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ba6a901850
test_dev_cgroup currently loads a small bpf program allowing any access on urandom and zero devices, disabling access to any other device. It makes migrating this test to test_progs impossible, since this one manipulates extensively /dev/null. Allow /dev/null manipulation in dev_cgroup program to make its usage in test_progs framework possible. Update test_dev_cgroup.c as well to match this change while it has not been removed. Reviewed-by: Alan Maguire <alan.maguire@oracle.com> Acked-by: Stanislav Fomichev <sdf@fomichev.me> Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com> Link: https://lore.kernel.org/r/20240731-convert_dev_cgroup-v4-1-849425d90de6@bootlin.com Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
59 lines
1.2 KiB
C
59 lines
1.2 KiB
C
/* Copyright (c) 2017 Facebook
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#include <linux/bpf.h>
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#include <linux/version.h>
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#include <bpf/bpf_helpers.h>
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SEC("cgroup/dev")
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int bpf_prog1(struct bpf_cgroup_dev_ctx *ctx)
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{
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short type = ctx->access_type & 0xFFFF;
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#ifdef DEBUG
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short access = ctx->access_type >> 16;
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char fmt[] = " %d:%d \n";
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switch (type) {
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case BPF_DEVCG_DEV_BLOCK:
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fmt[0] = 'b';
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break;
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case BPF_DEVCG_DEV_CHAR:
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fmt[0] = 'c';
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break;
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default:
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fmt[0] = '?';
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break;
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}
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if (access & BPF_DEVCG_ACC_READ)
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fmt[8] = 'r';
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if (access & BPF_DEVCG_ACC_WRITE)
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fmt[9] = 'w';
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if (access & BPF_DEVCG_ACC_MKNOD)
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fmt[10] = 'm';
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bpf_trace_printk(fmt, sizeof(fmt), ctx->major, ctx->minor);
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#endif
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/* Allow access to /dev/null and /dev/urandom.
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* Forbid everything else.
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*/
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if (ctx->major != 1 || type != BPF_DEVCG_DEV_CHAR)
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return 0;
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switch (ctx->minor) {
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case 3: /* 1:3 /dev/null */
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case 9: /* 1:9 /dev/urandom */
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return 1;
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}
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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