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

Daniel Borkmann says:

====================
pull-request: bpf 2019-03-29

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

The main changes are:

1) Bug fix in BTF deduplication that was mishandling an equivalence
comparison, from Andrii.

2) libbpf Makefile fixes to properly link against libelf for the shared
object and to actually export AF_XDP's xsk.h header, from Björn.

3) Fix use after free in bpf inode eviction, from Daniel.

4) Fix a bug in skb creation out of cpumap redirect, from Jesper.

5) Remove an unnecessary and triggerable WARN_ONCE() in max number
of call stack frames checking in verifier, from Paul.
====================

Signed-off-by: David S. Miller <[e-mail]>

Documentation/bpf/btf.rst

···
 for the type. The maximum value of ``BTF_INT_BITS()`` is 128.
 
 The ``BTF_INT_OFFSET()`` specifies the starting bit offset to calculate values
-for this int. For example, a bitfield struct member has: * btf member bit
-offset 100 from the start of the structure, * btf member pointing to an int
-type, * the int type has ``BTF_INT_OFFSET() = 2`` and ``BTF_INT_BITS() = 4``
+for this int. For example, a bitfield struct member has:
+ * btf member bit offset 100 from the start of the structure,
+ * btf member pointing to an int type,
+ * the int type has ``BTF_INT_OFFSET() = 2`` and ``BTF_INT_BITS() = 4``
 
 Then in the struct memory layout, this member will occupy ``4`` bits starting
 from bits ``100 + 2 = 102``.
 
 Alternatively, the bitfield struct member can be the following to access the
 same bits as the above:
-
  * btf member bit offset 102,
  * btf member pointing to an int type,
  * the int type has ``BTF_INT_OFFSET() = 0`` and ``BTF_INT_BITS() = 4``

kernel/bpf/cpumap.c

···
 static struct sk_buff *cpu_map_build_skb(struct bpf_cpu_map_entry *rcpu,
 					 struct xdp_frame *xdpf)
 {
+	unsigned int hard_start_headroom;
 	unsigned int frame_size;
 	void *pkt_data_start;
 	struct sk_buff *skb;
+
+	/* Part of headroom was reserved to xdpf */
+	hard_start_headroom = sizeof(struct xdp_frame) +  xdpf->headroom;
 
 	/* build_skb need to place skb_shared_info after SKB end, and
 	 * also want to know the memory "truesize".  Thus, need to
···
 	 * is not at a fixed memory location, with mixed length
 	 * packets, which is bad for cache-line hotness.
 	 */
-	frame_size = SKB_DATA_ALIGN(xdpf->len + xdpf->headroom) +
+	frame_size = SKB_DATA_ALIGN(xdpf->len + hard_start_headroom) +
 		SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 
-	pkt_data_start = xdpf->data - xdpf->headroom;
+	pkt_data_start = xdpf->data - hard_start_headroom;
 	skb = build_skb(pkt_data_start, frame_size);
 	if (!skb)
 		return NULL;
 
-	skb_reserve(skb, xdpf->headroom);
+	skb_reserve(skb, hard_start_headroom);
 	__skb_put(skb, xdpf->len);
 	if (xdpf->metasize)
 		skb_metadata_set(skb, xdpf->metasize);
···
 	 * - HW RX hash			(skb_set_hash)
 	 * - RX ring dev queue index	(skb_record_rx_queue)
 	 */
+
+	/* Allow SKB to reuse area used by xdp_frame */
+	xdp_scrub_frame(xdpf);
 
 	return skb;
 }

kernel/bpf/inode.c

···
 }
 EXPORT_SYMBOL(bpf_prog_get_type_path);
 
-static void bpf_evict_inode(struct inode *inode)
-{
-	enum bpf_type type;
-
-	truncate_inode_pages_final(&inode->i_data);
-	clear_inode(inode);
-
-	if (S_ISLNK(inode->i_mode))
-		kfree(inode->i_link);
-	if (!bpf_inode_type(inode, &type))
-		bpf_any_put(inode->i_private, type);
-}
-
 /*
  * Display the mount options in /proc/mounts.
  */
···
 	return 0;
 }
 
+static void bpf_destroy_inode_deferred(struct rcu_head *head)
+{
+	struct inode *inode = container_of(head, struct inode, i_rcu);
+	enum bpf_type type;
+
+	if (S_ISLNK(inode->i_mode))
+		kfree(inode->i_link);
+	if (!bpf_inode_type(inode, &type))
+		bpf_any_put(inode->i_private, type);
+	free_inode_nonrcu(inode);
+}
+
+static void bpf_destroy_inode(struct inode *inode)
+{
+	call_rcu(&inode->i_rcu, bpf_destroy_inode_deferred);
+}
+
 static const struct super_operations bpf_super_ops = {
 	.statfs		= simple_statfs,
 	.drop_inode	= generic_delete_inode,
 	.show_options	= bpf_show_options,
-	.evict_inode	= bpf_evict_inode,
+	.destroy_inode	= bpf_destroy_inode,
 };
 
 enum {

kernel/bpf/verifier.c

···
 		}
 		frame++;
 		if (frame >= MAX_CALL_FRAMES) {
-			WARN_ONCE(1, "verifier bug. Call stack is too deep\n");
-			return -EFAULT;
+			verbose(env, "the call stack of %d frames is too deep !\n",
+				frame);
+			return -E2BIG;
 		}
 		goto process_func;
 	}

tools/lib/bpf/Makefile

···
 
 $(OUTPUT)libbpf.so.$(LIBBPF_VERSION): $(BPF_IN)
 	$(QUIET_LINK)$(CC) --shared -Wl,-soname,libbpf.so.$(VERSION) \
-				    -Wl,--version-script=$(VERSION_SCRIPT) $^ -o $@
+				    -Wl,--version-script=$(VERSION_SCRIPT) $^ -lelf -o $@
 	@ln -sf $(@F) $(OUTPUT)libbpf.so
 	@ln -sf $(@F) $(OUTPUT)libbpf.so.$(VERSION)
 
···
 install_headers:
 	$(call QUIET_INSTALL, headers) \
 		$(call do_install,bpf.h,$(prefix)/include/bpf,644); \
-		$(call do_install,libbpf.h,$(prefix)/include/bpf,644);
-		$(call do_install,btf.h,$(prefix)/include/bpf,644);
+		$(call do_install,libbpf.h,$(prefix)/include/bpf,644); \
+		$(call do_install,btf.h,$(prefix)/include/bpf,644); \
+		$(call do_install,xsk.h,$(prefix)/include/bpf,644);
 
 install: install_lib
 

tools/lib/bpf/btf.c

···
 		return fwd_kind == real_kind;
 	}
 
+	if (cand_kind != canon_kind)
+		return 0;
+
 	switch (cand_kind) {
 	case BTF_KIND_INT:
 		return btf_equal_int(cand_type, canon_type);

tools/testing/selftests/bpf/test_btf.c

···
 	},
 },
 {
+	.descr = "dedup: void equiv check",
+	/*
+	 * // CU 1:
+	 * struct s {
+	 *	struct {} *x;
+	 * };
+	 * // CU 2:
+	 * struct s {
+	 *	int *x;
+	 * };
+	 */
+	.input = {
+		.raw_types = {
+			/* CU 1 */
+			BTF_STRUCT_ENC(0, 0, 1),				/* [1] struct {}  */
+			BTF_PTR_ENC(1),						/* [2] ptr -> [1] */
+			BTF_STRUCT_ENC(NAME_NTH(1), 1, 8),			/* [3] struct s   */
+				BTF_MEMBER_ENC(NAME_NTH(2), 2, 0),
+			/* CU 2 */
+			BTF_PTR_ENC(0),						/* [4] ptr -> void */
+			BTF_STRUCT_ENC(NAME_NTH(1), 1, 8),			/* [5] struct s   */
+				BTF_MEMBER_ENC(NAME_NTH(2), 4, 0),
+			BTF_END_RAW,
+		},
+		BTF_STR_SEC("\0s\0x"),
+	},
+	.expect = {
+		.raw_types = {
+			/* CU 1 */
+			BTF_STRUCT_ENC(0, 0, 1),				/* [1] struct {}  */
+			BTF_PTR_ENC(1),						/* [2] ptr -> [1] */
+			BTF_STRUCT_ENC(NAME_NTH(1), 1, 8),			/* [3] struct s   */
+				BTF_MEMBER_ENC(NAME_NTH(2), 2, 0),
+			/* CU 2 */
+			BTF_PTR_ENC(0),						/* [4] ptr -> void */
+			BTF_STRUCT_ENC(NAME_NTH(1), 1, 8),			/* [5] struct s   */
+				BTF_MEMBER_ENC(NAME_NTH(2), 4, 0),
+			BTF_END_RAW,
+		},
+		BTF_STR_SEC("\0s\0x"),
+	},
+	.opts = {
+		.dont_resolve_fwds = false,
+		.dedup_table_size = 1, /* force hash collisions */
+	},
+},
+{
 	.descr = "dedup: all possible kinds (no duplicates)",
 	.input = {
 		.raw_types = {

tools/testing/selftests/bpf/verifier/calls.c

···
 	.result = REJECT,
 },
 {
+	"calls: stack depth check in dead code",
+	.insns = {
+	/* main */
+	BPF_MOV64_IMM(BPF_REG_1, 0),
+	BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 1), /* call A */
+	BPF_EXIT_INSN(),
+	/* A */
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 1),
+	BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 2), /* call B */
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	/* B */
+	BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 1), /* call C */
+	BPF_EXIT_INSN(),
+	/* C */
+	BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 1), /* call D */
+	BPF_EXIT_INSN(),
+	/* D */
+	BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 1), /* call E */
+	BPF_EXIT_INSN(),
+	/* E */
+	BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 1), /* call F */
+	BPF_EXIT_INSN(),
+	/* F */
+	BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 1), /* call G */
+	BPF_EXIT_INSN(),
+	/* G */
+	BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 1), /* call H */
+	BPF_EXIT_INSN(),
+	/* H */
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.prog_type = BPF_PROG_TYPE_XDP,
+	.errstr = "call stack",
+	.result = REJECT,
+},
+{
 	"calls: spill into caller stack frame",
 	.insns = {
 	BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),