From c86ddbbc0eee0e8317d4ed180ee4505f10e8a52c Mon Sep 17 00:00:00 2001
From: Jari Vetoniemi <mailroxas@gmail.com>
Date: Thu, 18 Oct 2018 13:25:53 +0300
Subject: Initial commit
---
Makefile | 28 ++++++++
proc-region-rw.c | 191 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 219 insertions(+)
create mode 100644 Makefile
create mode 100644 proc-region-rw.c
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..4086d15
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,28 @@
+PREFIX ?= /usr/local
+bindir ?= /bin
+
+MAKEFLAGS += --no-builtin-rules
+
+WARNINGS := -Wall -Wextra -Wpedantic -Wformat=2 -Wstrict-aliasing=3 -Wstrict-overflow=5 -Wstack-usage=12500 \
+ -Wfloat-equal -Wcast-align -Wpointer-arith -Wchar-subscripts -Warray-bounds=2
+
+override CFLAGS ?= -g
+override CFLAGS += -std=c99 -D_DEFAULT_SOURCE $(WARNINGS)
+
+bins = proc-region-rw
+all: $(bins)
+
+$(bins): %:
+ $(LINK.c) $(filter %.c %.a,$^) $(LDLIBS) -o $@
+
+proc-region-rw: proc-region-rw.c
+
+install-bin: $(bins)
+ install -Dm755 $^ -t "$(DESTDIR)$(PREFIX)$(bindir)"
+
+install: install-bin
+
+clean:
+ $(RM) $(bins)
+
+.PHONY: all clean install
diff --git a/proc-region-rw.c b/proc-region-rw.c
new file mode 100644
index 0000000..0c1ca4f
--- /dev/null
+++ b/proc-region-rw.c
@@ -0,0 +1,191 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <sys/ptrace.h>
+#include <sys/wait.h>
+#include <err.h>
+
+struct context {
+ void *buf;
+
+ struct {
+ size_t offset, len;
+ bool with_offset_and_len;
+
+ struct {
+ FILE *src;
+ } write;
+
+ enum {
+ MODE_WRITE,
+ MODE_READ
+ } mode;
+ } op;
+
+ struct {
+ FILE *mem;
+ pid_t pid;
+ } proc;
+};
+
+static void
+usage(const char *argv0)
+{
+ fprintf(stderr, "usage: %s pid write file [offset len] < regions\n"
+ " %s pid read [offset len] < regions\n\n"
+ " regions must be in /proc/<pid>/maps format", argv0, argv0);
+ exit(EXIT_FAILURE);
+}
+
+static void
+context_init(struct context *ctx, int argc, const char *argv[])
+{
+ if (argc < 3)
+ usage(argv[0]);
+
+ *ctx = (struct context){0};
+ ctx->proc.pid = strtoull(argv[1], NULL, 10);
+
+ {
+ bool w, r;
+ const char *mode = argv[2];
+ if ((w = strcmp(mode, "write")) && (r = strcmp(mode, "read")))
+ err(EXIT_FAILURE, "mode must be write or read");
+
+ ctx->op.mode = (!w ? MODE_WRITE : MODE_READ);
+ }
+
+ if (ctx->op.mode == MODE_WRITE && argc < 4)
+ usage(argv[0]);
+
+ if (argc > (ctx->op.mode == MODE_WRITE) + 3) {
+ if (argc < (ctx->op.mode == MODE_WRITE) + 5)
+ usage(argv[0]);
+
+ ctx->op.offset = strtoull(argv[(ctx->op.mode == MODE_WRITE) + 3], NULL, 10);
+ ctx->op.len = strtoull(argv[(ctx->op.mode == MODE_WRITE) + 4], NULL, 10);
+ ctx->op.with_offset_and_len = true;
+ }
+
+ if (ctx->op.mode == MODE_WRITE && !(ctx->op.write.src = fopen(argv[3], "rb")))
+ err(EXIT_FAILURE, "fopen(%s)", argv[3]);
+
+ char path[128];
+ snprintf(path, sizeof(path), "/proc/%u/mem", ctx->proc.pid);
+ if (!(ctx->proc.mem = fopen(path, "w+b")))
+ err(EXIT_FAILURE, "fopen(%s)", path);
+}
+
+static void
+context_release(struct context *ctx)
+{
+ if (ctx->op.write.src)
+ fclose(ctx->op.write.src);
+
+ fclose(ctx->proc.mem);
+ free(ctx->buf);
+ *ctx = (struct context){0};
+}
+
+static void
+for_each_line_in_file(FILE *f, void (*cb)(const char *line, void *data), void *data)
+{
+ char *buffer = NULL;
+ size_t step = 1024, allocated = 0, written = 0, read = 0;
+ do {
+ if (written + read >= allocated && !(buffer = realloc(buffer, (allocated += step) + 1)))
+ err(EXIT_FAILURE, "realloc");
+ buffer[(written += read)] = 0;
+ size_t ate = 0;
+ for (char *line = buffer, *nl; (nl = strchr(line, '\n')); line = nl + 1) {
+ *nl = 0;
+ cb(line, data);
+ ate += nl + 1 - line;
+ }
+ memmove(buffer, buffer + ate, (written = written - ate));
+ } while ((read = fread(buffer + written, 1, allocated - written, f)));
+ free(buffer);
+}
+
+static void
+region_cb(const char *line, void *data)
+{
+ struct context *ctx = data;
+ unsigned long start, end, offset;
+ if (sscanf(line, "%lx-%lx %*s %lx", &start, &end, &offset) < 3) {
+ warnx("failed to parse mapping:\n%s", line);
+ return;
+ }
+
+ warnx("%s", line);
+
+ offset = (ctx->op.with_offset_and_len ? 0 : offset);
+ const size_t len = (ctx->op.with_offset_and_len ? ctx->op.len : end - start);
+ if (start + ctx->op.offset > end) {
+ warnx("write offset %lx is out of bounds", start + ctx->op.offset);
+ return;
+ }
+
+ if (len > (end - start - ctx->op.offset)) {
+ warnx("%zu bytes doesn't fit in the region", len);
+ return;
+ }
+
+ if (!len)
+ return;
+
+ if (!(ctx->buf = realloc(ctx->buf, len)))
+ err(EXIT_FAILURE, "realloc");
+
+ clearerr(ctx->proc.mem);
+ if (ctx->op.mode == MODE_WRITE) {
+ if (fseek(ctx->op.write.src, offset, SEEK_SET) != 0)
+ err(EXIT_FAILURE, "fseek");
+
+ const size_t rd = fread(ctx->buf, 1, len, ctx->op.write.src);
+
+ if (fseek(ctx->proc.mem, start + ctx->op.offset, SEEK_SET) != 0)
+ err(EXIT_FAILURE, "fseek");
+
+ const size_t wd = fwrite(ctx->buf, 1, rd, ctx->proc.mem);
+
+ if (ferror(ctx->proc.mem)) {
+ warn("fread(/proc/%u/mem)", ctx->proc.pid);
+ } else {
+ warnx("wrote %lu bytes from offset 0x%lx to offset 0x%lx", wd, offset, start + ctx->op.offset);
+ }
+ } else {
+ if (fseek(ctx->proc.mem, start + ctx->op.offset, SEEK_SET) != 0)
+ err(EXIT_FAILURE, "fseek");
+
+ const size_t rd = fread(ctx->buf, 1, len, ctx->proc.mem);
+
+ if (ferror(ctx->proc.mem))
+ warn("fread(/proc/%u/mem)", ctx->proc.pid);
+
+ if (fwrite(ctx->buf, 1, rd, stdout) != rd)
+ err(EXIT_FAILURE, "fwrite");
+ }
+}
+
+int
+main(int argc, const char *argv[])
+{
+ struct context ctx;
+ context_init(&ctx, argc, argv);
+
+ if (ptrace(PTRACE_ATTACH, ctx.proc.pid, NULL, NULL) == -1L)
+ err(EXIT_FAILURE, "ptrace(PTRACE_ATTACH, %u, NULL, NULL)", ctx.proc.pid);
+
+ {
+ int status;
+ if (waitpid(ctx.proc.pid, &status, 0) == -1 || !WIFSTOPPED(status))
+ err(EXIT_FAILURE, "waitpid");
+ }
+
+ for_each_line_in_file(stdin, region_cb, &ctx);
+ ptrace(PTRACE_DETACH, ctx.proc.pid, 1, 0);
+ context_release(&ctx);
+ return EXIT_SUCCESS;
+}
--
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