Changeset 2450

Timestamp:

06/18/08 22:29:34 (5 years ago)

Author:

pterjan

Message:

• Detach properly the process from the previous tty
• Use major to decide if a device is a pty slave

File:

• neercs/trunk/src/grab.c (modified) (13 diffs)

neercs/trunk/src/grab.c

@@ -14 +14 @@
 #include <sys/user.h>
 #include <sys/wait.h>
+
+#include <linux/kdev_t.h>
+#include <linux/major.h>
 
 #include "neercs.h"
@@ -61 +64 @@
     }
 
-    regs->esp -= 4;
+    regs->esp = oregs.esp-4;
 
     oinst = ptrace(PTRACE_PEEKTEXT, pid, regs->esp, 0);
@@ -86 +89 @@
     waitpid(pid, NULL, 0);
 
+    if(ptrace(PTRACE_GETREGS, pid, NULL, regs) < 0)
+    {
+        return errno;
+    }
+
     if(ptrace(PTRACE_SETREGS, pid, NULL, &oregs) < 0)
     {
+        fprintf(stderr, "PTRACE_SETREGS failed\n");
         return errno;
     }
@@ -93 +102 @@
     if(ptrace(PTRACE_POKETEXT, pid, oregs.esp-4 , oinst) < 0)
     {
+        fprintf(stderr, "PTRACE_POKETEXT failed\n");
         return errno;
     }
@@ -157 +167 @@
     regs.edx = 0755;
 
-    if((ret = do_syscall(pid, &regs)) < 0)
+    if((ret = do_syscall(pid, &regs)) != 0)
     {
         return ret;
@@ -193 +203 @@
     regs.edx = ((long)target_page);
 
-    if((ret = do_syscall(pid, &regs)) < 0)
+    if((ret = do_syscall(pid, &regs)) != 0)
     {
         return ret;
@@ -211 +221 @@
 }
 
-static int do_setpgrp(pid_t pid, int fd) {
-    struct user_regs_struct regs;
-    void *backup_page;
-    void *target_page = (void*)(0x08048000);
-    size_t size = (1<<12)*2; /* 8K */
-    int ret, pgrp;
-
-    /* Backup the pages that we will use */
-    backup_page = malloc(size);
-    if (memcpy_from_target(pid, backup_page, target_page, size) < 0)
-        return -1;
-
-    if(ptrace(PTRACE_GETREGS, pid, NULL, &regs) < 0)
-    {
-        fprintf(stderr, "PTRACE_GETREGS failed\n");
-        return errno;
-    }
-
-    pgrp = getpgrp();
-
-    memcpy_into_target(pid, target_page, &getpgrp, 4);
-
-    regs.eax = SYS_ioctl;
-    regs.ebx = fd;
-    regs.ecx = TIOCSPGRP;
-    regs.edx = (long)(target_page);
-    do_syscall(pid, &regs);
-
-
-    if((ret = do_syscall(pid, &regs)) < 0)
+static int do_setsid(pid_t pid) {
+    struct user_regs_struct regs;
+    int ret;
+
+    if(ptrace(PTRACE_GETREGS, pid, NULL, &regs) < 0)
+    {
+        fprintf(stderr, "PTRACE_GETREGS failed\n");
+        return errno;
+    }
+
+    debug("Running setsid on process %d (sid=%d)", pid, getsid(pid));
+
+    regs.eax = SYS_setpgid;
+    regs.ebx = 0;
+    regs.ecx = getsid(pid);
+
+    if((ret = do_syscall(pid, &regs)) != 0)
     {
         return ret;
     }
 
-    if (regs.eax < 0) {
-        fprintf(stderr, "ioctl failed\n");
-        return (-regs.eax);
-    }
-
-    /* Restore the pages */
-    memcpy_into_target(pid, target_page, backup_page, size);
+    if (regs.eax != 0) {
+        fprintf(stderr, "setpgid failed\n");
+        return -regs.eax;
+    }
+
+    regs.eax = SYS_setsid;
+
+    if((ret = do_syscall(pid, &regs)) != 0)
+    {
+        return ret;
+    }
+
+    debug("pid %d has now sid %d", pid, getsid(pid));
+
+    if (regs.eax == -1) {
+        fprintf(stderr, "getsid failed\n");
+        return -regs.eax;
+    }
 
     return 0;
@@ -261 +269 @@
     int i, fd = 0, mode, ret;
     char fdstr[1024];
+    char to_open[3];
     struct stat stat_buf;
 
     debug("pty is %s", ptyname);
 
+    kill(pid, SIGSTOP);
     if(ptrace(PTRACE_ATTACH, pid, 0, 0) < 0)
     {
@@ -270 +280 @@
         return errno;
     }
+    kill(pid, SIGCONT);
     waitpid(pid, NULL, 0);
 
@@ -275 +286 @@
     {
         snprintf(fdstr, sizeof(fdstr), "/proc/%d/fd/%d", pid, i);
+        to_open[i]=0;
         lstat(fdstr, &stat_buf);
         if ((stat_buf.st_mode & S_IRUSR) && (stat_buf.st_mode & S_IWUSR))
@@ -285 +297 @@
         if (stat(fdstr, &stat_buf) < 0)
             continue;
-        if (!S_ISCHR(stat_buf.st_mode)) //FIXME How to know for sure this is the pty and not /dev/null ?
+
+        if (!S_ISCHR(stat_buf.st_mode) || MAJOR(stat_buf.st_rdev) != UNIX98_PTY_SLAVE_MAJOR)
             continue;
 
@@ -297 +310 @@
             fprintf(stderr, "do_close %s\n", strerror(ret));
         }
+        to_open[i]=1;
+    }
+
+    if((ret = do_setsid(pid)))
+    {
+        fprintf(stderr, "do_setsid %s\n", strerror(ret));
+    }
+
+    for(i=0; i<=2; i++)
+    {
+        if(!to_open[i])
+            continue;
         if((ret = do_open(pid, ptyname, mode, &fd)))
         {
@@ -305 +330 @@
             fprintf(stderr, "do_dup2 %s\n", strerror(ret));
         }
-        if((ret = do_setpgrp(pid, i)))
-        {
-            fprintf(stderr, "do_setpgrp %s\n", strerror(ret));
-        }
     }
 
     kill(pid, SIGWINCH);
-
     ptrace(PTRACE_DETACH, pid, 0, 0);