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fs: refactor file ownership checks
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Refactor the file ownership checks so that callers can provide discrete
information about the ownership expectations to a single function.
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@ethomson
ethomson committed Jul 7, 2022
1 parent df354ec commit 433f016
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Showing 3 changed files with 53 additions and 103 deletions.
5 changes: 4 additions & 1 deletion src/libgit2/config.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1170,10 +1170,13 @@ int git_config_find_programdata(git_buf *path)

int git_config__find_programdata(git_str *path)
{
git_fs_path_owner_t owner_level =
GIT_FS_PATH_OWNER_CURRENT_USER |
GIT_FS_PATH_OWNER_ADMINISTRATOR;
bool is_safe;

if (git_sysdir_find_programdata_file(path, GIT_CONFIG_FILENAME_PROGRAMDATA) < 0 ||
git_fs_path_owner_is_system_or_current_user(&is_safe, path->ptr) < 0)
git_fs_path_owner_is(&is_safe, path->ptr, owner_level) < 0)
return -1;

if (!is_safe) {
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130 changes: 42 additions & 88 deletions src/util/fs_path.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1879,74 +1879,41 @@ static int file_owner_sid(PSID *out, const char *path)
return error;
}

int git_fs_path_owner_is_current_user(bool *out, const char *path)
int git_fs_path_owner_is(
bool *out,
const char *path,
git_fs_path_owner_t owner_type)
{
PSID owner_sid = NULL, user_sid = NULL;
int error = -1;
int error;

if (mock_owner) {
*out = (mock_owner == GIT_FS_PATH_OWNER_CURRENT_USER);
*out = ((mock_owner & owner_type) != 0);
return 0;
}

if ((error = file_owner_sid(&owner_sid, path)) < 0 ||
(error = current_user_sid(&user_sid)) < 0)
if ((error = file_owner_sid(&owner_sid, path)) < 0)
goto done;

*out = EqualSid(owner_sid, user_sid);
error = 0;

done:
git__free(owner_sid);
git__free(user_sid);
return error;
}

int git_fs_path_owner_is_system(bool *out, const char *path)
{
PSID owner_sid;

if (mock_owner) {
*out = (mock_owner == GIT_FS_PATH_OWNER_ADMINISTRATOR);
return 0;
}
if ((owner_type & GIT_FS_PATH_OWNER_CURRENT_USER) != 0) {
if ((error = current_user_sid(&user_sid)) < 0)
goto done;

if (file_owner_sid(&owner_sid, path) < 0)
return -1;

*out = IsWellKnownSid(owner_sid, WinBuiltinAdministratorsSid) ||
IsWellKnownSid(owner_sid, WinLocalSystemSid);

git__free(owner_sid);
return 0;
}

int git_fs_path_owner_is_system_or_current_user(bool *out, const char *path)
{
PSID owner_sid = NULL, user_sid = NULL;
int error = -1;

if (mock_owner) {
*out = (mock_owner == GIT_FS_PATH_OWNER_ADMINISTRATOR ||
mock_owner == GIT_FS_PATH_OWNER_CURRENT_USER);
return 0;
if (EqualSid(owner_sid, user_sid)) {
*out = true;
goto done;
}
}

if (file_owner_sid(&owner_sid, path) < 0)
goto done;

if (IsWellKnownSid(owner_sid, WinBuiltinAdministratorsSid) ||
IsWellKnownSid(owner_sid, WinLocalSystemSid)) {
*out = 1;
error = 0;
goto done;
if ((owner_type & GIT_FS_PATH_OWNER_ADMINISTRATOR) != 0) {
if (IsWellKnownSid(owner_sid, WinBuiltinAdministratorsSid) ||
IsWellKnownSid(owner_sid, WinLocalSystemSid)) {
*out = true;
goto done;
}
}

if (current_user_sid(&user_sid) < 0)
goto done;

*out = EqualSid(owner_sid, user_sid);
error = 0;
*out = false;

done:
git__free(owner_sid);
Expand All @@ -1956,10 +1923,25 @@ int git_fs_path_owner_is_system_or_current_user(bool *out, const char *path)

#else

static int fs_path_owner_is(bool *out, const char *path, uid_t *uids, size_t uids_len)
int git_fs_path_owner_is(
bool *out,
const char *path,
git_fs_path_owner_t owner_type)
{
uid_t uids[2] = { 0 };
size_t uid_count = 0, i;
struct stat st;
size_t i;

if (mock_owner) {
*out = ((mock_owner & owner_type) != 0);
return 0;
}

if (owner_type & GIT_FS_PATH_OWNER_CURRENT_USER)
uids[uid_count++] = geteuid();

if (owner_type & GIT_FS_PATH_OWNER_ADMINISTRATOR)
uids[uid_count++] = 0;

*out = false;

Expand All @@ -1971,7 +1953,7 @@ static int fs_path_owner_is(bool *out, const char *path, uid_t *uids, size_t uid
return -1;
}

for (i = 0; i < uids_len; i++) {
for (i = 0; i < uid_count; i++) {
if (uids[i] == st.st_uid) {
*out = true;
break;
Expand All @@ -1980,46 +1962,18 @@ static int fs_path_owner_is(bool *out, const char *path, uid_t *uids, size_t uid

return 0;
}
#endif

int git_fs_path_owner_is_current_user(bool *out, const char *path)
{
uid_t userid = geteuid();

if (mock_owner) {
*out = (mock_owner == GIT_FS_PATH_OWNER_CURRENT_USER);
return 0;
}

return fs_path_owner_is(out, path, &userid, 1);
return git_fs_path_owner_is(out, path, GIT_FS_PATH_OWNER_CURRENT_USER);
}

int git_fs_path_owner_is_system(bool *out, const char *path)
{
uid_t userid = 0;

if (mock_owner) {
*out = (mock_owner == GIT_FS_PATH_OWNER_ADMINISTRATOR);
return 0;
}

return fs_path_owner_is(out, path, &userid, 1);
return git_fs_path_owner_is(out, path, GIT_FS_PATH_OWNER_ADMINISTRATOR);
}

int git_fs_path_owner_is_system_or_current_user(bool *out, const char *path)
{
uid_t userids[2] = { geteuid(), 0 };

if (mock_owner) {
*out = (mock_owner == GIT_FS_PATH_OWNER_ADMINISTRATOR ||
mock_owner == GIT_FS_PATH_OWNER_CURRENT_USER);
return 0;
}

return fs_path_owner_is(out, path, userids, 2);
}

#endif

int git_fs_path_find_executable(git_str *fullpath, const char *executable)
{
#ifdef GIT_WIN32
Expand Down
21 changes: 7 additions & 14 deletions src/util/fs_path.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -740,15 +740,8 @@ typedef enum {
/** The file must be owned by the system account. */
GIT_FS_PATH_OWNER_ADMINISTRATOR = (1 << 1),

/**
* The file may be owned by a system account if the current
* user is in an administrator group. Windows only; this is
* a noop on non-Windows systems.
*/
GIT_FS_PATH_OWNER_CURRENT_USER_IS_ADMINISTRATOR = (1 << 2),

/** The file may be owned by another user. */
GIT_FS_PATH_OWNER_OTHER = (1 << 4)
GIT_FS_PATH_OWNER_OTHER = (1 << 2)
} git_fs_path_owner_t;

/**
Expand All @@ -758,6 +751,12 @@ typedef enum {
*/
void git_fs_path__set_owner(git_fs_path_owner_t owner);

/** Verify that the file in question is owned by the given owner. */
int git_fs_path_owner_is(
bool *out,
const char *path,
git_fs_path_owner_t owner_type);

/**
* Verify that the file in question is owned by an administrator or system
* account.
Expand All @@ -770,12 +769,6 @@ int git_fs_path_owner_is_system(bool *out, const char *path);

int git_fs_path_owner_is_current_user(bool *out, const char *path);

/**
* Verify that the file in question is owned by an administrator or system
* account _or_ the current user;
*/
int git_fs_path_owner_is_system_or_current_user(bool *out, const char *path);

/**
* Search the current PATH for the given executable, returning the full
* path if it is found.
Expand Down

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