--- /dev/null
+// 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 <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <linux/limits.h>
+
+#define MAX_CPUS 4096
+
+// FIXME: These should come from system headers
+typedef char bool;
+typedef int pid_t;
+typedef long long int __s64;
+typedef __s64 time64_t;
+
+struct timespec64 {
+ time64_t tv_sec;
+ long int tv_nsec;
+};
+
+/* bpf-output associated map */
+struct __augmented_syscalls__ {
+ __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+ __type(key, int);
+ __type(value, __u32);
+ __uint(max_entries, MAX_CPUS);
+} __augmented_syscalls__ SEC(".maps");
+
+/*
+ * What to augment at entry?
+ *
+ * Pointer arg payloads (filenames, etc) passed from userspace to the kernel
+ */
+struct syscalls_sys_enter {
+ __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
+ __type(key, __u32);
+ __type(value, __u32);
+ __uint(max_entries, 512);
+} syscalls_sys_enter SEC(".maps");
+
+/*
+ * What to augment at exit?
+ *
+ * Pointer arg payloads returned from the kernel (struct stat, etc) to userspace.
+ */
+struct syscalls_sys_exit {
+ __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
+ __type(key, __u32);
+ __type(value, __u32);
+ __uint(max_entries, 512);
+} syscalls_sys_exit SEC(".maps");
+
+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];
+};
+
+struct pids_filtered {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __type(key, pid_t);
+ __type(value, bool);
+ __uint(max_entries, 64);
+} pids_filtered SEC(".maps");
+
+/*
+ * Desired design of maximum size and alignment (see RFC2553)
+ */
+#define SS_MAXSIZE 128 /* Implementation specific max size */
+
+typedef unsigned short sa_family_t;
+
+/*
+ * FIXME: Should come from system headers
+ *
+ * The definition uses anonymous union and struct in order to control the
+ * default alignment.
+ */
+struct sockaddr_storage {
+ union {
+ struct {
+ sa_family_t ss_family; /* address family */
+ /* Following field(s) are implementation specific */
+ char __data[SS_MAXSIZE - sizeof(unsigned short)];
+ /* space to achieve desired size, */
+ /* _SS_MAXSIZE value minus size of ss_family */
+ };
+ void *__align; /* implementation specific desired alignment */
+ };
+};
+
+struct augmented_args_payload {
+ struct syscall_enter_args args;
+ union {
+ struct {
+ struct augmented_arg arg, arg2;
+ };
+ struct sockaddr_storage saddr;
+ char __data[sizeof(struct augmented_arg)];
+ };
+};
+
+// We need more tmp space than the BPF stack can give us
+struct augmented_args_tmp {
+ __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+ __type(key, int);
+ __type(value, struct augmented_args_payload);
+ __uint(max_entries, 1);
+} augmented_args_tmp SEC(".maps");
+
+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 bpf_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 = bpf_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("tp/raw_syscalls/sys_enter")
+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("tp/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);
+
+ bpf_probe_read(&augmented_args->saddr, socklen, sockaddr_arg);
+
+ return augmented__output(args, augmented_args, len + socklen);
+}
+
+SEC("tp/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);
+
+ bpf_probe_read(&augmented_args->saddr, socklen, sockaddr_arg);
+
+ return augmented__output(args, augmented_args, len + socklen);
+}
+
+SEC("tp/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("tp/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("tp/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("tp/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);
+}
+
+#define PERF_ATTR_SIZE_VER0 64 /* sizeof first published struct */
+
+// we need just the start, get the size to then copy it
+struct perf_event_attr_size {
+ __u32 type;
+ /*
+ * Size of the attr structure, for fwd/bwd compat.
+ */
+ __u32 size;
+};
+
+SEC("tp/syscalls/sys_enter_perf_event_open")
+int sys_enter_perf_event_open(struct syscall_enter_args *args)
+{
+ struct augmented_args_payload *augmented_args = augmented_args_payload();
+ const struct perf_event_attr_size *attr = (const struct perf_event_attr_size *)args->args[0], *attr_read;
+ unsigned int len = sizeof(augmented_args->args);
+
+ if (augmented_args == NULL)
+ goto failure;
+
+ if (bpf_probe_read(&augmented_args->__data, sizeof(*attr), attr) < 0)
+ goto failure;
+
+ attr_read = (const struct perf_event_attr_size *)augmented_args->__data;
+
+ __u32 size = attr_read->size;
+
+ if (!size)
+ size = PERF_ATTR_SIZE_VER0;
+
+ if (size > sizeof(augmented_args->__data))
+ goto failure;
+
+ // Now that we read attr->size and tested it against the size limits, read it completely
+ if (bpf_probe_read(&augmented_args->__data, size, attr) < 0)
+ goto failure;
+
+ return augmented__output(args, augmented_args, len + size);
+failure:
+ return 1; /* Failure: don't filter */
+}
+
+SEC("tp/syscalls/sys_enter_clock_nanosleep")
+int sys_enter_clock_nanosleep(struct syscall_enter_args *args)
+{
+ struct augmented_args_payload *augmented_args = augmented_args_payload();
+ const void *rqtp_arg = (const void *)args->args[2];
+ unsigned int len = sizeof(augmented_args->args);
+ __u32 size = sizeof(struct timespec64);
+
+ if (augmented_args == NULL)
+ goto failure;
+
+ if (size > sizeof(augmented_args->__data))
+ goto failure;
+
+ bpf_probe_read(&augmented_args->__data, size, rqtp_arg);
+
+ return augmented__output(args, augmented_args, len + size);
+failure:
+ return 1; /* Failure: don't filter */
+}
+
+static pid_t getpid(void)
+{
+ return bpf_get_current_pid_tgid();
+}
+
+static bool pid_filter__has(struct pids_filtered *pids, pid_t pid)
+{
+ return bpf_map_lookup_elem(pids, &pid) != NULL;
+}
+
+SEC("tp/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.
+ */
+
+ if (pid_filter__has(&pids_filtered, getpid()))
+ return 0;
+
+ augmented_args = augmented_args_payload();
+ if (augmented_args == NULL)
+ return 1;
+
+ bpf_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
+ * unaugmented 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("tp/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;
+
+ bpf_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
+ * unaugmented 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;
+}
+
+char _license[] SEC("license") = "GPL";
projects / linux-2.6-microblaze.git / blobdiff