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2020-01-07run-command: avoid undefined behavior in exists_in_PATHLibravatar brian m. carlson1-1/+2
In this function, we free the pointer we get from locate_in_PATH and then check whether it's NULL. However, this is undefined behavior if the pointer is non-NULL, since the C standard no longer permits us to use a valid pointer after freeing it. The only case in which the C standard would permit this to be defined behavior is if r were NULL, since it states that in such a case "no action occurs" as a result of calling free. It's easy to suggest that this is not likely to be a problem, but we know that GCC does aggressively exploit the fact that undefined behavior can never occur to optimize and rewrite code, even when that's contrary to the expectations of the programmer. It is, in fact, very common for it to omit NULL pointer checks, just as we have here. Since it's easy to fix, let's do so, and avoid a potential headache in the future. Noticed-by: Miriam R. <mirucam@gmail.com> Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-12-06Git 2.24.1Libravatar Johannes Schindelin3-2/+10
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06Sync with 2.23.1Libravatar Johannes Schindelin46-87/+983
* maint-2.23: (44 commits) Git 2.23.1 Git 2.22.2 Git 2.21.1 mingw: sh arguments need quoting in more circumstances mingw: fix quoting of empty arguments for `sh` mingw: use MSYS2 quoting even when spawning shell scripts mingw: detect when MSYS2's sh is to be spawned more robustly t7415: drop v2.20.x-specific work-around Git 2.20.2 t7415: adjust test for dubiously-nested submodule gitdirs for v2.20.x Git 2.19.3 Git 2.18.2 Git 2.17.3 Git 2.16.6 test-drop-caches: use `has_dos_drive_prefix()` Git 2.15.4 Git 2.14.6 mingw: handle `subst`-ed "DOS drives" mingw: refuse to access paths with trailing spaces or periods mingw: refuse to access paths with illegal characters ...
2019-12-06Git 2.23.1Libravatar Johannes Schindelin3-2/+10
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06Sync with 2.22.2Libravatar Johannes Schindelin45-87/+975
* maint-2.22: (43 commits) Git 2.22.2 Git 2.21.1 mingw: sh arguments need quoting in more circumstances mingw: fix quoting of empty arguments for `sh` mingw: use MSYS2 quoting even when spawning shell scripts mingw: detect when MSYS2's sh is to be spawned more robustly t7415: drop v2.20.x-specific work-around Git 2.20.2 t7415: adjust test for dubiously-nested submodule gitdirs for v2.20.x Git 2.19.3 Git 2.18.2 Git 2.17.3 Git 2.16.6 test-drop-caches: use `has_dos_drive_prefix()` Git 2.15.4 Git 2.14.6 mingw: handle `subst`-ed "DOS drives" mingw: refuse to access paths with trailing spaces or periods mingw: refuse to access paths with illegal characters unpack-trees: let merged_entry() pass through do_add_entry()'s errors ...
2019-12-06Git 2.22.2Libravatar Johannes Schindelin3-2/+10
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06Sync with 2.21.1Libravatar Johannes Schindelin44-87/+967
* maint-2.21: (42 commits) Git 2.21.1 mingw: sh arguments need quoting in more circumstances mingw: fix quoting of empty arguments for `sh` mingw: use MSYS2 quoting even when spawning shell scripts mingw: detect when MSYS2's sh is to be spawned more robustly t7415: drop v2.20.x-specific work-around Git 2.20.2 t7415: adjust test for dubiously-nested submodule gitdirs for v2.20.x Git 2.19.3 Git 2.18.2 Git 2.17.3 Git 2.16.6 test-drop-caches: use `has_dos_drive_prefix()` Git 2.15.4 Git 2.14.6 mingw: handle `subst`-ed "DOS drives" mingw: refuse to access paths with trailing spaces or periods mingw: refuse to access paths with illegal characters unpack-trees: let merged_entry() pass through do_add_entry()'s errors quote-stress-test: offer to test quoting arguments for MSYS2 sh ...
2019-12-06Git 2.21.1Libravatar Johannes Schindelin3-2/+14
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06Merge branch 'fix-msys2-quoting-bugs'Libravatar Johannes Schindelin1-5/+20
These patches fix several bugs in quoting arguments when spawning shell scripts on Windows. Note: these bugs are Windows-only, as we have to construct a command line for the process-to-spawn, unlike Linux/macOS, where `execv()` accepts an already-split command line. Furthermore, these fixes were not included in the CVE-2019-1350 part of v2.14.6 because the Windows-specific quoting when spawning shell scripts was contributed from Git for Windows into Git only in the v2.21.x era. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06mingw: sh arguments need quoting in more circumstancesLibravatar Johannes Schindelin1-2/+3
Previously, we failed to quote characters such as '*', '(' and the likes. Let's fix this. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06t7415: drop v2.20.x-specific work-aroundLibravatar Johannes Schindelin1-1/+1
This reverts the work-around that was introduced just for the v2.20.x release train in "t7415: adjust test for dubiously-nested submodule gitdirs for v2.20.x"; It is not necessary for v2.21.x. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06mingw: fix quoting of empty arguments for `sh`Libravatar Johannes Schindelin1-1/+1
When constructing command-lines to spawn processes, it is an unfortunate but necessary decision to quote arguments differently: MSYS2 has different dequoting rules (inherited from Cygwin) than the rest of Windows. To accommodate that, Git's Windows compatibility layer has two separate quoting helpers, one for MSYS2 (which it uses exclusively when spawning `sh`) and the other for regular Windows executables. The MSYS2 one had an unfortunate bug where a `,` somehow slipped in, instead of the `;`. As a consequence, empty arguments would not be enclosed in a pair of double quotes, but the closing double quote was skipped. Let's fix this. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06mingw: use MSYS2 quoting even when spawning shell scriptsLibravatar Johannes Schindelin1-1/+2
At the point where `mingw_spawn_fd()` is called, we already have a full path to the script interpreter in that scenario, and we pass it in as the executable to run, while the `argv` reflect what the script should receive as command-line. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06mingw: detect when MSYS2's sh is to be spawned more robustlyLibravatar Johannes Schindelin1-1/+14
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06Sync with 2.20.2Libravatar Johannes Schindelin43-82/+935
* maint-2.20: (36 commits) Git 2.20.2 t7415: adjust test for dubiously-nested submodule gitdirs for v2.20.x Git 2.19.3 Git 2.18.2 Git 2.17.3 Git 2.16.6 test-drop-caches: use `has_dos_drive_prefix()` Git 2.15.4 Git 2.14.6 mingw: handle `subst`-ed "DOS drives" mingw: refuse to access paths with trailing spaces or periods mingw: refuse to access paths with illegal characters unpack-trees: let merged_entry() pass through do_add_entry()'s errors quote-stress-test: offer to test quoting arguments for MSYS2 sh t6130/t9350: prepare for stringent Win32 path validation quote-stress-test: allow skipping some trials quote-stress-test: accept arguments to test via the command-line tests: add a helper to stress test argument quoting mingw: fix quoting of arguments Disallow dubiously-nested submodule git directories ...
2019-12-06Git 2.20.2Libravatar Johannes Schindelin3-2/+20
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06submodule: defend against submodule.update = !command in .gitmodulesLibravatar Jonathan Nieder1-0/+2
In v2.15.4, we started to reject `submodule.update` settings in `.gitmodules`. Let's raise a BUG if it somehow still made it through from anywhere but the Git config. Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
2019-12-06t7415: adjust test for dubiously-nested submodule gitdirs for v2.20.xLibravatar Johannes Schindelin1-1/+1
In v2.20.x, Git clones submodules recursively by first creating the submodules' gitdirs and _then_ "updating" the submodules. This can lead to the situation where the clone path is taken because the directory (while it exists already) is not a git directory, but then the clone fails because that gitdir is unexpectedly already a directory. This _also_ works around the vulnerability that was fixed in "Disallow dubiously-nested submodule git directories", but it produces a different error message than the one expected by the test case, therefore we adjust the test case accordingly. Note: as the two submodules "race each other", there are actually two possible error messages, therefore we have to teach the test case to expect _two_ possible (and good) outcomes in addition to the one it expected before. Note: this workaround is only necessary for the v2.20.x release train; The behavior changed again in v2.21.x so that the original test case's expectations are met again. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06Sync with 2.19.3Libravatar Johannes Schindelin40-82/+914
* maint-2.19: (34 commits) Git 2.19.3 Git 2.18.2 Git 2.17.3 Git 2.16.6 test-drop-caches: use `has_dos_drive_prefix()` Git 2.15.4 Git 2.14.6 mingw: handle `subst`-ed "DOS drives" mingw: refuse to access paths with trailing spaces or periods mingw: refuse to access paths with illegal characters unpack-trees: let merged_entry() pass through do_add_entry()'s errors quote-stress-test: offer to test quoting arguments for MSYS2 sh t6130/t9350: prepare for stringent Win32 path validation quote-stress-test: allow skipping some trials quote-stress-test: accept arguments to test via the command-line tests: add a helper to stress test argument quoting mingw: fix quoting of arguments Disallow dubiously-nested submodule git directories protect_ntfs: turn on NTFS protection by default path: also guard `.gitmodules` against NTFS Alternate Data Streams ...
2019-12-06Git 2.19.3Libravatar Johannes Schindelin3-2/+10
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06Sync with 2.18.2Libravatar Johannes Schindelin39-82/+906
* maint-2.18: (33 commits) Git 2.18.2 Git 2.17.3 Git 2.16.6 test-drop-caches: use `has_dos_drive_prefix()` Git 2.15.4 Git 2.14.6 mingw: handle `subst`-ed "DOS drives" mingw: refuse to access paths with trailing spaces or periods mingw: refuse to access paths with illegal characters unpack-trees: let merged_entry() pass through do_add_entry()'s errors quote-stress-test: offer to test quoting arguments for MSYS2 sh t6130/t9350: prepare for stringent Win32 path validation quote-stress-test: allow skipping some trials quote-stress-test: accept arguments to test via the command-line tests: add a helper to stress test argument quoting mingw: fix quoting of arguments Disallow dubiously-nested submodule git directories protect_ntfs: turn on NTFS protection by default path: also guard `.gitmodules` against NTFS Alternate Data Streams is_ntfs_dotgit(): speed it up ...
2019-12-06Git 2.18.2Libravatar Johannes Schindelin3-2/+10
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06Sync with 2.17.3Libravatar Johannes Schindelin38-83/+898
* maint-2.17: (32 commits) Git 2.17.3 Git 2.16.6 test-drop-caches: use `has_dos_drive_prefix()` Git 2.15.4 Git 2.14.6 mingw: handle `subst`-ed "DOS drives" mingw: refuse to access paths with trailing spaces or periods mingw: refuse to access paths with illegal characters unpack-trees: let merged_entry() pass through do_add_entry()'s errors quote-stress-test: offer to test quoting arguments for MSYS2 sh t6130/t9350: prepare for stringent Win32 path validation quote-stress-test: allow skipping some trials quote-stress-test: accept arguments to test via the command-line tests: add a helper to stress test argument quoting mingw: fix quoting of arguments Disallow dubiously-nested submodule git directories protect_ntfs: turn on NTFS protection by default path: also guard `.gitmodules` against NTFS Alternate Data Streams is_ntfs_dotgit(): speed it up mingw: disallow backslash characters in tree objects' file names ...
2019-12-06Git 2.17.3Libravatar Johannes Schindelin3-2/+14
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06fsck: reject submodule.update = !command in .gitmodulesLibravatar Jonathan Nieder2-0/+21
This allows hosting providers to detect whether they are being used to attack users using malicious 'update = !command' settings in .gitmodules. Since ac1fbbda2013 (submodule: do not copy unknown update mode from .gitmodules, 2013-12-02), in normal cases such settings have been treated as 'update = none', so forbidding them should not produce any collateral damage to legitimate uses. A quick search does not reveal any repositories making use of this construct, either. Reported-by: Joern Schneeweisz <jschneeweisz@gitlab.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06Sync with 2.16.6Libravatar Johannes Schindelin37-82/+865
* maint-2.16: (31 commits) Git 2.16.6 test-drop-caches: use `has_dos_drive_prefix()` Git 2.15.4 Git 2.14.6 mingw: handle `subst`-ed "DOS drives" mingw: refuse to access paths with trailing spaces or periods mingw: refuse to access paths with illegal characters unpack-trees: let merged_entry() pass through do_add_entry()'s errors quote-stress-test: offer to test quoting arguments for MSYS2 sh t6130/t9350: prepare for stringent Win32 path validation quote-stress-test: allow skipping some trials quote-stress-test: accept arguments to test via the command-line tests: add a helper to stress test argument quoting mingw: fix quoting of arguments Disallow dubiously-nested submodule git directories protect_ntfs: turn on NTFS protection by default path: also guard `.gitmodules` against NTFS Alternate Data Streams is_ntfs_dotgit(): speed it up mingw: disallow backslash characters in tree objects' file names path: safeguard `.git` against NTFS Alternate Streams Accesses ...
2019-12-06Git 2.16.6Libravatar Johannes Schindelin3-2/+10
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06test-drop-caches: use `has_dos_drive_prefix()`Libravatar Johannes Schindelin1-5/+8
This is a companion patch to 'mingw: handle `subst`-ed "DOS drives"': use the DOS drive prefix handling that is already provided by `compat/mingw.c` (and which just learned to handle non-alphabetical "drive letters"). Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06Sync with 2.15.4Libravatar Johannes Schindelin35-77/+842
* maint-2.15: (29 commits) Git 2.15.4 Git 2.14.6 mingw: handle `subst`-ed "DOS drives" mingw: refuse to access paths with trailing spaces or periods mingw: refuse to access paths with illegal characters unpack-trees: let merged_entry() pass through do_add_entry()'s errors quote-stress-test: offer to test quoting arguments for MSYS2 sh t6130/t9350: prepare for stringent Win32 path validation quote-stress-test: allow skipping some trials quote-stress-test: accept arguments to test via the command-line tests: add a helper to stress test argument quoting mingw: fix quoting of arguments Disallow dubiously-nested submodule git directories protect_ntfs: turn on NTFS protection by default path: also guard `.gitmodules` against NTFS Alternate Data Streams is_ntfs_dotgit(): speed it up mingw: disallow backslash characters in tree objects' file names path: safeguard `.git` against NTFS Alternate Streams Accesses clone --recurse-submodules: prevent name squatting on Windows is_ntfs_dotgit(): only verify the leading segment ...
2019-12-06Git 2.15.4Libravatar Johannes Schindelin3-2/+13
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-06submodule: reject submodule.update = !command in .gitmodulesLibravatar Jonathan Nieder3-11/+20
Since ac1fbbda2013 (submodule: do not copy unknown update mode from .gitmodules, 2013-12-02), Git has been careful to avoid copying [submodule "foo"] update = !run an arbitrary scary command from .gitmodules to a repository's local config, copying in the setting 'update = none' instead. The gitmodules(5) manpage documents the intention: The !command form is intentionally ignored here for security reasons Unfortunately, starting with v2.20.0-rc0 (which integrated ee69b2a9 (submodule--helper: introduce new update-module-mode helper, 2018-08-13, first released in v2.20.0-rc0)), there are scenarios where we *don't* ignore it: if the config store contains no submodule.foo.update setting, the submodule-config API falls back to reading .gitmodules and the repository-supplied !command gets run after all. This was part of a general change over time in submodule support to read more directly from .gitmodules, since unlike .git/config it allows a project to change values between branches and over time (while still allowing .git/config to override things). But it was never intended to apply to this kind of dangerous configuration. The behavior change was not advertised in ee69b2a9's commit message and was missed in review. Let's take the opportunity to make the protection more robust, even in Git versions that are technically not affected: instead of quietly converting 'update = !command' to 'update = none', noisily treat it as an error. Allowing the setting but treating it as meaning something else was just confusing; users are better served by seeing the error sooner. Forbidding the construct makes the semantics simpler and means we can check for it in fsck (in a separate patch). As a result, the submodule-config API cannot read this value from .gitmodules under any circumstance, and we can declare with confidence For security reasons, the '!command' form is not accepted here. Reported-by: Joern Schneeweisz <jschneeweisz@gitlab.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
2019-12-06Sync with 2.14.6Libravatar Johannes Schindelin31-66/+811
* maint-2.14: (28 commits) Git 2.14.6 mingw: handle `subst`-ed "DOS drives" mingw: refuse to access paths with trailing spaces or periods mingw: refuse to access paths with illegal characters unpack-trees: let merged_entry() pass through do_add_entry()'s errors quote-stress-test: offer to test quoting arguments for MSYS2 sh t6130/t9350: prepare for stringent Win32 path validation quote-stress-test: allow skipping some trials quote-stress-test: accept arguments to test via the command-line tests: add a helper to stress test argument quoting mingw: fix quoting of arguments Disallow dubiously-nested submodule git directories protect_ntfs: turn on NTFS protection by default path: also guard `.gitmodules` against NTFS Alternate Data Streams is_ntfs_dotgit(): speed it up mingw: disallow backslash characters in tree objects' file names path: safeguard `.git` against NTFS Alternate Streams Accesses clone --recurse-submodules: prevent name squatting on Windows is_ntfs_dotgit(): only verify the leading segment test-path-utils: offer to run a protectNTFS/protectHFS benchmark ...
2019-12-06Git 2.14.6Libravatar Johannes Schindelin3-2/+56
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-05Merge branch 'win32-accommodate-funny-drive-names'Libravatar Johannes Schindelin4-6/+54
While the only permitted drive letters for physical drives on Windows are letters of the US-English alphabet, this restriction does not apply to virtual drives assigned via `subst <letter>: <path>`. To prevent targeted attacks against systems where "funny" drive letters such as `1` or `!` are assigned, let's handle them as regular drive letters on Windows. This fixes CVE-2019-1351. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-05Merge branch 'win32-filenames-cannot-have-trailing-spaces-or-periods'Libravatar Johannes Schindelin11-4/+127
On Windows, filenames cannot have trailing spaces or periods, when opening such paths, they are stripped automatically. Read: you can open the file `README` via the file name `README . . .`. This ambiguity can be used in combination with other security bugs to cause e.g. remote code execution during recursive clones. This patch series fixes that. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-05Merge branch 'fix-mingw-quoting-bug'Libravatar Johannes Schindelin3-5/+156
This patch fixes a vulnerability in the Windows-specific code where a submodule names ending in a backslash were quoted incorrectly, and that bug could be abused to insert command-line parameters e.g. to `ssh` in a recursive clone. Note: this bug is Windows-only, as we have to construct a command line for the process-to-spawn, unlike Linux/macOS, where `execv()` accepts an already-split command line. While at it, other quoting issues are fixed as well. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-05Merge branch 'dubiously-nested-submodules'Libravatar Johannes Schindelin4-2/+79
Recursive clones are currently affected by a vulnerability that is caused by too-lax validation of submodule names. This topic branch fixes that. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-05Merge branch 'turn-on-protectntfs-by-default'Libravatar Johannes Schindelin3-28/+31
This patch series makes it safe to use Git on Windows drives, even if running on a mounted network share or within the Windows Subsystem for Linux (WSL). This topic branch addresses CVE-2019-1353. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-05mingw: handle `subst`-ed "DOS drives"Libravatar Johannes Schindelin4-3/+36
Over a decade ago, in 25fe217b86c (Windows: Treat Windows style path names., 2008-03-05), Git was taught to handle absolute Windows paths, i.e. paths that start with a drive letter and a colon. Unbeknownst to us, while drive letters of physical drives are limited to letters of the English alphabet, there is a way to assign virtual drive letters to arbitrary directories, via the `subst` command, which is _not_ limited to English letters. It is therefore possible to have absolute Windows paths of the form `1:\what\the\hex.txt`. Even "better": pretty much arbitrary Unicode letters can also be used, e.g. `ä:\tschibät.sch`. While it can be sensibly argued that users who set up such funny drive letters really seek adverse consequences, the Windows Operating System is known to be a platform where many users are at the mercy of administrators who have their very own idea of what constitutes a reasonable setup. Therefore, let's just make sure that such funny paths are still considered absolute paths by Git, on Windows. In addition to Unicode characters, pretty much any character is a valid drive letter, as far as `subst` is concerned, even `:` and `"` or even a space character. While it is probably the opposite of smart to use them, let's safeguard `is_dos_drive_prefix()` against all of them. Note: `[::1]:repo` is a valid URL, but not a valid path on Windows. As `[` is now considered a valid drive letter, we need to be very careful to avoid misinterpreting such a string as valid local path in `url_is_local_not_ssh()`. To do that, we use the just-introduced function `is_valid_path()` (which will label the string as invalid file name because of the colon characters). This fixes CVE-2019-1351. Reported-by: Nicolas Joly <Nicolas.Joly@microsoft.com> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-05Merge branch 'disallow-dotgit-via-ntfs-alternate-data-streams'Libravatar Johannes Schindelin6-8/+162
This patch series plugs an attack vector we had overlooked in our December 2014 work on `core.protectNTFS`. Essentially, the path `.git::$INDEX_ALLOCATION/config` is interpreted as `.git/config` when NTFS Alternate Data Streams are available (which they are on Windows, and at least on network shares that are SMB-mounted on macOS). Needless to say: we don't want that. In fact, we want to stay on the very safe side and not even special-case the `$INDEX_ALLOCATION` stream type: let's just prevent Git from touching _any_ explicitly specified Alternate Data Stream of `.git`. In essence, we'll prevent Git from tracking, or writing to, any path with a segment of the form `.git:<anything>`. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-05mingw: refuse to access paths with trailing spaces or periodsLibravatar Johannes Schindelin8-2/+123
When creating a directory on Windows whose path ends in a space or a period (or chains thereof), the Win32 API "helpfully" trims those. For example, `mkdir("abc ");` will return success, but actually create a directory called `abc` instead. This stems back to the DOS days, when all file names had exactly 8 characters plus exactly 3 characters for the file extension, and the only way to have shorter names was by padding with spaces. Sadly, this "helpful" behavior is a bit inconsistent: after a successful `mkdir("abc ");`, a `mkdir("abc /def")` will actually _fail_ (because the directory `abc ` does not actually exist). Even if it would work, we now have a serious problem because a Git repository could contain directories `abc` and `abc `, and on Windows, they would be "merged" unintentionally. As these paths are illegal on Windows, anyway, let's disallow any accesses to such paths on that Operating System. For practical reasons, this behavior is still guarded by the config setting `core.protectNTFS`: it is possible (and at least two regression tests make use of it) to create commits without involving the worktree. In such a scenario, it is of course possible -- even on Windows -- to create such file names. Among other consequences, this patch disallows submodules' paths to end in spaces on Windows (which would formerly have confused Git enough to try to write into incorrect paths, anyway). While this patch does not fix a vulnerability on its own, it prevents an attack vector that was exploited in demonstrations of a number of recently-fixed security bugs. The regression test added to `t/t7417-submodule-path-url.sh` reflects that attack vector. Note that we have to adjust the test case "prevent git~1 squatting on Windows" in `t/t7415-submodule-names.sh` because of a very subtle issue. It tries to clone two submodules whose names differ only in a trailing period character, and as a consequence their git directories differ in the same way. Previously, when Git tried to clone the second submodule, it thought that the git directory already existed (because on Windows, when you create a directory with the name `b.` it actually creates `b`), but with this patch, the first submodule's clone will fail because of the illegal name of the git directory. Therefore, when cloning the second submodule, Git will take a different code path: a fresh clone (without an existing git directory). Both code paths fail to clone the second submodule, both because the the corresponding worktree directory exists and is not empty, but the error messages are worded differently. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-05quote-stress-test: offer to test quoting arguments for MSYS2 shLibravatar Johannes Schindelin1-3/+10
It is unfortunate that we need to quote arguments differently on Windows, depending whether we build a command-line for MSYS2's `sh` or for other Windows executables. We already have a test helper to verify the latter, with this patch we can also verify the former. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-05mingw: refuse to access paths with illegal charactersLibravatar Johannes Schindelin3-3/+18
Certain characters are not admissible in file names on Windows, even if Cygwin/MSYS2 (and therefore, Git for Windows' Bash) pretend that they are, e.g. `:`, `<`, `>`, etc Let's disallow those characters explicitly in Windows builds of Git. Note: just like trailing spaces or periods, it _is_ possible on Windows to create commits adding files with such illegal characters, as long as the operation leaves the worktree untouched. To allow for that, we continue to guard `is_valid_win32_path()` behind the config setting `core.protectNTFS`, so that users _can_ continue to do that, as long as they turn the protections off via that config setting. Among other problems, this prevents Git from trying to write to an "NTFS Alternate Data Stream" (which refers to metadata stored alongside a file, under a special name: "<filename>:<stream-name>"). This fix therefore also prevents an attack vector that was exploited in demonstrations of a number of recently-fixed security bugs. Further reading on illegal characters in Win32 filenames: https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-05unpack-trees: let merged_entry() pass through do_add_entry()'s errorsLibravatar Johannes Schindelin1-1/+2
A `git clone` will end with exit code 0 when `merged_entry()` returns a positive value during a call of `unpack_trees()` to `traverse_trees()`. The reason is that `unpack_trees()` will interpret a positive value not to be an error. The problem is, however, that `add_index_entry()` (which is called by `merged_entry()` can report an error, and we really should fail the entire clone in such a case. Let's fix this problem, in preparation for a Windows-specific patch disallowing `mkdir()` with directory names that contain a trailing space (which is illegal on NTFS): we want `git clone` to abort when a path cannot be checked out due to that condition. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-05quote-stress-test: allow skipping some trialsLibravatar Johannes Schindelin1-1/+5
When the, say, 93rd trial run fails, it is a good idea to have a way to skip the first 92 trials and dig directly into the 93rd in a debugger. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-05t6130/t9350: prepare for stringent Win32 path validationLibravatar Johannes Schindelin2-1/+2
On Windows, file names cannot contain asterisks nor newline characters. In an upcoming commit, we will make this limitation explicit, disallowing even the creation of commits that introduce such file names. However, in the test scripts touched by this patch, we _know_ that those paths won't be checked out, so we _want_ to allow such file names. Happily, the stringent path validation will be guarded via the `core.protectNTFS` flag, so all we need to do is to force that flag off temporarily. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-05quote-stress-test: accept arguments to test via the command-lineLibravatar Johannes Schindelin1-13/+22
When the stress test reported a problem with quoting certain arguments, it is helpful to have a facility to play with those arguments in order to find out whether variations of those arguments are affected, too. Let's allow `test-run-command quote-stress-test -- <args>` to be used for that purpose. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-05tests: add a helper to stress test argument quotingLibravatar Garima Singh1-2/+116
On Windows, we have to do all the command-line argument quoting ourselves. Worse: we have to have two versions of said quoting, one for MSYS2 programs (which have their own dequoting rules) and the rest. We care mostly about the rest, and to make sure that that works, let's have a stress test that comes up with all kinds of awkward arguments, verifying that a spawned sub-process receives those unharmed. Signed-off-by: Garima Singh <garima.singh@microsoft.com> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-05Disallow dubiously-nested submodule git directoriesLibravatar Johannes Schindelin4-2/+79
Currently it is technically possible to let a submodule's git directory point right into the git dir of a sibling submodule. Example: the git directories of two submodules with the names `hippo` and `hippo/hooks` would be `.git/modules/hippo/` and `.git/modules/hippo/hooks/`, respectively, but the latter is already intended to house the former's hooks. In most cases, this is just confusing, but there is also a (quite contrived) attack vector where Git can be fooled into mistaking remote content for file contents it wrote itself during a recursive clone. Let's plug this bug. To do so, we introduce the new function `validate_submodule_git_dir()` which simply verifies that no git dir exists for any leading directories of the submodule name (if there are any). Note: this patch specifically continues to allow sibling modules names of the form `core/lib`, `core/doc`, etc, as long as `core` is not a submodule name. This fixes CVE-2019-1387. Reported-by: Nicolas Joly <Nicolas.Joly@microsoft.com> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2019-12-05protect_ntfs: turn on NTFS protection by defaultLibravatar Johannes Schindelin2-3/+1
Back in the DOS days, in the FAT file system, file names always consisted of a base name of length 8 plus a file extension of length 3. Shorter file names were simply padded with spaces to the full 8.3 format. Later, the FAT file system was taught to support _also_ longer names, with an 8.3 "short name" as primary file name. While at it, the same facility allowed formerly illegal file names, such as `.git` (empty base names were not allowed), which would have the "short name" `git~1` associated with it. For backwards-compatibility, NTFS supports alternative 8.3 short filenames, too, even if starting with Windows Vista, they are only generated on the system drive by default. We addressed the problem that the `.git/` directory can _also_ be accessed via `git~1/` (when short names are enabled) in 2b4c6efc821 (read-cache: optionally disallow NTFS .git variants, 2014-12-16), i.e. since Git v1.9.5, by introducing the config setting `core.protectNTFS` and enabling it by default on Windows. In the meantime, Windows 10 introduced the "Windows Subsystem for Linux" (short: WSL), i.e. a way to run Linux applications/distributions in a thinly-isolated subsystem on Windows (giving rise to many a "2016 is the Year of Linux on the Desktop" jokes). WSL is getting increasingly popular, also due to the painless way Linux application can operate directly ("natively") on files on Windows' file system: the Windows drives are mounted automatically (e.g. `C:` as `/mnt/c/`). Taken together, this means that we now have to enable the safe-guards of Git v1.9.5 also in WSL: it is possible to access a `.git` directory inside `/mnt/c/` via the 8.3 name `git~1` (unless short name generation was disabled manually). Since regular Linux distributions run in WSL, this means we have to enable `core.protectNTFS` at least on Linux, too. To enable Services for Macintosh in Windows NT to store so-called resource forks, NTFS introduced "Alternate Data Streams". Essentially, these constitute additional metadata that are connected to (and copied with) their associated files, and they are accessed via pseudo file names of the form `filename:<stream-name>:<stream-type>`. In a recent patch, we extended `core.protectNTFS` to also protect against accesses via NTFS Alternate Data Streams, e.g. to prevent contents of the `.git/` directory to be "tracked" via yet another alternative file name. While it is not possible (at least by default) to access files via NTFS Alternate Data Streams from within WSL, the defaults on macOS when mounting network shares via SMB _do_ allow accessing files and directories in that way. Therefore, we need to enable `core.protectNTFS` on macOS by default, too, and really, on any Operating System that can mount network shares via SMB/CIFS. A couple of approaches were considered for fixing this: 1. We could perform a dynamic NTFS check similar to the `core.symlinks` check in `init`/`clone`: instead of trying to create a symbolic link in the `.git/` directory, we could create a test file and try to access `.git/config` via 8.3 name and/or Alternate Data Stream. 2. We could simply "flip the switch" on `core.protectNTFS`, to make it "on by default". The obvious downside of 1. is that it won't protect worktrees that were clone with a vulnerable Git version already. We considered patching code paths that check out files to check whether we're running on an NTFS system dynamically and persist the result in the repository-local config setting `core.protectNTFS`, but in the end decided that this solution would be too fragile, and too involved. The obvious downside of 2. is that everybody will have to "suffer" the performance penalty incurred from calling `is_ntfs_dotgit()` on every path, even in setups where. After the recent work to accelerate `is_ntfs_dotgit()` in most cases, it looks as if the time spent on validating ten million random file names increases only negligibly (less than 20ms, well within the standard deviation of ~50ms). Therefore the benefits outweigh the cost. Another downside of this is that paths that might have been acceptable previously now will be forbidden. Realistically, though, this is an improvement because public Git hosters already would reject any `git push` that contains such file names. Note: There might be a similar problem mounting HFS+ on Linux. However, this scenario has been considered unlikely and in light of the cost (in the aforementioned benchmark, `core.protectHFS = true` increased the time from ~440ms to ~610ms), it was decided _not_ to touch the default of `core.protectHFS`. This change addresses CVE-2019-1353. Reported-by: Nicolas Joly <Nicolas.Joly@microsoft.com> Helped-by: Garima Singh <garima.singh@microsoft.com> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
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