On Fri, Sep 12, 2014 at 10:35 AM, Daniel Borkmann <dbork...@redhat.com> wrote: > This is the ARM64 variant for 314beb9bcab ("x86: bpf_jit_comp: secure bpf > jit against spraying attacks"). > > Thanks to commit 11d91a770f1f ("arm64: Add CONFIG_DEBUG_SET_MODULE_RONX > support") which added necessary infrastructure, we can now implement > RO marking of eBPF generated JIT image pages and randomize start offset > for the JIT code, so that it does not reside directly on a page boundary > anymore. Likewise, the holes are filled with illegal instructions. > > This is basically the ARM64 variant of what we already have in ARM via > commit 55309dd3d4cd ("net: bpf: arm: address randomize and write protect > JIT code"). Moreover, this commit also presents a merge resolution due to > conflicts with commit 60a3b2253c41 ("net: bpf: make eBPF interpreter images > read-only") as we don't use kfree() in bpf_jit_free() anymore to release > the locked bpf_prog structure, but instead bpf_prog_unlock_free() through > a different allocator. > > JIT tested on aarch64 with BPF test suite. > > Reference: > http://mainisusuallyafunction.blogspot.com/2012/11/attacking-hardened-linux-systems-with.html > Signed-off-by: Daniel Borkmann <dbork...@redhat.com> > Cc: Zi Shen Lim <zlim....@gmail.com> > Cc: Will Deacon <will.dea...@arm.com> > Cc: Catalin Marinas <catalin.mari...@arm.com> > Cc: David S. Miller <da...@davemloft.net> > Cc: Alexei Starovoitov <a...@plumgrid.com> > --- > v1 -> v2: > - Use brk insn as suggested by Catalin, thanks a lot for > your feedback! Rest unchanged. > Note: > - This patch depends on net-next being merged to mainline due > to the mentioned merge conflict. > > arch/arm64/net/bpf_jit_comp.c | 38 +++++++++++++++++++++++++++++--------- > 1 file changed, 29 insertions(+), 9 deletions(-) > > diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c > index 7ae3354..4b71779 100644 > --- a/arch/arm64/net/bpf_jit_comp.c > +++ b/arch/arm64/net/bpf_jit_comp.c > @@ -19,7 +19,6 @@ > #define pr_fmt(fmt) "bpf_jit: " fmt > > #include <linux/filter.h> > -#include <linux/moduleloader.h> > #include <linux/printk.h> > #include <linux/skbuff.h> > #include <linux/slab.h> > @@ -119,6 +118,15 @@ static inline int bpf2a64_offset(int bpf_to, int > bpf_from, > return to - from; > } > > +static void jit_fill_hole(void *area, unsigned int size) > +{ > + /* We use brk #0x100 to trigger a fault. */ > + u32 *ptr, fill_ins = 0xd4202000;
Missed this on first round of review, I think we also need cpu_to_le32(...) here. > + /* We are guaranteed to have aligned memory. */ > + for (ptr = area; size >= sizeof(u32); size -= sizeof(u32)) > + *ptr++ = fill_ins; > +} > + [...] Thanks Daniel. -- 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/