| Message ID | 51f44a12c4e81c9edea8dcd268f820f5d1fad87c.1559580831.git.andreyknvl@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | arm64: untag user pointers passed to the kernel | expand |
On Mon, Jun 03, 2019 at 06:55:10PM +0200, Andrey Konovalov wrote: > This patch is a part of a series that extends arm64 kernel ABI to allow to > pass tagged user pointers (with the top byte set to something else other > than 0x00) as syscall arguments. > > In copy_mount_options a user address is being subtracted from TASK_SIZE. > If the address is lower than TASK_SIZE, the size is calculated to not > allow the exact_copy_from_user() call to cross TASK_SIZE boundary. > However if the address is tagged, then the size will be calculated > incorrectly. > > Untag the address before subtracting. > > Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> > Signed-off-by: Andrey Konovalov <andreyknvl@google.com> One thing I just noticed in the commit titles... "arm64" is in the prefix, but these are arch-indep areas. Should the ", arm64" be left out? I would expect, instead: fs/namespace: untag user pointers in copy_mount_options Reviewed-by: Kees Cook <keescook@chromium.org> -Kees > --- > fs/namespace.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/namespace.c b/fs/namespace.c > index b26778bdc236..2e85712a19ed 100644 > --- a/fs/namespace.c > +++ b/fs/namespace.c > @@ -2993,7 +2993,7 @@ void *copy_mount_options(const void __user * data) > * the remainder of the page. > */ > /* copy_from_user cannot cross TASK_SIZE ! */ > - size = TASK_SIZE - (unsigned long)data; > + size = TASK_SIZE - (unsigned long)untagged_addr(data); > if (size > PAGE_SIZE) > size = PAGE_SIZE; > > -- > 2.22.0.rc1.311.g5d7573a151-goog >
On Sat, Jun 8, 2019 at 6:02 AM Kees Cook <keescook@chromium.org> wrote: > > On Mon, Jun 03, 2019 at 06:55:10PM +0200, Andrey Konovalov wrote: > > This patch is a part of a series that extends arm64 kernel ABI to allow to > > pass tagged user pointers (with the top byte set to something else other > > than 0x00) as syscall arguments. > > > > In copy_mount_options a user address is being subtracted from TASK_SIZE. > > If the address is lower than TASK_SIZE, the size is calculated to not > > allow the exact_copy_from_user() call to cross TASK_SIZE boundary. > > However if the address is tagged, then the size will be calculated > > incorrectly. > > > > Untag the address before subtracting. > > > > Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com> > > One thing I just noticed in the commit titles... "arm64" is in the > prefix, but these are arch-indep areas. Should the ", arm64" be left > out? > > I would expect, instead: > > fs/namespace: untag user pointers in copy_mount_options Hm, I've added the arm64 tag in all of the patches because they are related to changes in arm64 kernel ABI. I can remove it from all the patches that only touch common code if you think that it makes sense. Thanks! > > Reviewed-by: Kees Cook <keescook@chromium.org> > > -Kees > > > --- > > fs/namespace.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/fs/namespace.c b/fs/namespace.c > > index b26778bdc236..2e85712a19ed 100644 > > --- a/fs/namespace.c > > +++ b/fs/namespace.c > > @@ -2993,7 +2993,7 @@ void *copy_mount_options(const void __user * data) > > * the remainder of the page. > > */ > > /* copy_from_user cannot cross TASK_SIZE ! */ > > - size = TASK_SIZE - (unsigned long)data; > > + size = TASK_SIZE - (unsigned long)untagged_addr(data); > > if (size > PAGE_SIZE) > > size = PAGE_SIZE; > > > > -- > > 2.22.0.rc1.311.g5d7573a151-goog > > > > -- > Kees Cook
On Tue, Jun 11, 2019 at 4:38 PM Andrey Konovalov <andreyknvl@google.com> wrote: > > On Sat, Jun 8, 2019 at 6:02 AM Kees Cook <keescook@chromium.org> wrote: > > > > On Mon, Jun 03, 2019 at 06:55:10PM +0200, Andrey Konovalov wrote: > > > This patch is a part of a series that extends arm64 kernel ABI to allow to > > > pass tagged user pointers (with the top byte set to something else other > > > than 0x00) as syscall arguments. > > > > > > In copy_mount_options a user address is being subtracted from TASK_SIZE. > > > If the address is lower than TASK_SIZE, the size is calculated to not > > > allow the exact_copy_from_user() call to cross TASK_SIZE boundary. > > > However if the address is tagged, then the size will be calculated > > > incorrectly. > > > > > > Untag the address before subtracting. > > > > > > Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> > > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com> > > > > One thing I just noticed in the commit titles... "arm64" is in the > > prefix, but these are arch-indep areas. Should the ", arm64" be left > > out? > > > > I would expect, instead: > > > > fs/namespace: untag user pointers in copy_mount_options > > Hm, I've added the arm64 tag in all of the patches because they are > related to changes in arm64 kernel ABI. I can remove it from all the > patches that only touch common code if you think that it makes sense. I'll keep the arm64 tags in commit titles for v17. Please reply explicitly if you think I should remove them. Thanks! :) > > Thanks! > > > > > Reviewed-by: Kees Cook <keescook@chromium.org> > > > > -Kees > > > > > --- > > > fs/namespace.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/fs/namespace.c b/fs/namespace.c > > > index b26778bdc236..2e85712a19ed 100644 > > > --- a/fs/namespace.c > > > +++ b/fs/namespace.c > > > @@ -2993,7 +2993,7 @@ void *copy_mount_options(const void __user * data) > > > * the remainder of the page. > > > */ > > > /* copy_from_user cannot cross TASK_SIZE ! */ > > > - size = TASK_SIZE - (unsigned long)data; > > > + size = TASK_SIZE - (unsigned long)untagged_addr(data); > > > if (size > PAGE_SIZE) > > > size = PAGE_SIZE; > > > > > > -- > > > 2.22.0.rc1.311.g5d7573a151-goog > > > > > > > -- > > Kees Cook
diff --git a/fs/namespace.c b/fs/namespace.c index b26778bdc236..2e85712a19ed 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2993,7 +2993,7 @@ void *copy_mount_options(const void __user * data) * the remainder of the page. */ /* copy_from_user cannot cross TASK_SIZE ! */ - size = TASK_SIZE - (unsigned long)data; + size = TASK_SIZE - (unsigned long)untagged_addr(data); if (size > PAGE_SIZE) size = PAGE_SIZE;