Exec system call - Revision history

Heth at 10:10, 19 December 2022

2022-12-19T10:10:34Z

Heth: /* Security */

2022-12-19T10:07:25Z

‎Security

Heth at 09:13, 19 December 2022

2022-12-19T09:13:19Z

Heth at 09:12, 19 December 2022

2022-12-19T09:12:30Z

Heth: /* Security */

2022-12-17T09:31:06Z

‎Security

Heth at 08:06, 17 December 2022

2022-12-17T08:06:52Z

Heth: /* Simple use */

2022-12-17T07:51:03Z

‎Simple use

Heth at 07:50, 17 December 2022

2022-12-17T07:50:36Z

Heth at 07:49, 17 December 2022

2022-12-17T07:49:19Z

Heth: Created page with "The '''exec()''' family executes a file as a new process. See fork system call for "cloning" a process. The =Simple use= The '''execlp()''' is one of the function call in..."

2022-12-17T07:42:00Z

Created page with "The '''exec()''' family executes a file as a new process. See fork system call for "cloning" a process. The =Simple use= The '''execlp()''' is one of the function call in..."

New page

The '''exec()''' family executes a file as a new process. See [[fork system call]] for "cloning" a process.

The
=Simple use=
The '''execlp()''' is one of the function call in the exec family. See manpage
<source lang=c>
#include <stdio.h>
#include <unistd.h>
int main()
{
execlp("ls","ls","/etc", NULL);
return 1;
}
</source>

[[Category:Linux]][[Category:C]]

@@ Line 24: / Line 24: @@
 ==Security==
 As '''execlp()''' searches through $PATH to find the executable file - it is possible to put an executable with the same name earlier in $PATH and run a bogus and evil program. Use '''execl("/usr/bin/ls", "ls", "-l", "/etc", NULL);''' instead.
 =Parent and child with different code=
 {{:fork system call#Parent and child with different code}}
 [[Category:Linux]][[Category:C]]

@@ Line 23: / Line 23: @@
 </source>
 ==Security==
-As '''execlp()''' searches through $PATH to find the executable file - it is possible to put an executable with the same name earlier in $PATH and run a bogus and evil program. Use '''execl("/usr/bin/ls", "ls", "-l", "/etc", NULL);''' instead if possible.
+As '''execlp()''' searches through $PATH to find the executable file - it is possible to put an executable with the same name earlier in $PATH and run a bogus and evil program. Use '''execl("/usr/bin/ls", "ls", "-l", "/etc", NULL);''' instead.
 =Parent and child with different code=
 {{:fork system call#Parent and child with different code}}
 [[Category:Linux]][[Category:C]]

@@ Line 19: / Line 19: @@
+{
          execlp("ls", "ls", "-l", "/etc", NULL); // See security note below!!!
-         return 1;
+         return 1; // This line only runs if execlp() fails
+}
 </source>

@@ Line 22: / Line 22: @@
 ==Security==
 As '''execlp()''' searches through $PATH to find the executable file - it is possible to put an executable with the same name earlier in $PATH and run a bogus and evil program. Use '''execl("/usr/bin/ls", "ls", "-l", "/etc", NULL);''' instead if possible.
+=Parent and child with different code=
 [[Category:Linux]][[Category:C]]

@@ Line 10: / Line 10: @@
 #''-l'' - argv[1] as seen from the executable file
 #''/etc'' - argv[2] as seen from the executable file
-#''NULL'' argv[3] as seen from the executable file - end of argument list
+#''NULL'' - argv[3] as seen from the executable file - end of argument list
 <source lang=c>
 #include <stdio.h>

@@ Line 1: / Line 1: @@
 The '''exec()''' family executes a file as a new process. See [[fork system call]] for "cloning" a process.
-The
+*The '''exec()''' family replaces the current process image with a new process image.
 =Simple use=
 The '''execlp()''' is one of the function call in the exec family. See manpage

@@ Line 5: / Line 5: @@
 The '''execlp()''' is one of the function call in the exec family. See manpage
- '''execlp("ls", "ls", "-l", "/etc", NULL);''' arguments
+The five arguments in the '''execlp()''' below is:
 #''ls'' - the executable file must be in $PATH
 #''ls'' - argv[0] as seen from the executable file