From: "Peter Wächtler" <pwaechtler@mac.com>
To: Chris Wright <chrisw@osdl.org>
Cc: Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org, torvalds@osdl.org
Subject: Re: [PATCH] coredump - as root not only if euid switched
Date: Fri, 23 Apr 2004 21:05:54 +0200 [thread overview]
Message-ID: <1082747153.2713.91.camel@picklock.adams.family> (raw)
In-Reply-To: <20040423101025.J21045@build.pdx.osdl.net>
[-- Attachment #1: Type: text/plain, Size: 835 bytes --]
Am Fr, 2004-04-23 um 19.10 schrieb Chris Wright:
> * Peter Waechtler (pwaechtler@mac.com) wrote:
> > On Thursday, April 22, 2004, at 09:53PM, Chris Wright <chrisw@osdl.org> wrote:
> > >This patch breaks various ptrace() checks.
> >
> > Care to share your wisdom? No? Then please don't reply
>
> - current->mm->dumpable = 0;
> + current->mm->dump_as_root = 1;
>
> Changes like that break ptrace authentication checks. Look more closely
> at what mm->dumpable is used for, you'll see checks like:
>
> if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
> goto out;
added checks like
if ((task->mm->dump_as_root || !task->mm->dumpable)
&& !capable(CAP_SYS_PTRACE))
in kernel/ptrace.c and fs/proc/base.c
I guess the checks will get more and more complicated, perhaps
we should invent a special flag dont_ptrace or so
[-- Attachment #2: coredump-patch --]
[-- Type: text/x-patch, Size: 4938 bytes --]
diff -Nur -X dontdiff linux-2.6.5/fs/exec.c linux-2.6/fs/exec.c
--- linux-2.6.5/fs/exec.c 2004-04-08 22:06:32.000000000 +0200
+++ linux-2.6/fs/exec.c 2004-04-22 21:17:42.000000000 +0200
@@ -1378,6 +1378,10 @@
goto fail;
}
mm->dumpable = 0;
+ if (mm->dump_as_root){
+ current->fsuid = 0;
+ current->fsgid = 0;
+ }
init_completion(&mm->core_done);
current->signal->group_exit = 1;
current->signal->group_exit_code = exit_code;
@@ -1387,9 +1391,23 @@
goto fail_unlock;
format_corename(corename, core_pattern, signr);
- file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE, 0600);
- if (IS_ERR(file))
- goto fail_unlock;
+ file = filp_open(corename, O_CREAT | O_EXCL | 2 | O_NOFOLLOW | O_LARGEFILE, 0600);
+ if (IS_ERR(file)){
+ long error;
+ mm_segment_t old_fs = get_fs();
+
+ set_fs(KERNEL_DS);
+ error = sys_unlink(corename);
+ set_fs(old_fs);
+ if (error)
+ goto fail_unlock;
+ file = filp_open(corename, O_CREAT | O_EXCL | 2 | O_NOFOLLOW | O_LARGEFILE, 0600);
+ if (IS_ERR(file)){
+ printk(KERN_WARNING "pid %d doesn't dump core to %s because of creation race\n",
+ current->pid, corename);
+ goto fail_unlock;
+ }
+ }
inode = file->f_dentry->d_inode;
if (inode->i_nlink > 1)
goto close_fail; /* multiple links - don't dump */
diff -Nur -X dontdiff linux-2.6.5/fs/proc/base.c linux-2.6/fs/proc/base.c
--- linux-2.6.5/fs/proc/base.c 2004-04-08 22:06:33.000000000 +0200
+++ linux-2.6/fs/proc/base.c 2004-04-23 19:41:57.000000000 +0200
@@ -299,7 +299,8 @@
(current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
goto out;
rmb();
- if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
+ if ((task->mm->dump_as_root || !task->mm->dumpable)
+ && !capable(CAP_SYS_PTRACE))
goto out;
if (security_ptrace(current, task))
goto out;
@@ -924,7 +925,7 @@
task_lock(task);
mm = task->mm;
if (mm)
- dumpable = mm->dumpable;
+ dumpable = !mm->dump_as_root || mm->dumpable;
task_unlock(task);
return dumpable;
}
diff -Nur -X dontdiff linux-2.6.5/include/linux/sched.h linux-2.6/include/linux/sched.h
--- linux-2.6.5/include/linux/sched.h 2004-04-08 22:07:23.000000000 +0200
+++ linux-2.6/include/linux/sched.h 2004-04-08 19:14:17.000000000 +0200
@@ -211,6 +211,7 @@
unsigned long saved_auxv[40]; /* for /proc/PID/auxv */
unsigned dumpable:1;
+ unsigned dump_as_root:1;
#ifdef CONFIG_HUGETLB_PAGE
int used_hugetlb;
#endif
diff -Nur -X dontdiff linux-2.6.5/kernel/ptrace.c linux-2.6/kernel/ptrace.c
--- linux-2.6.5/kernel/ptrace.c 2004-04-08 22:07:24.000000000 +0200
+++ linux-2.6/kernel/ptrace.c 2004-04-23 19:38:45.000000000 +0200
@@ -97,7 +97,8 @@
(current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
goto bad;
rmb();
- if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE))
+ if ((task->mm->dump_as_root || !task->mm->dumpable)
+ && !capable(CAP_SYS_PTRACE))
goto bad;
/* the same process cannot be attached many times */
if (task->ptrace & PT_PTRACED)
diff -Nur -X dontdiff linux-2.6.5/kernel/sys.c linux-2.6/kernel/sys.c
--- linux-2.6.5/kernel/sys.c 2004-04-08 22:06:37.000000000 +0200
+++ linux-2.6/kernel/sys.c 2004-04-08 19:22:10.000000000 +0200
@@ -573,7 +573,7 @@
}
if (new_egid != old_egid)
{
- current->mm->dumpable = 0;
+ current->mm->dump_as_root = 1;
wmb();
}
if (rgid != (gid_t) -1 ||
@@ -603,7 +603,7 @@
{
if(old_egid != gid)
{
- current->mm->dumpable=0;
+ current->mm->dump_as_root = 1;
wmb();
}
current->gid = current->egid = current->sgid = current->fsgid = gid;
@@ -612,7 +612,7 @@
{
if(old_egid != gid)
{
- current->mm->dumpable=0;
+ current->mm->dump_as_root = 1;
wmb();
}
current->egid = current->fsgid = gid;
@@ -641,7 +641,7 @@
if(dumpclear)
{
- current->mm->dumpable = 0;
+ current->mm->dump_as_root = 1;
wmb();
}
current->uid = new_ruid;
@@ -698,7 +698,7 @@
if (new_euid != old_euid)
{
- current->mm->dumpable=0;
+ current->mm->dump_as_root = 1;
wmb();
}
current->fsuid = current->euid = new_euid;
@@ -746,7 +746,7 @@
if (old_euid != uid)
{
- current->mm->dumpable = 0;
+ current->mm->dump_as_root = 1;
wmb();
}
current->fsuid = current->euid = uid;
@@ -789,7 +789,7 @@
if (euid != (uid_t) -1) {
if (euid != current->euid)
{
- current->mm->dumpable = 0;
+ current->mm->dump_as_root = 1;
wmb();
}
current->euid = euid;
@@ -837,7 +837,7 @@
if (egid != (gid_t) -1) {
if (egid != current->egid)
{
- current->mm->dumpable = 0;
+ current->mm->dump_as_root = 1;
wmb();
}
current->egid = egid;
@@ -882,7 +882,7 @@
{
if (uid != old_fsuid)
{
- current->mm->dumpable = 0;
+ current->mm->dump_as_root = 1;
wmb();
}
current->fsuid = uid;
@@ -910,7 +910,7 @@
{
if (gid != old_fsgid)
{
- current->mm->dumpable = 0;
+ current->mm->dump_as_root = 1;
wmb();
}
current->fsgid = gid;
next prev parent reply other threads:[~2004-04-23 19:03 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-04-23 7:16 Peter Waechtler
2004-04-23 17:10 ` Chris Wright
2004-04-23 19:05 ` Peter Wächtler [this message]
-- strict thread matches above, loose matches on Subject: below --
2004-04-23 15:35 Albert Cahalan
2004-04-23 19:14 ` Peter Wächtler
2004-04-23 17:22 ` Albert Cahalan
2004-04-23 7:46 Peter Waechtler
2004-04-23 7:14 Peter Waechtler
2004-04-22 9:40 Peter Waechtler
2004-04-22 9:56 ` Andrew Morton
2004-04-22 19:43 ` Peter Wächtler
2004-04-22 19:53 ` Chris Wright
2004-04-22 20:05 ` Linus Torvalds
2004-04-22 8:51 Peter Waechtler
2004-04-22 8:55 ` Andrew Morton
2004-04-21 19:20 Peter Wächtler
2004-04-22 1:18 ` Andrew Morton
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