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-rw-r--r--kernel/bpf/verifier.c1283
1 files changed, 1164 insertions, 119 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a5c369e60343..a2e763703c30 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -168,7 +168,7 @@ struct bpf_verifier_stack_elem {
struct bpf_verifier_stack_elem *next;
};
-#define BPF_COMPLEXITY_LIMIT_STACK 1024
+#define BPF_COMPLEXITY_LIMIT_JMP_SEQ 8192
#define BPF_COMPLEXITY_LIMIT_STATES 64
#define BPF_MAP_PTR_UNPRIV 1UL
@@ -326,7 +326,8 @@ static bool type_is_sk_pointer(enum bpf_reg_type type)
{
return type == PTR_TO_SOCKET ||
type == PTR_TO_SOCK_COMMON ||
- type == PTR_TO_TCP_SOCK;
+ type == PTR_TO_TCP_SOCK ||
+ type == PTR_TO_XDP_SOCK;
}
static bool reg_type_may_be_null(enum bpf_reg_type type)
@@ -398,6 +399,7 @@ static const char * const reg_type_str[] = {
[PTR_TO_TCP_SOCK] = "tcp_sock",
[PTR_TO_TCP_SOCK_OR_NULL] = "tcp_sock_or_null",
[PTR_TO_TP_BUFFER] = "tp_buffer",
+ [PTR_TO_XDP_SOCK] = "xdp_sock",
};
static char slot_type_char[] = {
@@ -445,12 +447,12 @@ static void print_verifier_state(struct bpf_verifier_env *env,
verbose(env, " R%d", i);
print_liveness(env, reg->live);
verbose(env, "=%s", reg_type_str[t]);
+ if (t == SCALAR_VALUE && reg->precise)
+ verbose(env, "P");
if ((t == SCALAR_VALUE || t == PTR_TO_STACK) &&
tnum_is_const(reg->var_off)) {
/* reg->off should be 0 for SCALAR_VALUE */
verbose(env, "%lld", reg->var_off.value + reg->off);
- if (t == PTR_TO_STACK)
- verbose(env, ",call_%d", func(env, reg)->callsite);
} else {
verbose(env, "(id=%d", reg->id);
if (reg_type_may_be_refcounted_or_null(t))
@@ -512,11 +514,17 @@ static void print_verifier_state(struct bpf_verifier_env *env,
continue;
verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE);
print_liveness(env, state->stack[i].spilled_ptr.live);
- if (state->stack[i].slot_type[0] == STACK_SPILL)
- verbose(env, "=%s",
- reg_type_str[state->stack[i].spilled_ptr.type]);
- else
+ if (state->stack[i].slot_type[0] == STACK_SPILL) {
+ reg = &state->stack[i].spilled_ptr;
+ t = reg->type;
+ verbose(env, "=%s", reg_type_str[t]);
+ if (t == SCALAR_VALUE && reg->precise)
+ verbose(env, "P");
+ if (t == SCALAR_VALUE && tnum_is_const(reg->var_off))
+ verbose(env, "%lld", reg->var_off.value + reg->off);
+ } else {
verbose(env, "=%s", types_buf);
+ }
}
if (state->acquired_refs && state->refs[0].id) {
verbose(env, " refs=%d", state->refs[0].id);
@@ -665,6 +673,13 @@ static void free_func_state(struct bpf_func_state *state)
kfree(state);
}
+static void clear_jmp_history(struct bpf_verifier_state *state)
+{
+ kfree(state->jmp_history);
+ state->jmp_history = NULL;
+ state->jmp_history_cnt = 0;
+}
+
static void free_verifier_state(struct bpf_verifier_state *state,
bool free_self)
{
@@ -674,6 +689,7 @@ static void free_verifier_state(struct bpf_verifier_state *state,
free_func_state(state->frame[i]);
state->frame[i] = NULL;
}
+ clear_jmp_history(state);
if (free_self)
kfree(state);
}
@@ -701,8 +717,18 @@ static int copy_verifier_state(struct bpf_verifier_state *dst_state,
const struct bpf_verifier_state *src)
{
struct bpf_func_state *dst;
+ u32 jmp_sz = sizeof(struct bpf_idx_pair) * src->jmp_history_cnt;
int i, err;
+ if (dst_state->jmp_history_cnt < src->jmp_history_cnt) {
+ kfree(dst_state->jmp_history);
+ dst_state->jmp_history = kmalloc(jmp_sz, GFP_USER);
+ if (!dst_state->jmp_history)
+ return -ENOMEM;
+ }
+ memcpy(dst_state->jmp_history, src->jmp_history, jmp_sz);
+ dst_state->jmp_history_cnt = src->jmp_history_cnt;
+
/* if dst has more stack frames then src frame, free them */
for (i = src->curframe + 1; i <= dst_state->curframe; i++) {
free_func_state(dst_state->frame[i]);
@@ -711,6 +737,10 @@ static int copy_verifier_state(struct bpf_verifier_state *dst_state,
dst_state->speculative = src->speculative;
dst_state->curframe = src->curframe;
dst_state->active_spin_lock = src->active_spin_lock;
+ dst_state->branches = src->branches;
+ dst_state->parent = src->parent;
+ dst_state->first_insn_idx = src->first_insn_idx;
+ dst_state->last_insn_idx = src->last_insn_idx;
for (i = 0; i <= src->curframe; i++) {
dst = dst_state->frame[i];
if (!dst) {
@@ -726,6 +756,23 @@ static int copy_verifier_state(struct bpf_verifier_state *dst_state,
return 0;
}
+static void update_branch_counts(struct bpf_verifier_env *env, struct bpf_verifier_state *st)
+{
+ while (st) {
+ u32 br = --st->branches;
+
+ /* WARN_ON(br > 1) technically makes sense here,
+ * but see comment in push_stack(), hence:
+ */
+ WARN_ONCE((int)br < 0,
+ "BUG update_branch_counts:branches_to_explore=%d\n",
+ br);
+ if (br)
+ break;
+ st = st->parent;
+ }
+}
+
static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx,
int *insn_idx)
{
@@ -774,10 +821,23 @@ static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
if (err)
goto err;
elem->st.speculative |= speculative;
- if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) {
- verbose(env, "BPF program is too complex\n");
+ if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) {
+ verbose(env, "The sequence of %d jumps is too complex.\n",
+ env->stack_size);
goto err;
}
+ if (elem->st.parent) {
+ ++elem->st.parent->branches;
+ /* WARN_ON(branches > 2) technically makes sense here,
+ * but
+ * 1. speculative states will bump 'branches' for non-branch
+ * instructions
+ * 2. is_state_visited() heuristics may decide not to create
+ * a new state for a sequence of branches and all such current
+ * and cloned states will be pointing to a single parent state
+ * which might have large 'branches' count.
+ */
+ }
return &elem->st;
err:
free_verifier_state(env->cur_state, true);
@@ -925,6 +985,9 @@ static void __mark_reg_unbounded(struct bpf_reg_state *reg)
reg->smax_value = S64_MAX;
reg->umin_value = 0;
reg->umax_value = U64_MAX;
+
+ /* constant backtracking is enabled for root only for now */
+ reg->precise = capable(CAP_SYS_ADMIN) ? false : true;
}
/* Mark a register as having a completely unknown (scalar) value. */
@@ -973,6 +1036,7 @@ static void mark_reg_not_init(struct bpf_verifier_env *env,
__mark_reg_not_init(regs + regno);
}
+#define DEF_NOT_SUBREG (0)
static void init_reg_state(struct bpf_verifier_env *env,
struct bpf_func_state *state)
{
@@ -983,6 +1047,7 @@ static void init_reg_state(struct bpf_verifier_env *env,
mark_reg_not_init(env, regs, i);
regs[i].live = REG_LIVE_NONE;
regs[i].parent = NULL;
+ regs[i].subreg_def = DEF_NOT_SUBREG;
}
/* frame pointer */
@@ -1128,7 +1193,7 @@ next:
*/
static int mark_reg_read(struct bpf_verifier_env *env,
const struct bpf_reg_state *state,
- struct bpf_reg_state *parent)
+ struct bpf_reg_state *parent, u8 flag)
{
bool writes = parent == state->parent; /* Observe write marks */
int cnt = 0;
@@ -1143,17 +1208,26 @@ static int mark_reg_read(struct bpf_verifier_env *env,
parent->var_off.value, parent->off);
return -EFAULT;
}
- if (parent->live & REG_LIVE_READ)
+ /* The first condition is more likely to be true than the
+ * second, checked it first.
+ */
+ if ((parent->live & REG_LIVE_READ) == flag ||
+ parent->live & REG_LIVE_READ64)
/* The parentage chain never changes and
* this parent was already marked as LIVE_READ.
* There is no need to keep walking the chain again and
* keep re-marking all parents as LIVE_READ.
* This case happens when the same register is read
* multiple times without writes into it in-between.
+ * Also, if parent has the stronger REG_LIVE_READ64 set,
+ * then no need to set the weak REG_LIVE_READ32.
*/
break;
/* ... then we depend on parent's value */
- parent->live |= REG_LIVE_READ;
+ parent->live |= flag;
+ /* REG_LIVE_READ64 overrides REG_LIVE_READ32. */
+ if (flag == REG_LIVE_READ64)
+ parent->live &= ~REG_LIVE_READ32;
state = parent;
parent = state->parent;
writes = true;
@@ -1165,12 +1239,129 @@ static int mark_reg_read(struct bpf_verifier_env *env,
return 0;
}
+/* This function is supposed to be used by the following 32-bit optimization
+ * code only. It returns TRUE if the source or destination register operates
+ * on 64-bit, otherwise return FALSE.
+ */
+static bool is_reg64(struct bpf_verifier_env *env, struct bpf_insn *insn,
+ u32 regno, struct bpf_reg_state *reg, enum reg_arg_type t)
+{
+ u8 code, class, op;
+
+ code = insn->code;
+ class = BPF_CLASS(code);
+ op = BPF_OP(code);
+ if (class == BPF_JMP) {
+ /* BPF_EXIT for "main" will reach here. Return TRUE
+ * conservatively.
+ */
+ if (op == BPF_EXIT)
+ return true;
+ if (op == BPF_CALL) {
+ /* BPF to BPF call will reach here because of marking
+ * caller saved clobber with DST_OP_NO_MARK for which we
+ * don't care the register def because they are anyway
+ * marked as NOT_INIT already.
+ */
+ if (insn->src_reg == BPF_PSEUDO_CALL)
+ return false;
+ /* Helper call will reach here because of arg type
+ * check, conservatively return TRUE.
+ */
+ if (t == SRC_OP)
+ return true;
+
+ return false;
+ }
+ }
+
+ if (class == BPF_ALU64 || class == BPF_JMP ||
+ /* BPF_END always use BPF_ALU class. */
+ (class == BPF_ALU && op == BPF_END && insn->imm == 64))
+ return true;
+
+ if (class == BPF_ALU || class == BPF_JMP32)
+ return false;
+
+ if (class == BPF_LDX) {
+ if (t != SRC_OP)
+ return BPF_SIZE(code) == BPF_DW;
+ /* LDX source must be ptr. */
+ return true;
+ }
+
+ if (class == BPF_STX) {
+ if (reg->type != SCALAR_VALUE)
+ return true;
+ return BPF_SIZE(code) == BPF_DW;
+ }
+
+ if (class == BPF_LD) {
+ u8 mode = BPF_MODE(code);
+
+ /* LD_IMM64 */
+ if (mode == BPF_IMM)
+ return true;
+
+ /* Both LD_IND and LD_ABS return 32-bit data. */
+ if (t != SRC_OP)
+ return false;
+
+ /* Implicit ctx ptr. */
+ if (regno == BPF_REG_6)
+ return true;
+
+ /* Explicit source could be any width. */
+ return true;
+ }
+
+ if (class == BPF_ST)
+ /* The only source register for BPF_ST is a ptr. */
+ return true;
+
+ /* Conservatively return true at default. */
+ return true;
+}
+
+/* Return TRUE if INSN doesn't have explicit value define. */
+static bool insn_no_def(struct bpf_insn *insn)
+{
+ u8 class = BPF_CLASS(insn->code);
+
+ return (class == BPF_JMP || class == BPF_JMP32 ||
+ class == BPF_STX || class == BPF_ST);
+}
+
+/* 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))
+ return false;
+
+ return !is_reg64(env, insn, insn->dst_reg, NULL, DST_OP);
+}
+
+static void mark_insn_zext(struct bpf_verifier_env *env,
+ struct bpf_reg_state *reg)
+{
+ s32 def_idx = reg->subreg_def;
+
+ if (def_idx == DEF_NOT_SUBREG)
+ return;
+
+ env->insn_aux_data[def_idx - 1].zext_dst = true;
+ /* The dst will be zero extended, so won't be sub-register anymore. */
+ reg->subreg_def = DEF_NOT_SUBREG;
+}
+
static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
enum reg_arg_type t)
{
struct bpf_verifier_state *vstate = env->cur_state;
struct bpf_func_state *state = vstate->frame[vstate->curframe];
+ struct bpf_insn *insn = env->prog->insnsi + env->insn_idx;
struct bpf_reg_state *reg, *regs = state->regs;
+ bool rw64;
if (regno >= MAX_BPF_REG) {
verbose(env, "R%d is invalid\n", regno);
@@ -1178,6 +1369,7 @@ static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
}
reg = &regs[regno];
+ rw64 = is_reg64(env, insn, regno, reg, t);
if (t == SRC_OP) {
/* check whether register used as source operand can be read */
if (reg->type == NOT_INIT) {
@@ -1188,7 +1380,11 @@ static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
if (regno == BPF_REG_FP)
return 0;
- return mark_reg_read(env, reg, reg->parent);
+ if (rw64)
+ mark_insn_zext(env, reg);
+
+ return mark_reg_read(env, reg, reg->parent,
+ rw64 ? REG_LIVE_READ64 : REG_LIVE_READ32);
} else {
/* check whether register used as dest operand can be written to */
if (regno == BPF_REG_FP) {
@@ -1196,12 +1392,441 @@ static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
return -EACCES;
}
reg->live |= REG_LIVE_WRITTEN;
+ reg->subreg_def = rw64 ? DEF_NOT_SUBREG : env->insn_idx + 1;
if (t == DST_OP)
mark_reg_unknown(env, regs, regno);
}
return 0;
}
+/* for any branch, call, exit record the history of jmps in the given state */
+static int push_jmp_history(struct bpf_verifier_env *env,
+ struct bpf_verifier_state *cur)
+{
+ u32 cnt = cur->jmp_history_cnt;
+ struct bpf_idx_pair *p;
+
+ cnt++;
+ p = krealloc(cur->jmp_history, cnt * sizeof(*p), GFP_USER);
+ if (!p)
+ return -ENOMEM;
+ p[cnt - 1].idx = env->insn_idx;
+ p[cnt - 1].prev_idx = env->prev_insn_idx;
+ cur->jmp_history = p;
+ cur->jmp_history_cnt = cnt;
+ return 0;
+}
+
+/* Backtrack one insn at a time. If idx is not at the top of recorded
+ * history then previous instruction came from straight line execution.
+ */
+static int get_prev_insn_idx(struct bpf_verifier_state *st, int i,
+ u32 *history)
+{
+ u32 cnt = *history;
+
+ if (cnt && st->jmp_history[cnt - 1].idx == i) {
+ i = st->jmp_history[cnt - 1].prev_idx;
+ (*history)--;
+ } else {
+ i--;
+ }
+ return i;
+}
+
+/* For given verifier state backtrack_insn() is called from the last insn to
+ * the first insn. Its purpose is to compute a bitmask of registers and
+ * stack slots that needs precision in the parent verifier state.
+ */
+static int backtrack_insn(struct bpf_verifier_env *env, int idx,
+ u32 *reg_mask, u64 *stack_mask)
+{
+ const struct bpf_insn_cbs cbs = {
+ .cb_print = verbose,
+ .private_data = env,
+ };
+ struct bpf_insn *insn = env->prog->insnsi + idx;
+ u8 class = BPF_CLASS(insn->code);
+ u8 opcode = BPF_OP(insn->code);
+ u8 mode = BPF_MODE(insn->code);
+ u32 dreg = 1u << insn->dst_reg;
+ u32 sreg = 1u << insn->src_reg;
+ u32 spi;
+
+ if (insn->code == 0)
+ return 0;
+ if (env->log.level & BPF_LOG_LEVEL) {
+ verbose(env, "regs=%x stack=%llx before ", *reg_mask, *stack_mask);
+ verbose(env, "%d: ", idx);
+ print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
+ }
+
+ if (class == BPF_ALU || class == BPF_ALU64) {
+ if (!(*reg_mask & dreg))
+ return 0;
+ if (opcode == BPF_MOV) {
+ if (BPF_SRC(insn->code) == BPF_X) {
+ /* dreg = sreg
+ * dreg needs precision after this insn
+ * sreg needs precision before this insn
+ */
+ *reg_mask &= ~dreg;
+ *reg_mask |= sreg;
+ } else {
+ /* dreg = K
+ * dreg needs precision after this insn.
+ * Corresponding register is already marked
+ * as precise=true in this verifier state.
+ * No further markings in parent are necessary
+ */
+ *reg_mask &= ~dreg;
+ }
+ } else {
+ if (BPF_SRC(insn->code) == BPF_X) {
+ /* dreg += sreg
+ * both dreg and sreg need precision
+ * before this insn
+ */
+ *reg_mask |= sreg;
+ } /* else dreg += K
+ * dreg still needs precision before this insn
+ */
+ }
+ } else if (class == BPF_LDX) {
+ if (!(*reg_mask & dreg))
+ return 0;
+ *reg_mask &= ~dreg;
+
+ /* scalars can only be spilled into stack w/o losing precision.
+ * Load from any other memory can be zero extended.
+ * The desire to keep that precision is already indicated
+ * by 'precise' mark in corresponding register of this state.
+ * No further tracking necessary.
+ */
+ if (insn->src_reg != BPF_REG_FP)
+ return 0;
+ if (BPF_SIZE(insn->code) != BPF_DW)
+ return 0;
+
+ /* dreg = *(u64 *)[fp - off] was a fill from the stack.
+ * that [fp - off] slot contains scalar that needs to be
+ * tracked with precision
+ */
+ spi = (-insn->off - 1) / BPF_REG_SIZE;
+ if (spi >= 64) {
+ verbose(env, "BUG spi %d\n", spi);
+ WARN_ONCE(1, "verifier backtracking bug");
+ return -EFAULT;
+ }
+ *stack_mask |= 1ull << spi;
+ } else if (class == BPF_STX) {
+ if (*reg_mask & dreg)
+ /* stx shouldn't be using _scalar_ dst_reg
+ * to access memory. It means backtracking
+ * encountered a case of pointer subtraction.
+ */
+ return -ENOTSUPP;
+ /* scalars can only be spilled into stack */
+ if (insn->dst_reg != BPF_REG_FP)
+ return 0;
+ if (BPF_SIZE(insn->code) != BPF_DW)
+ return 0;
+ spi = (-insn->off - 1) / BPF_REG_SIZE;
+ if (spi >= 64) {
+ verbose(env, "BUG spi %d\n", spi);
+ WARN_ONCE(1, "verifier backtracking bug");
+ return -EFAULT;
+ }
+ if (!(*stack_mask & (1ull << spi)))
+ return 0;
+ *stack_mask &= ~(1ull << spi);
+ *reg_mask |= sreg;
+ } else if (class == BPF_JMP || class == BPF_JMP32) {
+ if (opcode == BPF_CALL) {
+ if (insn->src_reg == BPF_PSEUDO_CALL)
+ return -ENOTSUPP;
+ /* regular helper call sets R0 */
+ *reg_mask &= ~1;
+ if (*reg_mask & 0x3f) {
+ /* if backtracing was looking for registers R1-R5
+ * they should have been found already.
+ */
+ verbose(env, "BUG regs %x\n", *reg_mask);
+ WARN_ONCE(1, "verifier backtracking bug");
+ return -EFAULT;
+ }
+ } else if (opcode == BPF_EXIT) {
+ return -ENOTSUPP;
+ }
+ } else if (class == BPF_LD) {
+ if (!(*reg_mask & dreg))
+ return 0;
+ *reg_mask &= ~dreg;
+ /* It's ld_imm64 or ld_abs or ld_ind.
+ * For ld_imm64 no further tracking of precision
+ * into parent is necessary
+ */
+ if (mode == BPF_IND || mode == BPF_ABS)
+ /* to be analyzed */
+ return -ENOTSUPP;
+ } else if (class == BPF_ST) {
+ if (*reg_mask & dreg)
+ /* likely pointer subtraction */
+ return -ENOTSUPP;
+ }
+ return 0;
+}
+
+/* the scalar precision tracking algorithm:
+ * . at the start all registers have precise=false.
+ * . scalar ranges are tracked as normal through alu and jmp insns.
+ * . once precise value of the scalar register is used in:
+ * . ptr + scalar alu
+ * . if (scalar cond K|scalar)
+ * . helper_call(.., scalar, ...) where ARG_CONST is expected
+ * backtrack through the verifier states and mark all registers and
+ * stack slots with spilled constants that these scalar regisers
+ * should be precise.
+ * . during state pruning two registers (or spilled stack slots)
+ * are equivalent if both are not precise.
+ *
+ * Note the verifier cannot simply walk register parentage chain,
+ * since many different registers and stack slots could have been
+ * used to compute single precise scalar.
+ *
+ * The approach of starting with precise=true for all registers and then
+ * backtrack to mark a register as not precise when the verifier detects
+ * that program doesn't care about specific value (e.g., when helper
+ * takes register as ARG_ANYTHING parameter) is not safe.
+ *
+ * It's ok to walk single parentage chain of the verifier states.
+ * It's possible that this backtracking will go all the way till 1st insn.
+ * All other branches will be explored for needing precision later.
+ *
+ * The backtracking needs to deal with cases like:
+ * R8=map_value(id=0,off=0,ks=4,vs=1952,imm=0) R9_w=map_value(id=0,off=40,ks=4,vs=1952,imm=0)
+ * r9 -= r8
+ * r5 = r9
+ * if r5 > 0x79f goto pc+7
+ * R5_w=inv(id=0,umax_value=1951,var_off=(0x0; 0x7ff))
+ * r5 += 1
+ * ...
+ * call bpf_perf_event_output#25
+ * where .arg5_type = ARG_CONST_SIZE_OR_ZERO
+ *
+ * and this case:
+ * r6 = 1
+ * call foo // uses callee's r6 inside to compute r0
+ * r0 += r6
+ * if r0 == 0 goto
+ *
+ * to track above reg_mask/stack_mask needs to be independent for each frame.
+ *
+ * Also if parent's curframe > frame where backtracking started,
+ * the verifier need to mark registers in both frames, otherwise callees
+ * may incorrectly prune callers. This is similar to
+ * commit 7640ead93924 ("bpf: verifier: make sure callees don't prune with caller differences")
+ *
+ * For now backtracking falls back into conservative marking.
+ */
+static void mark_all_scalars_precise(struct bpf_verifier_env *env,
+ struct bpf_verifier_state *st)
+{
+ struct bpf_func_state *func;
+ struct bpf_reg_state *reg;
+ int i, j;
+
+ /* big hammer: mark all scalars precise in this path.
+ * pop_stack may still get !precise scalars.
+ */
+ for (; st; st = st->parent)
+ for (i = 0; i <= st->curframe; i++) {
+ func = st->frame[i];
+ for (j = 0; j < BPF_REG_FP; j++) {
+ reg = &func->regs[j];
+ if (reg->type != SCALAR_VALUE)
+ continue;
+ reg->precise = true;
+ }
+ for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) {
+ if (func->stack[j].slot_type[0] != STACK_SPILL)
+ continue;
+ reg = &func->stack[j].spilled_ptr;
+ if (reg->type != SCALAR_VALUE)
+ continue;
+ reg->precise = true;
+ }
+ }
+}
+
+static int __mark_chain_precision(struct bpf_verifier_env *env, int regno,
+ int spi)
+{
+ struct bpf_verifier_state *st = env->cur_state;
+ int first_idx = st->first_insn_idx;
+ int last_idx = env->insn_idx;
+ struct bpf_func_state *func;
+ struct bpf_reg_state *reg;
+ u32 reg_mask = regno >= 0 ? 1u << regno : 0;
+ u64 stack_mask = spi >= 0 ? 1ull << spi : 0;
+ bool skip_first = true;
+ bool new_marks = false;
+ int i, err;
+
+ if (!env->allow_ptr_leaks)
+ /* backtracking is root only for now */
+ return 0;
+
+ func = st->frame[st->curframe];
+ if (regno >= 0) {
+ reg = &func->regs[regno];
+ if (reg->type != SCALAR_VALUE) {
+ WARN_ONCE(1, "backtracing misuse");
+ return -EFAULT;
+ }
+ if (!reg->precise)
+ new_marks = true;
+ else
+ reg_mask = 0;
+ reg->precise = true;
+ }
+
+ while (spi >= 0) {
+ if (func->stack[spi].slot_type[0] != STACK_SPILL) {
+ stack_mask = 0;
+ break;
+ }
+ reg = &func->stack[spi].spilled_ptr;
+ if (reg->type != SCALAR_VALUE) {
+ stack_mask = 0;
+ break;
+ }
+ if (!reg->precise)
+ new_marks = true;
+ else
+ stack_mask = 0;
+ reg->precise = true;
+ break;
+ }
+
+ if (!new_marks)
+ return 0;
+ if (!reg_mask && !stack_mask)
+ return 0;
+ for (;;) {
+ DECLARE_BITMAP(mask, 64);
+ u32 history = st->jmp_history_cnt;
+
+ if (env->log.level & BPF_LOG_LEVEL)
+ verbose(env, "last_idx %d first_idx %d\n", last_idx, first_idx);
+ for (i = last_idx;;) {
+ if (skip_first) {
+ err = 0;
+ skip_first = false;
+ } else {
+ err = backtrack_insn(env, i, &reg_mask, &stack_mask);
+ }
+ if (err == -ENOTSUPP) {
+ mark_all_scalars_precise(env, st);
+ return 0;
+ } else if (err) {
+ return err;
+ }
+ if (!reg_mask && !stack_mask)
+ /* Found assignment(s) into tracked register in this state.
+ * Since this state is already marked, just return.
+ * Nothing to be tracked further in the parent state.
+ */
+ return 0;
+ if (i == first_idx)
+ break;
+ i = get_prev_insn_idx(st, i, &history);
+ if (i >= env->prog->len) {
+ /* This can happen if backtracking reached insn 0
+ * and there are still reg_mask or stack_mask
+ * to backtrack.
+ * It means the backtracking missed the spot where
+ * particular register was initialized with a constant.
+ */
+ verbose(env, "BUG backtracking idx %d\n", i);
+ WARN_ONCE(1, "verifier backtracking bug");
+ return -EFAULT;
+ }
+ }
+ st = st->parent;
+ if (!st)
+ break;
+
+ new_marks = false;
+ func = st->frame[st->curframe];
+ bitmap_from_u64(mask, reg_mask);
+ for_each_set_bit(i, mask, 32) {
+ reg = &func->regs[i];
+ if (reg->type != SCALAR_VALUE) {
+ reg_mask &= ~(1u << i);
+ continue;
+ }
+ if (!reg->precise)
+ new_marks = true;
+ reg->precise = true;
+ }
+
+ bitmap_from_u64(mask, stack_mask);
+ for_each_set_bit(i, mask, 64) {
+ if (i >= func->allocated_stack / BPF_REG_SIZE) {
+ /* This can happen if backtracking
+ * is propagating stack precision where
+ * caller has larger stack frame
+ * than callee, but backtrack_insn() should
+ * have returned -ENOTSUPP.
+ */
+ verbose(env, "BUG spi %d stack_size %d\n",
+ i, func->allocated_stack);
+ WARN_ONCE(1, "verifier backtracking bug");
+ return -EFAULT;
+ }
+
+ if (func->stack[i].slot_type[0] != STACK_SPILL) {
+ stack_mask &= ~(1ull << i);
+ continue;
+ }
+ reg = &func->stack[i].spilled_ptr;
+ if (reg->type != SCALAR_VALUE) {
+ stack_mask &= ~(1ull << i);
+ continue;
+ }
+ if (!reg->precise)
+ new_marks = true;
+ reg->precise = true;
+ }
+ if (env->log.level & BPF_LOG_LEVEL) {
+ print_verifier_state(env, func);
+ verbose(env, "parent %s regs=%x stack=%llx marks\n",
+ new_marks ? "didn't have" : "already had",
+ reg_mask, stack_mask);
+ }
+
+ if (!reg_mask && !stack_mask)
+ break;
+ if (!new_marks)
+ break;
+
+ last_idx = st->last_insn_idx;
+ first_idx = st->first_insn_idx;
+ }
+ return 0;
+}
+
+static int mark_chain_precision(struct bpf_verifier_env *env, int regno)
+{
+ return __mark_chain_precision(env, regno, -1);
+}
+
+static int mark_chain_precision_stack(struct bpf_verifier_env *env, int spi)
+{
+ return __mark_chain_precision(env, -1, spi);
+}
+
static bool is_spillable_regtype(enum bpf_reg_type type)
{
switch (type) {
@@ -1220,6 +1845,7 @@ static bool is_spillable_regtype(enum bpf_reg_type type)
case PTR_TO_SOCK_COMMON_OR_NULL:
case PTR_TO_TCP_SOCK:
case PTR_TO_TCP_SOCK_OR_NULL:
+ case PTR_TO_XDP_SOCK:
return true;
default:
return false;
@@ -1232,6 +1858,23 @@ static bool register_is_null(struct bpf_reg_state *reg)
return reg->type == SCALAR_VALUE && tnum_equals_const(reg->var_off, 0);
}
+static bool register_is_const(struct bpf_reg_state *reg)
+{
+ return reg->type == SCALAR_VALUE && tnum_is_const(reg->var_off);
+}
+
+static void save_register_state(struct bpf_func_state *state,
+ int spi, struct bpf_reg_state *reg)
+{
+ int i;
+
+ state->stack[spi].spilled_ptr = *reg;
+ state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
+
+ for (i = 0; i < BPF_REG_SIZE; i++)
+ state->stack[spi].slot_type[i] = STACK_SPILL;
+}
+
/* check_stack_read/write functions track spill/fill of registers,
* stack boundary and alignment are checked in check_mem_access()
*/
@@ -1241,7 +1884,8 @@ static int check_stack_write(struct bpf_verifier_env *env,
{
struct bpf_func_state *cur; /* state of the current function */
int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err;
- enum bpf_reg_type type;
+ u32 dst_reg = env->prog->insnsi[insn_idx].dst_reg;
+ struct bpf_reg_state *reg = NULL;
err = realloc_func_state(state, round_up(slot + 1, BPF_REG_SIZE),
state->acquired_refs, true);
@@ -1258,27 +1902,48 @@ static int check_stack_write(struct bpf_verifier_env *env,
}
cur = env->cur_state->frame[env->cur_state->curframe];
- if (value_regno >= 0 &&
- is_spillable_regtype((type = cur->regs[value_regno].type))) {
-
+ if (value_regno >= 0)
+ reg = &cur->regs[value_regno];
+
+ if (reg && size == BPF_REG_SIZE && register_is_const(reg) &&
+ !register_is_null(reg) && env->allow_ptr_leaks) {
+ if (dst_reg != BPF_REG_FP) {
+ /* The backtracking logic can only recognize explicit
+ * stack slot address like [fp - 8]. Other spill of
+ * scalar via different register has to be conervative.
+ * Backtrack from here and mark all registers as precise
+ * that contributed into 'reg' being a constant.
+ */
+ err = mark_chain_precision(env, value_regno);
+ if (err)
+ return err;
+ }
+ save_register_state(state, spi, reg);
+ } else if (reg && is_spillable_regtype(reg->type)) {
/* register containing pointer is being spilled into stack */
if (size != BPF_REG_SIZE) {
+ verbose_linfo(env, insn_idx, "; ");
verbose(env, "invalid size of register spill\n");
return -EACCES;
}
- if (state != cur && type == PTR_TO_STACK) {
+ if (state != cur && reg->type == PTR_TO_STACK) {
verbose(env, "cannot spill pointers to stack into stack frame of the caller\n");
return -EINVAL;
}
- /* save register state */
- state->stack[spi].spilled_ptr = cur->regs[value_regno];
- state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
+ if (!env->allow_ptr_leaks) {
+ bool sanitize = false;
- for (i = 0; i < BPF_REG_SIZE; i++) {
- if (state->stack[spi].slot_type[i] == STACK_MISC &&
- !env->allow_ptr_leaks) {
+ if (state->stack[spi].slot_type[0] == STACK_SPILL &&
+ register_is_const(&state->stack[spi].spilled_ptr))
+ sanitize = true;
+ for (i = 0; i < BPF_REG_SIZE; i++)
+ if (state->stack[spi].slot_type[i] == STACK_MISC) {
+ sanitize = true;
+ break;
+ }
+ if (sanitize) {
int *poff = &env->insn_aux_data[insn_idx].sanitize_stack_off;
int soff = (-spi - 1) * BPF_REG_SIZE;
@@ -1301,8 +1966,8 @@ static int check_stack_write(struct bpf_verifier_env *env,
}
*poff = soff;
}
- state->stack[spi].slot_type[i] = STACK_SPILL;
}
+ save_register_state(state, spi, reg);
} else {
u8 type = STACK_MISC;
@@ -1325,9 +1990,13 @@ static int check_stack_write(struct bpf_verifier_env *env,
state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
/* when we zero initialize stack slots mark them as such */
- if (value_regno >= 0 &&
- register_is_null(&cur->regs[value_regno]))
+ if (reg && register_is_null(reg)) {
+ /* backtracking doesn't work for STACK_ZERO yet. */
+ err = mark_chain_precision(env, value_regno);
+ if (err)
+ return err;
type = STACK_ZERO;
+ }
/* Mark slots affected by this stack write. */
for (i = 0; i < size; i++)
@@ -1344,6 +2013,7 @@ static int check_stack_read(struct bpf_verifier_env *env,
struct bpf_verifier_state *vstate = env->cur_state;
struct bpf_func_state *state = vstate->frame[vstate->curframe];
int i, slot = -off - 1, spi = slot / BPF_REG_SIZE;
+ struct bpf_reg_state *reg;
u8 *stype;
if (reg_state->allocated_stack <= slot) {
@@ -1352,11 +2022,21 @@ static int check_stack_read(struct bpf_verifier_env *env,
return -EACCES;
}
stype = reg_state->stack[spi].slot_type;
+ reg = &reg_state->stack[spi].spilled_ptr;
if (stype[0] == STACK_SPILL) {
if (size != BPF_REG_SIZE) {
- verbose(env, "invalid size of register spill\n");
- return -EACCES;
+ if (reg->type != SCALAR_VALUE) {
+ verbose_linfo(env, env->insn_idx, "; ");
+ verbose(env, "invalid size of register fill\n");
+ return -EACCES;
+ }
+ if (value_regno >= 0) {
+ mark_reg_unknown(env, state->regs, value_regno);
+ state->regs[value_regno].live |= REG_LIVE_WRITTEN;
+ }
+ mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
+ return 0;
}
for (i = 1; i < BPF_REG_SIZE; i++) {
if (stype[(slot - i) % BPF_REG_SIZE] != STACK_SPILL) {
@@ -1367,16 +2047,14 @@ static int check_stack_read(struct bpf_verifier_env *env,
if (value_regno >= 0) {
/* restore register state from stack */
- state->regs[value_regno] = reg_state->stack[spi].spilled_ptr;
+ state->regs[value_regno] = *reg;
/* mark reg as written since spilled pointer state likely
* has its liveness marks cleared by is_state_visited()
* which resets stack/reg liveness for state transitions
*/
state->regs[value_regno].live |= REG_LIVE_WRITTEN;
}
- mark_reg_read(env, &reg_state->stack[spi].spilled_ptr,
- reg_state->stack[spi].spilled_ptr.parent);
- return 0;
+ mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
} else {
int zeros = 0;
@@ -1391,22 +2069,32 @@ static int check_stack_read(struct bpf_verifier_env *env,
off, i, size);
return -EACCES;
}
- mark_reg_read(env, &reg_state->stack[spi].spilled_ptr,
- reg_state->stack[spi].spilled_ptr.parent);
+ mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
if (value_regno >= 0) {
if (zeros == size) {
/* any size read into register is zero extended,
* so the whole register == const_zero
*/
__mark_reg_const_zero(&state->regs[value_regno]);
+ /* backtracking doesn't support STACK_ZERO yet,
+ * so mark it precise here, so that later
+ * backtracking can stop here.
+ * Backtracking may not need this if this register
+ * doesn't participate in pointer adjustment.
+ * Forward propagation of precise flag is not
+ * necessary either. This mark is only to stop
+ * backtracking. Any register that contributed
+ * to const 0 was marked precise before spill.
+ */
+ state->regs[value_regno].precise = true;
} else {
/* have read misc data from the stack */
mark_reg_unknown(env, state->regs, value_regno);
}
state->regs[value_regno].live |= REG_LIVE_WRITTEN;
}
- return 0;
}
+ return 0;
}
static int check_stack_access(struct bpf_verifier_env *env,
@@ -1572,6 +2260,13 @@ static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
env->seen_direct_write = true;
return true;
+
+ case BPF_PROG_TYPE_CGROUP_SOCKOPT:
+ if (t == BPF_WRITE)
+ env->seen_direct_write = true;
+
+ return true;
+
default:
return false;
}
@@ -1698,6 +2393,9 @@ static int check_sock_access(struct bpf_verifier_env *env, int insn_idx,
case PTR_TO_TCP_SOCK:
valid = bpf_tcp_sock_is_valid_access(off, size, t, &info);
break;
+ case PTR_TO_XDP_SOCK:
+ valid = bpf_xdp_sock_is_valid_access(off, size, t, &info);
+ break;
default:
valid = false;
}
@@ -1862,6 +2560,9 @@ static int check_ptr_alignment(struct bpf_verifier_env *env,
case PTR_TO_TCP_SOCK:
pointer_desc = "tcp_sock ";
break;
+ case PTR_TO_XDP_SOCK:
+ pointer_desc = "xdp_sock ";
+ break;
default:
break;
}
@@ -2101,6 +2802,12 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
value_regno);
if (reg_type_may_be_null(reg_type))
regs[value_regno].id = ++env->id_gen;
+ /* A load of ctx field could have different
+ * actual load size with the one encoded in the
+ * insn. When the dst is PTR, it is for sure not
+ * a sub-register.
+ */
+ regs[value_regno].subreg_def = DEF_NOT_SUBREG;
}
regs[value_regno].type = reg_type;
}
@@ -2255,7 +2962,7 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
{
struct bpf_reg_state *reg = reg_state(env, regno);
struct bpf_func_state *state = func(env, reg);
- int err, min_off, max_off, i, slot, spi;
+ int err, min_off, max_off, i, j, slot, spi;
if (reg->type != PTR_TO_STACK) {
/* Allow zero-byte read from NULL, regardless of pointer type */
@@ -2343,6 +3050,14 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
*stype = STACK_MISC;
goto mark;
}
+ if (state->stack[spi].slot_type[0] == STACK_SPILL &&
+ state->stack[spi].spilled_ptr.type == SCALAR_VALUE) {
+ __mark_reg_unknown(&state->stack[spi].spilled_ptr);