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Diffstat (limited to 'kernel/bpf/verifier.c')
-rw-r--r--kernel/bpf/verifier.c133
1 files changed, 88 insertions, 45 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 1dda9d81f12c..3a738724a380 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -504,6 +504,13 @@ static bool is_ptr_cast_function(enum bpf_func_id func_id)
func_id == BPF_FUNC_skc_to_tcp_request_sock;
}
+static bool is_cmpxchg_insn(const struct bpf_insn *insn)
+{
+ return BPF_CLASS(insn->code) == BPF_STX &&
+ BPF_MODE(insn->code) == BPF_ATOMIC &&
+ insn->imm == BPF_CMPXCHG;
+}
+
/* string representation of 'enum bpf_reg_type' */
static const char * const reg_type_str[] = {
[NOT_INIT] = "?",
@@ -1120,7 +1127,7 @@ static void mark_ptr_not_null_reg(struct bpf_reg_state *reg)
reg->type = PTR_TO_RDWR_BUF;
break;
default:
- WARN_ON("unknown nullable register type");
+ WARN_ONCE(1, "unknown nullable register type");
}
}
@@ -1703,7 +1710,11 @@ static bool is_reg64(struct bpf_verifier_env *env, struct bpf_insn *insn,
}
if (class == BPF_STX) {
- if (reg->type != SCALAR_VALUE)
+ /* BPF_STX (including atomic variants) has multiple source
+ * operands, one of which is a ptr. Check whether the caller is
+ * asking about it.
+ */
+ if (t == SRC_OP && reg->type != SCALAR_VALUE)
return true;
return BPF_SIZE(code) == BPF_DW;
}
@@ -1735,22 +1746,38 @@ static bool is_reg64(struct bpf_verifier_env *env, struct bpf_insn *insn,
return true;
}
-/* Return TRUE if INSN doesn't have explicit value define. */
-static bool insn_no_def(struct bpf_insn *insn)
+/* Return the regno defined by the insn, or -1. */
+static int insn_def_regno(const struct bpf_insn *insn)
{
- u8 class = BPF_CLASS(insn->code);
-
- return (class == BPF_JMP || class == BPF_JMP32 ||
- class == BPF_STX || class == BPF_ST);
+ switch (BPF_CLASS(insn->code)) {
+ case BPF_JMP:
+ case BPF_JMP32:
+ case BPF_ST:
+ return -1;
+ case BPF_STX:
+ if (BPF_MODE(insn->code) == BPF_ATOMIC &&
+ (insn->imm & BPF_FETCH)) {
+ if (insn->imm == BPF_CMPXCHG)
+ return BPF_REG_0;
+ else
+ return insn->src_reg;
+ } else {
+ return -1;
+ }
+ default:
+ return insn->dst_reg;
+ }
}
/* Return TRUE if INSN has defined any 32-bit value explicitly. */
static bool insn_has_def32(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
- if (insn_no_def(insn))
+ int dst_reg = insn_def_regno(insn);
+
+ if (dst_reg == -1)
return false;
- return !is_reg64(env, insn, insn->dst_reg, NULL, DST_OP);
+ return !is_reg64(env, insn, dst_reg, NULL, DST_OP);
}
static void mark_insn_zext(struct bpf_verifier_env *env,
@@ -5834,10 +5861,14 @@ static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg,
{
bool mask_to_left = (opcode == BPF_ADD && off_is_neg) ||
(opcode == BPF_SUB && !off_is_neg);
- u32 off;
+ u32 off, max;
switch (ptr_reg->type) {
case PTR_TO_STACK:
+ /* Offset 0 is out-of-bounds, but acceptable start for the
+ * left direction, see BPF_REG_FP.
+ */
+ max = MAX_BPF_STACK + mask_to_left;
/* Indirect variable offset stack access is prohibited in
* unprivileged mode so it's not handled here.
*/
@@ -5845,16 +5876,17 @@ static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg,
if (mask_to_left)
*ptr_limit = MAX_BPF_STACK + off;
else
- *ptr_limit = -off;
- return 0;
+ *ptr_limit = -off - 1;
+ return *ptr_limit >= max ? -ERANGE : 0;
case PTR_TO_MAP_VALUE:
+ max = ptr_reg->map_ptr->value_size;
if (mask_to_left) {
*ptr_limit = ptr_reg->umax_value + ptr_reg->off;
} else {
off = ptr_reg->smin_value + ptr_reg->off;
- *ptr_limit = ptr_reg->map_ptr->value_size - off;
+ *ptr_limit = ptr_reg->map_ptr->value_size - off - 1;
}
- return 0;
+ return *ptr_limit >= max ? -ERANGE : 0;
default:
return -EINVAL;
}
@@ -5907,6 +5939,7 @@ static int sanitize_ptr_alu(struct bpf_verifier_env *env,
u32 alu_state, alu_limit;
struct bpf_reg_state tmp;
bool ret;
+ int err;
if (can_skip_alu_sanitation(env, insn))
return 0;
@@ -5922,10 +5955,13 @@ static int sanitize_ptr_alu(struct bpf_verifier_env *env,
alu_state |= ptr_is_dst_reg ?
BPF_ALU_SANITIZE_SRC : BPF_ALU_SANITIZE_DST;
- if (retrieve_ptr_limit(ptr_reg, &alu_limit, opcode, off_is_neg))
- return 0;
- if (update_alu_sanitation_state(aux, alu_state, alu_limit))
- return -EACCES;
+ err = retrieve_ptr_limit(ptr_reg, &alu_limit, opcode, off_is_neg);
+ if (err < 0)
+ return err;
+
+ err = update_alu_sanitation_state(aux, alu_state, alu_limit);
+ if (err < 0)
+ return err;
do_sim:
/* Simulate and find potential out-of-bounds access under
* speculative execution from truncation as a result of
@@ -6076,7 +6112,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
case BPF_ADD:
ret = sanitize_ptr_alu(env, insn, ptr_reg, dst_reg, smin_val < 0);
if (ret < 0) {
- verbose(env, "R%d tried to add from different maps or paths\n", dst);
+ verbose(env, "R%d tried to add from different maps, paths, or prohibited types\n", dst);
return ret;
}
/* We can take a fixed offset as long as it doesn't overflow
@@ -6131,7 +6167,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
case BPF_SUB:
ret = sanitize_ptr_alu(env, insn, ptr_reg, dst_reg, smin_val < 0);
if (ret < 0) {
- verbose(env, "R%d tried to sub from different maps or paths\n", dst);
+ verbose(env, "R%d tried to sub from different maps, paths, or prohibited types\n", dst);
return ret;
}
if (dst_reg == off_reg) {
@@ -9029,6 +9065,10 @@ static int check_btf_info(struct bpf_verifier_env *env,
btf = btf_get_by_fd(attr->prog_btf_fd);
if (IS_ERR(btf))
return PTR_ERR(btf);
+ if (btf_is_kernel(btf)) {
+ btf_put(btf);
+ return -EACCES;
+ }
env->prog->aux->btf = btf;
err = check_btf_func(env, attr, uattr);
@@ -11006,9 +11046,10 @@ static int opt_subreg_zext_lo32_rnd_hi32(struct bpf_verifier_env *env,
for (i = 0; i < len; i++) {
int adj_idx = i + delta;
struct bpf_insn insn;
- u8 load_reg;
+ int load_reg;
insn = insns[adj_idx];
+ load_reg = insn_def_regno(&insn);
if (!aux[adj_idx].zext_dst) {
u8 code, class;
u32 imm_rnd;
@@ -11018,14 +11059,14 @@ static int opt_subreg_zext_lo32_rnd_hi32(struct bpf_verifier_env *env,
code = insn.code;
class = BPF_CLASS(code);
- if (insn_no_def(&insn))
+ if (load_reg == -1)
continue;
/* NOTE: arg "reg" (the fourth one) is only used for
- * BPF_STX which has been ruled out in above
- * check, it is safe to pass NULL here.
+ * BPF_STX + SRC_OP, so it is safe to pass NULL
+ * here.
*/
- if (is_reg64(env, &insn, insn.dst_reg, NULL, DST_OP)) {
+ if (is_reg64(env, &insn, load_reg, NULL, DST_OP)) {
if (class == BPF_LD &&
BPF_MODE(code) == BPF_IMM)
i++;
@@ -11040,31 +11081,28 @@ static int opt_subreg_zext_lo32_rnd_hi32(struct bpf_verifier_env *env,
imm_rnd = get_random_int();
rnd_hi32_patch[0] = insn;
rnd_hi32_patch[1].imm = imm_rnd;
- rnd_hi32_patch[3].dst_reg = insn.dst_reg;
+ rnd_hi32_patch[3].dst_reg = load_reg;
patch = rnd_hi32_patch;
patch_len = 4;
goto apply_patch_buffer;
}
- if (!bpf_jit_needs_zext())
+ /* Add in an zero-extend instruction if a) the JIT has requested
+ * it or b) it's a CMPXCHG.
+ *
+ * The latter is because: BPF_CMPXCHG always loads a value into
+ * R0, therefore always zero-extends. However some archs'
+ * equivalent instruction only does this load when the
+ * comparison is successful. This detail of CMPXCHG is
+ * orthogonal to the general zero-extension behaviour of the
+ * CPU, so it's treated independently of bpf_jit_needs_zext.
+ */
+ if (!bpf_jit_needs_zext() && !is_cmpxchg_insn(&insn))
continue;
- /* zext_dst means that we want to zero-extend whatever register
- * the insn defines, which is dst_reg most of the time, with
- * the notable exception of BPF_STX + BPF_ATOMIC + BPF_FETCH.
- */
- if (BPF_CLASS(insn.code) == BPF_STX &&
- BPF_MODE(insn.code) == BPF_ATOMIC) {
- /* BPF_STX + BPF_ATOMIC insns without BPF_FETCH do not
- * define any registers, therefore zext_dst cannot be
- * set.
- */
- if (WARN_ON(!(insn.imm & BPF_FETCH)))
- return -EINVAL;
- load_reg = insn.imm == BPF_CMPXCHG ? BPF_REG_0
- : insn.src_reg;
- } else {
- load_reg = insn.dst_reg;
+ if (WARN_ON(load_reg == -1)) {
+ verbose(env, "verifier bug. zext_dst is set, but no reg is defined\n");
+ return -EFAULT;
}
zext_patch[0] = insn;
@@ -11635,7 +11673,7 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env)
off_reg = issrc ? insn->src_reg : insn->dst_reg;
if (isneg)
*patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1);
- *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit - 1);
+ *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit);
*patch++ = BPF_ALU64_REG(BPF_SUB, BPF_REG_AX, off_reg);
*patch++ = BPF_ALU64_REG(BPF_OR, BPF_REG_AX, off_reg);
*patch++ = BPF_ALU64_IMM(BPF_NEG, BPF_REG_AX, 0);
@@ -12120,6 +12158,11 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env)
u32 btf_id, member_idx;
const char *mname;
+ if (!prog->gpl_compatible) {
+ verbose(env, "struct ops programs must have a GPL compatible license\n");
+ return -EINVAL;
+ }
+
btf_id = prog->aux->attach_btf_id;
st_ops = bpf_struct_ops_find(btf_id);
if (!st_ops) {
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.