From 7aed35cb65348fc8b9ce0c2394ff675e5fc750da Mon Sep 17 00:00:00 2001 From: Nicolas Schichan Date: Tue, 21 Jul 2015 14:14:12 +0200 Subject: ARM: net: fix condition for load_order > 0 when translating load instructions. To check whether the load should take the fast path or not, the code would check that (r_skb_hlen - load_order) is greater than the offset of the access using an "Unsigned higher or same" condition. For halfword accesses and an skb length of 1 at offset 0, that test is valid, as we end up comparing 0xffffffff(-1) and 0, so the fast path is taken and the filter allows the load to wrongly succeed. A similar issue exists for word loads at offset 0 and an skb length of less than 4. Fix that by using the condition "Signed greater than or equal" condition for the fast path code for load orders greater than 0. Signed-off-by: Nicolas Schichan Signed-off-by: David S. Miller --- arch/arm/net/bpf_jit_32.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c index 4550d247e308..21f5ace156fd 100644 --- a/arch/arm/net/bpf_jit_32.c +++ b/arch/arm/net/bpf_jit_32.c @@ -547,7 +547,7 @@ load_common: emit(ARM_SUB_I(r_scratch, r_skb_hl, 1 << load_order), ctx); emit(ARM_CMP_R(r_scratch, r_off), ctx); - condt = ARM_COND_HS; + condt = ARM_COND_GE; } else { emit(ARM_CMP_R(r_skb_hl, r_off), ctx); condt = ARM_COND_HI; -- cgit v1.2.3 From 6d715e301e950e3314d590bdbabf0c26e4fed94b Mon Sep 17 00:00:00 2001 From: Nicolas Schichan Date: Tue, 21 Jul 2015 14:14:13 +0200 Subject: ARM: net: handle negative offsets in BPF JIT. Previously, the JIT would reject negative offsets known during code generation and mishandle negative offsets provided at runtime. Fix that by calling bpf_internal_load_pointer_neg_helper() appropriately in the jit_get_skb_{b,h,w} slow path helpers and by forcing the execution flow to the slow path helpers when the offset is negative. Signed-off-by: Nicolas Schichan Signed-off-by: David S. Miller --- arch/arm/net/bpf_jit_32.c | 47 ++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 38 insertions(+), 9 deletions(-) (limited to 'arch') diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c index 21f5ace156fd..d9b25242f743 100644 --- a/arch/arm/net/bpf_jit_32.c +++ b/arch/arm/net/bpf_jit_32.c @@ -74,32 +74,52 @@ struct jit_ctx { int bpf_jit_enable __read_mostly; -static u64 jit_get_skb_b(struct sk_buff *skb, unsigned offset) +static inline int call_neg_helper(struct sk_buff *skb, int offset, void *ret, + unsigned int size) +{ + void *ptr = bpf_internal_load_pointer_neg_helper(skb, offset, size); + + if (!ptr) + return -EFAULT; + memcpy(ret, ptr, size); + return 0; +} + +static u64 jit_get_skb_b(struct sk_buff *skb, int offset) { u8 ret; int err; - err = skb_copy_bits(skb, offset, &ret, 1); + if (offset < 0) + err = call_neg_helper(skb, offset, &ret, 1); + else + err = skb_copy_bits(skb, offset, &ret, 1); return (u64)err << 32 | ret; } -static u64 jit_get_skb_h(struct sk_buff *skb, unsigned offset) +static u64 jit_get_skb_h(struct sk_buff *skb, int offset) { u16 ret; int err; - err = skb_copy_bits(skb, offset, &ret, 2); + if (offset < 0) + err = call_neg_helper(skb, offset, &ret, 2); + else + err = skb_copy_bits(skb, offset, &ret, 2); return (u64)err << 32 | ntohs(ret); } -static u64 jit_get_skb_w(struct sk_buff *skb, unsigned offset) +static u64 jit_get_skb_w(struct sk_buff *skb, int offset) { u32 ret; int err; - err = skb_copy_bits(skb, offset, &ret, 4); + if (offset < 0) + err = call_neg_helper(skb, offset, &ret, 4); + else + err = skb_copy_bits(skb, offset, &ret, 4); return (u64)err << 32 | ntohl(ret); } @@ -536,9 +556,6 @@ static int build_body(struct jit_ctx *ctx) case BPF_LD | BPF_B | BPF_ABS: load_order = 0; load: - /* the interpreter will deal with the negative K */ - if ((int)k < 0) - return -ENOTSUPP; emit_mov_i(r_off, k, ctx); load_common: ctx->seen |= SEEN_DATA | SEEN_CALL; @@ -553,6 +570,18 @@ load_common: condt = ARM_COND_HI; } + /* + * test for negative offset, only if we are + * currently scheduled to take the fast + * path. this will update the flags so that + * the slowpath instruction are ignored if the + * offset is negative. + * + * for loard_order == 0 the HI condition will + * make loads at offset 0 take the slow path too. + */ + _emit(condt, ARM_CMP_I(r_off, 0), ctx); + _emit(condt, ARM_ADD_R(r_scratch, r_off, r_skb_data), ctx); -- cgit v1.2.3 From c18fe54b3f8d7daa6a43270f82676d6a563582a4 Mon Sep 17 00:00:00 2001 From: Nicolas Schichan Date: Tue, 21 Jul 2015 14:14:14 +0200 Subject: ARM: net: fix vlan access instructions in ARM JIT. This makes BPF_ANC | SKF_AD_VLAN_TAG and BPF_ANC | SKF_AD_VLAN_TAG_PRESENT have the same behaviour as the in kernel VM and makes the test_bpf LD_VLAN_TAG and LD_VLAN_TAG_PRESENT tests pass. Signed-off-by: Nicolas Schichan Signed-off-by: David S. Miller --- arch/arm/net/bpf_jit_32.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'arch') diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c index d9b25242f743..c011e2296cb1 100644 --- a/arch/arm/net/bpf_jit_32.c +++ b/arch/arm/net/bpf_jit_32.c @@ -889,9 +889,11 @@ b_epilogue: off = offsetof(struct sk_buff, vlan_tci); emit(ARM_LDRH_I(r_A, r_skb, off), ctx); if (code == (BPF_ANC | SKF_AD_VLAN_TAG)) - OP_IMM3(ARM_AND, r_A, r_A, VLAN_VID_MASK, ctx); - else - OP_IMM3(ARM_AND, r_A, r_A, VLAN_TAG_PRESENT, ctx); + OP_IMM3(ARM_AND, r_A, r_A, ~VLAN_TAG_PRESENT, ctx); + else { + OP_IMM3(ARM_LSR, r_A, r_A, 12, ctx); + OP_IMM3(ARM_AND, r_A, r_A, 0x1, ctx); + } break; case BPF_ANC | SKF_AD_QUEUE: ctx->seen |= SEEN_SKB; -- cgit v1.2.3