lkml.org 
[lkml]   [2014]   [Feb]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 1/3] prctl: reduce permissions to change boundaries of data, brk and stack
Date
Currently this operation requires the global CAP_SYS_RESOURCE.
It's required, because a task can exceed limits (RLIMIT_DATA,
RLIMIT_STACK).

So let's allow task to change these parameters if a proper limit is
unlimited.

When we restore a task we need to set up text, data and data heap sizes
from userspace to the values a task had at checkpoint time.

Currently we can not restore these parameters, if a task lives in
a non-root user name space, because it has no capabilities in the
parent namespace.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Aditya Kali <adityakali@google.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
---
kernel/sys.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/kernel/sys.c b/kernel/sys.c
index c0a58be..939370c 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1701,8 +1701,23 @@ static int prctl_set_mm(int opt, unsigned long addr,
if (arg5 || (arg4 && opt != PR_SET_MM_AUXV))
return -EINVAL;

- if (!capable(CAP_SYS_RESOURCE))
- return -EPERM;
+ if (!capable(CAP_SYS_RESOURCE)) {
+ switch (opt) {
+ case PR_SET_MM_START_DATA:
+ case PR_SET_MM_END_DATA:
+ case PR_SET_MM_START_BRK:
+ case PR_SET_MM_BRK:
+ if (rlim < RLIM_INFINITY)
+ return -EPERM;
+ break;
+ case PR_SET_MM_START_STACK:
+ if (rlimit(RLIMIT_STACK) < RLIM_INFINITY)
+ return -EPERM;
+ break;
+ default:
+ return -EPERM;
+ }
+ }

if (opt == PR_SET_MM_EXE_FILE)
return prctl_set_mm_exe_file(mm, (unsigned int)addr);
--
1.8.5.3


\
 
 \ /
  Last update: 2014-02-14 16:01    [W:0.160 / U:0.512 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site