Messages in this thread Patch in this message |  | | From | Andrey Vagin <> | Subject | [PATCH 1/3] prctl: reduce permissions to change boundaries of data, brk and stack | Date | Fri, 14 Feb 2014 18:13:27 +0400 |
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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
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