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xz: Support Landlock ABI version 4.

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Linux 6.7 added support for ABI version 4 which restricts
TCP connections which xz won't need and thus those can be
forbidden now. Since the ABI version is handled at runtime,
supporting version 4 won't cause any compatibility issues.

Note that new enough kernel headers are required to get
version 4 support enabled at build time.
This commit is contained in:
Lasse Collin 2024-02-17 23:07:35 +02:00
parent 374868d81d
commit 02e3505991
1 changed files with 20 additions and 5 deletions
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25
src/xz/sandbox.c
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@ -107,8 +107,18 @@ sandbox_enable_strict_if_allowed(int src_fd lzma_attribute((__unused__)),
#include <sys/prctl.h>
// Highest Landlock ABI version supported by this file
#define LANDLOCK_ABI_MAX 3
// Highest Landlock ABI version supported by this file:
// - For ABI versions 1-3 we don't need anything from <linux/landlock.h>
// that isn't part of version 1.
// - For ABI version 4 we need the larger struct landlock_ruleset_attr
// with the handled_access_net member. That is bundled with the macros
// LANDLOCK_ACCESS_NET_BIND_TCP and LANDLOCK_ACCESS_NET_CONNECT_TCP.
#ifdef LANDLOCK_ACCESS_NET_BIND_TCP
# define LANDLOCK_ABI_MAX 4
#else
# define LANDLOCK_ABI_MAX 3
#endif
/// Landlock ABI version supported by the kernel
static int landlock_abi;
@ -142,10 +152,15 @@ enable_landlock(uint64_t required_rights)
//
// This makes it simple to set the mask based on the ABI
// version and we don't need to care which flags are #defined
// in the installed <linux/landlock.h>.
// in the installed <linux/landlock.h> for ABI versions 1-3.
const struct landlock_ruleset_attr attr = {
.handled_access_fs = ((1ULL << (12 + landlock_abi)) - 1)
& ~required_rights,
.handled_access_fs = ~required_rights
& ((1ULL << (12 + my_min(3, landlock_abi))) - 1),
#if LANDLOCK_ABI_MAX >= 4
.handled_access_net = landlock_abi < 4 ? 0 :
(LANDLOCK_ACCESS_NET_BIND_TCP
| LANDLOCK_ACCESS_NET_CONNECT_TCP),
#endif
};
const int ruleset_fd = syscall(SYS_landlock_create_ruleset,