Messages in this thread Patch in this message | | | Date | Fri, 9 Aug 2019 17:03:01 +0100 | From | Catalin Marinas <> | Subject | Re: [PATCH v19 04/15] mm: untag user pointers passed to memory syscalls |
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On Tue, Jul 23, 2019 at 07:58:41PM +0200, Andrey Konovalov wrote: > This patch is a part of a series that extends kernel ABI to allow to pass > tagged user pointers (with the top byte set to something else other than > 0x00) as syscall arguments. > > This patch allows tagged pointers to be passed to the following memory > syscalls: get_mempolicy, madvise, mbind, mincore, mlock, mlock2, mprotect, > mremap, msync, munlock, move_pages. > > The mmap and mremap syscalls do not currently accept tagged addresses. > Architectures may interpret the tag as a background colour for the > corresponding vma. > > Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com> > Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> > Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> > Reviewed-by: Kees Cook <keescook@chromium.org> > Signed-off-by: Andrey Konovalov <andreyknvl@google.com> > --- > mm/madvise.c | 2 ++ > mm/mempolicy.c | 3 +++ > mm/migrate.c | 2 +- > mm/mincore.c | 2 ++ > mm/mlock.c | 4 ++++ > mm/mprotect.c | 2 ++ > mm/mremap.c | 7 +++++++ > mm/msync.c | 2 ++ > 8 files changed, 23 insertions(+), 1 deletion(-)
More back and forth discussions on how to specify the exceptions here. I'm proposing just dropping the exceptions and folding in the diff below.
Andrew, if you prefer a standalone patch instead, please let me know:
------------------8<---------------------------- From 9a5286acaa638c6a917d96986bf28dad35e24a0c Mon Sep 17 00:00:00 2001 From: Catalin Marinas <catalin.marinas@arm.com> Date: Fri, 9 Aug 2019 14:21:33 +0100 Subject: [PATCH] fixup! mm: untag user pointers passed to memory syscalls
mmap, mremap, munmap, brk added to the list of syscalls that accept tagged pointers.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> --- mm/mmap.c | 5 +++++ mm/mremap.c | 6 +----- 2 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c index 7e8c3e8ae75f..b766b633b7ae 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -201,6 +201,8 @@ SYSCALL_DEFINE1(brk, unsigned long, brk) bool downgraded = false; LIST_HEAD(uf); + brk = untagged_addr(brk); + if (down_write_killable(&mm->mmap_sem)) return -EINTR; @@ -1573,6 +1575,8 @@ unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len, struct file *file = NULL; unsigned long retval; + addr = untagged_addr(addr); + if (!(flags & MAP_ANONYMOUS)) { audit_mmap_fd(fd, flags); file = fget(fd); @@ -2874,6 +2878,7 @@ EXPORT_SYMBOL(vm_munmap); SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) { + addr = untagged_addr(addr); profile_munmap(addr); return __vm_munmap(addr, len, true); } diff --git a/mm/mremap.c b/mm/mremap.c index 64c9a3b8be0a..1fc8a29fbe3f 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -606,12 +606,8 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, LIST_HEAD(uf_unmap_early); LIST_HEAD(uf_unmap); - /* - * Architectures may interpret the tag passed to mmap as a background - * colour for the corresponding vma. For mremap we don't allow tagged - * new_addr to preserve similar behaviour to mmap. - */ addr = untagged_addr(addr); + new_addr = untagged_addr(new_addr); if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE)) return ret;
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