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-rw-r--r--include/linux/bpf_verifier.h2
-rw-r--r--kernel/bpf/verifier.c129
2 files changed, 108 insertions, 23 deletions
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index e83ef6f6bf43..306869d4743b 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -45,7 +45,7 @@ struct bpf_reg_state {
enum bpf_reg_type type;
union {
/* valid when type == PTR_TO_PACKET */
- u16 range;
+ int range;
/* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE |
* PTR_TO_MAP_VALUE_OR_NULL
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 10da26e55130..7b1f85aa9741 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2739,7 +2739,9 @@ static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off,
regno);
return -EACCES;
}
- err = __check_mem_access(env, regno, off, size, reg->range,
+
+ err = reg->range < 0 ? -EINVAL :
+ __check_mem_access(env, regno, off, size, reg->range,
zero_size_allowed);
if (err) {
verbose(env, "R%d offset is outside of the packet\n", regno);
@@ -4697,6 +4699,32 @@ static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
__clear_all_pkt_pointers(env, vstate->frame[i]);
}
+enum {
+ AT_PKT_END = -1,
+ BEYOND_PKT_END = -2,
+};
+
+static void mark_pkt_end(struct bpf_verifier_state *vstate, int regn, bool range_open)
+{
+ struct bpf_func_state *state = vstate->frame[vstate->curframe];
+ struct bpf_reg_state *reg = &state->regs[regn];
+
+ if (reg->type != PTR_TO_PACKET)
+ /* PTR_TO_PACKET_META is not supported yet */
+ return;
+
+ /* The 'reg' is pkt > pkt_end or pkt >= pkt_end.
+ * How far beyond pkt_end it goes is unknown.
+ * if (!range_open) it's the case of pkt >= pkt_end
+ * if (range_open) it's the case of pkt > pkt_end
+ * hence this pointer is at least 1 byte bigger than pkt_end
+ */
+ if (range_open)
+ reg->range = BEYOND_PKT_END;
+ else
+ reg->range = AT_PKT_END;
+}
+
static void release_reg_references(struct bpf_verifier_env *env,
struct bpf_func_state *state,
int ref_obj_id)
@@ -6708,7 +6736,7 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
static void __find_good_pkt_pointers(struct bpf_func_state *state,
struct bpf_reg_state *dst_reg,
- enum bpf_reg_type type, u16 new_range)
+ enum bpf_reg_type type, int new_range)
{
struct bpf_reg_state *reg;
int i;
@@ -6733,8 +6761,7 @@ static void find_good_pkt_pointers(struct bpf_verifier_state *vstate,
enum bpf_reg_type type,
bool range_right_open)
{
- u16 new_range;
- int i;
+ int new_range, i;
if (dst_reg->off < 0 ||
(dst_reg->off == 0 && range_right_open))
@@ -6985,6 +7012,67 @@ static int is_branch_taken(struct bpf_reg_state *reg, u64 val, u8 opcode,
return is_branch64_taken(reg, val, opcode);
}
+static int flip_opcode(u32 opcode)
+{
+ /* How can we transform "a <op> b" into "b <op> a"? */
+ static const u8 opcode_flip[16] = {
+ /* these stay the same */
+ [BPF_JEQ >> 4] = BPF_JEQ,
+ [BPF_JNE >> 4] = BPF_JNE,
+ [BPF_JSET >> 4] = BPF_JSET,
+ /* these swap "lesser" and "greater" (L and G in the opcodes) */
+ [BPF_JGE >> 4] = BPF_JLE,
+ [BPF_JGT >> 4] = BPF_JLT,
+ [BPF_JLE >> 4] = BPF_JGE,
+ [BPF_JLT >> 4] = BPF_JGT,
+ [BPF_JSGE >> 4] = BPF_JSLE,
+ [BPF_JSGT >> 4] = BPF_JSLT,
+ [BPF_JSLE >> 4] = BPF_JSGE,
+ [BPF_JSLT >> 4] = BPF_JSGT
+ };
+ return opcode_flip[opcode >> 4];
+}
+
+static int is_pkt_ptr_branch_taken(struct bpf_reg_state *dst_reg,
+ struct bpf_reg_state *src_reg,
+ u8 opcode)
+{
+ struct bpf_reg_state *pkt;
+
+ if (src_reg->type == PTR_TO_PACKET_END) {
+ pkt = dst_reg;
+ } else if (dst_reg->type == PTR_TO_PACKET_END) {
+ pkt = src_reg;
+ opcode = flip_opcode(opcode);
+ } else {
+ return -1;
+ }
+
+ if (pkt->range >= 0)
+ return -1;
+
+ switch (opcode) {
+ case BPF_JLE:
+ /* pkt <= pkt_end */
+ fallthrough;
+ case BPF_JGT:
+ /* pkt > pkt_end */
+ if (pkt->range == BEYOND_PKT_END)
+ /* pkt has at last one extra byte beyond pkt_end */
+ return opcode == BPF_JGT;
+ break;
+ case BPF_JLT:
+ /* pkt < pkt_end */
+ fallthrough;
+ case BPF_JGE:
+ /* pkt >= pkt_end */
+ if (pkt->range == BEYOND_PKT_END || pkt->range == AT_PKT_END)
+ return opcode == BPF_JGE;
+ break;
+ }
+ return -1;
+}
+
/* Adjusts the register min/max values in the case that the dst_reg is the
* variable register that we are working on, and src_reg is a constant or we're
* simply doing a BPF_K check.
@@ -7148,23 +7236,7 @@ static void reg_set_min_max_inv(struct bpf_reg_state *true_reg,
u64 val, u32 val32,
u8 opcode, bool is_jmp32)
{
- /* How can we transform "a <op> b" into "b <op> a"? */
- static const u8 opcode_flip[16] = {
- /* these stay the same */
- [BPF_JEQ >> 4] = BPF_JEQ,
- [BPF_JNE >> 4] = BPF_JNE,
- [BPF_JSET >> 4] = BPF_JSET,
- /* these swap "lesser" and "greater" (L and G in the opcodes) */
- [BPF_JGE >> 4] = BPF_JLE,
- [BPF_JGT >> 4] = BPF_JLT,
- [BPF_JLE >> 4] = BPF_JGE,
- [BPF_JLT >> 4] = BPF_JGT,
- [BPF_JSGE >> 4] = BPF_JSLE,
- [BPF_JSGT >> 4] = BPF_JSLT,
- [BPF_JSLE >> 4] = BPF_JSGE,
- [BPF_JSLT >> 4] = BPF_JSGT
- };
- opcode = opcode_flip[opcode >> 4];
+ opcode = flip_opcode(opcode);
/* This uses zero as "not present in table"; luckily the zero opcode,
* BPF_JA, can't get here.
*/
@@ -7346,6 +7418,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn,
/* pkt_data' > pkt_end, pkt_meta' > pkt_data */
find_good_pkt_pointers(this_branch, dst_reg,
dst_reg->type, false);
+ mark_pkt_end(other_branch, insn->dst_reg, true);
} else if ((dst_reg->type == PTR_TO_PACKET_END &&
src_reg->type == PTR_TO_PACKET) ||
(reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
@@ -7353,6 +7426,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn,
/* pkt_end > pkt_data', pkt_data > pkt_meta' */
find_good_pkt_pointers(other_branch, src_reg,
src_reg->type, true);
+ mark_pkt_end(this_branch, insn->src_reg, false);
} else {
return false;
}
@@ -7365,6 +7439,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn,
/* pkt_data' < pkt_end, pkt_meta' < pkt_data */
find_good_pkt_pointers(other_branch, dst_reg,
dst_reg->type, true);
+ mark_pkt_end(this_branch, insn->dst_reg, false);
} else if ((dst_reg->type == PTR_TO_PACKET_END &&
src_reg->type == PTR_TO_PACKET) ||
(reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
@@ -7372,6 +7447,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn,
/* pkt_end < pkt_data', pkt_data > pkt_meta' */
find_good_pkt_pointers(this_branch, src_reg,
src_reg->type, false);
+ mark_pkt_end(other_branch, insn->src_reg, true);
} else {
return false;
}
@@ -7384,6 +7460,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn,
/* pkt_data' >= pkt_end, pkt_meta' >= pkt_data */
find_good_pkt_pointers(this_branch, dst_reg,
dst_reg->type, true);
+ mark_pkt_end(other_branch, insn->dst_reg, false);
} else if ((dst_reg->type == PTR_TO_PACKET_END &&
src_reg->type == PTR_TO_PACKET) ||
(reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
@@ -7391,6 +7468,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn,
/* pkt_end >= pkt_data', pkt_data >= pkt_meta' */
find_good_pkt_pointers(other_branch, src_reg,
src_reg->type, false);
+ mark_pkt_end(this_branch, insn->src_reg, true);
} else {
return false;
}
@@ -7403,6 +7481,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn,
/* pkt_data' <= pkt_end, pkt_meta' <= pkt_data */
find_good_pkt_pointers(other_branch, dst_reg,
dst_reg->type, false);
+ mark_pkt_end(this_branch, insn->dst_reg, true);
} else if ((dst_reg->type == PTR_TO_PACKET_END &&
src_reg->type == PTR_TO_PACKET) ||
(reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
@@ -7410,6 +7489,7 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn,
/* pkt_end <= pkt_data', pkt_data <= pkt_meta' */
find_good_pkt_pointers(this_branch, src_reg,
src_reg->type, true);
+ mark_pkt_end(other_branch, insn->src_reg, false);
} else {
return false;
}
@@ -7509,6 +7589,10 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,
src_reg->var_off.value,
opcode,
is_jmp32);
+ } else if (reg_is_pkt_pointer_any(dst_reg) &&
+ reg_is_pkt_pointer_any(src_reg) &&
+ !is_jmp32) {
+ pred = is_pkt_ptr_branch_taken(dst_reg, src_reg, opcode);
}
if (pred >= 0) {
@@ -7517,7 +7601,8 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,
*/
if (!__is_pointer_value(false, dst_reg))
err = mark_chain_precision(env, insn->dst_reg);
- if (BPF_SRC(insn->code) == BPF_X && !err)
+ if (BPF_SRC(insn->code) == BPF_X && !err &&
+ !__is_pointer_value(false, src_reg))
err = mark_chain_precision(env, insn->src_reg);
if (err)
return err;
generated by cgit (git 2.34.1) at 2024-05-27 05:55:09 +0000