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Recent libcap versions (>= 2.60) cause problems with BPF kselftests, so backport an upstream patch that replaces libcap and drops the dependency. Signed-off-by: Tony Ambardar <itugrok@yahoo.com>
124 lines
3.4 KiB
Diff
124 lines
3.4 KiB
Diff
From 5287acc6f097c0c18e54401b611a877a3083b68c Mon Sep 17 00:00:00 2001
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From: Martin KaFai Lau <kafai@fb.com>
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Date: Wed, 16 Mar 2022 10:38:23 -0700
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Subject: [PATCH 1/3] bpf: selftests: Add helpers to directly use the capget
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and capset syscall
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After upgrading to the newer libcap (>= 2.60),
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the libcap commit aca076443591 ("Make cap_t operations thread safe.")
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added a "__u8 mutex;" to the "struct _cap_struct". It caused a few byte
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shift that breaks the assumption made in the "struct libcap" definition
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in test_verifier.c.
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The bpf selftest usage only needs to enable and disable the effective
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caps of the running task. It is easier to directly syscall the
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capget and capset instead. It can also remove the libcap
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library dependency.
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The cap_helpers.{c,h} is added. One __u64 is used for all CAP_*
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bits instead of two __u32.
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Signed-off-by: Martin KaFai Lau <kafai@fb.com>
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Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Acked-by: John Fastabend <john.fastabend@gmail.com>
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Link: https://lore.kernel.org/bpf/20220316173823.2036955-1-kafai@fb.com
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---
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tools/testing/selftests/bpf/cap_helpers.c | 67 +++++++++++++++++++++++
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tools/testing/selftests/bpf/cap_helpers.h | 19 +++++++
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2 files changed, 86 insertions(+)
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create mode 100644 tools/testing/selftests/bpf/cap_helpers.c
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create mode 100644 tools/testing/selftests/bpf/cap_helpers.h
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--- /dev/null
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+++ b/tools/testing/selftests/bpf/cap_helpers.c
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@@ -0,0 +1,67 @@
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+// SPDX-License-Identifier: GPL-2.0
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+#include "cap_helpers.h"
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+
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+/* Avoid including <sys/capability.h> from the libcap-devel package,
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+ * so directly declare them here and use them from glibc.
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+ */
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+int capget(cap_user_header_t header, cap_user_data_t data);
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+int capset(cap_user_header_t header, const cap_user_data_t data);
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+
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+int cap_enable_effective(__u64 caps, __u64 *old_caps)
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+{
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+ struct __user_cap_data_struct data[_LINUX_CAPABILITY_U32S_3];
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+ struct __user_cap_header_struct hdr = {
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+ .version = _LINUX_CAPABILITY_VERSION_3,
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+ };
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+ __u32 cap0 = caps;
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+ __u32 cap1 = caps >> 32;
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+ int err;
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+
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+ err = capget(&hdr, data);
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+ if (err)
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+ return err;
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+
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+ if (old_caps)
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+ *old_caps = (__u64)(data[1].effective) << 32 | data[0].effective;
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+
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+ if ((data[0].effective & cap0) == cap0 &&
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+ (data[1].effective & cap1) == cap1)
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+ return 0;
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+
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+ data[0].effective |= cap0;
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+ data[1].effective |= cap1;
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+ err = capset(&hdr, data);
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+ if (err)
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+ return err;
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+
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+ return 0;
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+}
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+
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+int cap_disable_effective(__u64 caps, __u64 *old_caps)
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+{
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+ struct __user_cap_data_struct data[_LINUX_CAPABILITY_U32S_3];
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+ struct __user_cap_header_struct hdr = {
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+ .version = _LINUX_CAPABILITY_VERSION_3,
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+ };
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+ __u32 cap0 = caps;
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+ __u32 cap1 = caps >> 32;
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+ int err;
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+
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+ err = capget(&hdr, data);
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+ if (err)
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+ return err;
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+
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+ if (old_caps)
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+ *old_caps = (__u64)(data[1].effective) << 32 | data[0].effective;
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+
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+ if (!(data[0].effective & cap0) && !(data[1].effective & cap1))
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+ return 0;
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+
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+ data[0].effective &= ~cap0;
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+ data[1].effective &= ~cap1;
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+ err = capset(&hdr, data);
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+ if (err)
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+ return err;
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+
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+ return 0;
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+}
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--- /dev/null
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+++ b/tools/testing/selftests/bpf/cap_helpers.h
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@@ -0,0 +1,19 @@
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+/* SPDX-License-Identifier: GPL-2.0 */
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+#ifndef __CAP_HELPERS_H
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+#define __CAP_HELPERS_H
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+
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+#include <linux/types.h>
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+#include <linux/capability.h>
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+
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+#ifndef CAP_PERFMON
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+#define CAP_PERFMON 38
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+#endif
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+
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+#ifndef CAP_BPF
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+#define CAP_BPF 39
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+#endif
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+
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+int cap_enable_effective(__u64 caps, __u64 *old_caps);
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+int cap_disable_effective(__u64 caps, __u64 *old_caps);
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+
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+#endif
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