50 lines
2 KiB
Diff
50 lines
2 KiB
Diff
From 4f95ab1f8110a8ab9d7b0e192731ce467f6e5c26 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Janne=20He=C3=9F?= <janne@hess.ooo>
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Date: Sun, 4 Sep 2022 11:15:02 -0600
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Subject: [PATCH] Allow loading token handlers from the default search path
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Since [1] landed in cryptsetup, token handlers (libcryptsetup-token-*.so)
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are loaded from a fixed path defined at compile-time. This is
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problematic with NixOS since it introduces a dependency cycle
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between cryptsetup and systemd.
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This downstream patch [2] allows loading token plugins from the
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default library search path. This approach is not accepted upstream [3]
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due to security concerns, but the potential attack vectors require
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root access and they are sufficiently addressed:
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* cryptsetup could be used as a setuid binary (not used in NixOS).
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In this case, LD_LIBRARY_PATH is ignored because of secure-execution
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mode.
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* cryptsetup running as root could lead to a malicious token handler
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being loaded through LD_LIBRARY_PATH. However, fixing the path
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doesn't prevent the same malicious .so being loaded through LD_PRELOAD.
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[1] https://gitlab.com/cryptsetup/cryptsetup/-/commit/5b9e98f94178d3cd179d9f6e2a0a68c7d9eb6507
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[2] https://github.com/NixOS/nixpkgs/issues/167994#issuecomment-1094249369
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[3] https://gitlab.com/cryptsetup/cryptsetup/-/issues/733
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---
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lib/luks2/luks2_token.c | 4 +---
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1 file changed, 1 insertion(+), 3 deletions(-)
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diff --git a/lib/luks2/luks2_token.c b/lib/luks2/luks2_token.c
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index 26467253..6f8329f0 100644
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--- a/lib/luks2/luks2_token.c
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+++ b/lib/luks2/luks2_token.c
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@@ -151,12 +151,10 @@ crypt_token_load_external(struct crypt_device *cd, const char *name, struct cryp
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token = &ret->u.v2;
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- r = snprintf(buf, sizeof(buf), "%s/libcryptsetup-token-%s.so", crypt_token_external_path(), name);
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+ r = snprintf(buf, sizeof(buf), "libcryptsetup-token-%s.so", name);
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if (r < 0 || (size_t)r >= sizeof(buf))
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return -EINVAL;
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- assert(*buf == '/');
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-
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log_dbg(cd, "Trying to load %s.", buf);
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h = dlopen(buf, RTLD_LAZY);
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--
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2.37.2
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