From a8e19d5d8057e82cbda2705d755f3d4e1d3da20a Mon Sep 17 00:00:00 2001
From: Andrew Cady <d@jerkface.net>
Date: Sun, 1 May 2016 05:25:14 -0400
Subject: remove references to files outside of this repo

(commit the files into this repo)
---
 src/samizdat-pinentry.c | 455 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 455 insertions(+)
 create mode 100644 src/samizdat-pinentry.c

(limited to 'src/samizdat-pinentry.c')

diff --git a/src/samizdat-pinentry.c b/src/samizdat-pinentry.c
new file mode 100644
index 0000000..e1f7fee
--- /dev/null
+++ b/src/samizdat-pinentry.c
@@ -0,0 +1,455 @@
+#include <error.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+
+
+// TODO: implement multiple ttys
+// TODO: inotify on a password file (kills pinentry)
+// TODO: secure memory
+
+
+/* Buffers:
+ *
+ * assuan info page "The implementation is line based with a maximum line size
+ * of 1000 octets.  The default IPC mechanism are Unix Domain Sockets.
+ *
+ * pinentry info page "Although it is called a PIN-Entry, it does allow to
+ * enter reasonably long strings (at least 2048 characters are supported by
+ * every pinentry).  The client using the PIN-Entry has to check for
+ * correctness."
+ */
+#define MAXLINE 1000 // It's assumed this is > 2. 
+
+
+static int
+open2(const char *argv[], int *result_in, int *result_out, pid_t *result_child)
+{
+  int pipe_out[2]; /* out of parent */
+  int pipe_in[2];  /* into parent */
+  pid_t cpid;
+
+  if (pipe(pipe_out) < 0)
+    return -1;
+  if (pipe(pipe_in) < 0)
+    return -1;
+
+  cpid = fork();
+  if (cpid < 0)
+    return -1;
+
+  if (cpid == 0) { /* child */
+    int *input = pipe_out; /* for sanity */
+    int *output = pipe_in;
+    close(output[0]);
+    close(input[1]);
+
+    /* see http://unixwiz.net/techtips/remap-pipe-fds.c.txt */
+    if (output[1] == 0)
+      if ((output[1] = dup(output[1]) < 0))
+	error(1, errno, "in child process: dup");
+    if (output[0] == 1)
+      if ((output[0] = dup(output[0]) < 0))
+	error(1, errno, "in child process: dup");
+
+    if (dup2(output[1], 1) < 0)
+      error(1, errno, "in child process: dup2");
+    if (dup2(input[0], 0) < 0)
+      error(1, errno, "in child process: dup2");
+
+    if (output[1] != 1)
+      close(output[1]);
+    if (input[0] != 0)
+      close(input[0]);
+
+    execv(argv[0],(char *const*) &argv[1]);
+    error(1, errno, "in child process: exec");
+    return -1; /* fucking warning */
+
+  } else { /* parent */
+    close(pipe_out[0]);
+    close(pipe_in[1]);
+
+    *result_in = pipe_in[0];
+    *result_out = pipe_out[1];
+    if (*result_child)
+      *result_child = cpid;
+    return 0;
+  }
+}
+
+typedef struct {
+  FILE *in, *out;
+  pid_t pid;
+} pipe2_t;
+
+
+pipe2_t fopen2(const char *argv[]) 
+{
+  pipe2_t res = { 0, 0, 0 };
+  int in = 0;
+  int out = 0;
+  if( open2(argv, &in, &out, &res.pid) < 0 )
+    error(1,0, "open2");
+  res.out = fdopen(out, "w");
+  res.in  = fdopen(in, "r");
+  return res;
+}
+
+void pinentry_send(pipe2_t pinentry, const char *msg)
+{
+  fprintf(pinentry.out, "%s\n", msg);
+  fflush(pinentry.out);
+  // printf("C: %s\n", msg);
+}
+int pinentry_get(pipe2_t pinentry, char *data, size_t len)
+{
+  char *ret=fgets(data,len,pinentry.in); 
+  char *p=ret;
+  int gotnewline=0;
+  for(;*p;p++); 
+  if(p!=ret && p[-1]=='\n') {
+    p[-1]='\0';
+    gotnewline=1;
+  }
+  if( !gotnewline ) {
+      int c = ' ';
+      do {
+        c=fgetc(pinentry.in);
+      } while( c!=-1 && c!='\n' );
+  }
+  // printf("S: %s%s", ret, gotnewline?"\n":" <truncated>\n");
+  return !gotnewline;
+}
+
+void pinentry_seterror(pipe2_t pinentry, const char *s)
+{
+    fprintf(pinentry.out,"SETERROR ");
+    pinentry_send( pinentry, s );
+    char data[4] = { 0 };
+    pinentry_get(pinentry,data,4); // OK
+}
+
+void pinentry_set(pipe2_t pinentry, const char *k, const char *v)
+{
+    fprintf(pinentry.out,"SET%s %s\n", k, v);
+    fflush(pinentry.out);
+    char data[4] = { 0 };
+    pinentry_get(pinentry,data,4); // OK
+}
+
+static const char *arg_prompt = "Passphrase:";
+static const char *arg_desc = "Enter your passphrase to unlock the secret key.                         ";
+
+int pinentry_getpin(pipe2_t pinentry, char *secret, size_t maxline)
+{
+  char data[MAXLINE] = { 0 }; 
+
+  // pinentry_send( pinentry, "OPTION lc-ctype=en_US.UTF-8");
+  // pinentry_get( pinentry, data, MAXLINE); // OK
+
+  if (strlen(arg_prompt))
+    pinentry_set( pinentry, "PROMPT", arg_prompt );
+  if (strlen(arg_desc))
+    pinentry_set( pinentry, "DESC", arg_desc );
+
+  pinentry_send( pinentry, "GETPIN");
+  int e = pinentry_get(pinentry, data, MAXLINE);
+  if( strncmp(data,"D ",2)==0 ) {
+    if(!e && strlen(data+2)<=maxline-1 ) {
+      // D <secret>
+      snprintf(secret,maxline,"%s", data+2);
+      //printf("secret = %s\n", secret);
+      pinentry_get(pinentry,data,MAXLINE); // OK
+      return 0;
+    }
+    else {
+      // SECRET TOO BIG, discarding
+      pinentry_seterror(pinentry, "Too big.");
+      return 4;
+    }
+  }
+  else if( strncmp(data,"OK",2)==0 ) {
+    // EMPTY (not an error)
+    secret[0]='\0';
+    //printf("empty secret\n");
+    return 0;
+  }
+  else if( strncmp(data,"ERR ",4)==0 ) {
+    // CANCELED (ERR 83886179 canceled)
+    // ERR 83886246 locale problem
+    // xxx printf("canceled.\n");
+    return 2;
+  }
+  else {
+    // WTF?
+    // xxx printf("Unexpected: %s\n", data);
+    char buf[1024];
+    snprintf(buf,1024,"Unexpected: %s", data );
+    pinentry_seterror(pinentry, buf);
+    return 3;
+  }
+}
+
+pipe2_t do_shell(const char *shell_code) {
+  pipe2_t ret;
+  const char *argv[] = { "/bin/sh", "/bin/sh","-c",NULL,NULL };
+  argv[3]=shell_code;
+  return fopen2(argv);
+}
+
+int validate(pipe2_t pinentry, const char *secret, const char *arg_validate)
+{
+  int retv = 0;
+  if( !arg_validate ) return 1;
+  pipe2_t validate_script = do_shell( arg_validate );
+
+  fprintf( validate_script.out, "%s\n", secret );
+  fclose( validate_script.out );
+  char error_string[1024] = "Error%0Aunspecified error";
+
+  int c;
+  char *p = error_string;
+  while( p!=&error_string[1024-4] && -1!=(c=getc( validate_script.in )) )
+    switch(c){
+    case '%':
+    case '\n':
+      snprintf(p,4, "%%%0.02X", c);
+      p+=3;
+      break;
+    default:
+      *p++ = c;
+  }
+  *p='\0';
+
+  // pinentry ruins its display if this message ends with a newline
+  while(p-3>error_string && memcmp(&p[-3],"%0A",3)==0 ) p-=3;
+  *p='\0';
+
+  fclose( validate_script.in );
+  waitpid(validate_script.pid, &retv, 0 );
+  if( retv ) {
+    fprintf(stderr, "error_string: %s\n", error_string);
+    pinentry_seterror(pinentry, error_string );
+  }
+  return !retv;
+}
+
+FILE *open_socket(const char *socket_path)
+{
+  int sok = socket(PF_LOCAL, SOCK_STREAM, 0);
+  if( sok<0 ) {
+    return NULL;
+  }
+  struct sockaddr_un address;
+  memset(&address, 0, sizeof(struct sockaddr_un));
+  address.sun_family = AF_UNIX;
+  snprintf(address.sun_path, 108, socket_path);
+  if(connect(sok, 
+              (struct sockaddr *) &address, 
+              sizeof(struct sockaddr_un)) != 0)
+  {
+    return NULL;
+  }
+  return fdopen(sok,"r+");
+}
+
+const char *arg_socket = NULL;
+const char *arg_resocket = NULL;
+const char *arg_tellsecret = NULL;
+char secret[MAXLINE]; // TODO: secure memory
+
+void tell_encoded_secret(FILE *out)
+{
+  char *encoded_secret = malloc(strlen(secret)*2 + 1);
+  for (char *p = secret; *p; ++p)
+    snprintf(encoded_secret + 2*(p - secret), 3, "%0.02X", *p);
+
+  fprintf(out, "%s\n", encoded_secret);
+  fflush(out);
+  free(encoded_secret);
+}
+
+void signal_usr1(int val)
+{
+  if( !arg_tellsecret ) {
+    fprintf(stderr, "USR1, no action\n");
+    return;
+  } else
+    fprintf(stderr, "Received SIGUSR1; will tell secret.\n");
+
+  pipe2_t tellsecret = do_shell( arg_tellsecret );
+  tell_encoded_secret(tellsecret.out);
+
+  FILE *sock = NULL;
+  if (arg_socket) sock=open_socket(arg_socket);
+
+  for (;;) {
+    char *response = 0;
+    size_t len;
+    if (sock && (getline(&response, &len, sock) > 0)) {
+      fprintf(tellsecret.out, "%s", response);
+      fflush(tellsecret.out);
+    }
+
+    if (getline(&response, &len, tellsecret.in) > 0) {
+      if (sock) {
+	fprintf(sock, "%s", response);
+	fflush(sock);
+      } else {
+	fprintf(stderr, "?> %s", response);
+      }
+    } else {
+      break;
+    }
+  }
+
+  if (sock) fclose(sock);
+  fclose(tellsecret.out);
+  fclose(tellsecret.in);
+  int status = 0;
+  waitpid(tellsecret.pid, &status, 0 );
+}
+
+void signal_usr2(int wat)
+{
+  fprintf(stderr, "Received SIGUSR2; will change socket and emulate SIGUSR1.\n");
+  if (arg_resocket)
+    arg_socket = arg_resocket;
+  signal_usr1(wat);
+}
+
+void signal_term(int val)
+{
+  // TODO: Wipe secret
+  exit(0);
+}
+
+int main(int argc, char **argv) 
+{
+  pipe2_t pinentry = { 0 };
+
+  char tty_name_buf[256];
+  if( ttyname_r(1, tty_name_buf, sizeof(tty_name_buf)) ) {
+    tty_name_buf[0]='\0';
+    //error(2,0,"ttyname_r");
+  }
+  const char *arg_ttyname = tty_name_buf;
+  const char *arg_pinentry = "/usr/bin/pinentry-curses";
+  const char *arg_validate = NULL;
+  const char *arg_pidfile = NULL; //same as "/dev/stdout";
+  int tell_at_start=0;
+
+  const char **expect = NULL;
+  int i=0;
+  for(i=1;i<argc;i++) {
+    if(expect) {
+      *expect = argv[i];
+      expect = NULL;
+    }
+    else if( strcmp(argv[i],"--setdesc")==0 )
+      expect = &arg_desc;
+    else if( strcmp(argv[i],"--setprompt")==0 )
+      expect = &arg_prompt;
+    else if( strcmp(argv[i],"--validate")==0 )
+      expect = &arg_validate;
+    else if( strcmp(argv[i],"--ttyname")==0 )
+      expect = &arg_ttyname;
+    else if( strcmp(argv[i],"--pinentry")==0 )
+      expect = &arg_pinentry;
+    else if( strcmp(argv[i],"--pidfile")==0 )
+      expect = &arg_pidfile;
+    else if( strcmp(argv[i],"--tell")==0 )
+      expect = &arg_tellsecret;
+    else if( strcmp(argv[i],"--tell-immediately")==0 ) {
+      expect = &arg_tellsecret;
+      tell_at_start=1;
+    }
+    else if( strcmp(argv[i],"--socket")==0 )
+      expect = &arg_socket;
+    else if( strcmp(argv[i],"--resocket")==0 )
+      expect = &arg_resocket;
+  }
+
+  if(!arg_ttyname || !arg_ttyname[0]) {
+    error(2,0,"unknown tty, use --ttyname");
+  }
+ 
+  // xxx printf("validate script = \n%s\n", arg_validate );
+  // xxx printf("ttyname = %s\n", arg_ttyname );
+
+  char dummy[123];
+  //fgets(dummy,sizeof(dummy),stdin);
+
+  // pinentry-curses --lc-ctype en_US.UTF-8 --ttyname /dev/pts/5
+  const char *cmd[] = {
+    NULL /* pinentry command */, 
+    "pinentry-curses",
+    "--lc-ctype", "en_US.UTF-8",
+    "--ttyname", NULL,
+    0 };
+  cmd[0] = arg_pinentry;
+  cmd[sizeof(cmd)/sizeof(cmd[0]) - 2] = arg_ttyname;
+  for(i=0; cmd[i]; i++ ) {
+    // xxx printf("cmd[%d]=%s\n", i, cmd[i] );
+  }
+
+  char data[MAXLINE];
+
+  pinentry = fopen2(cmd);
+  pinentry_get(pinentry,data,MAXLINE); // OK
+
+  int e=0;
+  while(   0!=(e=pinentry_getpin(pinentry,secret,MAXLINE))
+        || !validate(pinentry,secret, arg_validate) ) {
+      //printf("e=%d\n",e);
+      if(e==2) break; // Canceled
+    }
+
+  fclose(pinentry.out);
+  fclose(pinentry.in);
+
+  if(e) return e;
+
+  if( tell_at_start ) {
+    signal_usr1(0);
+  }
+
+  int pid = fork();
+  if( !pid ) {
+
+    if (isatty(0)) fclose(stdin);
+    if (isatty(1)) fclose(stdout);
+    if (isatty(2)) fclose(stderr);
+    setsid();
+
+    struct sigaction act = { 0 };
+    sigemptyset(&act.sa_mask);
+    sigaddset(&act.sa_mask, SIGTERM);
+    sigaddset(&act.sa_mask, SIGUSR1);
+    sigaddset(&act.sa_mask, SIGUSR2);
+    act.sa_handler = signal_usr1;
+    sigaction( SIGUSR1, &act, NULL );
+    act.sa_handler = signal_usr2;
+    sigaction( SIGUSR2, &act, NULL );
+    act.sa_handler = signal_term;
+    sigaction( SIGTERM, &act, NULL );
+
+    for(;;) {
+      pause();
+    }
+    return 0;
+  }
+
+  FILE *pidfile = arg_pidfile ? fopen(arg_pidfile,"w") : stdout;
+  fprintf(pidfile, "%d\n", pid );
+  if(arg_pidfile) fclose(pidfile);
+
+  return 0;
+}
-- 
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