Initial commit

mtd-rw.zig

@@ -0,0 +1,69 @@
+const std = @import("std");
+const os = std.os;
+
+const mtd_rw_ko = @embedFile("mtd-rw.ko");
+
+const InitModuleError = error {
+    ModuleSignatureMisformatted,
+    TimeoutResolvingSymbol,
+    BadAddress,
+    ModuleSigInvalid,
+    OutOfMemory,
+    PermissionDenied,
+    AlreadyLoaded,
+    BadParams,
+    InvalidModule,
+
+};
+
+const DeleteModuleError = error {
+    ModuleNotLive,
+    BadAddress,
+    ModuleNotFound,
+    PermissionDenied,
+    ModuleInUse,
+};
+
+pub fn load() !void {
+    try insmod(mtd_rw_ko, "i_want_a_brick=1");
+}
+
+pub fn unload() void {
+    rmmod("mtd_rw", os.O_NONBLOCK) catch |err| {
+        std.debug.warn("Failed to unload module: {}\n", .{err});
+    };
+}
+
+pub fn insmod(buf: []const u8, args: [*:0]const u8) !void {
+    const errno = os.linux.getErrno(
+        os.linux.syscall3(
+            os.linux.SYS_init_module, @ptrToInt(&buf[0]), buf.len, @ptrToInt(args)));
+    switch (errno) {
+        0 => return,
+        os.EEXIST => return, // It's not a failure if we have what we need
+        os.EBADMSG => return InitModuleError.ModuleSignatureMisformatted,
+        os.EBUSY => return InitModuleError.TimeoutResolvingSymbol,
+        os.EFAULT => return InitModuleError.BadAddress,
+        // os.ENOKEY => return InitModuleError.ModuleSigInvalid,
+        os.ENOMEM => return InitModuleError.OutOfMemory,
+        os.EPERM => return InitModuleError.PermissionDenied,
+        os.EINVAL => return InitModuleError.BadParams,
+        os.ENOEXEC => return InitModuleError.InvalidModule,
+        else => |err| return os.unexpectedErrno(err),
+    }
+}
+
+pub fn rmmod(mod_name: [*:0]const u8, flags: u32) !void {
+    const errno = os.linux.getErrno(
+        std.os.linux.syscall2(
+            std.os.linux.SYS_delete_module, @ptrToInt(mod_name), flags));
+    switch (errno) {
+        0 => return,
+        os.EBUSY => return DeleteModuleError.ModuleNotLive,
+        os.EFAULT => return DeleteModuleError.BadAddress,
+        os.ENOENT => return DeleteModuleError.ModuleNotFound,
+        os.EPERM => return DeleteModuleError.PermissionDenied,
+        os.EWOULDBLOCK => return DeleteModuleError.ModuleInUse,
+        else => |err| return os.unexpectedErrno(err),
+    }
+}

update-uboot.zig

@@ -0,0 +1,106 @@
+const std = @import("std");
+const math = std.math;
+const mtd_user = @cImport(@cInclude("mtd/mtd-user.h"));
+
+const uboot = @embedFile("uboot-feb2019.bin");
+const mtd_rw = @import("mtd-rw.zig");
+
+const Allocator = std.heap.c_allocator;
+
+const c_allocator = std.heap.c_allocator;
+
+fn stripTrailingNulls(buf: []const u8) []const u8 {
+    var end: usize = buf.len;
+    while (true) {
+        if (end > 0) {
+            const new_end = end - 1;
+            if (buf[new_end] == 0) {
+                end = new_end;
+                continue;
+            }
+        }
+        break;
+    }
+    return buf[0..end];
+}
+
+test "stripTrailingNulls" {
+    const farts0: []const u8 = "farts\x00";
+    const farts: []const u8 = "farts";
+    var farts0_stripped = stripTrailingNulls(farts0);
+    var farts_stripped = stripTrailingNulls(farts);
+    std.debug.assert(farts0_stripped.len == 5);
+    std.debug.assert(farts_stripped.len == 5);
+    std.debug.assert(std.mem.eql(u8, farts0_stripped, farts));
+    std.debug.assert(std.mem.eql(u8, farts_stripped, farts));
+}
+
+fn mtd_info_get(name: []const u8, out: []u8) !void {
+    var path_buf: [64]u8 = undefined;
+    const path = try std.fmt.bufPrint(path_buf[0..], "{}/{}", .{"/sys/class/mtd/mtd0/", name});
+
+    //const path = try std.fmt.allocPrint(
+    //    c_allocator, "{}/{}", .{"/sys/class/mtd/mtd0", name});
+    //defer c_allocator.free(path);
+
+    var f = try std.fs.openFileAbsolute(path, .{.read = true});
+    defer f.close();
+    const num_read = try f.read(out);
+    out = out[0..num_read-1];
+}
+
+fn mtd_info_get_usize(name: []const u8) !usize {
+    var buf: [64]u8 = undefined;
+    var buf_sl = buf[0..];
+    try mtd_info_get(name, buf_sl);
+    return try std.fmt.parseUnsigned(usize, buf_sl, 10);
+}
+
+pub fn main() !u8 {
+    try mtd_rw.load();
+    defer mtd_rw.unload();
+
+    // Read and hash mtd0
+
+    const mtd0_size = try mtd_info_get_usize("size");
+
+    if (uboot.len > mtd0_size) {
+         std.debug.warn("Error: mtd0 isn\'t large enough to hold the new image ({} > {})\n",
+                        .{uboot.len, mtd0_size});
+         return 1;
+    }
+    var current_uboot = try Allocator.alloc(u8, mtd0_size);
+    var f = try std.fs.openFileAbsolute("/dev/mtd0", .{.read = true});
+    defer f.close();
+    const num_read = try f.read(current_uboot[0..]);
+    if (num_read != mtd0_size) {
+        std.debug.warn("Failed to read /dev/mtd0", .{});
+        return 2;
+    }
+
+    var current_digest: [std.crypto.Md5.digest_length]u8 = undefined;
+    std.crypto.Md5.hash(current_uboot, current_digest[0..]);
+
+    var embedded_digest: [std.crypto.Md5.digest_length]u8 = undefined;
+    std.crypto.Md5.hash(uboot, embedded_digest[0..]);
+
+    // Compare against payload
+    if (std.mem.eql(u8, current_digest[0..], embedded_digest[0..])) {
+        std.debug.warn("U-Boot is up to date. Exiting.\n", .{});
+        return 0;
+    }
+
+    // Erase mtd0
+    const mtd0_erasesize = try mtd_info_get_usize("erasesize");
+    var erased = 0;
+    while (erased < mtd0_size) {
+        //erase page
+        erased += mtd0_erasesize;
+    }
+    // Write mtd0
+
+    // Verify mtd0
+
+    std.debug.warn("Done\n", .{});
+    return 0;
+}