mirror of
https://github.com/morgan9e/systemd
synced 2026-04-14 08:25:20 +09:00
24832d10b6
Until now, using any form of seccomp while being unprivileged (User=) resulted in systemd enabling no_new_privs. There's no need for doing this because: * We trust the filters we apply * If User= is set and a process wants to apply a new seccomp filter, it will need to set no_new_privs itself An example of application that might want seccomp + !no_new_privs is a program that wants to run as an unprivileged user but uses file capabilities to start a web server on a privileged port while benefitting from a restrictive seccomp profile. We now keep the privileges needed to do seccomp before calling enforce_user() and drop them after the seccomp filters are applied. If the syscall filter doesn't allow the needed syscalls to drop the privileges, we keep the previous behavior by enabling no_new_privs.
89 lines
3.1 KiB
C
89 lines
3.1 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#pragma once
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#include <stdbool.h>
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#include <stdint.h>
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#include <sys/capability.h>
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#include <sys/types.h>
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#include "macro.h"
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#include "missing_capability.h"
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/* Special marker used when storing a capabilities mask as "unset" */
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#define CAP_MASK_UNSET UINT64_MAX
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/* All possible capabilities bits on */
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#define CAP_MASK_ALL UINT64_C(0x7fffffffffffffff)
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/* The largest capability we can deal with, given we want to be able to store cap masks in uint64_t but still
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* be able to use UINT64_MAX as indicator for "not set". The latter makes capability 63 unavailable. */
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#define CAP_LIMIT 62
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unsigned cap_last_cap(void);
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int have_effective_cap(int value);
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int capability_gain_cap_setpcap(cap_t *return_caps);
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int capability_bounding_set_drop(uint64_t keep, bool right_now);
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int capability_bounding_set_drop_usermode(uint64_t keep);
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int capability_ambient_set_apply(uint64_t set, bool also_inherit);
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int capability_update_inherited_set(cap_t caps, uint64_t ambient_set);
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int drop_privileges(uid_t uid, gid_t gid, uint64_t keep_capabilities);
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int drop_capability(cap_value_t cv);
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int keep_capability(cap_value_t cv);
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DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(cap_t, cap_free, NULL);
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#define _cleanup_cap_free_ _cleanup_(cap_freep)
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static inline void cap_free_charpp(char **p) {
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if (*p)
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cap_free(*p);
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}
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#define _cleanup_cap_free_charp_ _cleanup_(cap_free_charpp)
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static inline uint64_t all_capabilities(void) {
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return UINT64_MAX >> (63 - cap_last_cap());
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}
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static inline bool cap_test_all(uint64_t caps) {
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return FLAGS_SET(caps, all_capabilities());
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}
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bool ambient_capabilities_supported(void);
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/* Identical to linux/capability.h's CAP_TO_MASK(), but uses an unsigned 1U instead of a signed 1 for shifting left, in
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* order to avoid complaints about shifting a signed int left by 31 bits, which would make it negative. */
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#define CAP_TO_MASK_CORRECTED(x) (1U << ((x) & 31U))
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typedef struct CapabilityQuintet {
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/* Stores all five types of capabilities in one go. Note that we use UINT64_MAX for unset here. This hence
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* needs to be updated as soon as Linux learns more than 63 caps. */
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uint64_t effective;
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uint64_t bounding;
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uint64_t inheritable;
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uint64_t permitted;
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uint64_t ambient;
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} CapabilityQuintet;
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assert_cc(CAP_LAST_CAP < 64);
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#define CAPABILITY_QUINTET_NULL { CAP_MASK_UNSET, CAP_MASK_UNSET, CAP_MASK_UNSET, CAP_MASK_UNSET, CAP_MASK_UNSET }
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static inline bool capability_quintet_is_set(const CapabilityQuintet *q) {
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return q->effective != CAP_MASK_UNSET ||
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q->bounding != CAP_MASK_UNSET ||
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q->inheritable != CAP_MASK_UNSET ||
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q->permitted != CAP_MASK_UNSET ||
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q->ambient != CAP_MASK_UNSET;
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}
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/* Mangles the specified caps quintet taking the current bounding set into account:
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* drops all caps from all five sets if our bounding set doesn't allow them.
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* Returns true if the quintet was modified. */
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bool capability_quintet_mangle(CapabilityQuintet *q);
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int capability_quintet_enforce(const CapabilityQuintet *q);
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int capability_get_ambient(uint64_t *ret);
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