77 lines
2.6 KiB
C
77 lines
2.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Augment the filename syscalls with the contents of the filename pointer argument
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* filtering only those that do not start with /etc/.
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*
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* Test it with:
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*
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* perf trace -e tools/perf/examples/bpf/augmented_syscalls.c cat /etc/passwd > /dev/null
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*
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* It'll catch some openat syscalls related to the dynamic linked and
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* the last one should be the one for '/etc/passwd'.
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*
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* This matches what is marshalled into the raw_syscall:sys_enter payload
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* expected by the 'perf trace' beautifiers, and can be used by them unmodified,
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* which will be done as that feature is implemented in the next csets, for now
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* it will appear in a dump done by the default tracepoint handler in 'perf trace',
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* that uses bpf_output__fprintf() to just dump those contents, as done with
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* the bpf-output event associated with the __bpf_output__ map declared in
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* tools/perf/include/bpf/stdio.h.
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*/
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#include <stdio.h>
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/* bpf-output associated map */
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bpf_map(__augmented_syscalls__, PERF_EVENT_ARRAY, int, u32, __NR_CPUS__);
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struct augmented_filename {
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int size;
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int reserved;
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char value[64];
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};
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#define augmented_filename_syscall_enter(syscall) \
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struct augmented_enter_##syscall##_args { \
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struct syscall_enter_##syscall##_args args; \
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struct augmented_filename filename; \
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}; \
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int syscall_enter(syscall)(struct syscall_enter_##syscall##_args *args) \
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{ \
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char etc[6] = "/etc/"; \
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struct augmented_enter_##syscall##_args augmented_args = { .filename.reserved = 0, }; \
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probe_read(&augmented_args.args, sizeof(augmented_args.args), args); \
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augmented_args.filename.size = probe_read_str(&augmented_args.filename.value, \
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sizeof(augmented_args.filename.value), \
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args->filename_ptr); \
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if (__builtin_memcmp(augmented_args.filename.value, etc, 4) != 0) \
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return 0; \
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/* If perf_event_output fails, return non-zero so that it gets recorded unaugmented */ \
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return perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU, \
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&augmented_args, \
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(sizeof(augmented_args) - sizeof(augmented_args.filename.value) + \
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augmented_args.filename.size)); \
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}
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struct syscall_enter_openat_args {
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unsigned long long common_tp_fields;
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long syscall_nr;
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long dfd;
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char *filename_ptr;
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long flags;
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long mode;
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};
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augmented_filename_syscall_enter(openat);
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struct syscall_enter_open_args {
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unsigned long long common_tp_fields;
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long syscall_nr;
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char *filename_ptr;
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long flags;
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long mode;
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};
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augmented_filename_syscall_enter(open);
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license(GPL);
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