Databases
StackOverflow2013
Postsdbo
POptrace attach to vsftpd hangs
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POptrace attach to vsftpd hangs
    primarykey
    data
    text
    <p>I am trying to ptrace a vsftpd server process on linux to be able to get control whenever vsftpd process makes a system call. I start the vsftpd process and pass this process id as command line to the following program which traces vsftpd.</p> <p>however, when I run the following program it just hangs and does not print anything.Can anyone point out what could be wrong? Thanks a lot for your help!!</p> <pre><code>#include &lt;sys/ptrace.h&gt; #include &lt;sys/types.h&gt; #include &lt;sys/wait.h&gt; #include &lt;unistd.h&gt; #include &lt;linux/user.h&gt; #include &lt;sys/syscall.h&gt; /* For SYS_write etc */ #include&lt;sys/reg.h&gt; int main(int argc,char* argv[]) { pid_t child; long orig_eax, eax; long params[3]; int status; int insyscall = 0; child = atoi(argv[1]); ptrace(PTRACE_ATTACH,child,NULL,NULL); while(1) { wait(&amp;status); if(WIFEXITED(status)) break; orig_eax = ptrace(PTRACE_PEEKUSER, child, 4 * ORIG_EAX, NULL); if(orig_eax == __NR_clone || orig_eax == __NR_open || orig_eax == __NR_write) { if(insyscall == 0) { /* Syscall entry */ insyscall = 1; params[0] = ptrace(PTRACE_PEEKUSER, child, 4 * EBX, NULL); params[1] = ptrace(PTRACE_PEEKUSER, child, 4 * ECX, NULL); params[2] = ptrace(PTRACE_PEEKUSER, child, 4 * EDX, NULL); if(orig_eax == __NR_clone) { printf("\nClone"); } else if(orig_eax == __NR_open) printf("\nOpen"); else if(orig_eax == __NR_write) printf("\nWrite"); printf(" called with " "%ld, %ld, %ld\n", params[0], params[1], params[2]); } else { /* Syscall exit */ eax = ptrace(PTRACE_PEEKUSER, child, 4 * EAX, NULL); printf("Returned " "with %ld\n", eax); insyscall = 0; } } ptrace(PTRACE_SYSCALL, child, NULL, NULL); } return 0; } </code></pre>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USAlfred Huang
    1. USvbser
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. COwhy not add some temporary printf status statements? Then you'll be able to see where it is hanging, and then it would be easier to develop theories about why it is hanging. Are you sure wait(&status) is doing what you think? Good luck!
      singulars
      1. POptrace attach to vsftpd hangs
      1. USshellter
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload