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Date:	Fri, 14 Feb 2014 18:13:27 +0400
From:	Andrey Vagin <>
Cc:, Andrey Vagin <>,
	Andrew Morton <>,
	Oleg Nesterov <>,
	Al Viro <>,
	Kees Cook <>,
	"Eric W. Biederman" <>,
	Stephen Rothwell <>,
	Pavel Emelyanov <>,
	Aditya Kali <>
Subject: [PATCH 1/3] prctl: reduce permissions to change boundaries of data, brk and stack

Currently this operation requires the global CAP_SYS_RESOURCE.
It's required, because a task can exceed limits (RLIMIT_DATA,

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

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 <>
Cc: Oleg Nesterov <>
Cc: Al Viro <>
Cc: Kees Cook <>
Cc: "Eric W. Biederman" <>
Cc: Stephen Rothwell <>
Cc: Pavel Emelyanov <>
Cc: Aditya Kali <>
Signed-off-by: Andrey Vagin <>
 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_BRK:
+			if (rlim < RLIM_INFINITY)
+				return -EPERM;
+			break;
+				return -EPERM;
+			break;
+		default:
+			return -EPERM;
+		}
+	}
 	if (opt == PR_SET_MM_EXE_FILE)
 		return prctl_set_mm_exe_file(mm, (unsigned int)addr);

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