su: Use termios ioctls to turn off echoing and read a password

Only handles echoing for now.

apps/su.cpp

@@ -1,16 +1,63 @@
+#include <bits/termios.h>
 #include <os/ArgumentParser.h>
 #include <pwd.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <sys/ioctl.h>
 #include <unistd.h>
 
+static struct termios orig;
+
+void restore_terminal()
+{
+    ioctl(fileno(stdin), TCSETS, &orig);
+}
+
+char* getpass()
+{
+    fputs("Password: ", stdout);
+
+    if (ioctl(fileno(stdin), TCGETS, &orig) < 0)
+    {
+        perror("ioctl(TCGETS)");
+        return nullptr;
+    }
+
+    atexit(restore_terminal);
+
+    struct termios tc = orig;
+    tc.c_lflag &= ~ECHO;
+    if (ioctl(fileno(stdin), TCSETS, &tc) < 0)
+    {
+        perror("ioctl(TCSETS)");
+        return nullptr;
+    }
+
+    static char buf[1024];
+    char* rc = fgets(buf, sizeof(buf), stdin);
+
+    restore_terminal();
+    putchar('\n');
+
+    if (!rc)
+    {
+        perror("fgets");
+        return nullptr;
+    }
+
+    char* newline = strrchr(rc, '\n');
+    if (newline) *newline = 0;
+
+    return buf;
+}
+
 int main(int argc, char** argv)
 {
     StringView name;
 
     if (geteuid() != 0)
     {
-        fprintf(stderr, "su must be run as root!\n");
+        fprintf(stderr, "su must be setuid root!\n");
         return 1;
     }
 
@@ -25,12 +72,20 @@ int main(int argc, char** argv)
         return 1;
     }
 
-    if (getuid() != geteuid())
+    if (getuid() != geteuid() && *entry->pw_passwd)
     {
-        fprintf(stderr, "FIXME: you have to enter %s's password first!\n", name.chars());
+        char* pass = getpass();
+        if (!pass) return 1;
+
+        if (strcmp(pass, entry->pw_passwd))
+        {
+            fprintf(stderr, "Wrong password!\n");
             return 1;
         }
 
+        memset(pass, 0, strlen(pass));
+    }
+
     setgid(entry->pw_gid);
     setuid(entry->pw_uid);
 

kernel/src/fs/VFS.h

@@ -27,6 +27,11 @@ namespace VFS
     class Inode
     {
       public:
+        virtual Result<u64> ioctl(int, void*)
+        {
+            return err(ENOTTY);
+        }
+
         // Directory-specific methods
         virtual Result<SharedPtr<Inode>> find(const char* name) const = 0;
 

kernel/src/fs/devices/ConsoleDevice.cpp

@@ -1,12 +1,15 @@
 #include "fs/devices/ConsoleDevice.h"
 #include "arch/Keyboard.h"
+#include "memory/MemoryManager.h"
 #include "video/TextConsole.h"
+#include <bits/termios.h>
 #include <luna/Buffer.h>
 #include <luna/CString.h>
 #include <luna/Vector.h>
 
 static Buffer g_console_input;
 static bool g_eof { false };
+static bool g_echo { true };
 
 Result<SharedPtr<Device>> ConsoleDevice::create()
 {
@@ -45,7 +48,10 @@ void ConsoleDevice::did_press_key(char key)
 {
     if (key == '\b')
     {
-        if (g_temp_input.try_pop().has_value()) TextConsole::putwchar(L'\b');
+        if (g_temp_input.try_pop().has_value())
+        {
+            if (g_echo) TextConsole::putwchar(L'\b');
+        }
 
         return;
     }
@@ -65,5 +71,32 @@ void ConsoleDevice::did_press_key(char key)
         g_temp_input.clear();
     }
 
+    if (!g_echo) return;
     TextConsole::putchar(key);
 }
+
+Result<u64> ConsoleDevice::ioctl(int request, void* arg)
+{
+    switch (request)
+    {
+    case TCGETS: {
+        struct termios tc
+        {
+            .c_lflag = 0
+        };
+
+        if (g_echo) tc.c_lflag |= ECHO;
+        return MemoryManager::copy_to_user_typed((struct termios*)arg, &tc) ? 0 : err(EFAULT);
+    }
+    case TCSETS: {
+        struct termios tc;
+        if (!MemoryManager::copy_from_user_typed((const struct termios*)arg, &tc)) return err(EFAULT);
+        if (tc.c_lflag & ECHO) g_echo = true;
+        else
+            g_echo = false;
+
+        return 0;
+    }
+    default: return err(EINVAL);
+    }
+}

kernel/src/fs/devices/ConsoleDevice.h

@@ -15,5 +15,7 @@ class ConsoleDevice : public Device
 
     bool blocking() const override;
 
+    Result<u64> ioctl(int request, void* arg) override;
+
     virtual ~ConsoleDevice() = default;
 };

kernel/src/fs/devices/Device.h

@@ -8,6 +8,11 @@ class Device
 
     virtual Result<usize> write(const u8* buf, usize offset, usize length) = 0;
 
+    virtual Result<u64> ioctl(int, void*)
+    {
+        return err(ENOTTY);
+    }
+
     virtual bool blocking() const = 0;
 
     virtual ~Device() = default;

kernel/src/fs/tmpfs/FileSystem.h

@@ -153,6 +153,11 @@ namespace TmpFS
             return err(EINVAL);
         }
 
+        Result<u64> ioctl(int request, void* arg) override
+        {
+            return m_device->ioctl(request, arg);
+        }
+
         bool blocking() const override
         {
             return m_device->blocking();

kernel/src/sys/file.cpp

@@ -135,3 +135,15 @@ Result<u64> sys_fcntl(Registers*, SyscallArgs args)
     default: return err(EINVAL);
     }
 }
+
+Result<u64> sys_ioctl(Registers*, SyscallArgs args)
+{
+    int fd = (int)args[0];
+    int request = (int)args[1];
+    void* arg = (void*)args[2];
+
+    Thread* current = Scheduler::current();
+    auto& descriptor = *TRY(current->resolve_fd(fd));
+
+    return descriptor.inode->ioctl(request, arg);
+}

libc/CMakeLists.txt

@@ -20,6 +20,7 @@ set(SOURCES
     src/sys/stat.cpp
     src/sys/mman.cpp
     src/sys/wait.cpp
+    src/sys/ioctl.cpp
 )
 
 if(${LUNA_ARCH} STREQUAL "x86_64")

libc/include/bits/termios.h

@@ -0,0 +1,21 @@
+/* bits/termios.h: Terminal control definitions. */
+
+#ifndef _BITS_TERMIOS_H
+#define _BITS_TERMIOS_H
+
+typedef long tcflag_t;
+
+// VERY incomplete termios structure.
+struct termios
+{
+    tcflag_t c_lflag;
+};
+
+// Values for c_lflag.
+#define ECHO 1
+
+// termios ioctl() requests.
+#define TCGETS 0
+#define TCSETS 1
+
+#endif

libc/include/sys/ioctl.h

@@ -0,0 +1,18 @@
+/* sys/ioctl.h: IO device control. */
+
+#ifndef _SYS_IOCTL_H
+#define _SYS_IOCTL_H
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+    /* Perform an IO control operation on a device. */
+    int ioctl(int fd, int request, ...);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

libc/src/sys/ioctl.cpp

@@ -0,0 +1,22 @@
+#include <bits/errno-return.h>
+#include <stdarg.h>
+#include <sys/ioctl.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+extern "C"
+{
+    int ioctl(int fd, int request, ...)
+    {
+        va_list ap;
+        va_start(ap, request);
+
+        void* arg = va_arg(ap, void*);
+
+        long rc = syscall(SYS_ioctl, fd, request, arg);
+
+        va_end(ap);
+
+        __errno_return(rc, int);
+    }
+}

libluna/include/luna/Syscall.h

@@ -3,7 +3,8 @@
 #define enumerate_syscalls(_e)                                                                                         \
     _e(exit) _e(clock_gettime) _e(mmap) _e(munmap) _e(usleep) _e(open) _e(close) _e(read) _e(getpid) _e(write)         \
         _e(lseek) _e(mkdir) _e(execve) _e(mknod) _e(fork) _e(waitpid) _e(getppid) _e(fcntl) _e(getdents) _e(getuid)    \
-            _e(geteuid) _e(getgid) _e(getegid) _e(setuid) _e(setgid) _e(seteuid) _e(setegid) _e(chmod) _e(chown)
+            _e(geteuid) _e(getgid) _e(getegid) _e(setuid) _e(setgid) _e(seteuid) _e(setegid) _e(chmod) _e(chown)       \
+                _e(ioctl)
 
 enum Syscalls
 {