Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Daniel Borkmann says:

====================
pull-request: bpf 2017-12-17

The following pull-request contains BPF updates for your *net* tree.

The main changes are:

1) Fix a corner case in generic XDP where we have non-linear skbs
   but enough tailroom in the skb to not miss to linearizing there,
   from Song.

2) Fix BPF JIT bugs in s390x and ppc64 to not recache skb data when
   BPF context is not skb, from Daniel.

3) Fix a BPF JIT bug in sparc64 where recaching skb data after helper
   call would use the wrong register for the skb, from Daniel.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

arch/powerpc/net/bpf_jit_comp64.c

@@ -763,7 +763,8 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
 			func = (u8 *) __bpf_call_base + imm;
 
 			/* Save skb pointer if we need to re-cache skb data */
-			if (bpf_helper_changes_pkt_data(func))
+			if ((ctx->seen & SEEN_SKB) &&
+			    bpf_helper_changes_pkt_data(func))
 				PPC_BPF_STL(3, 1, bpf_jit_stack_local(ctx));
 
 			bpf_jit_emit_func_call(image, ctx, (u64)func);
@@ -772,7 +773,8 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
 			PPC_MR(b2p[BPF_REG_0], 3);
 
 			/* refresh skb cache */
-			if (bpf_helper_changes_pkt_data(func)) {
+			if ((ctx->seen & SEEN_SKB) &&
+			    bpf_helper_changes_pkt_data(func)) {
 				/* reload skb pointer to r3 */
 				PPC_BPF_LL(3, 1, bpf_jit_stack_local(ctx));
 				bpf_jit_emit_skb_loads(image, ctx);

arch/s390/net/bpf_jit_comp.c

@@ -55,8 +55,7 @@ struct bpf_jit {
 #define SEEN_LITERAL	8	/* code uses literals */
 #define SEEN_FUNC	16	/* calls C functions */
 #define SEEN_TAIL_CALL	32	/* code uses tail calls */
-#define SEEN_SKB_CHANGE	64	/* code changes skb data */
-#define SEEN_REG_AX	128	/* code uses constant blinding */
+#define SEEN_REG_AX	64	/* code uses constant blinding */
 #define SEEN_STACK	(SEEN_FUNC | SEEN_MEM | SEEN_SKB)
 
 /*
@@ -448,12 +447,12 @@ static void bpf_jit_prologue(struct bpf_jit *jit, u32 stack_depth)
 			EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0,
 				      REG_15, 152);
 	}
-	if (jit->seen & SEEN_SKB)
+	if (jit->seen & SEEN_SKB) {
 		emit_load_skb_data_hlen(jit);
-	if (jit->seen & SEEN_SKB_CHANGE)
 		/* stg %b1,ST_OFF_SKBP(%r0,%r15) */
 		EMIT6_DISP_LH(0xe3000000, 0x0024, BPF_REG_1, REG_0, REG_15,
 			      STK_OFF_SKBP);
+	}
 }
 
 /*
@@ -983,8 +982,8 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
 		EMIT2(0x0d00, REG_14, REG_W1);
 		/* lgr %b0,%r2: load return value into %b0 */
 		EMIT4(0xb9040000, BPF_REG_0, REG_2);
-		if (bpf_helper_changes_pkt_data((void *)func)) {
-			jit->seen |= SEEN_SKB_CHANGE;
+		if ((jit->seen & SEEN_SKB) &&
+		    bpf_helper_changes_pkt_data((void *)func)) {
 			/* lg %b1,ST_OFF_SKBP(%r15) */
 			EMIT6_DISP_LH(0xe3000000, 0x0004, BPF_REG_1, REG_0,
 				      REG_15, STK_OFF_SKBP);

arch/sparc/net/bpf_jit_comp_64.c

@@ -1245,14 +1245,16 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
 		u8 *func = ((u8 *)__bpf_call_base) + imm;
 
 		ctx->saw_call = true;
+		if (ctx->saw_ld_abs_ind && bpf_helper_changes_pkt_data(func))
+			emit_reg_move(bpf2sparc[BPF_REG_1], L7, ctx);
 
 		emit_call((u32 *)func, ctx);
 		emit_nop(ctx);
 
 		emit_reg_move(O0, bpf2sparc[BPF_REG_0], ctx);
 
-		if (bpf_helper_changes_pkt_data(func) && ctx->saw_ld_abs_ind)
-			load_skb_regs(ctx, bpf2sparc[BPF_REG_6]);
+		if (ctx->saw_ld_abs_ind && bpf_helper_changes_pkt_data(func))
+			load_skb_regs(ctx, L7);
 		break;
 	}
 

kernel/bpf/verifier.c

@@ -1674,7 +1674,13 @@ static int check_call(struct bpf_verifier_env *env, int func_id, int insn_idx)
 		return -EINVAL;
 	}
 
+	/* With LD_ABS/IND some JITs save/restore skb from r1. */
 	changes_data = bpf_helper_changes_pkt_data(fn->func);
+	if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) {
+		verbose(env, "kernel subsystem misconfigured func %s#%d: r1 != ctx\n",
+			func_id_name(func_id), func_id);
+		return -EINVAL;
+	}
 
 	memset(&meta, 0, sizeof(meta));
 	meta.pkt_access = fn->pkt_access;

lib/test_bpf.c

@@ -435,6 +435,41 @@ static int bpf_fill_ld_abs_vlan_push_pop(struct bpf_test *self)
 	return 0;
 }
 
+static int bpf_fill_ld_abs_vlan_push_pop2(struct bpf_test *self)
+{
+	struct bpf_insn *insn;
+
+	insn = kmalloc_array(16, sizeof(*insn), GFP_KERNEL);
+	if (!insn)
+		return -ENOMEM;
+
+	/* Due to func address being non-const, we need to
+	 * assemble this here.
+	 */
+	insn[0] = BPF_MOV64_REG(R6, R1);
+	insn[1] = BPF_LD_ABS(BPF_B, 0);
+	insn[2] = BPF_LD_ABS(BPF_H, 0);
+	insn[3] = BPF_LD_ABS(BPF_W, 0);
+	insn[4] = BPF_MOV64_REG(R7, R6);
+	insn[5] = BPF_MOV64_IMM(R6, 0);
+	insn[6] = BPF_MOV64_REG(R1, R7);
+	insn[7] = BPF_MOV64_IMM(R2, 1);
+	insn[8] = BPF_MOV64_IMM(R3, 2);
+	insn[9] = BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+			       bpf_skb_vlan_push_proto.func - __bpf_call_base);
+	insn[10] = BPF_MOV64_REG(R6, R7);
+	insn[11] = BPF_LD_ABS(BPF_B, 0);
+	insn[12] = BPF_LD_ABS(BPF_H, 0);
+	insn[13] = BPF_LD_ABS(BPF_W, 0);
+	insn[14] = BPF_MOV64_IMM(R0, 42);
+	insn[15] = BPF_EXIT_INSN();
+
+	self->u.ptr.insns = insn;
+	self->u.ptr.len = 16;
+
+	return 0;
+}
+
 static int bpf_fill_jump_around_ld_abs(struct bpf_test *self)
 {
 	unsigned int len = BPF_MAXINSNS;
@@ -6066,6 +6101,14 @@ static struct bpf_test tests[] = {
 		{},
 		{ {0x1, 0x42 } },
 	},
+	{
+		"LD_ABS with helper changing skb data",
+		{ },
+		INTERNAL,
+		{ 0x34 },
+		{ { ETH_HLEN, 42 } },
+		.fill_helper = bpf_fill_ld_abs_vlan_push_pop2,
+	},
 };
 
 static struct net_device dev;

net/core/dev.c

@@ -3904,7 +3904,7 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb,
 				     hroom > 0 ? ALIGN(hroom, NET_SKB_PAD) : 0,
 				     troom > 0 ? troom + 128 : 0, GFP_ATOMIC))
 			goto do_drop;
-		if (troom > 0 && __skb_linearize(skb))
+		if (skb_linearize(skb))
 			goto do_drop;
 	}
 

tools/testing/selftests/bpf/test_verifier.c

@@ -6116,6 +6116,30 @@ static struct bpf_test tests[] = {
 		},
 		.result = ACCEPT,
 	},
+	{
+		"ld_abs: tests on r6 and skb data reload helper",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
+			BPF_LD_ABS(BPF_B, 0),
+			BPF_LD_ABS(BPF_H, 0),
+			BPF_LD_ABS(BPF_W, 0),
+			BPF_MOV64_REG(BPF_REG_7, BPF_REG_6),
+			BPF_MOV64_IMM(BPF_REG_6, 0),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
+			BPF_MOV64_IMM(BPF_REG_2, 1),
+			BPF_MOV64_IMM(BPF_REG_3, 2),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+				     BPF_FUNC_skb_vlan_push),
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_7),
+			BPF_LD_ABS(BPF_B, 0),
+			BPF_LD_ABS(BPF_H, 0),
+			BPF_LD_ABS(BPF_W, 0),
+			BPF_MOV64_IMM(BPF_REG_0, 42),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.result = ACCEPT,
+	},
 	{
 		"ld_ind: check calling conv, r1",
 		.insns = {