d5810139cc
The LSM hook userns_create was introduced to provide LSM's an
opportunity to block or allow unprivileged user namespace creation. This
test serves two purposes: it provides a test eBPF implementation, and
tests the hook successfully blocks or allows user namespace creation.
This tests 3 cases:
1. Unattached bpf program does not block unpriv user namespace
creation.
2. Attached bpf program allows user namespace creation given
CAP_SYS_ADMIN privileges.
3. Attached bpf program denies user namespace creation for a
user without CAP_SYS_ADMIN.
Acked-by: KP Singh <kpsingh@kernel.org>
Signed-off-by: Frederick Lawler <fred@cloudflare.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
34 lines
763 B
C
34 lines
763 B
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/bpf.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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#include <errno.h>
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#include <linux/capability.h>
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struct kernel_cap_struct {
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__u32 cap[_LINUX_CAPABILITY_U32S_3];
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} __attribute__((preserve_access_index));
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struct cred {
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struct kernel_cap_struct cap_effective;
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} __attribute__((preserve_access_index));
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char _license[] SEC("license") = "GPL";
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SEC("lsm.s/userns_create")
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int BPF_PROG(test_userns_create, const struct cred *cred, int ret)
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{
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struct kernel_cap_struct caps = cred->cap_effective;
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int cap_index = CAP_TO_INDEX(CAP_SYS_ADMIN);
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__u32 cap_mask = CAP_TO_MASK(CAP_SYS_ADMIN);
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if (ret)
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return 0;
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ret = -EPERM;
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if (caps.cap[cap_index] & cap_mask)
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return 0;
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return -EPERM;
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}
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