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-rw-r--r--include/linux/bpf_verifier.h4
-rw-r--r--include/linux/limits.h1
-rw-r--r--include/linux/tnum.h12
-rw-r--r--kernel/bpf/tnum.c15
-rw-r--r--kernel/bpf/verifier.c1118
5 files changed, 869 insertions, 281 deletions
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 5406e6e96585..6abd5a778fcd 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -123,6 +123,10 @@ struct bpf_reg_state {
s64 smax_value; /* maximum possible (s64)value */
u64 umin_value; /* minimum possible (u64)value */
u64 umax_value; /* maximum possible (u64)value */
+ s32 s32_min_value; /* minimum possible (s32)value */
+ s32 s32_max_value; /* maximum possible (s32)value */
+ u32 u32_min_value; /* minimum possible (u32)value */
+ u32 u32_max_value; /* maximum possible (u32)value */
/* parentage chain for liveness checking */
struct bpf_reg_state *parent;
/* Inside the callee two registers can be both PTR_TO_STACK like
diff --git a/include/linux/limits.h b/include/linux/limits.h
index 76afcd24ff8c..0d3de82dd354 100644
--- a/include/linux/limits.h
+++ b/include/linux/limits.h
@@ -27,6 +27,7 @@
#define S16_MAX ((s16)(U16_MAX >> 1))
#define S16_MIN ((s16)(-S16_MAX - 1))
#define U32_MAX ((u32)~0U)
+#define U32_MIN ((u32)0)
#define S32_MAX ((s32)(U32_MAX >> 1))
#define S32_MIN ((s32)(-S32_MAX - 1))
#define U64_MAX ((u64)~0ULL)
diff --git a/include/linux/tnum.h b/include/linux/tnum.h
index ea627d1ab7e3..498dbcedb451 100644
--- a/include/linux/tnum.h
+++ b/include/linux/tnum.h
@@ -86,4 +86,16 @@ int tnum_strn(char *str, size_t size, struct tnum a);
/* Format a tnum as tristate binary expansion */
int tnum_sbin(char *str, size_t size, struct tnum a);
+/* Returns the 32-bit subreg */
+struct tnum tnum_subreg(struct tnum a);
+/* Returns the tnum with the lower 32-bit subreg cleared */
+struct tnum tnum_clear_subreg(struct tnum a);
+/* Returns the tnum with the lower 32-bit subreg set to value */
+struct tnum tnum_const_subreg(struct tnum a, u32 value);
+/* Returns true if 32-bit subreg @a is a known constant*/
+static inline bool tnum_subreg_is_const(struct tnum a)
+{
+ return !(tnum_subreg(a)).mask;
+}
+
#endif /* _LINUX_TNUM_H */
diff --git a/kernel/bpf/tnum.c b/kernel/bpf/tnum.c
index d4f335a9a899..ceac5281bd31 100644
--- a/kernel/bpf/tnum.c
+++ b/kernel/bpf/tnum.c
@@ -194,3 +194,18 @@ int tnum_sbin(char *str, size_t size, struct tnum a)
str[min(size - 1, (size_t)64)] = 0;
return 64;
}
+
+struct tnum tnum_subreg(struct tnum a)
+{
+ return tnum_cast(a, 4);
+}
+
+struct tnum tnum_clear_subreg(struct tnum a)
+{
+ return tnum_lshift(tnum_rshift(a, 32), 32);
+}
+
+struct tnum tnum_const_subreg(struct tnum a, u32 value)
+{
+ return tnum_or(tnum_clear_subreg(a), tnum_const(value));
+}
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index dda3b94d9661..1c60d001bb46 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -550,6 +550,22 @@ static void print_verifier_state(struct bpf_verifier_env *env,
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
verbose(env, ",var_off=%s", tn_buf);
}
+ if (reg->s32_min_value != reg->smin_value &&
+ reg->s32_min_value != S32_MIN)
+ verbose(env, ",s32_min_value=%d",
+ (int)(reg->s32_min_value));
+ if (reg->s32_max_value != reg->smax_value &&
+ reg->s32_max_value != S32_MAX)
+ verbose(env, ",s32_max_value=%d",
+ (int)(reg->s32_max_value));
+ if (reg->u32_min_value != reg->umin_value &&
+ reg->u32_min_value != U32_MIN)
+ verbose(env, ",u32_min_value=%d",
+ (int)(reg->u32_min_value));
+ if (reg->u32_max_value != reg->umax_value &&
+ reg->u32_max_value != U32_MAX)
+ verbose(env, ",u32_max_value=%d",
+ (int)(reg->u32_max_value));
}
verbose(env, ")");
}
@@ -924,6 +940,20 @@ static void __mark_reg_known(struct bpf_reg_state *reg, u64 imm)
reg->smax_value = (s64)imm;
reg->umin_value = imm;
reg->umax_value = imm;
+
+ reg->s32_min_value = (s32)imm;
+ reg->s32_max_value = (s32)imm;
+ reg->u32_min_value = (u32)imm;
+ reg->u32_max_value = (u32)imm;
+}
+
+static void __mark_reg32_known(struct bpf_reg_state *reg, u64 imm)
+{
+ reg->var_off = tnum_const_subreg(reg->var_off, imm);
+ reg->s32_min_value = (s32)imm;
+ reg->s32_max_value = (s32)imm;
+ reg->u32_min_value = (u32)imm;
+ reg->u32_max_value = (u32)imm;
}
/* Mark the 'variable offset' part of a register as zero. This should be
@@ -978,8 +1008,52 @@ static bool reg_is_init_pkt_pointer(const struct bpf_reg_state *reg,
tnum_equals_const(reg->var_off, 0);
}
-/* Attempts to improve min/max values based on var_off information */
-static void __update_reg_bounds(struct bpf_reg_state *reg)
+/* Reset the min/max bounds of a register */
+static void __mark_reg_unbounded(struct bpf_reg_state *reg)
+{
+ reg->smin_value = S64_MIN;
+ reg->smax_value = S64_MAX;
+ reg->umin_value = 0;
+ reg->umax_value = U64_MAX;
+
+ reg->s32_min_value = S32_MIN;
+ reg->s32_max_value = S32_MAX;
+ reg->u32_min_value = 0;
+ reg->u32_max_value = U32_MAX;
+}
+
+static void __mark_reg64_unbounded(struct bpf_reg_state *reg)
+{
+ reg->smin_value = S64_MIN;
+ reg->smax_value = S64_MAX;
+ reg->umin_value = 0;
+ reg->umax_value = U64_MAX;
+}
+
+static void __mark_reg32_unbounded(struct bpf_reg_state *reg)
+{
+ reg->s32_min_value = S32_MIN;
+ reg->s32_max_value = S32_MAX;
+ reg->u32_min_value = 0;
+ reg->u32_max_value = U32_MAX;
+}
+
+static void __update_reg32_bounds(struct bpf_reg_state *reg)
+{
+ struct tnum var32_off = tnum_subreg(reg->var_off);
+
+ /* min signed is max(sign bit) | min(other bits) */
+ reg->s32_min_value = max_t(s32, reg->s32_min_value,
+ var32_off.value | (var32_off.mask & S32_MIN));
+ /* max signed is min(sign bit) | max(other bits) */
+ reg->s32_max_value = min_t(s32, reg->s32_max_value,
+ var32_off.value | (var32_off.mask & S32_MAX));
+ reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)var32_off.value);
+ reg->u32_max_value = min(reg->u32_max_value,
+ (u32)(var32_off.value | var32_off.mask));
+}
+
+static void __update_reg64_bounds(struct bpf_reg_state *reg)
{
/* min signed is max(sign bit) | min(other bits) */
reg->smin_value = max_t(s64, reg->smin_value,
@@ -992,8 +1066,48 @@ static void __update_reg_bounds(struct bpf_reg_state *reg)
reg->var_off.value | reg->var_off.mask);
}
+static void __update_reg_bounds(struct bpf_reg_state *reg)
+{
+ __update_reg32_bounds(reg);
+ __update_reg64_bounds(reg);
+}
+
/* Uses signed min/max values to inform unsigned, and vice-versa */
-static void __reg_deduce_bounds(struct bpf_reg_state *reg)
+static void __reg32_deduce_bounds(struct bpf_reg_state *reg)
+{
+ /* Learn sign from signed bounds.
+ * If we cannot cross the sign boundary, then signed and unsigned bounds
+ * are the same, so combine. This works even in the negative case, e.g.
+ * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
+ */
+ if (reg->s32_min_value >= 0 || reg->s32_max_value < 0) {
+ reg->s32_min_value = reg->u32_min_value =
+ max_t(u32, reg->s32_min_value, reg->u32_min_value);
+ reg->s32_max_value = reg->u32_max_value =
+ min_t(u32, reg->s32_max_value, reg->u32_max_value);
+ return;
+ }
+ /* Learn sign from unsigned bounds. Signed bounds cross the sign
+ * boundary, so we must be careful.
+ */
+ if ((s32)reg->u32_max_value >= 0) {
+ /* Positive. We can't learn anything from the smin, but smax
+ * is positive, hence safe.
+ */
+ reg->s32_min_value = reg->u32_min_value;
+ reg->s32_max_value = reg->u32_max_value =
+ min_t(u32, reg->s32_max_value, reg->u32_max_value);
+ } else if ((s32)reg->u32_min_value < 0) {
+ /* Negative. We can't learn anything from the smax, but smin
+ * is negative, hence safe.
+ */
+ reg->s32_min_value = reg->u32_min_value =
+ max_t(u32, reg->s32_min_value, reg->u32_min_value);
+ reg->s32_max_value = reg->u32_max_value;
+ }
+}
+
+static void __reg64_deduce_bounds(struct bpf_reg_state *reg)
{
/* Learn sign from signed bounds.
* If we cannot cross the sign boundary, then signed and unsigned bounds
@@ -1027,21 +1141,106 @@ static void __reg_deduce_bounds(struct bpf_reg_state *reg)
}
}
+static void __reg_deduce_bounds(struct bpf_reg_state *reg)
+{
+ __reg32_deduce_bounds(reg);
+ __reg64_deduce_bounds(reg);
+}
+
/* Attempts to improve var_off based on unsigned min/max information */
static void __reg_bound_offset(struct bpf_reg_state *reg)
{
- reg->var_off = tnum_intersect(reg->var_off,
- tnum_range(reg->umin_value,
- reg->umax_value));
+ struct tnum var64_off = tnum_intersect(reg->var_off,
+ tnum_range(reg->umin_value,
+ reg->umax_value));
+ struct tnum var32_off = tnum_intersect(tnum_subreg(reg->var_off),
+ tnum_range(reg->u32_min_value,
+ reg->u32_max_value));
+
+ reg->var_off = tnum_or(tnum_clear_subreg(var64_off), var32_off);
}
-/* Reset the min/max bounds of a register */
-static void __mark_reg_unbounded(struct bpf_reg_state *reg)
+static void __reg_assign_32_into_64(struct bpf_reg_state *reg)
{
- reg->smin_value = S64_MIN;
- reg->smax_value = S64_MAX;
- reg->umin_value = 0;
- reg->umax_value = U64_MAX;
+ reg->umin_value = reg->u32_min_value;
+ reg->umax_value = reg->u32_max_value;
+ /* Attempt to pull 32-bit signed bounds into 64-bit bounds
+ * but must be positive otherwise set to worse case bounds
+ * and refine later from tnum.
+ */
+ if (reg->s32_min_value > 0)
+ reg->smin_value = reg->s32_min_value;
+ else
+ reg->smin_value = 0;
+ if (reg->s32_max_value > 0)
+ reg->smax_value = reg->s32_max_value;
+ else
+ reg->smax_value = U32_MAX;
+}
+
+static void __reg_combine_32_into_64(struct bpf_reg_state *reg)
+{
+ /* special case when 64-bit register has upper 32-bit register
+ * zeroed. Typically happens after zext or <<32, >>32 sequence
+ * allowing us to use 32-bit bounds directly,
+ */
+ if (tnum_equals_const(tnum_clear_subreg(reg->var_off), 0)) {
+ __reg_assign_32_into_64(reg);
+ } else {
+ /* Otherwise the best we can do is push lower 32bit known and
+ * unknown bits into register (var_off set from jmp logic)
+ * then learn as much as possible from the 64-bit tnum
+ * known and unknown bits. The previous smin/smax bounds are
+ * invalid here because of jmp32 compare so mark them unknown
+ * so they do not impact tnum bounds calculation.
+ */
+ __mark_reg64_unbounded(reg);
+ __update_reg_bounds(reg);
+ }
+
+ /* Intersecting with the old var_off might have improved our bounds
+ * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
+ * then new var_off is (0; 0x7f...fc) which improves our umax.
+ */
+ __reg_deduce_bounds(reg);
+ __reg_bound_offset(reg);
+ __update_reg_bounds(reg);
+}
+
+static bool __reg64_bound_s32(s64 a)
+{
+ if (a > S32_MIN && a < S32_MAX)
+ return true;
+ return false;
+}
+
+static bool __reg64_bound_u32(u64 a)
+{
+ if (a > U32_MIN && a < U32_MAX)
+ return true;
+ return false;
+}
+
+static void __reg_combine_64_into_32(struct bpf_reg_state *reg)
+{
+ __mark_reg32_unbounded(reg);
+
+ if (__reg64_bound_s32(reg->smin_value))
+ reg->s32_min_value = (s32)reg->smin_value;
+ if (__reg64_bound_s32(reg->smax_value))
+ reg->s32_max_value = (s32)reg->smax_value;
+ if (__reg64_bound_u32(reg->umin_value))
+ reg->u32_min_value = (u32)reg->umin_value;
+ if (__reg64_bound_u32(reg->umax_value))
+ reg->u32_max_value = (u32)reg->umax_value;
+
+ /* Intersecting with the old var_off might have improved our bounds
+ * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
+ * then new var_off is (0; 0x7f...fc) which improves our umax.
+ */
+ __reg_deduce_bounds(reg);
+ __reg_bound_offset(reg);
+ __update_reg_bounds(reg);
}
/* Mark a register as having a completely unknown (scalar) value. */
@@ -2774,6 +2973,12 @@ static int check_tp_buffer_access(struct bpf_verifier_env *env,
return 0;
}
+/* BPF architecture zero extends alu32 ops into 64-bit registesr */
+static void zext_32_to_64(struct bpf_reg_state *reg)
+{
+ reg->var_off = tnum_subreg(reg->var_off);
+ __reg_assign_32_into_64(reg);
+}
/* truncate register to smaller size (in bytes)
* must be called with size < BPF_REG_SIZE
@@ -2796,6 +3001,14 @@ static void coerce_reg_to_size(struct bpf_reg_state *reg, int size)
}
reg->smin_value = reg->umin_value;
reg->smax_value = reg->umax_value;
+
+ /* If size is smaller than 32bit register the 32bit register
+ * values are also truncated so we push 64-bit bounds into
+ * 32-bit bounds. Above were truncated < 32-bits already.
+ */
+ if (size >= 4)
+ return;
+ __reg_combine_64_into_32(reg);
}
static bool bpf_map_is_rdonly(const struct bpf_map *map)
@@ -4431,7 +4644,17 @@ static bool signed_add_overflows(s64 a, s64 b)
return res < a;
}
-static bool signed_sub_overflows(s64 a, s64 b)
+static bool signed_add32_overflows(s64 a, s64 b)
+{
+ /* Do the add in u32, where overflow is well-defined */
+ s32 res = (s32)((u32)a + (u32)b);
+
+ if (b < 0)
+ return res > a;
+ return res < a;
+}
+
+static bool signed_sub_overflows(s32 a, s32 b)
{
/* Do the sub in u64, where overflow is well-defined */
s64 res = (s64)((u64)a - (u64)b);
@@ -4441,6 +4664,16 @@ static bool signed_sub_overflows(s64 a, s64 b)
return res > a;
}
+static bool signed_sub32_overflows(s32 a, s32 b)
+{
+ /* Do the sub in u64, where overflow is well-defined */
+ s32 res = (s32)((u32)a - (u32)b);
+
+ if (b < 0)
+ return res < a;
+ return res > a;
+}
+
static bool check_reg_sane_offset(struct bpf_verifier_env *env,
const struct bpf_reg_state *reg,
enum bpf_reg_type type)
@@ -4677,6 +4910,9 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
!check_reg_sane_offset(env, ptr_reg, ptr_reg->type))
return -EINVAL;
+ /* pointer types do not carry 32-bit bounds at the moment. */
+ __mark_reg32_unbounded(dst_reg);
+
switch (opcode) {
case BPF_ADD:
ret = sanitize_ptr_alu(env, insn, ptr_reg, dst_reg, smin_val < 0);
@@ -4840,6 +5076,32 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
return 0;
}
+static void scalar32_min_max_add(struct bpf_reg_state *dst_reg,
+ struct bpf_reg_state *src_reg)
+{
+ s32 smin_val = src_reg->s32_min_value;
+ s32 smax_val = src_reg->s32_max_value;
+ u32 umin_val = src_reg->u32_min_value;
+ u32 umax_val = src_reg->u32_max_value;
+
+ if (signed_add32_overflows(dst_reg->s32_min_value, smin_val) ||
+ signed_add32_overflows(dst_reg->s32_max_value, smax_val)) {
+ dst_reg->s32_min_value = S32_MIN;
+ dst_reg->s32_max_value = S32_MAX;
+ } else {
+ dst_reg->s32_min_value += smin_val;
+ dst_reg->s32_max_value += smax_val;
+ }
+ if (dst_reg->u32_min_value + umin_val < umin_val ||
+ dst_reg->u32_max_value + umax_val < umax_val) {
+ dst_reg->u32_min_value = 0;
+ dst_reg->u32_max_value = U32_MAX;
+ } else {
+ dst_reg->u32_min_value += umin_val;
+ dst_reg->u32_max_value += umax_val;
+ }
+}
+
static void scalar_min_max_add(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
@@ -4864,7 +5126,34 @@ static void scalar_min_max_add(struct bpf_reg_state *dst_reg,
dst_reg->umin_value += umin_val;
dst_reg->umax_value += umax_val;
}
- dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg->var_off);
+}
+
+static void scalar32_min_max_sub(struct bpf_reg_state *dst_reg,
+ struct bpf_reg_state *src_reg)
+{
+ s32 smin_val = src_reg->s32_min_value;
+ s32 smax_val = src_reg->s32_max_value;
+ u32 umin_val = src_reg->u32_min_value;
+ u32 umax_val = src_reg->u32_max_value;
+
+ if (signed_sub32_overflows(dst_reg->s32_min_value, smax_val) ||
+ signed_sub32_overflows(dst_reg->s32_max_value, smin_val)) {
+ /* Overflow possible, we know nothing */
+ dst_reg->s32_min_value = S32_MIN;
+ dst_reg->s32_max_value = S32_MAX;
+ } else {
+ dst_reg->s32_min_value -= smax_val;
+ dst_reg->s32_max_value -= smin_val;
+ }
+ if (dst_reg->u32_min_value < umax_val) {
+ /* Overflow possible, we know nothing */
+ dst_reg->u32_min_value = 0;
+ dst_reg->u32_max_value = U32_MAX;
+ } else {
+ /* Cannot overflow (as long as bounds are consistent) */
+ dst_reg->u32_min_value -= umax_val;
+ dst_reg->u32_max_value -= umin_val;
+ }
}
static void scalar_min_max_sub(struct bpf_reg_state *dst_reg,
@@ -4893,7 +5182,38 @@ static void scalar_min_max_sub(struct bpf_reg_state *dst_reg,
dst_reg->umin_value -= umax_val;
dst_reg->umax_value -= umin_val;
}
- dst_reg->var_off = tnum_sub(dst_reg->var_off, src_reg->var_off);
+}
+
+static void scalar32_min_max_mul(struct bpf_reg_state *dst_reg,
+ struct bpf_reg_state *src_reg)
+{
+ s32 smin_val = src_reg->s32_min_value;
+ u32 umin_val = src_reg->u32_min_value;
+ u32 umax_val = src_reg->u32_max_value;
+
+ if (smin_val < 0 || dst_reg->s32_min_value < 0) {
+ /* Ain't nobody got time to multiply that sign */
+ __mark_reg32_unbounded(dst_reg);
+ return;
+ }
+ /* Both values are positive, so we can work with unsigned and
+ * copy the result to signed (unless it exceeds S32_MAX).
+ */
+ if (umax_val > U16_MAX || dst_reg->u32_max_value > U16_MAX) {
+ /* Potential overflow, we know nothing */
+ __mark_reg32_unbounded(dst_reg);
+ return;
+ }
+ dst_reg->u32_min_value *= umin_val;
+ dst_reg->u32_max_value *= umax_val;
+ if (dst_reg->u32_max_value > S32_MAX) {
+ /* Overflow possible, we know nothing */
+ dst_reg->s32_min_value = S32_MIN;
+ dst_reg->s32_max_value = S32_MAX;
+ } else {
+ dst_reg->s32_min_value = dst_reg->u32_min_value;
+ dst_reg->s32_max_value = dst_reg->u32_max_value;
+ }
}
static void scalar_min_max_mul(struct bpf_reg_state *dst_reg,
@@ -4903,11 +5223,9 @@ static void scalar_min_max_mul(struct bpf_reg_state *dst_reg,
u64 umin_val = src_reg->umin_value;
u64 umax_val = src_reg->umax_value;
- dst_reg->var_off = tnum_mul(dst_reg->var_off, src_reg->var_off);
if (smin_val < 0 || dst_reg->smin_value < 0) {
/* Ain't nobody got time to multiply that sign */
- __mark_reg_unbounded(dst_reg);
- __update_reg_bounds(dst_reg);
+ __mark_reg64_unbounded(dst_reg);
return;
}
/* Both values are positive, so we can work with unsigned and
@@ -4915,9 +5233,7 @@ static void scalar_min_max_mul(struct bpf_reg_state *dst_reg,
*/
if (umax_val > U32_MAX || dst_reg->umax_value > U32_MAX) {
/* Potential overflow, we know nothing */
- __mark_reg_unbounded(dst_reg);
- /* (except what we can learn from the var_off) */
- __update_reg_bounds(dst_reg);
+ __mark_reg64_unbounded(dst_reg);
return;
}
dst_reg->umin_value *= umin_val;
@@ -4932,16 +5248,59 @@ static void scalar_min_max_mul(struct bpf_reg_state *dst_reg,
}
}
+static void scalar32_min_max_and(struct bpf_reg_state *dst_reg,
+ struct bpf_reg_state *src_reg)
+{
+ bool src_known = tnum_subreg_is_const(src_reg->var_off);
+ bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
+ struct tnum var32_off = tnum_subreg(dst_reg->var_off);
+ s32 smin_val = src_reg->s32_min_value;
+ u32 umax_val = src_reg->u32_max_value;
+
+ /* Assuming scalar64_min_max_and will be called so its safe
+ * to skip updating register for known 32-bit case.
+ */
+ if (src_known && dst_known)
+ return;
+
+ /* We get our minimum from the var_off, since that's inherently
+ * bitwise. Our maximum is the minimum of the operands' maxima.
+ */
+ dst_reg->u32_min_value = var32_off.value;
+ dst_reg->u32_max_value = min(dst_reg->u32_max_value, umax_val);
+ if (dst_reg->s32_min_value < 0 || smin_val < 0) {
+ /* Lose signed bounds when ANDing negative numbers,
+ * ain't nobody got time for that.
+ */
+ dst_reg->s32_min_value = S32_MIN;
+ dst_reg->s32_max_value = S32_MAX;
+ } else {
+ /* ANDing two positives gives a positive, so safe to
+ * cast result into s64.
+ */
+ dst_reg->s32_min_value = dst_reg->u32_min_value;
+ dst_reg->s32_max_value = dst_reg->u32_max_value;
+ }
+
+}
+
static void scalar_min_max_and(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
+ bool src_known = tnum_is_const(src_reg->var_off);
+ bool dst_known = tnum_is_const(dst_reg->var_off);
s64 smin_val = src_reg->smin_value;
u64 umax_val = src_reg->umax_value;
+ if (src_known && dst_known) {
+ __mark_reg_known(dst_reg, dst_reg->var_off.value &
+ src_reg->var_off.value);
+ return;
+ }
+
/* We get our minimum from the var_off, since that's inherently
* bitwise. Our maximum is the minimum of the operands' maxima.
*/
- dst_reg->var_off = tnum_and(dst_reg->var_off, src_reg->var_off);
dst_reg->umin_value = dst_reg->var_off.value;
dst_reg->umax_value = min(dst_reg->umax_value, umax_val);
if (dst_reg->smin_value < 0 || smin_val < 0) {
@@ -4961,16 +5320,58 @@ static void scalar_min_max_and(struct bpf_reg_state *dst_reg,
__update_reg_bounds(dst_reg);
}
+static void scalar32_min_max_or(struct bpf_reg_state *dst_reg,
+ struct bpf_reg_state *src_reg)
+{
+ bool src_known = tnum_subreg_is_const(src_reg->var_off);
+ bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
+ struct tnum var32_off = tnum_subreg(dst_reg->var_off);
+ s32 smin_val = src_reg->smin_value;
+ u32 umin_val = src_reg->umin_value;
+
+ /* Assuming scalar64_min_max_or will be called so it is safe
+ * to skip updating register for known case.
+ */
+ if (src_known && dst_known)
+ return;
+
+ /* We get our maximum from the var_off, and our minimum is the
+ * maximum of the operands' minima
+ */
+ dst_reg->u32_min_value = max(dst_reg->u32_min_value, umin_val);
+ dst_reg->u32_max_value = var32_off.value | var32_off.mask;
+ if (dst_reg->s32_min_value < 0 || smin_val < 0) {
+ /* Lose signed bounds when ORing negative numbers,
+ * ain't nobody got time for that.
+ */
+ dst_reg->s32_min_value = S32_MIN;
+ dst_reg->s32_max_value = S32_MAX;
+ } else {
+ /* ORing two positives gives a positive, so safe to
+ * cast result into s64.
+ */
+ dst_reg->s32_min_value = dst_reg->umin_value;
+ dst_reg->s32_max_value = dst_reg->umax_value;
+ }
+}
+
static void scalar_min_max_or(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
+ bool src_known = tnum_is_const(src_reg->var_off);
+ bool dst_known = tnum_is_const(dst_reg->var_off);
s64 smin_val = src_reg->smin_value;
u64 umin_val = src_reg->umin_value;
+ if (src_known && dst_known) {
+ __mark_reg_known(dst_reg, dst_reg->var_off.value |
+ src_reg->var_off.value);
+ return;
+ }
+
/* We get our maximum from the var_off, and our minimum is the
* maximum of the operands' minima
*/
- dst_reg->var_off = tnum_or(dst_reg->var_off, src_reg->var_off);
dst_reg->umin_value = max(dst_reg->umin_value, umin_val);
dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask;
if (dst_reg->smin_value < 0 || smin_val < 0) {
@@ -4990,17 +5391,62 @@ static void scalar_min_max_or(struct bpf_reg_state *dst_reg,
__update_reg_bounds(dst_reg);
}
-static void scalar_min_max_lsh(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
+static void __scalar32_min_max_lsh(struct bpf_reg_state *dst_reg,
+ u64 umin_val, u64 umax_val)
{
- u64 umax_val = src_reg->umax_value;
- u64 umin_val = src_reg->umin_value;
-
/* We lose all sign bit information (except what we can pick
* up from var_off)
*/
- dst_reg->smin_value = S64_MIN;
- dst_reg->smax_value = S64_MAX;
+ dst_reg->s32_min_value = S32_MIN;
+ dst_reg->s32_max_value = S32_MAX;
+ /* If we might shift our top bit out, then we know nothing */
+ if (umax_val > 31 || dst_reg->u32_max_value > 1ULL << (31 - umax_val)) {
+ dst_reg->u32_min_value = 0;
+ dst_reg->u32_max_value = U32_MAX;
+ } else {
+ dst_reg->u32_min_value <<= umin_val;
+ dst_reg->u32_max_value <<= umax_val;
+ }
+}
+
+static void scalar32_min_max_lsh(struct bpf_reg_state *dst_reg,
+ struct bpf_reg_state *src_reg)
+{
+ u32 umax_val = src_reg->u32_max_value;
+ u32 umin_val = src_reg->u32_min_value;
+ /* u32 alu operation will zext upper bits */
+ struct tnum subreg = tnum_subreg(dst_reg->var_off);
+
+ __scalar32_min_max_lsh(dst_reg, umin_val, umax_val);
+ dst_reg->var_off = tnum_subreg(tnum_lshift(subreg, umin_val));
+ /* Not required but being careful mark reg64 bounds as unknown so
+ * that we are forced to pick them up from tnum and zext later and
+ * if some path skips this step we are still safe.
+ */
+ __mark_reg64_unbounded(dst_reg);
+ __update_reg32_bounds(dst_reg);
+}
+
+static void __scalar64_min_max_lsh(struct bpf_reg_state *dst_reg,
+ u64 umin_val, u64 umax_val)
+{
+ /* Special case <<32 because it is a common compiler pattern to sign
+ * extend subreg by doing <<32 s>>32. In this case if 32bit bounds are
+ * positive we know this shift will also be positive so we can track
+ * bounds correctly. Otherwise we lose all sign bit information except
+ * what we can pick up from var_off. Perhaps we can generalize this
+ * later to shifts of any length.
+ */
+ if (umin_val == 32 && umax_val == 32 && dst_reg->s32_max_value >= 0)
+ dst_reg->smax_value = (s64)dst_reg->s32_max_value << 32;
+ else
+ dst_reg->smax_value = S64_MAX;
+
+ if (umin_val == 32 && umax_val == 32 && dst_reg->s32_min_value >= 0)
+ dst_reg->smin_value = (s64)dst_reg->s32_min_value << 32;
+ else
+ dst_reg->smin_value = S64_MIN;
+
/* If we might shift our top bit out, then we know nothing */
if (dst_reg->umax_value > 1ULL << (63 - umax_val)) {
dst_reg->umin_value = 0;
@@ -5009,11 +5455,55 @@ static void scalar_min_max_lsh(struct bpf_reg_state *dst_reg,
dst_reg->umin_value <<= umin_val;
dst_reg->umax_value <<= umax_val;
}
+}
+
+static void scalar_min_max_lsh(struct bpf_reg_state *dst_reg,
+ struct bpf_reg_state *src_reg)
+{
+ u64 umax_val = src_reg->umax_value;
+ u64 umin_val = src_reg->umin_value;
+
+ /* scalar64 calc uses 32bit unshifted bounds so must be called first */
+ __scalar64_min_max_lsh(dst_reg, umin_val, umax_val);
+ __scalar32_min_max_lsh(dst_reg, umin_val, umax_val);
+
dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val);
/* We may learn something more from the var_off */
__update_reg_bounds(dst_reg);
}
+static void scalar32_min_max_rsh(struct bpf_reg_state *dst_reg,
+ struct bpf_reg_state *src_reg)
+{
+ struct tnum subreg = tnum_subreg(dst_reg->var_off);
+ u32 umax_val = src_reg->u32_max_value;
+ u32 umin_val = src_reg->u32_min_value;
+
+ /* BPF_RSH is an unsigned shift. If the value in dst_reg might
+ * be negative, then either:
+ * 1) src_reg might be zero, so the sign bit of the result is
+ * unknown, so we lose our signed bounds
+ * 2) it's known negative, thus the unsigned bounds capture the
+ * signed bounds
+ * 3) the signed bounds cross zero, so they tell us nothing
+ * about the result
+ * If the value in dst_reg is known nonnegative, then again the
+ * unsigned bounts capture the signed bounds.
+ * Thus, in all cases it suffices to blow away our signed bounds
+ * and rely on inferring new ones from the unsigned bounds and
+ * var_off of the result.
+ */
+ dst_reg->s32_min_value = S32_MIN;
+ dst_reg->s32_max_value = S32_MAX;
+
+ dst_reg->var_off = tnum_rshift(subreg, umin_val);
+ dst_reg->u32_min_value >>= umax_val;
+ dst_reg->u32_max_value >>= umin_val;
+
+ __mark_reg64_unbounded(dst_reg);
+ __update_reg32_bounds(dst_reg);
+}
+
static void scalar_min_max_rsh(struct bpf_reg_state *dst_reg,
struct bpf_reg_state *src_reg)
{
@@ -5039,35 +5529,62 @@ static void scalar_min_max_rsh(struct bpf_reg_state *dst_reg,
dst_reg->var_off = tnum_rshift(dst_reg->var_off, umin_val);
dst_reg->umin_value >>= umax_val;
dst_reg->umax_value >>= umin_val;
- /* We may learn something more from the var_off */
+
+ /* Its not easy to operate on alu32 bounds here because it depends
+ * on bits being shifted in. Take easy way out and mark unbounded
+ * so we can recalculate later from tnum.
+ */
+ __mark_reg32_unbounded(dst_reg);
__update_reg_bounds(dst_reg);
}
-static void scalar_min_max_arsh(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg,
- u64 insn_bitness)
+static void scalar32_min_max_arsh(struct bpf_reg_state *dst_reg,
+ struct bpf_reg_state *src_reg)
{
- u64 umin_val = src_reg->umin_value;
+ u64 umin_val = src_reg->u32_min_value;
/* Upon reaching here, src_known is true and
* umax_val is equal to umin_val.
*/
- if (insn_bitness == 32) {
- dst_reg->smin_value = (u32)(((s32)dst_reg->smin_value) >> umin_val);
- dst_reg->smax_value = (u32)(((s32)dst_reg->smax_value) >> umin_val);
- } else {
- dst_reg->smin_value >>= umin_val;
- dst_reg->smax_value >>= umin_val;
- }
+ dst_reg->s32_min_value = (u32)(((s32)dst_reg->s32_min_value) >> umin_val);
+ dst_reg->s32_max_value = (u32)(((s32)dst_reg->s32_max_value) >> umin_val);
- dst_reg->var_off = tnum_arshift(dst_reg->var_off, umin_val,
- insn_bitness);
+ dst_reg->var_off = tnum_arshift(tnum_subreg(dst_reg->var_off), umin_val, 32);
+
+ /* blow away the dst_reg umin_value/umax_value and rely on
+ * dst_reg var_off to refine the result.
+ */
+ dst_reg->u32_min_value = 0;
+ dst_reg->u32_max_value = U32_MAX;
+
+ __mark_reg64_unbounded(dst_reg);
+ __update_reg32_bounds(dst_reg);
+}
+
+static void scalar_min_max_arsh(struct bpf_reg_state *dst_reg,
+ struct bpf_reg_state *src_reg)
+{
+ u64 umin_val = src_reg->umin_value;
+
+ /* Upon reaching here, src_known is true and umax_val is equal
+ * to umin_val.
+ */
+ dst_reg->smin_value >>= umin_val;
+ dst_reg->smax_value >>= umin_val;
+
+ dst_reg->var_off = tnum_arshift(dst_reg->var_off, umin_val, 64);
/* blow away the dst_reg umin_value/umax_value and rely on
* dst_reg var_off to refine the result.
*/
dst_reg->umin_value = 0;
dst_reg->umax_value = U64_MAX;
+
+ /* Its not easy to operate on alu32 bounds here because it depends
+ * on bits being shifted in from upper 32-bits. Take easy way out
+ * and mark unbounded so we can recalculate later from tnum.
+ */
+ __mark_reg32_unbounded(dst_reg);
__update_reg_bounds(dst_reg);
}
@@ -5085,33 +5602,47 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
bool src_known, dst_known;
s64 smin_val, smax_val;
u64 umin_val, umax_val;
+ s32 s32_min_val, s32_max_val;
+ u32 u32_min_val, u32_max_val;
u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? 64 : 32;
u32 dst = insn->dst_reg;
int ret;
-
- if (insn_bitness == 32) {
- /* Relevant for 32-bit RSH: Information can propagate towards
- * LSB, so it isn't sufficient to only truncate the output to
- * 32 bits.
- */
- coerce_reg_to_size(dst_reg, 4);
- coerce_reg_to_size(&src_reg, 4);
- }
+ bool alu32 = (BPF_CLASS(insn->code) != BPF_ALU64);
smin_val = src_reg.smin_value;
smax_val = src_reg.smax_value;
umin_val = src_reg.umin_value;
umax_val = src_reg.umax_value;
- src_known = tnum_is_const(src_reg.var_off);
- dst_known = tnum_is_const(dst_reg->var_off);
- if ((src_known && (smin_val != smax_val || umin_val != umax_val)) ||
- smin_val > smax_val || umin_val > umax_val) {
- /* Taint dst register if offset had invalid bounds derived from
- * e.g. dead branches.
- */
- __mark_reg_unknown(env, dst_reg);
- return 0;
+ s32_min_val = src_reg.s32_min_value;
+ s32_max_val = src_reg.s32_max_value;
+ u32_min_val = src_reg.u32_min_value;
+ u32_max_val = src_reg.u32_max_value;
+
+ if (alu32) {
+ src_known = tnum_subreg_is_const(src_reg.var_off);
+ dst_known = tnum_subreg_is_const(dst_reg->var_off);
+ if ((src_known &&
+ (s32_min_val != s32_max_val || u32_min_val != u32_max_val)) ||
+ s32_min_val > s32_max_val || u32_min_val > u32_max_val) {
+ /* Taint dst register if offset had invalid bounds
+ * derived from e.g. dead branches.
+ */
+ __mark_reg_unknown(env, dst_reg);
+ return 0;
+ }
+ } else {
+ src_known = tnum_is_const(src_reg.var_off);
+ dst_known = tnum_is_const(dst_reg->var_off);
+ if ((src_known &&
+ (smin_val != smax_val || umin_val != umax_val)) ||
+ smin_val > smax_val || umin_val > umax_val) {
+ /* Taint dst register if offset had invalid bounds
+ * derived from e.g. dead branches.
+ */
+ __mark_reg_unknown(env, dst_reg);
+ return 0;
+ }
}
if (!src_known &&
@@ -5120,6 +5651,20 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
return 0;
}
+ /* Calculate sign/unsigned bounds and tnum for alu32 and alu64 bit ops.
+ * There are two classes of instructions: The first class we track both
+ * alu32 and alu64 sign/unsigned bounds independently this provides the
+ * greatest amount of precision when alu operations are mixed with jmp32
+ * operations. These operations are BPF_ADD, BPF_SUB, BPF_MUL, BPF_ADD,
+ * and BPF_OR. This is possible because these ops have fairly easy to
+ * understand and calculate behavior in both 32-bit and 64-bit alu ops.
+ * See alu32 verifier tests for examples. The second class of
+ * operations, BPF_LSH, BPF_RSH, and BPF_ARSH, however are not so easy
+ * with regards to tracking sign/unsigned bounds because the bits may
+ * cross subreg boundaries in the alu64 case. When this happens we mark
+ * the reg unbounded in the subreg bound space and use the resulting
+ * tnum to calculate an approximation of the sign/unsigned bounds.
+ */
switch (opcode) {
case BPF_ADD:
ret = sanitize_val_alu(env, insn);
@@ -5127,7 +5672,9 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
verbose(env, "R%d tried to add from different pointers or scalars\n", dst);
return ret;
}
+ scalar32_min_max_add(dst_reg, &src_reg);
scalar_min_max_add(dst_reg, &src_reg);
+ dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off);
break;
case BPF_SUB:
ret = sanitize_val_alu(env, insn);
@@ -5135,25 +5682,23 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
verbose(env, "R%d tried to sub from different pointers or scalars\n", dst);
return ret;
}
+ scalar32_min_max_sub(dst_reg, &src_reg);
scalar_min_max_sub(dst_reg, &src_reg);
+ dst_reg->var_off = tnum_sub(dst_reg->var_off, src_reg.var_off);
break;
case BPF_MUL:
+ dst_reg->var_off = tnum_mul(dst_reg->var_off, src_reg.var_off);
+ scalar32_min_max_mul(dst_reg, &src_reg);
scalar_min_max_mul(dst_reg, &src_reg);
break;
case BPF_AND:
- if (src_known && dst_known) {
- __mark_reg_known(dst_reg, dst_reg->var_off.value &
- src_reg.var_off.value);
- break;
- }
+ dst_reg->var_off = tnum_and(dst_reg->var_off, src_reg.var_off);
+ scalar32_min_max_and(dst_reg, &src_reg);
scalar_min_max_and(dst_reg, &src_reg);
break;
case BPF_OR:
- if (src_known && dst_known) {
- __mark_reg_known(dst_reg, dst_reg->var_off.value |
- src_reg.var_off.value);
- break;
- }
+ dst_reg->var_off = tnum_or(dst_reg->var_off, src_reg.var_off);
+ scalar32_min_max_or(dst_reg, &src_reg);
scalar_min_max_or(dst_reg, &src_reg);
break;
case BPF_LSH:
@@ -5164,7 +5709,10 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
mark_reg_unknown(env, regs, insn->dst_reg);
break;
}
- scalar_min_max_lsh(dst_reg, &src_reg);
+ if (alu32)
+ scalar32_min_max_lsh(dst_reg, &src_reg);
+ else
+ scalar_min_max_lsh(dst_reg, &src_reg);
break;
case BPF_RSH:
if (umax_val >= insn_bitness) {
@@ -5174,7 +5722,10 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
mark_reg_unknown(env, regs, insn->dst_reg);
break;
}
- scalar_min_max_rsh(dst_reg, &src_reg);
+ if (alu32)
+ scalar32_min_max_rsh(dst_reg, &src_reg);
+ else
+ scalar_min_max_rsh(dst_reg, &src_reg);
break;
case BPF_ARSH:
if (umax_val >= insn_bitness) {
@@ -5184,17 +5735,19 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
mark_reg_unknown(env, regs, insn->dst_reg);
break;
}
- scalar_min_max_arsh(dst_reg, &src_reg, insn_bitness);
+ if (alu32)
+ scalar32_min_max_arsh(dst_reg, &src_reg);
+ else
+ scalar_min_max_arsh(dst_reg, &src_reg);
break;
default:
mark_reg_unknown(env, regs, insn->dst_reg);
break;
}
- if (BPF_CLASS(insn->code) != BPF_ALU64) {
- /* 32-bit ALU ops are (32,32)->32 */
- coerce_reg_to_size(dst_reg, 4);
- }
+ /* ALU32 ops are zero extended into 64bit register */
+ if (alu32)
+ zext_32_to_64(dst_reg);
__update_reg_bounds(dst_reg);
__reg_deduce_bounds(dst_reg);
@@ -5370,7 +5923,7 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
mark_reg_unknown(env, regs,
insn->dst_reg);
}
- coerce_reg_to_size(dst_reg, 4);
+ zext_32_to_64(dst_reg);
}
} else {
/* case: R = imm
@@ -5540,55 +6093,83 @@ static void find_good_pkt_pointers(struct bpf_verifier_state *vstate,
new_range);
}
-/* compute branch direction of the expression "if (reg opcode val) goto target;"
- * and return:
- * 1 - branch will be taken and "goto target" will be executed
- * 0 - branch will not be taken and fall-through to next insn
- * -1 - unknown. Example: "if (reg < 5)" is unknown when register value range [0,10]
- */
-static int is_branch_taken(struct bpf_reg_state *reg, u64 val, u8 opcode,
- bool is_jmp32)
+static int is_branch32_taken(struct bpf_reg_state *reg, u32 val, u8 opcode)
{
- struct bpf_reg_state reg_lo;
- s64 sval;
+ struct tnum subreg = tnum_subreg(reg->var_off);
+ s32 sval = (s32)val;
- if (__is_pointer_value(false, reg))
- return -1;
+ switch (opcode) {
+ case BPF_JEQ:
+ if (tnum_is_const(subreg))
+ return !!tnum_equals_const(subreg, val);
+ break;
+ case BPF_JNE:
+ if (tnum_is_const(subreg))
+ return !tnum_equals_const(subreg, val);
+ break;
+ case BPF_JSET:
+ if ((~subreg.mask & subreg.value) & val)
+ return 1;
+ if (!((subreg.mask | subreg.value) & val))
+ return 0;
+ break;
+ case BPF_JGT:
+ if (reg->u32_min_value > val)
+ return 1;
+ else if (reg->u32_max_value <= val)
+ return 0;
+ break;
+ case BPF_JSGT:
+ if (reg->s32_min_value > sval)
+ return 1;
+ else if (reg->s32_max_value < sval)
+ return 0;
+ break;
+ case BPF_JLT:
+ if (reg->u32_max_value < val)
+ return 1;
+ else if (reg->u32_min_value >= val)
+ return 0;
+ break;
+ case BPF_JSLT:
+ if (reg->s32_max_value < sval)
+ return 1;
+ else if (reg->s32_min_value >= sval)
+ return 0;
+ break;
+ case BPF_JGE:
+ if (reg->u32_min_value >= val)
+ return 1;
+ else if (reg->u32_max_value < val)
+ return 0;
+ break;
+ case BPF_JSGE:
+ if (reg->s32_min_value >= sval)
+ return 1;
+ else if (reg->s32_max_value < sval)
+ return 0;
+ break;
+ case BPF_JLE:
+ if (reg->u32_max_value <= val)
+ return 1;
+ else if (reg->u32_min_value > val)
+ return 0;
+ break;
+ case BPF_JSLE:
+ if (reg->s32_max_value <= sval)
+ return 1;
+ else if (reg->s32_min_value > sval)
+ return 0;
+ break;
+ }
- if (is_jmp32) {
- reg_lo = *reg;
- reg = &reg_lo;
- /* For JMP32, only low 32 bits are compared, coerce_reg_to_size
- * could truncate high bits and update umin/umax according to
- * information of low bits.
- */
- coerce_reg_to_size(reg, 4);
- /* smin/smax need special handling. For example, after coerce,
- * if smin_value is 0x00000000ffffffffLL, the value is -1 when
- * used as operand to JMP32. It is a negative number from s32's
- * point of view, while it is a positive number when seen as
- * s64. The smin/smax are kept as s64, therefore, when used with
- * JMP32, they need to be transformed into s32, then sign
- * extended back to s64.
- *
- * Also, smin/smax were copied from umin/umax. If umin/umax has
- * different sign bit, then min/max relationship doesn't
- * maintain after casting into s32, for this case, set smin/smax
- * to safest range.
- */
- if ((reg->umax_value ^ reg->umin_value) &
- (1ULL << 31)) {
- reg->smin_value = S32_MIN;
- reg->smax_value = S32_MAX;
- }
- reg->smin_value = (s64)(s32)reg->smin_value;
- reg->smax_value = (s64)(s32)reg->smax_value;
+ return -1;
+}
- val = (u32)val;
- sval = (s64)(s32)val;
- } else {
- sval = (s64)val;
- }
+
+static int is_branch64_taken(struct bpf_reg_state *reg, u64 val, u8 opcode)
+{
+ s64 sval = (s64)val;
switch (opcode) {
case BPF_JEQ:
@@ -5658,91 +6239,22 @@ static int is_branch_taken(struct bpf_reg_state *reg, u64 val, u8 opcode,
return -1;
}
-/* Generate min value of the high 32-bit from TNUM info. */
-static u64 gen_hi_min(struct tnum var)
-{
- return var.value & ~0xffffffffULL;
-}
-
-/* Generate max value of the high 32-bit from TNUM info. */
-static u64 gen_hi_max(struct tnum var)
-{
- return (var.value | var.mask) & ~0xffffffffULL;
-}
-
-/* Return true if VAL is compared with a s64 sign extended from s32, and they
- * are with the same signedness.
- */
-static bool cmp_val_with_extended_s64(s64 sval, struct bpf_reg_state *reg)
-{
- return ((s32)sval >= 0 &&
- reg->smin_value >= 0 && reg->smax_value <= S32_MAX) ||
- ((s32)sval < 0 &&
- reg->smax_value <= 0 && reg->smin_value >= S32_MIN);
-}
-
-/* Constrain the possible values of @reg with unsigned upper bound @bound.
- * If @is_exclusive, @bound is an exclusive limit, otherwise it is inclusive.
- * If @is_jmp32, @bound is a 32-bit value that only constrains the low 32 bits
- * of @reg.
- */
-static void set_upper_bound(struct bpf_reg_state *reg, u64 bound, bool is_jmp32,
- bool is_exclusive)
-{
- if (is_exclusive) {
- /* There are no values for `reg` that make `reg<0` true. */
- if (bound == 0)
- return;
- bound--;
- }
- if (is_jmp32) {
- /* Constrain the register's value in the tnum representation.
- * For 64-bit comparisons this happens later in
- * __reg_bound_offset(), but for 32-bit comparisons, we can be
- * more precise than what can be derived from the updated
- * numeric bounds.
- */
- struct tnum t = tnum_range(0, bound);
-
- t.mask |= ~0xffffffffULL; /* upper half is unknown */
- reg->var_off = tnum_intersect(reg->var_off, t);
-
- /* Compute the 64-bit bound from the 32-bit bound. */
- bound += gen_hi_max(reg->var_off);
- }
- reg->umax_value = min(reg->umax_value, bound);
-}
-
-/* Constrain the possible values of @reg with unsigned lower bound @bound.
- * If @is_exclusive, @bound is an exclusive limit, otherwise it is inclusive.
- * If @is_jmp32, @bound is a 32-bit value that only constrains the low 32 bits
- * of @reg.
+/* compute branch direction of the expression "if (reg opcode val) goto target;"
+ * and return:
+ * 1 - branch will be taken and "goto target" will be executed
+ * 0 - branch will not be taken and fall-through to next insn
+ * -1 - unknown. Example: "if (reg < 5)" is unknown when register value
+ * range [0,10]
*/
-static void set_lower_bound(struct bpf_reg_state *reg, u64 bound, bool is_jmp32,
- bool is_exclusive)
+static int is_branch_taken(struct bpf_reg_state *reg, u64 val, u8 opcode,
+ bool is_jmp32)
{
- if (is_exclusive) {
- /* There are no values for `reg` that make `reg>MAX` true. */
- if (bound == (is_jmp32 ? U32_MAX : U64_MAX))
- return;
- bound++;
- }
- if (is_jmp32) {
- /* Constrain the register's value in the tnum representation.
- * For 64-bit comparisons this happens later in
- * __reg_bound_offset(), but for 32-bit comparisons, we can be
- * more precise than what can be derived from the updated
- * numeric bounds.
- */
- struct tnum t = tnum_range(bound, U32_MAX);
-
- t.mask |= ~0xffffffffULL; /* upper half is unknown */
- reg->var_off = tnum_intersect(reg->var_off, t);
+ if (__is_pointer_value(false, reg))
+ return -1;
- /* Compute the 64-bit bound from the 32-bit bound. */
- bound += gen_hi_min(reg->var_off);
- }
- reg->umin_value = max(reg->umin_value, bound);
+ if (is_jmp32)
+ return is_branch32_taken(reg, val, opcode);
+ return is_branch64_taken(reg, val, opcode);
}
/* Adjusts the register min/max values in the case that the dst_reg is the
@@ -5751,10 +6263,16 @@ static void set_lower_bound(struct bpf_reg_state *reg, u64 bound, bool is_jmp32,
* In JEQ/JNE cases we also adjust the var_off values.
*/
static void reg_set_min_max(struct bpf_reg_state *true_reg,
- struct bpf_reg_state *false_reg, u64 val,
+ struct bpf_reg_state *false_reg,
+ u64 val, u32 val32,
u8 opcode, bool is_jmp32)
{
- s64 sval;
+ struct tnum false_32off = tnum_subreg(false_reg->var_off);
+ struct tnum false_64off = false_reg->var_off;
+ struct tnum true_32off = tnum_subreg(true_reg->var_off);
+ struct tnum true_64off = true_reg->var_off;
+ s64 sval = (s64)val;
+ s32 sval32 = (s32)val32;
/* If the dst_reg is a pointer, we can't learn anything about its
* variable offset from the compare (unless src_reg were a pointer into
@@ -5765,9 +6283,6 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg,
if (__is_pointer_value(false, false_reg))
return;
- val = is_jmp32 ? (u32)val : val;
- sval = is_jmp32 ? (s64)(s32)val : (s64)val;
-
switch (opcode) {
case BPF_JEQ:
case BPF_JNE:
@@ -5779,87 +6294,126 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg,
* if it is true we know the value for sure. Likewise for
* BPF_JNE.
*/
- if (is_jmp32) {
- u64 old_v = reg->var_off.value;
- u64 hi_mask = ~0xffffffffULL;
-
- reg->var_off.value = (old_v & hi_mask) | val;
- reg->var_off.mask &= hi_mask;
- } else {
+ if (is_jmp32)
+ __mark_reg32_known(reg, val32);
+ else
__mark_reg_known(reg, val);
- }
break;
}
case BPF_JSET:
- false_reg->var_off = tnum_and(false_reg->var_off,
- tnum_const(~val));
- if (is_power_of_2(val))
- true_reg->var_off = tnum_or(true_reg->var_off,
- tnum_const(val));
+ if (is_jmp32) {
+ false_32off = tnum_and(false_32off, tnum_const(~val32));
+ if (is_power_of_2(val32))
+ true_32off = tnum_or(true_32off,
+ tnum_const(val32));
+ } else {
+ false_64off = tnum_and(false_64off, tnum_const(~val));
+ if (is_power_of_2(val))
+ true_64off = tnum_or(true_64off,
+ tnum_const(val));
+ }
break;
case BPF_JGE:
case BPF_JGT:
{
- set_upper_bound(false_reg, val, is_jmp32, opcode == BPF_JGE);
- set_lower_bound(true_reg, val, is_jmp32, opcode == BPF_JGT);
+ if (is_jmp32) {
+ u32 false_umax = opcode == BPF_JGT ? val32 : val32 - 1;
+ u32 true_umin = opcode == BPF_JGT ? val32 + 1 : val32;
+
+ false_reg->u32_max_value = min(false_reg->u32_max_value,
+ false_umax);
+ true_reg->u32_min_value = max(true_reg->u32_min_value,
+ true_umin);
+ } else {
+ u64 false_umax = opcode == BPF_JGT ? val : val - 1;
+ u64 true_umin = opcode == BPF_JGT ? val + 1 : val;
+
+ false_reg->umax_value = min(false_reg->umax_value, false_umax);
+ true_reg->umin_value = max(true_reg->umin_value, true_umin);
+ }
break;
}
case BPF_JSGE:
case BPF_JSGT:
{
- s64 false_smax = opcode == BPF_JSGT ? sval : sval - 1;
- s64 true_smin = opcode == BPF_JSGT ? sval + 1 : sval;
+ if (is_jmp32) {
+ s32 false_smax = opcode == BPF_JSGT ? sval32 : sval32 - 1;
+ s32 true_smin = opcode == BPF_JSGT ? sval32 + 1 : sval32;
- /* If the full s64 was not sign-extended from s32 then don't
- * deduct further info.
- */
- if (is_jmp32 && !cmp_val_with_extended_s64(sval, false_reg))
- break;
- false_reg->smax_value = min(false_reg->smax_value, false_smax);
- true_reg->smin_value = max(true_reg->smin_value, true_smin);
+ false_reg->s32_max_value = min(false_reg->s32_max_value, false_smax);
+ true_reg->s32_min_value = max(true_reg->s32_min_value, true_smin);
+ } else {
+ s64 false_smax = opcode == BPF_JSGT ? sval : sval - 1;
+ s64 true_smin = opcode == BPF_JSGT ? sval + 1 : sval;
+
+ false_reg->smax_value = min(false_reg->smax_value, false_smax);
+ true_reg->smin_value = max(true_reg->smin_value, true_smin);
+ }
break;
}
case BPF_JLE:
case BPF_JLT:
{
- set_lower_bound(false_reg, val, is_jmp32, opcode == BPF_JLE);
- set_upper_bound(true_reg, val, is_jmp32, opcode == BPF_JLT);
+ if (is_jmp32) {
+ u32 false_umin = opcode == BPF_JLT ? val32 : val32 + 1;
+ u32 true_umax = opcode == BPF_JLT ? val32 - 1 : val32;
+
+ false_reg->u32_min_value = max(false_reg->u32_min_value,
+ false_umin);
+ true_reg->u32_max_value = min(true_reg->u32_max_value,
+ true_umax);
+ } else {
+ u64 false_umin = opcode == BPF_JLT ? val : val + 1;
+ u64 true_umax = opcode == BPF_JLT ? val - 1 : val;
+
+ false_reg->umin_value = max(false_reg->umin_value, false_umin);
+ true_reg->umax_value = min(true_reg->umax_value, true_umax);
+ }
break;
}
case BPF_JSLE:
case BPF_JSLT:
{
- s64 false_smin = opcode == BPF_JSLT ? sval : sval + 1;
- s64 true_smax = opcode == BPF_JSLT ? sval - 1 : sval;
+ if (is_jmp32) {
+ s32 false_smin = opcode == BPF_JSLT ? sval32 : sval32 + 1;
+ s32 true_smax = opcode == BPF_JSLT ? sval32 - 1 : sval32;
- if (is_jmp32 && !cmp_val_with_extended_s64(sval, false_reg))
- break;
- false_reg->smin_value = max(false_reg->smin_value, false_smin);
- true_reg->smax_value = min(true_reg->smax_value, true_smax);
+ false_reg->s32_min_value = max(false_reg->s32_min_value, false_smin);
+ true_reg->s32_max_value = min(true_reg->s32_max_value, true_smax);
+ } else {
+ s64 false_smin = opcode == BPF_JSLT ? sval : sval + 1;
+ s64 true_smax = opcode == BPF_JSLT ? sval - 1 : sval;
+
+ false_reg->smin_value = max(false_reg->smin_value, false_smin);
+ true_reg->smax_value = min(true_reg->smax_value, true_smax);
+ }
break;
}
default:
return;
}
- __reg_deduce_bounds(false_reg);
- __reg_deduce_bounds(true_reg);
- /* We might have learned some bits from the bounds. */
- __reg_bound_offset(false_reg);
- __reg_bound_offset(true_reg);
- /* Intersecting with the old var_off might have improved our bounds
- * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
- * then new var_off is (0; 0x7f...fc) which improves our umax.
- */
- __update_reg_bounds(false_reg);
- __update_reg_bounds(true_reg);
+ if (is_jmp32) {
+ false_reg->var_off = tnum_or(tnum_clear_subreg(false_64off),
+ tnum_subreg(false_32off));
+ true_reg->var_off = tnum_or(tnum_clear_subreg(true_64off),
+ tnum_subreg(true_32off));
+ __reg_combine_32_into_64(false_reg);
+ __reg_combine_32_into_64(true_reg);
+ } else {
+ false_reg->var_off = false_64off;
+ true_reg->var_off = true_64off;
+ __reg_combine_64_into_32(false_reg);
+ __reg_combine_64_into_32(true_reg);
+ }
}
/* Same as above, but for the case that dst_reg holds a constant and src_reg is
* the variable reg.
*/
static void reg_set_min_max_inv(struct bpf_reg_state *true_reg,
- struct bpf_reg_state *false_reg, u64 val,
+ struct bpf_reg_state *false_reg,
+ u64 val, u32 val32,
u8 opcode, bool is_jmp32)
{
/* How can we transform "a <op> b" into "b <op> a"? */
@@ -5883,7 +6437,7 @@ static void reg_set_min_max_inv(struct bpf_reg_state *true_reg,
* BPF_JA, can't get here.
*/
if (opcode)
- reg_set_min_max(true_reg, false_reg, val, opcode, is_jmp32);
+ reg_set_min_max(true_reg, false_reg, val, val32, opcode, is_jmp32);
}
/* Regs are known to be equal, so intersect their min/max/var_off */
@@ -6172,13 +6726,22 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,
dst_reg = &regs[insn->dst_reg];
is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;
- if (BPF_SRC(insn->code) == BPF_K)
- pred = is_branch_taken(dst_reg, insn->imm,
- opcode, is_jmp32);
- else if (src_reg->type == SCALAR_VALUE &&
- tnum_is_const(src_reg->var_off))
- pred = is_branch_taken(dst_reg, src_reg->var_off.value,
- opcode, is_jmp32);
+ if (BPF_SRC(insn->code) == BPF_K) {
+ pred = is_branch_taken(dst_reg, insn->imm, opcode, is_jmp32);
+ } else if (src_reg->type == SCALAR_VALUE &&
+ is_jmp32 && tnum_is_const(tnum_subreg(src_reg->var_off))) {
+ pred = is_branch_taken(dst_reg,
+ tnum_subreg(src_reg->var_off).value,
+ opcode,
+ is_jmp32);
+ } else if (src_reg->type == SCALAR_VALUE &&
+ !is_jmp32 && tnum_is_const(src_reg->var_off)) {
+ pred = is_branch_taken(dst_reg,
+ src_reg->var_off.value,
+ opcode,
+ is_jmp32);
+ }
+
if (pred >= 0) {
err = mark_chain_precision(env, insn->dst_reg);
if (BPF_SRC(insn->code) == BPF_X && !err)
@@ -6212,32 +6775,24 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,
*/
if (BPF_SRC(insn->code) == BPF_X) {
struct bpf_reg_state *src_reg = &regs[insn->src_reg];
- struct bpf_reg_state lo_reg0 = *dst_reg;
- struct bpf_reg_state lo_reg1 = *src_reg;
- struct bpf_reg_state *src_lo, *dst_lo;
-
- dst_lo = &lo_reg0;
- src_lo = &lo_reg1;
- coerce_reg_to_size(dst_lo, 4);
- coerce_reg_to_size(src_lo, 4);
if (dst_reg->type == SCALAR_VALUE &&
src_reg->type == SCALAR_VALUE) {
if (tnum_is_const(src_reg->var_off) ||
- (is_jmp32 && tnum_is_const(src_lo->var_off)))
+ (is_jmp32 &&
+ tnum_is_const(tnum_subreg(src_reg->var_off))))
reg_set_min_max(&other_branch_regs[insn->dst_reg],
dst_reg,
- is_jmp32
- ? src_lo->var_off.value
- : src_reg->var_off.value,
+ src_reg->var_off.value,
+ tnum_subreg(src_reg->var_off).value,
opcode, is_jmp32);
else if (tnum_is_const(dst_reg->var_off) ||
- (is_jmp32 && tnum_is_const(dst_lo->var_off)))
+ (is_jmp32 &&
+ tnum_is_const(tnum_subreg(dst_reg->var_off))))
reg_set_min_max_inv(&other_branch_regs[insn->src_reg],
src_reg,
- is_jmp32
- ? dst_lo->var_off.value
- : dst_reg->var_off.value,
+ dst_reg->var_off.value,
+ tnum_subreg(dst_reg->var_off).value,
opcode, is_jmp32);
else if (!is_jmp32 &&
(opcode == BPF_JEQ || opcode == BPF_JNE))
@@ -6248,7 +6803,8 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,
}
} else if (dst_reg->type == SCALAR_VALUE) {
reg_set_min_max(&other_branch_regs[insn->dst_reg],
- dst_reg, insn->imm, opcode, is_jmp32);
+ dst_reg, insn->imm, (u32)insn->imm,
+ opcode, is_jmp32);
}
/* detect if R == 0 where R is returned from bpf_map_lookup_elem().
generated by cgit (git 2.34.1) at 2024-06-15 01:05:24 +0000