69 lines
1.7 KiB
C
69 lines
1.7 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2020 Facebook */
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#include "bpf_iter.h"
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#include <bpf/bpf_helpers.h>
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char _license[] SEC("license") = "GPL";
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#define MAX_STACK_TRACE_DEPTH 64
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unsigned long entries[MAX_STACK_TRACE_DEPTH] = {};
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#define SIZE_OF_ULONG (sizeof(unsigned long))
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SEC("iter/task")
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int dump_task_stack(struct bpf_iter__task *ctx)
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{
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struct seq_file *seq = ctx->meta->seq;
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struct task_struct *task = ctx->task;
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long i, retlen;
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if (task == (void *)0)
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return 0;
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retlen = bpf_get_task_stack(task, entries,
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MAX_STACK_TRACE_DEPTH * SIZE_OF_ULONG, 0);
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if (retlen < 0)
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return 0;
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BPF_SEQ_PRINTF(seq, "pid: %8u num_entries: %8u\n", task->pid,
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retlen / SIZE_OF_ULONG);
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for (i = 0; i < MAX_STACK_TRACE_DEPTH; i++) {
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if (retlen > i * SIZE_OF_ULONG)
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BPF_SEQ_PRINTF(seq, "[<0>] %pB\n", (void *)entries[i]);
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}
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BPF_SEQ_PRINTF(seq, "\n");
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return 0;
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}
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int num_user_stacks = 0;
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SEC("iter/task")
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int get_task_user_stacks(struct bpf_iter__task *ctx)
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{
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struct seq_file *seq = ctx->meta->seq;
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struct task_struct *task = ctx->task;
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uint64_t buf_sz = 0;
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int64_t res;
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if (task == (void *)0)
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return 0;
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res = bpf_get_task_stack(task, entries,
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MAX_STACK_TRACE_DEPTH * SIZE_OF_ULONG, BPF_F_USER_STACK);
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if (res <= 0)
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return 0;
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/* Only one task, the current one, should succeed */
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++num_user_stacks;
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buf_sz += res;
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/* If the verifier doesn't refine bpf_get_task_stack res, and instead
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* assumes res is entirely unknown, this program will fail to load as
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* the verifier will believe that max buf_sz value allows reading
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* past the end of entries in bpf_seq_write call
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*/
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bpf_seq_write(seq, &entries, buf_sz);
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return 0;
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}
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