On Sun, Dec 30, 2012 at 05:03:07PM -0500, Eric Paris wrote: > On Sat, 2012-12-29 at 15:00 +0400, Andrey Vagin wrote: > > The address should be bigger than dac_mmap_min_addr, because > > a process with CAP_RAWIO can map a vma bellow mmap_min_addr. > > NAK
Currently prctl(PR_SET_MM_*, addr, ) returns EINVAL for valid addresses. I think it's a bug. Are you agree? > > This doesn't make any sense. dac_mmap_min_addr should ONLY be used in > security/min_addr.c and security/commoncap.c. Period. You should not We can add a function to security/commoncap.c... > be allowed to circumvent LSM protections. Maybe you are missing that > mmap_min_addr = max(dac_mmap_min_addr, CONFIG_LSM_MMAP_MIN_ADDR) ? Or maybe you are missing ;) that /* * cap_mmap_addr - check if able to map given addr * @addr: address attempting to be mapped * * If the process is attempting to map memory below dac_mmap_min_addr * they need CAP_SYS_RAWIO. It was a real case. I have an application, which is failed due to prlctl. This application uses vm.mmap_min_addr to calculate an adress for a new vma. $ sysctl -a | grep min_add vm.mmap_min_addr = 4096 CONFIG_LSM_MMAP_MIN_ADDR could not be got from user space. This application can use a real value of mmap_min_addr, but it is not provided into userspace. > > But this patch is absolutely unacceptable. Maybe you can help me > understand what problem you had and what you were hoping for? Currently a task can have user memory area bellow dac_mmap_min_addr, but prctl returns -EINVAL for such addresses. How can I understand the reason, if I know that the address is valid? I like Linux, because I always can predict its behavior, but this dac_mmap_min_addr vs mmap_min_addr looks stange for me. > > -Eric > > > > Cc: Andrew Morton <a...@linux-foundation.org> > > Cc: Kees Cook <keesc...@chromium.org> > > Cc: Cyrill Gorcunov <gorcu...@openvz.org> > > Cc: Serge Hallyn <serge.hal...@canonical.com> > > Cc: "Eric W. Biederman" <ebied...@xmission.com> > > Cc: Eric Paris <epa...@redhat.com> > > Cc: James Morris <jmor...@namei.org> > > Signed-off-by: Andrey Vagin <ava...@openvz.org> > > --- > > kernel/sys.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/kernel/sys.c b/kernel/sys.c > > index 265b376..e0e1bbd 100644 > > --- a/kernel/sys.c > > +++ b/kernel/sys.c > > @@ -1868,7 +1868,7 @@ static int prctl_set_mm(int opt, unsigned long addr, > > if (opt == PR_SET_MM_EXE_FILE) > > return prctl_set_mm_exe_file(mm, (unsigned int)addr); > > > > - if (addr >= TASK_SIZE || addr < mmap_min_addr) > > + if (addr >= TASK_SIZE || addr < dac_mmap_min_addr) > > return -EINVAL; > > > > error = -EINVAL; > > -- 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/
