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115 lines
3.2 KiB
C
115 lines
3.2 KiB
C
/*
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* Setup a sandbox using the Landlock LSM, if available.
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# Copyright (C) 2023 Yves Rutschle
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#
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# This program is free software; you can redistribute it
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# and/or modify it under the terms of the GNU General Public
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# License as published by the Free Software Foundation; either
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# version 2 of the License, or (at your option) any later
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# version.
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#
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# This program is distributed in the hope that it will be
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# useful, but WITHOUT ANY WARRANTY; without even the implied
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# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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# PURPOSE. See the GNU General Public License for more
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# details.
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#
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# The full text for the General Public License is here:
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# http://www.gnu.org/licenses/gpl.html
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#
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*/
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#include "config.h"
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#include "log.h"
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#ifdef HAVE_LANDLOCK
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#define _GNU_SOURCE
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#include <linux/landlock.h>
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#include <sys/prctl.h>
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#include <sys/syscall.h>
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#ifndef landlock_create_ruleset
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static inline int
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landlock_create_ruleset(const struct landlock_ruleset_attr *const attr,
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const size_t size, const __u32 flags)
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{
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return syscall(__NR_landlock_create_ruleset, attr, size, flags);
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}
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#endif
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#ifndef landlock_add_rule
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static inline int landlock_add_rule(const int ruleset_fd,
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const enum landlock_rule_type rule_type,
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const void *const rule_attr,
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const __u32 flags)
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{
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return syscall(__NR_landlock_add_rule, ruleset_fd, rule_type, rule_attr,
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flags);
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}
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#endif
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#ifndef landlock_restrict_self
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static inline int landlock_restrict_self(const int ruleset_fd,
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const __u32 flags)
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{
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return syscall(__NR_landlock_restrict_self, ruleset_fd, flags);
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}
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#endif
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void setup_landlock(void)
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{
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__u64 restrict_rules =
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LANDLOCK_ACCESS_FS_EXECUTE |
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LANDLOCK_ACCESS_FS_READ_FILE |
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LANDLOCK_ACCESS_FS_READ_DIR |
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LANDLOCK_ACCESS_FS_WRITE_FILE |
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LANDLOCK_ACCESS_FS_REMOVE_DIR |
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LANDLOCK_ACCESS_FS_REMOVE_FILE |
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LANDLOCK_ACCESS_FS_MAKE_CHAR |
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LANDLOCK_ACCESS_FS_MAKE_DIR |
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LANDLOCK_ACCESS_FS_MAKE_REG |
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LANDLOCK_ACCESS_FS_MAKE_SOCK |
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LANDLOCK_ACCESS_FS_MAKE_FIFO |
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LANDLOCK_ACCESS_FS_MAKE_BLOCK |
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LANDLOCK_ACCESS_FS_MAKE_SYM |
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LANDLOCK_ACCESS_FS_REFER;
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struct landlock_ruleset_attr ruleset_attr = {
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.handled_access_fs = restrict_rules
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};
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/* ruleset_addr.handled_access_fs contains all rights that will be restricted
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* unless explicitly added */
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int ruleset_fd = landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
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if (ruleset_fd < 0) {
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print_message(msg_config_error, "Landlock: Failed to create a ruleset");
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return;
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}
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/* No call to landlock_add_rule: we retain no rights whatsoever */
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if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
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print_message(msg_config_error, "Landlock: Failed to restrict privileges");
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return;
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}
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if (landlock_restrict_self(ruleset_fd, 0)) {
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print_message(msg_config_error, "Landlock: Failed to enforce ruleset");
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return;
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}
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close(ruleset_fd);
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print_message(msg_config, "Landlock: all restricted\n");
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}
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#else /* HAVE_LANDLOCK */
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void setup_landlock(void)
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{
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print_message(msg_config, "Landlock: not built in\n");
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return;
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}
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#endif /* HAVE_LANDLOCK */
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