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98254a7c1f
This change reconciles our pledge() implementation with the OpenBSD
kernel source code. We now a polyfill that's much closer to OpenBSD's
behavior. For example, it was discovered that "stdio" permits threads.
There were a bunch of Linux system calls that needed to be added, like
sched_yield(). The exec / execnative category division is now dropped.
We're instead using OpenBSD's "prot_exec" promise for launching APE
binaries and dynamic shared objects. We also now filter clone() flags.
The pledge.com command has been greatly improved. It now does unveiling
by default when Landlock is available. It's now smart enough to unveil a
superset of paths that OpenBSD automatically unveils with pledge(), such
as /etc/localtime. pledge.com also now checks if the executable being
launched is a dynamic shared object, in which case it unveils libraries.
These changes now make it possible to pledge curl on ubuntu 20.04 glibc:
pledge.com -p 'stdio rpath prot_exec inet dns tty sendfd recvfd' \
curl -s https://justine.lol/hello.txt
Here's what pledging curl on Alpine 3.16 with Musl Libc looks like:
pledge.com -p 'stdio rpath prot_exec dns inet' \
curl -s https://justine.lol/hello.txt
Here's what pledging curl.com w/ ape loader looks like:
pledge.com -p 'stdio rpath prot_exec dns inet' \
o//examples/curl.com https://justine.lol/hello.txt
The most secure sandbox, is curl.com converted to static ELF:
o//tool/build/assimilate.com o//examples/curl.com
pledge.com -p 'stdio rpath dns inet' \
o//examples/curl.com https://justine.lol/hello.txt
A weird corner case needed to be handled when resolving symbolic links
during the unveiling process, that's arguably a Landlock bug. It's not
surprising since Musl and Glibc are also inconsistent here too.
48 lines
3.1 KiB
C
48 lines
3.1 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2022 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/calls/landlock.h"
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#include "libc/calls/strace.internal.h"
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int sys_landlock_add_rule(int, enum landlock_rule_type, const void *, uint32_t);
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/**
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* Adds new rule to Landlock ruleset.
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*
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* @error ENOSYS if Landlock isn't supported
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* @error EPERM if Landlock supported but SECCOMP BPF shut it down
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* @error EOPNOTSUPP if Landlock supported but disabled at boot time
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* @error EINVAL if flags not 0, or inconsistent access in the rule,
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* i.e. landlock_path_beneath_attr::allowed_access is not a subset
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* of the ruleset handled accesses
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* @error ENOMSG empty allowed_access
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* @error EBADF `fd` is not a file descriptor for current thread, or
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* member of `rule_attr` is not a file descriptor as expected
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* @error EBADFD `fd` is not a ruleset file descriptor, or a member
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* of `rule_attr` is not the expected file descriptor type
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* @error EPERM `fd` has no write access to the underlying ruleset
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* @error EFAULT `rule_attr` inconsistency
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*/
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int landlock_add_rule(int fd, enum landlock_rule_type rule_type,
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const void *rule_attr, uint32_t flags) {
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int rc;
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rc = sys_landlock_add_rule(fd, rule_type, rule_attr, flags);
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KERNTRACE("landlock_add_rule(%d, %d, %p, %#x) → %d% m", fd, rule_type,
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rule_attr, flags, rc);
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return rc;
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}
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