO_CURL, though it could go unnoticed if you had a stale
git-remote-https in your build directory).
Noticed-by: Junio C Hamano <junio@pobox.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Some tests run diff or grep to produce an output, and then
compare the output to an expected value. We know the exit
code we expect these processes to have (e.g., grep yields 0
if it produced output and 1 otherwise), so it would not make
the test wrong to look for it. But the difference between
their output and the expected output (e.g., shown by
test_cmp) is much more useful to somebody debugging the test
than the test just bailing out.
These tests break the &&-chain to skip the exit-code check
of the process. However, we can get the same effect by using
test_might_fail. Note that in some cases the test did use
"|| return 1", which meant the test was not wrong, but it
did fool --chain-lint.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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These are tests which are missing a link in their &&-chain,
but during a setup phase. We may fail to notice failure in
commands that build the test environment, but these are
typically not expected to fail at all (but it's still good
to double-check that our test environment is what we
expect).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Using environment variable LANGUAGE and friends on the client side,
HTTP-based transports now send Accept-Language when making requests.
* ye/http-accept-language:
http: add Accept-Language header if possible
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A broken pack .idx file in the receiving repository prevented the
dumb http transport from fetching a good copy of it from the other
side.
* jk/dumb-http-idx-fetch-fix:
dumb-http: do not pass NULL path to parse_pack_index
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Add an Accept-Language header which indicates the user's preferred
languages defined by $LANGUAGE, $LC_ALL, $LC_MESSAGES and $LANG.
Examples:
LANGUAGE= -> ""
LANGUAGE=ko:en -> "Accept-Language: ko, en;q=0.9, *;q=0.1"
LANGUAGE=ko LANG=en_US.UTF-8 -> "Accept-Language: ko, *;q=0.1"
LANGUAGE= LANG=en_US.UTF-8 -> "Accept-Language: en-US, *;q=0.1"
This gives git servers a chance to display remote error messages in
the user's preferred language.
Limit the number of languages to 1,000 because q-value must not be
smaller than 0.001, and limit the length of Accept-Language header to
4,000 bytes for some HTTP servers which cannot accept such long header.
Signed-off-by: Yi EungJun <eungjun.yi@navercorp.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Once upon a time, dumb http always fetched .idx files
directly into their final location, and then checked their
validity with parse_pack_index. This was refactored in
commit 750ef42 (http-fetch: Use temporary files for
pack-*.idx until verified, 2010-04-19), which uses the
following logic:
1. If we have the idx already in place, see if it's
valid (using parse_pack_index). If so, use it.
2. Otherwise, fetch the .idx to a tempfile, check
that, and if so move it into place.
3. Either way, fetch the pack itself if necessary.
However, it got step 1 wrong. We pass a NULL path parameter
to parse_pack_index, so an existing .idx file always looks
broken. Worse, we do not treat this broken .idx as an
opportunity to re-fetch, but instead return an error,
ignoring the pack entirely. This can lead to a dumb-http
fetch failing to retrieve the necessary objects.
This doesn't come up much in practice, because it must be a
packfile that we found out about (and whose .idx we stored)
during an earlier dumb-http fetch, but whose packfile we
_didn't_ fetch. I.e., we did a partial clone of a
repository, didn't need some packfiles, and now a followup
fetch needs them.
Discovery and tests by Charles Bailey <charles@hashpling.org>.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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extract_content_type() could not extract a charset parameter if the
parameter is not the first one and there is a whitespace and a following
semicolon just before the parameter. For example:
text/plain; format=fixed ;charset=utf-8
And it also could not handle correctly some other cases, such as:
text/plain; charset=utf-8; format=fixed
text/plain; some-param="a long value with ;semicolons;"; charset=utf-8
Thanks-to: Jeff King <peff@peff.net>
Signed-off-by: Yi EungJun <eungjun.yi@navercorp.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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We currently recognize an error message with a content-type
"text/plain; charset=utf-16" as text, but we ignore the
charset parameter entirely. Let's encode it to
log_output_encoding, which is presumably something the
user's terminal can handle.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When we get a content-type from curl, we get the whole
header line, including any parameters, and without any
normalization (like downcasing or whitespace) applied.
If we later try to match it with strcmp() or even
strcasecmp(), we may get false negatives.
This could cause two visible behaviors:
1. We might fail to recognize a smart-http server by its
content-type.
2. We might fail to relay text/plain error messages to
users (especially if they contain a charset parameter).
This patch teaches the http code to extract and normalize
just the type/subtype portion of the string. This is
technically passing out less information to the callers, who
can no longer see the parameters. But none of the current
callers cares, and a future patch will add back an
easier-to-use method for accessing those parameters.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Since commit 426e70d (remote-curl: show server content on
http errors, 2013-04-05), we relay any text/plain error
messages from the remote server to the user. However, we
never tested it.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Make clear which one is for dumb protocol, which one is for smart from
their file name.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Junio C Hamano
Jeff King
Elia Pinto
Jacob Keller
Yi EungJun
Nguyễn Thái Ngọc Duy