WHC
8efd63bb31
- Child installs a seccomp filter with a listener; a supervisor thread resolves the path of write-type syscalls (cwd, dirfd, .., symlinks, /proc/self, /dev/stdout, both ends of rename/link) and answers CONTINUE or EACCES; IPv4/IPv6 sockets are refused - Probe order Landlock -> seccomp -> none, checked in a throwaway child; CST_SANDBOX=landlock|seccomp|off - curl connect failures count as sandbox refusals - test_sandbox runs the detected sandbox and forced seccomp, with escape, symlink, rename, link, chmod, stdout, ENOENT, background and network cases - Docs: platform matrix, limits (not a security boundary, Yama and background jobs)
72 lines
2.5 KiB
C
72 lines
2.5 KiB
C
#ifndef CST_SANDBOX_H
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#define CST_SANDBOX_H
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/*
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* OS sandbox for run_shell: reads and exec stay allowed everywhere, writes
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* are limited to the workspace, the temp dir, /dev/null and /dev/tty, and
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* the network is cut where the OS can do it.
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* Linux Landlock (network needs ABI 4, kernel 6.7+)
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* Linux seccomp user-notify when Landlock is missing (Android/Termux,
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* older kernels): a supervisor thread checks the path of every
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* write-type syscall and IPv4/IPv6 sockets are refused. Guards
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* against mistakes, not hostile code (the path is checked before
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* the kernel reads it again).
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* macOS sandbox_init (Seatbelt profile)
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* other none: callers fall back to rule-based approval
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*/
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#include "os_compat.h"
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#include <stddef.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef enum {
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CST_SANDBOX_NONE = 0,
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CST_SANDBOX_LANDLOCK,
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CST_SANDBOX_SEATBELT,
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CST_SANDBOX_SECCOMP
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} cst_sandbox_kind_t;
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/* What this process can use; cached. CST_SANDBOX=off|0|none forces NONE,
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* CST_SANDBOX=landlock|seccomp allows only that kind. */
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int cst_sandbox_probe(void);
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/* Drops the cache and probes again (tests that change CST_SANDBOX). */
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int cst_sandbox_reprobe(void);
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/* "landlock" | "seatbelt" | "seccomp" | "none" */
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const char *cst_sandbox_name(int kind);
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/* Landlock ABI version (0 when unavailable); ≥4 also blocks TCP. */
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int cst_sandbox_landlock_abi(void);
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typedef struct {
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int kind;
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int ruleset_fd; /* Landlock, built in the parent */
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char *profile; /* Seatbelt */
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void *sc; /* seccomp: filter program and supervisor thread */
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} cst_sandbox_plan_t;
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/* Parent side: build the policy. Returns 0, or -1 (plan->kind = NONE). */
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int cst_sandbox_prepare(const char *workspace, const char *tmpdir,
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cst_sandbox_plan_t *plan);
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/* Child side, after fork and before exec (os_run_capture_ex hook):
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* async-signal-safe. Returns 0 when confined. */
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int cst_sandbox_enter(void *plan);
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void cst_sandbox_release(cst_sandbox_plan_t *plan);
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/* `sh -c cmd` confined to workspace (+ temp dir). Fails closed: if the
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* policy cannot be applied the command does not run (exit 126). */
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int cst_sandbox_run_shell(const char *workspace, const char *cmd,
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size_t max_out, os_run_result_t *r);
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/* Output of a failed sandboxed run that looks like the sandbox got in the
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* way (EACCES / EPERM / EROFS / blocked network). */
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int cst_sandbox_blocked(const char *out, size_t n, int exit_code);
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#ifdef __cplusplus
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}
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#endif
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#endif
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