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Diffstat (limited to '')
-rw-r--r-- | tools/perf/examples/bpf/augmented_raw_syscalls.c | 294 |
1 files changed, 294 insertions, 0 deletions
diff --git a/tools/perf/examples/bpf/augmented_raw_syscalls.c b/tools/perf/examples/bpf/augmented_raw_syscalls.c new file mode 100644 index 000000000..b80437971 --- /dev/null +++ b/tools/perf/examples/bpf/augmented_raw_syscalls.c @@ -0,0 +1,294 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Augment the raw_syscalls tracepoints with the contents of the pointer arguments. + * + * Test it with: + * + * perf trace -e tools/perf/examples/bpf/augmented_raw_syscalls.c cat /etc/passwd > /dev/null + * + * This exactly matches what is marshalled into the raw_syscall:sys_enter + * payload expected by the 'perf trace' beautifiers. + * + * For now it just uses the existing tracepoint augmentation code in 'perf + * trace', in the next csets we'll hook up these with the sys_enter/sys_exit + * code that will combine entry/exit in a strace like way. + */ + +#include <unistd.h> +#include <linux/limits.h> +#include <linux/socket.h> +#include <pid_filter.h> + +/* bpf-output associated map */ +bpf_map(__augmented_syscalls__, PERF_EVENT_ARRAY, int, u32, __NR_CPUS__); + +/* + * string_args_len: one per syscall arg, 0 means not a string or don't copy it, + * PATH_MAX for copying everything, any other value to limit + * it a la 'strace -s strsize'. + */ +struct syscall { + bool enabled; + u16 string_args_len[6]; +}; + +bpf_map(syscalls, ARRAY, int, struct syscall, 512); + +/* + * What to augment at entry? + * + * Pointer arg payloads (filenames, etc) passed from userspace to the kernel + */ +bpf_map(syscalls_sys_enter, PROG_ARRAY, u32, u32, 512); + +/* + * What to augment at exit? + * + * Pointer arg payloads returned from the kernel (struct stat, etc) to userspace. + */ +bpf_map(syscalls_sys_exit, PROG_ARRAY, u32, u32, 512); + +struct syscall_enter_args { + unsigned long long common_tp_fields; + long syscall_nr; + unsigned long args[6]; +}; + +struct syscall_exit_args { + unsigned long long common_tp_fields; + long syscall_nr; + long ret; +}; + +struct augmented_arg { + unsigned int size; + int err; + char value[PATH_MAX]; +}; + +pid_filter(pids_filtered); + +struct augmented_args_payload { + struct syscall_enter_args args; + union { + struct { + struct augmented_arg arg, arg2; + }; + struct sockaddr_storage saddr; + }; +}; + +// We need more tmp space than the BPF stack can give us +bpf_map(augmented_args_tmp, PERCPU_ARRAY, int, struct augmented_args_payload, 1); + +static inline struct augmented_args_payload *augmented_args_payload(void) +{ + int key = 0; + return bpf_map_lookup_elem(&augmented_args_tmp, &key); +} + +static inline int augmented__output(void *ctx, struct augmented_args_payload *args, int len) +{ + /* If perf_event_output fails, return non-zero so that it gets recorded unaugmented */ + return perf_event_output(ctx, &__augmented_syscalls__, BPF_F_CURRENT_CPU, args, len); +} + +static inline +unsigned int augmented_arg__read_str(struct augmented_arg *augmented_arg, const void *arg, unsigned int arg_len) +{ + unsigned int augmented_len = sizeof(*augmented_arg); + int string_len = probe_read_str(&augmented_arg->value, arg_len, arg); + + augmented_arg->size = augmented_arg->err = 0; + /* + * probe_read_str may return < 0, e.g. -EFAULT + * So we leave that in the augmented_arg->size that userspace will + */ + if (string_len > 0) { + augmented_len -= sizeof(augmented_arg->value) - string_len; + augmented_len &= sizeof(augmented_arg->value) - 1; + augmented_arg->size = string_len; + } else { + /* + * So that username notice the error while still being able + * to skip this augmented arg record + */ + augmented_arg->err = string_len; + augmented_len = offsetof(struct augmented_arg, value); + } + + return augmented_len; +} + +SEC("!raw_syscalls:unaugmented") +int syscall_unaugmented(struct syscall_enter_args *args) +{ + return 1; +} + +/* + * These will be tail_called from SEC("raw_syscalls:sys_enter"), so will find in + * augmented_args_tmp what was read by that raw_syscalls:sys_enter and go + * on from there, reading the first syscall arg as a string, i.e. open's + * filename. + */ +SEC("!syscalls:sys_enter_connect") +int sys_enter_connect(struct syscall_enter_args *args) +{ + struct augmented_args_payload *augmented_args = augmented_args_payload(); + const void *sockaddr_arg = (const void *)args->args[1]; + unsigned int socklen = args->args[2]; + unsigned int len = sizeof(augmented_args->args); + + if (augmented_args == NULL) + return 1; /* Failure: don't filter */ + + if (socklen > sizeof(augmented_args->saddr)) + socklen = sizeof(augmented_args->saddr); + + probe_read(&augmented_args->saddr, socklen, sockaddr_arg); + + return augmented__output(args, augmented_args, len + socklen); +} + +SEC("!syscalls:sys_enter_sendto") +int sys_enter_sendto(struct syscall_enter_args *args) +{ + struct augmented_args_payload *augmented_args = augmented_args_payload(); + const void *sockaddr_arg = (const void *)args->args[4]; + unsigned int socklen = args->args[5]; + unsigned int len = sizeof(augmented_args->args); + + if (augmented_args == NULL) + return 1; /* Failure: don't filter */ + + if (socklen > sizeof(augmented_args->saddr)) + socklen = sizeof(augmented_args->saddr); + + probe_read(&augmented_args->saddr, socklen, sockaddr_arg); + + return augmented__output(args, augmented_args, len + socklen); +} + +SEC("!syscalls:sys_enter_open") +int sys_enter_open(struct syscall_enter_args *args) +{ + struct augmented_args_payload *augmented_args = augmented_args_payload(); + const void *filename_arg = (const void *)args->args[0]; + unsigned int len = sizeof(augmented_args->args); + + if (augmented_args == NULL) + return 1; /* Failure: don't filter */ + + len += augmented_arg__read_str(&augmented_args->arg, filename_arg, sizeof(augmented_args->arg.value)); + + return augmented__output(args, augmented_args, len); +} + +SEC("!syscalls:sys_enter_openat") +int sys_enter_openat(struct syscall_enter_args *args) +{ + struct augmented_args_payload *augmented_args = augmented_args_payload(); + const void *filename_arg = (const void *)args->args[1]; + unsigned int len = sizeof(augmented_args->args); + + if (augmented_args == NULL) + return 1; /* Failure: don't filter */ + + len += augmented_arg__read_str(&augmented_args->arg, filename_arg, sizeof(augmented_args->arg.value)); + + return augmented__output(args, augmented_args, len); +} + +SEC("!syscalls:sys_enter_rename") +int sys_enter_rename(struct syscall_enter_args *args) +{ + struct augmented_args_payload *augmented_args = augmented_args_payload(); + const void *oldpath_arg = (const void *)args->args[0], + *newpath_arg = (const void *)args->args[1]; + unsigned int len = sizeof(augmented_args->args), oldpath_len; + + if (augmented_args == NULL) + return 1; /* Failure: don't filter */ + + oldpath_len = augmented_arg__read_str(&augmented_args->arg, oldpath_arg, sizeof(augmented_args->arg.value)); + len += oldpath_len + augmented_arg__read_str((void *)(&augmented_args->arg) + oldpath_len, newpath_arg, sizeof(augmented_args->arg.value)); + + return augmented__output(args, augmented_args, len); +} + +SEC("!syscalls:sys_enter_renameat") +int sys_enter_renameat(struct syscall_enter_args *args) +{ + struct augmented_args_payload *augmented_args = augmented_args_payload(); + const void *oldpath_arg = (const void *)args->args[1], + *newpath_arg = (const void *)args->args[3]; + unsigned int len = sizeof(augmented_args->args), oldpath_len; + + if (augmented_args == NULL) + return 1; /* Failure: don't filter */ + + oldpath_len = augmented_arg__read_str(&augmented_args->arg, oldpath_arg, sizeof(augmented_args->arg.value)); + len += oldpath_len + augmented_arg__read_str((void *)(&augmented_args->arg) + oldpath_len, newpath_arg, sizeof(augmented_args->arg.value)); + + return augmented__output(args, augmented_args, len); +} + +SEC("raw_syscalls:sys_enter") +int sys_enter(struct syscall_enter_args *args) +{ + struct augmented_args_payload *augmented_args; + /* + * We start len, the amount of data that will be in the perf ring + * buffer, if this is not filtered out by one of pid_filter__has(), + * syscall->enabled, etc, with the non-augmented raw syscall payload, + * i.e. sizeof(augmented_args->args). + * + * We'll add to this as we add augmented syscalls right after that + * initial, non-augmented raw_syscalls:sys_enter payload. + */ + unsigned int len = sizeof(augmented_args->args); + struct syscall *syscall; + + if (pid_filter__has(&pids_filtered, getpid())) + return 0; + + augmented_args = augmented_args_payload(); + if (augmented_args == NULL) + return 1; + + probe_read(&augmented_args->args, sizeof(augmented_args->args), args); + + /* + * Jump to syscall specific augmenter, even if the default one, + * "!raw_syscalls:unaugmented" that will just return 1 to return the + * unagmented tracepoint payload. + */ + bpf_tail_call(args, &syscalls_sys_enter, augmented_args->args.syscall_nr); + + // If not found on the PROG_ARRAY syscalls map, then we're filtering it: + return 0; +} + +SEC("raw_syscalls:sys_exit") +int sys_exit(struct syscall_exit_args *args) +{ + struct syscall_exit_args exit_args; + + if (pid_filter__has(&pids_filtered, getpid())) + return 0; + + probe_read(&exit_args, sizeof(exit_args), args); + /* + * Jump to syscall specific return augmenter, even if the default one, + * "!raw_syscalls:unaugmented" that will just return 1 to return the + * unagmented tracepoint payload. + */ + bpf_tail_call(args, &syscalls_sys_exit, exit_args.syscall_nr); + /* + * If not found on the PROG_ARRAY syscalls map, then we're filtering it: + */ + return 0; +} + +license(GPL); |