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Author SHA1 Message Date
cb95038137 Git 2.30.3
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2022-03-24 00:22:17 +01:00
fdcad5a53e Fix GIT_CEILING_DIRECTORIES with C:\ and the likes
When determining the length of the longest ancestor of a given path with
respect to to e.g. `GIT_CEILING_DIRECTORIES`, we special-case the root
directory by returning 0 (i.e. we pretend that the path `/` does not end
in a slash by virtually stripping it).

That is the correct behavior because when normalizing paths, the root
directory is special: all other directory paths have their trailing
slash stripped, but not the root directory's path (because it would
become the empty string, which is not a legal path).

However, this special-casing of the root directory in
`longest_ancestor_length()` completely forgets about Windows-style root
directories, e.g. `C:\`. These _also_ get normalized with a trailing
slash (because `C:` would actually refer to the current directory on
that drive, not necessarily to its root directory).

In fc56c7b34b (mingw: accomodate t0060-path-utils for MSYS2,
2016-01-27), we almost got it right. We noticed that
`longest_ancestor_length()` expects a slash _after_ the matched prefix,
and if the prefix already ends in a slash, the normalized path won't
ever match and -1 is returned.

But then that commit went astray: The correct fix is not to adjust the
_tests_ to expect an incorrect -1 when that function is fed a prefix
that ends in a slash, but instead to treat such a prefix as if the
trailing slash had been removed.

Likewise, that function needs to handle the case where it is fed a path
that ends in a slash (not only a prefix that ends in a slash): if it
matches the prefix (plus trailing slash), we still need to verify that
the path does not end there, otherwise the prefix is not actually an
ancestor of the path but identical to it (and we need to return -1 in
that case).

With these two adjustments, we no longer need to play games in t0060
where we only add `$rootoff` if the passed prefix is different from the
MSYS2 pseudo root, instead we also add it for the MSYS2 pseudo root
itself. We do have to be careful to skip that logic entirely for Windows
paths, though, because they do are not subject to that MSYS2 pseudo root
treatment.

This patch fixes the scenario where a user has set
`GIT_CEILING_DIRECTORIES=C:\`, which would be ignored otherwise.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2022-03-24 00:21:08 +01:00
8959555cee setup_git_directory(): add an owner check for the top-level directory
It poses a security risk to search for a git directory outside of the
directories owned by the current user.

For example, it is common e.g. in computer pools of educational
institutes to have a "scratch" space: a mounted disk with plenty of
space that is regularly swiped where any authenticated user can create
a directory to do their work. Merely navigating to such a space with a
Git-enabled `PS1` when there is a maliciously-crafted `/scratch/.git/`
can lead to a compromised account.

The same holds true in multi-user setups running Windows, as `C:\` is
writable to every authenticated user by default.

To plug this vulnerability, we stop Git from accepting top-level
directories owned by someone other than the current user. We avoid
looking at the ownership of each and every directories between the
current and the top-level one (if there are any between) to avoid
introducing a performance bottleneck.

This new default behavior is obviously incompatible with the concept of
shared repositories, where we expect the top-level directory to be owned
by only one of its legitimate users. To re-enable that use case, we add
support for adding exceptions from the new default behavior via the
config setting `safe.directory`.

The `safe.directory` config setting is only respected in the system and
global configs, not from repository configs or via the command-line, and
can have multiple values to allow for multiple shared repositories.

We are particularly careful to provide a helpful message to any user
trying to use a shared repository.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2022-03-21 13:16:26 +01:00
bdc77d1d68 Add a function to determine whether a path is owned by the current user
This function will be used in the next commit to prevent
`setup_git_directory()` from discovering a repository in a directory
that is owned by someone other than the current user.

Note: We cannot simply use `st.st_uid` on Windows just like we do on
Linux and other Unix-like platforms: according to
https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/stat-functions
this field is always zero on Windows (because Windows' idea of a user ID
does not fit into a single numerical value). Therefore, we have to do
something a little involved to replicate the same functionality there.

Also note: On Windows, a user's home directory is not actually owned by
said user, but by the administrator. For all practical purposes, it is
under the user's control, though, therefore we pretend that it is owned
by the user.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2022-03-21 13:16:26 +01:00
2a9a5862e5 Merge branch 'cb/mingw-gmtime-r'
Build fix on Windows.

* cb/mingw-gmtime-r:
  mingw: avoid fallback for {local,gm}time_r()

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2022-03-17 12:52:12 +01:00
6e7ad1e4c2 mingw: avoid fallback for {local,gm}time_r()
mingw-w64's pthread_unistd.h had a bug that mistakenly (because there is
no support for the *lockfile() functions required[1]) defined
_POSIX_THREAD_SAFE_FUNCTIONS and that was being worked around since
3ecd153a3b (compat/mingw: support MSys2-based MinGW build, 2016-01-14).

The bug was fixed in winphtreads, but as a side effect, leaves the
reentrant functions from time.h no longer visible and therefore breaks
the build.

Since the intention all along was to avoid using the fallback functions,
formalize the use of POSIX by setting the corresponding feature flag and
compile out the implementation for the fallback functions.

[1] https://unix.org/whitepapers/reentrant.html

Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Acked-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-03-17 12:52:12 +01:00
11 changed files with 239 additions and 15 deletions

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@ -0,0 +1,24 @@
Git v2.30.2 Release Notes
=========================
This release addresses the security issue CVE-2022-24765.
Fixes since v2.30.2
-------------------
* Build fix on Windows.
* Fix `GIT_CEILING_DIRECTORIES` with Windows-style root directories.
* CVE-2022-24765:
On multi-user machines, Git users might find themselves
unexpectedly in a Git worktree, e.g. when another user created a
repository in `C:\.git`, in a mounted network drive or in a
scratch space. Merely having a Git-aware prompt that runs `git
status` (or `git diff`) and navigating to a directory which is
supposedly not a Git worktree, or opening such a directory in an
editor or IDE such as VS Code or Atom, will potentially run
commands defined by that other user.
Credit for finding this vulnerability goes to 俞晨东; The fix was
authored by Johannes Schindelin.

View File

@ -438,6 +438,8 @@ include::config/rerere.txt[]
include::config/reset.txt[]
include::config/safe.txt[]
include::config/sendemail.txt[]
include::config/sequencer.txt[]

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@ -0,0 +1,21 @@
safe.directory::
These config entries specify Git-tracked directories that are
considered safe even if they are owned by someone other than the
current user. By default, Git will refuse to even parse a Git
config of a repository owned by someone else, let alone run its
hooks, and this config setting allows users to specify exceptions,
e.g. for intentionally shared repositories (see the `--shared`
option in linkgit:git-init[1]).
+
This is a multi-valued setting, i.e. you can add more than one directory
via `git config --add`. To reset the list of safe directories (e.g. to
override any such directories specified in the system config), add a
`safe.directory` entry with an empty value.
+
This config setting is only respected when specified in a system or global
config, not when it is specified in a repository config or via the command
line option `-c safe.directory=<path>`.
+
The value of this setting is interpolated, i.e. `~/<path>` expands to a
path relative to the home directory and `%(prefix)/<path>` expands to a
path relative to Git's (runtime) prefix.

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@ -1,7 +1,7 @@
#!/bin/sh
GVF=GIT-VERSION-FILE
DEF_VER=v2.30.2
DEF_VER=v2.30.3
LF='
'

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@ -1 +1 @@
Documentation/RelNotes/2.30.2.txt
Documentation/RelNotes/2.30.3.txt

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@ -1,5 +1,6 @@
#include "../git-compat-util.h"
#include "win32.h"
#include <aclapi.h>
#include <conio.h>
#include <wchar.h>
#include "../strbuf.h"
@ -1060,6 +1061,7 @@ int pipe(int filedes[2])
return 0;
}
#ifndef __MINGW64__
struct tm *gmtime_r(const time_t *timep, struct tm *result)
{
if (gmtime_s(result, timep) == 0)
@ -1073,6 +1075,7 @@ struct tm *localtime_r(const time_t *timep, struct tm *result)
return result;
return NULL;
}
#endif
char *mingw_getcwd(char *pointer, int len)
{
@ -2599,6 +2602,92 @@ static void setup_windows_environment(void)
}
}
static PSID get_current_user_sid(void)
{
HANDLE token;
DWORD len = 0;
PSID result = NULL;
if (!OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, &token))
return NULL;
if (!GetTokenInformation(token, TokenUser, NULL, 0, &len)) {
TOKEN_USER *info = xmalloc((size_t)len);
if (GetTokenInformation(token, TokenUser, info, len, &len)) {
len = GetLengthSid(info->User.Sid);
result = xmalloc(len);
if (!CopySid(len, result, info->User.Sid)) {
error(_("failed to copy SID (%ld)"),
GetLastError());
FREE_AND_NULL(result);
}
}
FREE_AND_NULL(info);
}
CloseHandle(token);
return result;
}
int is_path_owned_by_current_sid(const char *path)
{
WCHAR wpath[MAX_PATH];
PSID sid = NULL;
PSECURITY_DESCRIPTOR descriptor = NULL;
DWORD err;
static wchar_t home[MAX_PATH];
int result = 0;
if (xutftowcs_path(wpath, path) < 0)
return 0;
/*
* On Windows, the home directory is owned by the administrator, but for
* all practical purposes, it belongs to the user. Do pretend that it is
* owned by the user.
*/
if (!*home) {
DWORD size = ARRAY_SIZE(home);
DWORD len = GetEnvironmentVariableW(L"HOME", home, size);
if (!len || len > size)
wcscpy(home, L"::N/A::");
}
if (!wcsicmp(wpath, home))
return 1;
/* Get the owner SID */
err = GetNamedSecurityInfoW(wpath, SE_FILE_OBJECT,
OWNER_SECURITY_INFORMATION |
DACL_SECURITY_INFORMATION,
&sid, NULL, NULL, NULL, &descriptor);
if (err != ERROR_SUCCESS)
error(_("failed to get owner for '%s' (%ld)"), path, err);
else if (sid && IsValidSid(sid)) {
/* Now, verify that the SID matches the current user's */
static PSID current_user_sid;
if (!current_user_sid)
current_user_sid = get_current_user_sid();
if (current_user_sid &&
IsValidSid(current_user_sid) &&
EqualSid(sid, current_user_sid))
result = 1;
}
/*
* We can release the security descriptor struct only now because `sid`
* actually points into this struct.
*/
if (descriptor)
LocalFree(descriptor);
return result;
}
int is_valid_win32_path(const char *path, int allow_literal_nul)
{
const char *p = path;

View File

@ -452,6 +452,13 @@ char *mingw_query_user_email(void);
#include <inttypes.h>
#endif
/**
* Verifies that the specified path is owned by the user running the
* current process.
*/
int is_path_owned_by_current_sid(const char *path);
#define is_path_owned_by_current_user is_path_owned_by_current_sid
/**
* Verifies that the given path is a valid one on Windows.
*

View File

@ -127,7 +127,9 @@
/* Approximation of the length of the decimal representation of this type. */
#define decimal_length(x) ((int)(sizeof(x) * 2.56 + 0.5) + 1)
#if defined(__sun__)
#ifdef __MINGW64__
#define _POSIX_C_SOURCE 1
#elif defined(__sun__)
/*
* On Solaris, when _XOPEN_EXTENDED is set, its header file
* forces the programs to be XPG4v2, defeating any _XOPEN_SOURCE
@ -390,6 +392,18 @@ static inline int git_offset_1st_component(const char *path)
#define is_valid_path(path) 1
#endif
#ifndef is_path_owned_by_current_user
static inline int is_path_owned_by_current_uid(const char *path)
{
struct stat st;
if (lstat(path, &st))
return 0;
return st.st_uid == geteuid();
}
#define is_path_owned_by_current_user is_path_owned_by_current_uid
#endif
#ifndef find_last_dir_sep
static inline char *git_find_last_dir_sep(const char *path)
{

14
path.c
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@ -1218,11 +1218,15 @@ int longest_ancestor_length(const char *path, struct string_list *prefixes)
const char *ceil = prefixes->items[i].string;
int len = strlen(ceil);
if (len == 1 && ceil[0] == '/')
len = 0; /* root matches anything, with length 0 */
else if (!strncmp(path, ceil, len) && path[len] == '/')
; /* match of length len */
else
/*
* For root directories (`/`, `C:/`, `//server/share/`)
* adjust the length to exclude the trailing slash.
*/
if (len > 0 && ceil[len - 1] == '/')
len--;
if (strncmp(path, ceil, len) ||
path[len] != '/' || !path[len + 1])
continue; /* no match */
if (len > max_len)

57
setup.c
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@ -5,6 +5,7 @@
#include "string-list.h"
#include "chdir-notify.h"
#include "promisor-remote.h"
#include "quote.h"
static int inside_git_dir = -1;
static int inside_work_tree = -1;
@ -1024,6 +1025,42 @@ static int canonicalize_ceiling_entry(struct string_list_item *item,
}
}
struct safe_directory_data {
const char *path;
int is_safe;
};
static int safe_directory_cb(const char *key, const char *value, void *d)
{
struct safe_directory_data *data = d;
if (!value || !*value)
data->is_safe = 0;
else {
const char *interpolated = NULL;
if (!git_config_pathname(&interpolated, key, value) &&
!fspathcmp(data->path, interpolated ? interpolated : value))
data->is_safe = 1;
free((char *)interpolated);
}
return 0;
}
static int ensure_valid_ownership(const char *path)
{
struct safe_directory_data data = { .path = path };
if (is_path_owned_by_current_user(path))
return 1;
read_very_early_config(safe_directory_cb, &data);
return data.is_safe;
}
enum discovery_result {
GIT_DIR_NONE = 0,
GIT_DIR_EXPLICIT,
@ -1032,7 +1069,8 @@ enum discovery_result {
/* these are errors */
GIT_DIR_HIT_CEILING = -1,
GIT_DIR_HIT_MOUNT_POINT = -2,
GIT_DIR_INVALID_GITFILE = -3
GIT_DIR_INVALID_GITFILE = -3,
GIT_DIR_INVALID_OWNERSHIP = -4
};
/*
@ -1122,11 +1160,15 @@ static enum discovery_result setup_git_directory_gently_1(struct strbuf *dir,
}
strbuf_setlen(dir, offset);
if (gitdirenv) {
if (!ensure_valid_ownership(dir->buf))
return GIT_DIR_INVALID_OWNERSHIP;
strbuf_addstr(gitdir, gitdirenv);
return GIT_DIR_DISCOVERED;
}
if (is_git_directory(dir->buf)) {
if (!ensure_valid_ownership(dir->buf))
return GIT_DIR_INVALID_OWNERSHIP;
strbuf_addstr(gitdir, ".");
return GIT_DIR_BARE;
}
@ -1253,6 +1295,19 @@ const char *setup_git_directory_gently(int *nongit_ok)
dir.buf);
*nongit_ok = 1;
break;
case GIT_DIR_INVALID_OWNERSHIP:
if (!nongit_ok) {
struct strbuf quoted = STRBUF_INIT;
sq_quote_buf_pretty(&quoted, dir.buf);
die(_("unsafe repository ('%s' is owned by someone else)\n"
"To add an exception for this directory, call:\n"
"\n"
"\tgit config --global --add safe.directory %s"),
dir.buf, quoted.buf);
}
*nongit_ok = 1;
break;
case GIT_DIR_NONE:
/*
* As a safeguard against setup_git_directory_gently_1 returning

View File

@ -55,12 +55,15 @@ fi
ancestor() {
# We do some math with the expected ancestor length.
expected=$3
if test -n "$rootoff" && test "x$expected" != x-1; then
expected=$(($expected-$rootslash))
test $expected -lt 0 ||
expected=$(($expected+$rootoff))
fi
test_expect_success "longest ancestor: $1 $2 => $expected" \
case "$rootoff,$expected,$2" in
*,*,//*) ;; # leave UNC paths alone
[0-9]*,[0-9]*,/*)
# On Windows, expect MSYS2 pseudo root translation for
# Unix-style absolute paths
expected=$(($expected-$rootslash+$rootoff))
;;
esac
test_expect_success $4 "longest ancestor: $1 $2 => $expected" \
"actual=\$(test-tool path-utils longest_ancestor_length '$1' '$2') &&
test \"\$actual\" = '$expected'"
}
@ -156,6 +159,11 @@ ancestor /foo/bar /foo 4
ancestor /foo/bar /foo:/bar 4
ancestor /foo/bar /bar -1
# Windows-specific: DOS drives, network shares
ancestor C:/Users/me C:/ 2 MINGW
ancestor D:/Users/me C:/ -1 MINGW
ancestor //server/share/my-directory //server/share/ 14 MINGW
test_expect_success 'strip_path_suffix' '
test c:/msysgit = $(test-tool path-utils strip_path_suffix \
c:/msysgit/libexec//git-core libexec/git-core)