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