49 lines
1.8 KiB
C
49 lines
1.8 KiB
C
/* SPDX-License-Identifier: GPL-3.0-only */
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/* SPDX-FileCopyrightText: 2026 afiw <afiw@linuxposting.xyz> */
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/*
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* can - query filesystem permissions
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* Copyright (C) 2026 afiw <afiw@linuxposting.xyz>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, exclusively version 3 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#include <err.h>
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#include <grp.h>
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#include <pwd.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include "action.h"
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#include "user.h"
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bool can_user(struct passwd* pw, enum action action, char const* path) {
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gid_t groups_a[1]; /* just to be sure, passing stack memory or nullptr might invoke UB */
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gid_t* groups = groups_a;
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int ngroups = 0;
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struct stat st;
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if (stat(path, &st) == -1) {
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err(EXIT_FAILURE, "%s", path); }
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if (st.st_mode & other_bit_of_action(action)) {
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return true; }
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if (pw->pw_uid == st.st_uid) {
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if (st.st_mode & user_bit_of_action(action)) {
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return true; } }
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(void)getgrouplist(pw->pw_name, pw->pw_gid, groups, &ngroups); /* just to get the value of ngroups */
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groups = malloc(ngroups * sizeof(*groups));
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(void)getgrouplist(pw->pw_name, pw->pw_gid, groups, &ngroups); /* getgrouplist doesn't fail */
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for (int i = 0; i < ngroups; ++i) {
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if (groups[i] == st.st_gid) {
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if (st.st_mode & group_bit_of_action(action)) {
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return true; } } }
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return false; }
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