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

Daniel Borkmann says:

====================
pull-request: bpf 2022-01-19

We've added 12 non-merge commits during the last 8 day(s) which contain
a total of 12 files changed, 262 insertions(+), 64 deletions(-).

The main changes are:

1) Various verifier fixes mainly around register offset handling when
   passed to helper functions, from Daniel Borkmann.

2) Fix XDP BPF link handling to assert program type,
   from Toke Høiland-Jørgensen.

3) Fix regression in mount parameter handling for BPF fs,
   from Yafang Shao.

4) Fix incorrect integer literal when marking scratched stack slots
   in verifier, from Christy Lee.

* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  bpf, selftests: Add ringbuf memory type confusion test
  bpf, selftests: Add various ringbuf tests with invalid offset
  bpf: Fix ringbuf memory type confusion when passing to helpers
  bpf: Fix out of bounds access for ringbuf helpers
  bpf: Generally fix helper register offset check
  bpf: Mark PTR_TO_FUNC register initially with zero offset
  bpf: Generalize check_ctx_reg for reuse with other types
  bpf: Fix incorrect integer literal used for marking scratched stack.
  bpf/selftests: Add check for updating XDP bpf_link with wrong program type
  bpf/selftests: convert xdp_link test to ASSERT_* macros
  xdp: check prog type before updating BPF link
  bpf: Fix mount source show for bpffs
====================

Link: https://lore.kernel.org/r/20220119011825.9082-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 56 insertions, 25 deletions

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index bfb45381fb3f..a39eedecc93a 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -570,6 +570,8 @@ static const char *reg_type_str(struct bpf_verifier_env *env,
 
 	if (type & MEM_RDONLY)
 		strncpy(prefix, "rdonly_", 16);
+	if (type & MEM_ALLOC)
+		strncpy(prefix, "alloc_", 16);
 
 	snprintf(env->type_str_buf, TYPE_STR_BUF_LEN, "%s%s%s",
 		 prefix, str[base_type(type)], postfix);
@@ -616,7 +618,7 @@ static void mark_reg_scratched(struct bpf_verifier_env *env, u32 regno)
 
 static void mark_stack_slot_scratched(struct bpf_verifier_env *env, u32 spi)
 {
-	env->scratched_stack_slots |= 1UL << spi;
+	env->scratched_stack_slots |= 1ULL << spi;
 }
 
 static bool reg_scratched(const struct bpf_verifier_env *env, u32 regno)
@@ -637,14 +639,14 @@ static bool verifier_state_scratched(const struct bpf_verifier_env *env)
 static void mark_verifier_state_clean(struct bpf_verifier_env *env)
 {
 	env->scratched_regs = 0U;
-	env->scratched_stack_slots = 0UL;
+	env->scratched_stack_slots = 0ULL;
 }
 
 /* Used for printing the entire verifier state. */
 static void mark_verifier_state_scratched(struct bpf_verifier_env *env)
 {
 	env->scratched_regs = ~0U;
-	env->scratched_stack_slots = ~0UL;
+	env->scratched_stack_slots = ~0ULL;
 }
 
 /* The reg state of a pointer or a bounded scalar was saved when
@@ -3969,16 +3971,17 @@ static int get_callee_stack_depth(struct bpf_verifier_env *env,
 }
 #endif
 
-int check_ctx_reg(struct bpf_verifier_env *env,
-		  const struct bpf_reg_state *reg, int regno)
+static int __check_ptr_off_reg(struct bpf_verifier_env *env,
+			       const struct bpf_reg_state *reg, int regno,
+			       bool fixed_off_ok)
 {
-	/* Access to ctx or passing it to a helper is only allowed in
-	 * its original, unmodified form.
+	/* Access to this pointer-typed register or passing it to a helper
+	 * is only allowed in its original, unmodified form.
 	 */
 
-	if (reg->off) {
-		verbose(env, "dereference of modified ctx ptr R%d off=%d disallowed\n",
-			regno, reg->off);
+	if (!fixed_off_ok && reg->off) {
+		verbose(env, "dereference of modified %s ptr R%d off=%d disallowed\n",
+			reg_type_str(env, reg->type), regno, reg->off);
 		return -EACCES;
 	}
 
@@ -3986,13 +3989,20 @@ int check_ctx_reg(struct bpf_verifier_env *env,
 		char tn_buf[48];
 
 		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
-		verbose(env, "variable ctx access var_off=%s disallowed\n", tn_buf);
+		verbose(env, "variable %s access var_off=%s disallowed\n",
+			reg_type_str(env, reg->type), tn_buf);
 		return -EACCES;
 	}
 
 	return 0;
 }
 
+int check_ptr_off_reg(struct bpf_verifier_env *env,
+		      const struct bpf_reg_state *reg, int regno)
+{
+	return __check_ptr_off_reg(env, reg, regno, false);
+}
+
 static int __check_buffer_access(struct bpf_verifier_env *env,
 				 const char *buf_info,
 				 const struct bpf_reg_state *reg,
@@ -4437,7 +4447,7 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 			return -EACCES;
 		}
 
-		err = check_ctx_reg(env, reg, regno);
+		err = check_ptr_off_reg(env, reg, regno);
 		if (err < 0)
 			return err;
 
@@ -5127,6 +5137,7 @@ static const struct bpf_reg_types mem_types = {
 		PTR_TO_MAP_KEY,
 		PTR_TO_MAP_VALUE,
 		PTR_TO_MEM,
+		PTR_TO_MEM | MEM_ALLOC,
 		PTR_TO_BUF,
 	},
 };
@@ -5144,7 +5155,7 @@ static const struct bpf_reg_types int_ptr_types = {
 static const struct bpf_reg_types fullsock_types = { .types = { PTR_TO_SOCKET } };
 static const struct bpf_reg_types scalar_types = { .types = { SCALAR_VALUE } };
 static const struct bpf_reg_types context_types = { .types = { PTR_TO_CTX } };
-static const struct bpf_reg_types alloc_mem_types = { .types = { PTR_TO_MEM } };
+static const struct bpf_reg_types alloc_mem_types = { .types = { PTR_TO_MEM | MEM_ALLOC } };
 static const struct bpf_reg_types const_map_ptr_types = { .types = { CONST_PTR_TO_MAP } };
 static const struct bpf_reg_types btf_ptr_types = { .types = { PTR_TO_BTF_ID } };
 static const struct bpf_reg_types spin_lock_types = { .types = { PTR_TO_MAP_VALUE } };
@@ -5244,12 +5255,6 @@ found:
 				kernel_type_name(btf_vmlinux, *arg_btf_id));
 			return -EACCES;
 		}
-
-		if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
-			verbose(env, "R%d is a pointer to in-kernel struct with non-zero offset\n",
-				regno);
-			return -EACCES;
-		}
 	}
 
 	return 0;
@@ -5304,10 +5309,33 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 	if (err)
 		return err;
 
-	if (type == PTR_TO_CTX) {
-		err = check_ctx_reg(env, reg, regno);
+	switch ((u32)type) {
+	case SCALAR_VALUE:
+	/* Pointer types where reg offset is explicitly allowed: */
+	case PTR_TO_PACKET:
+	case PTR_TO_PACKET_META:
+	case PTR_TO_MAP_KEY:
+	case PTR_TO_MAP_VALUE:
+	case PTR_TO_MEM:
+	case PTR_TO_MEM | MEM_RDONLY:
+	case PTR_TO_MEM | MEM_ALLOC:
+	case PTR_TO_BUF:
+	case PTR_TO_BUF | MEM_RDONLY:
+	case PTR_TO_STACK:
+		/* Some of the argument types nevertheless require a
+		 * zero register offset.
+		 */
+		if (arg_type == ARG_PTR_TO_ALLOC_MEM)
+			goto force_off_check;
+		break;
+	/* All the rest must be rejected: */
+	default:
+force_off_check:
+		err = __check_ptr_off_reg(env, reg, regno,
+					  type == PTR_TO_BTF_ID);
 		if (err < 0)
 			return err;
+		break;
 	}
 
 skip_type_check:
@@ -9507,9 +9535,13 @@ static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
 		return 0;
 	}
 
-	if (insn->src_reg == BPF_PSEUDO_BTF_ID) {
-		mark_reg_known_zero(env, regs, insn->dst_reg);
+	/* All special src_reg cases are listed below. From this point onwards
+	 * we either succeed and assign a corresponding dst_reg->type after
+	 * zeroing the offset, or fail and reject the program.
+	 */
+	mark_reg_known_zero(env, regs, insn->dst_reg);
 
+	if (insn->src_reg == BPF_PSEUDO_BTF_ID) {
 		dst_reg->type = aux->btf_var.reg_type;
 		switch (base_type(dst_reg->type)) {
 		case PTR_TO_MEM:
@@ -9547,7 +9579,6 @@ static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
 	}
 
 	map = env->used_maps[aux->map_index];
-	mark_reg_known_zero(env, regs, insn->dst_reg);
 	dst_reg->map_ptr = map;
 
 	if (insn->src_reg == BPF_PSEUDO_MAP_VALUE ||
@@ -9651,7 +9682,7 @@ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
 			return err;
 	}
 
-	err = check_ctx_reg(env, &regs[ctx_reg], ctx_reg);
+	err = check_ptr_off_reg(env, &regs[ctx_reg], ctx_reg);
 	if (err < 0)
 		return err;