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);