On Wed, Feb 12, 2014 at 01:32:28PM -0800, Andrew Morton wrote: > On Wed, 12 Feb 2014 19:40:11 +0400 Andrey Vagin <ava...@openvz.org> wrote: > > > Currently prctl_set_mm requires the global CAP_SYS_RESOURCE, > > this patch reduce requiremence to CAP_SYS_RESOURCE in the current > > namespace. > > > > 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. > > > > prctl_set_mm() changes parameters of the current task and doesn't affect > > other tasks. > > > > This patch affects the RLIMIT_DATA limit, because a consumtiuon is > > calculated relatively to mm->end_data, mm->start_data, mm->start_brk. > > I can't for the life of me work out what you were trying to say here. > Please fix and resend this paragraph?
A task can exceed the RLIMIT_DATA limit by changing mm->start_brk, so this patch reduces required permission for RLIMIT_DATA too > > > rlim = rlimit(RLIMIT_DATA); > > if (rlim < RLIM_INFINITY && (brk - mm->start_brk) + > > (mm->end_data - mm->start_data) > rlim) > > goto out; > > > > This limit affects calls to brk() and sbrk(), but it doesn't affect > > mmap. So I think requirement of CAP_SYS_RESOURCE in the current > > namespace is enough for this limit. > > > > ... > > > > Cc: secur...@kernel.org > > That list is for reporting kernel security bugs. > > > > > --- a/kernel/sys.c > > +++ b/kernel/sys.c > > @@ -1701,7 +1701,7 @@ 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)) > > + if (!ns_capable(current_user_ns(), CAP_SYS_RESOURCE)) > > return -EPERM; > > > > if (opt == PR_SET_MM_EXE_FILE) > > This looks harmless. > > My relatively-up-to-date manpages don't mention prctl(PR_SET_MM). I > see from http://marc.info/?l=linux-man&m=133132612704130&w=2 that > manpage additions were prepared nearly three years ago. Michael, did > this fall through a crack? > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
