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-rw-r--r--kernel/bpf/verifier.c1075
1 files changed, 1074 insertions, 1 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index c689ab8e2713..a086dd3210a8 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -125,6 +125,70 @@
* are set to NOT_INIT to indicate that they are no longer readable.
*/
+/* types of values stored in eBPF registers */
+enum bpf_reg_type {
+ NOT_INIT = 0, /* nothing was written into register */
+ UNKNOWN_VALUE, /* reg doesn't contain a valid pointer */
+ PTR_TO_CTX, /* reg points to bpf_context */
+ CONST_PTR_TO_MAP, /* reg points to struct bpf_map */
+ PTR_TO_MAP_VALUE, /* reg points to map element value */
+ PTR_TO_MAP_VALUE_OR_NULL,/* points to map elem value or NULL */
+ FRAME_PTR, /* reg == frame_pointer */
+ PTR_TO_STACK, /* reg == frame_pointer + imm */
+ CONST_IMM, /* constant integer value */
+};
+
+struct reg_state {
+ enum bpf_reg_type type;
+ union {
+ /* valid when type == CONST_IMM | PTR_TO_STACK */
+ int imm;
+
+ /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE |
+ * PTR_TO_MAP_VALUE_OR_NULL
+ */
+ struct bpf_map *map_ptr;
+ };
+};
+
+enum bpf_stack_slot_type {
+ STACK_INVALID, /* nothing was stored in this stack slot */
+ STACK_SPILL, /* 1st byte of register spilled into stack */
+ STACK_SPILL_PART, /* other 7 bytes of register spill */
+ STACK_MISC /* BPF program wrote some data into this slot */
+};
+
+struct bpf_stack_slot {
+ enum bpf_stack_slot_type stype;
+ struct reg_state reg_st;
+};
+
+/* state of the program:
+ * type of all registers and stack info
+ */
+struct verifier_state {
+ struct reg_state regs[MAX_BPF_REG];
+ struct bpf_stack_slot stack[MAX_BPF_STACK];
+};
+
+/* linked list of verifier states used to prune search */
+struct verifier_state_list {
+ struct verifier_state state;
+ struct verifier_state_list *next;
+};
+
+/* verifier_state + insn_idx are pushed to stack when branch is encountered */
+struct verifier_stack_elem {
+ /* verifer state is 'st'
+ * before processing instruction 'insn_idx'
+ * and after processing instruction 'prev_insn_idx'
+ */
+ struct verifier_state st;
+ int insn_idx;
+ int prev_insn_idx;
+ struct verifier_stack_elem *next;
+};
+
#define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */
/* single container for all structs
@@ -132,6 +196,9 @@
*/
struct verifier_env {
struct bpf_prog *prog; /* eBPF program being verified */
+ struct verifier_stack_elem *head; /* stack of verifier states to be processed */
+ int stack_size; /* number of states to be processed */
+ struct verifier_state cur_state; /* current verifier state */
struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */
u32 used_map_cnt; /* number of used maps */
};
@@ -160,6 +227,45 @@ static void verbose(const char *fmt, ...)
va_end(args);
}
+/* string representation of 'enum bpf_reg_type' */
+static const char * const reg_type_str[] = {
+ [NOT_INIT] = "?",
+ [UNKNOWN_VALUE] = "inv",
+ [PTR_TO_CTX] = "ctx",
+ [CONST_PTR_TO_MAP] = "map_ptr",
+ [PTR_TO_MAP_VALUE] = "map_value",
+ [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null",
+ [FRAME_PTR] = "fp",
+ [PTR_TO_STACK] = "fp",
+ [CONST_IMM] = "imm",
+};
+
+static void print_verifier_state(struct verifier_env *env)
+{
+ enum bpf_reg_type t;
+ int i;
+
+ for (i = 0; i < MAX_BPF_REG; i++) {
+ t = env->cur_state.regs[i].type;
+ if (t == NOT_INIT)
+ continue;
+ verbose(" R%d=%s", i, reg_type_str[t]);
+ if (t == CONST_IMM || t == PTR_TO_STACK)
+ verbose("%d", env->cur_state.regs[i].imm);
+ else if (t == CONST_PTR_TO_MAP || t == PTR_TO_MAP_VALUE ||
+ t == PTR_TO_MAP_VALUE_OR_NULL)
+ verbose("(ks=%d,vs=%d)",
+ env->cur_state.regs[i].map_ptr->key_size,
+ env->cur_state.regs[i].map_ptr->value_size);
+ }
+ for (i = 0; i < MAX_BPF_STACK; i++) {
+ if (env->cur_state.stack[i].stype == STACK_SPILL)
+ verbose(" fp%d=%s", -MAX_BPF_STACK + i,
+ reg_type_str[env->cur_state.stack[i].reg_st.type]);
+ }
+ verbose("\n");
+}
+
static const char *const bpf_class_string[] = {
[BPF_LD] = "ld",
[BPF_LDX] = "ldx",
@@ -305,6 +411,735 @@ static void print_bpf_insn(struct bpf_insn *insn)
}
}
+static int pop_stack(struct verifier_env *env, int *prev_insn_idx)
+{
+ struct verifier_stack_elem *elem;
+ int insn_idx;
+
+ if (env->head == NULL)
+ return -1;
+
+ memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state));
+ insn_idx = env->head->insn_idx;
+ if (prev_insn_idx)
+ *prev_insn_idx = env->head->prev_insn_idx;
+ elem = env->head->next;
+ kfree(env->head);
+ env->head = elem;
+ env->stack_size--;
+ return insn_idx;
+}
+
+static struct verifier_state *push_stack(struct verifier_env *env, int insn_idx,
+ int prev_insn_idx)
+{
+ struct verifier_stack_elem *elem;
+
+ elem = kmalloc(sizeof(struct verifier_stack_elem), GFP_KERNEL);
+ if (!elem)
+ goto err;
+
+ memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state));
+ elem->insn_idx = insn_idx;
+ elem->prev_insn_idx = prev_insn_idx;
+ elem->next = env->head;
+ env->head = elem;
+ env->stack_size++;
+ if (env->stack_size > 1024) {
+ verbose("BPF program is too complex\n");
+ goto err;
+ }
+ return &elem->st;
+err:
+ /* pop all elements and return */
+ while (pop_stack(env, NULL) >= 0);
+ return NULL;
+}
+
+#define CALLER_SAVED_REGS 6
+static const int caller_saved[CALLER_SAVED_REGS] = {
+ BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5
+};
+
+static void init_reg_state(struct reg_state *regs)
+{
+ int i;
+
+ for (i = 0; i < MAX_BPF_REG; i++) {
+ regs[i].type = NOT_INIT;
+ regs[i].imm = 0;
+ regs[i].map_ptr = NULL;
+ }
+
+ /* frame pointer */
+ regs[BPF_REG_FP].type = FRAME_PTR;
+
+ /* 1st arg to a function */
+ regs[BPF_REG_1].type = PTR_TO_CTX;
+}
+
+static void mark_reg_unknown_value(struct reg_state *regs, u32 regno)
+{
+ BUG_ON(regno >= MAX_BPF_REG);
+ regs[regno].type = UNKNOWN_VALUE;
+ regs[regno].imm = 0;
+ regs[regno].map_ptr = NULL;
+}
+
+enum reg_arg_type {
+ SRC_OP, /* register is used as source operand */
+ DST_OP, /* register is used as destination operand */
+ DST_OP_NO_MARK /* same as above, check only, don't mark */
+};
+
+static int check_reg_arg(struct reg_state *regs, u32 regno,
+ enum reg_arg_type t)
+{
+ if (regno >= MAX_BPF_REG) {
+ verbose("R%d is invalid\n", regno);
+ return -EINVAL;
+ }
+
+ if (t == SRC_OP) {
+ /* check whether register used as source operand can be read */
+ if (regs[regno].type == NOT_INIT) {
+ verbose("R%d !read_ok\n", regno);
+ return -EACCES;
+ }
+ } else {
+ /* check whether register used as dest operand can be written to */
+ if (regno == BPF_REG_FP) {
+ verbose("frame pointer is read only\n");
+ return -EACCES;
+ }
+ if (t == DST_OP)
+ mark_reg_unknown_value(regs, regno);
+ }
+ return 0;
+}
+
+static int bpf_size_to_bytes(int bpf_size)
+{
+ if (bpf_size == BPF_W)
+ return 4;
+ else if (bpf_size == BPF_H)
+ return 2;
+ else if (bpf_size == BPF_B)
+ return 1;
+ else if (bpf_size == BPF_DW)
+ return 8;
+ else
+ return -EINVAL;
+}
+
+/* check_stack_read/write functions track spill/fill of registers,
+ * stack boundary and alignment are checked in check_mem_access()
+ */
+static int check_stack_write(struct verifier_state *state, int off, int size,
+ int value_regno)
+{
+ struct bpf_stack_slot *slot;
+ int i;
+
+ if (value_regno >= 0 &&
+ (state->regs[value_regno].type == PTR_TO_MAP_VALUE ||
+ state->regs[value_regno].type == PTR_TO_STACK ||
+ state->regs[value_regno].type == PTR_TO_CTX)) {
+
+ /* register containing pointer is being spilled into stack */
+ if (size != 8) {
+ verbose("invalid size of register spill\n");
+ return -EACCES;
+ }
+
+ slot = &state->stack[MAX_BPF_STACK + off];
+ slot->stype = STACK_SPILL;
+ /* save register state */
+ slot->reg_st = state->regs[value_regno];
+ for (i = 1; i < 8; i++) {
+ slot = &state->stack[MAX_BPF_STACK + off + i];
+ slot->stype = STACK_SPILL_PART;
+ slot->reg_st.type = UNKNOWN_VALUE;
+ slot->reg_st.map_ptr = NULL;
+ }
+ } else {
+
+ /* regular write of data into stack */
+ for (i = 0; i < size; i++) {
+ slot = &state->stack[MAX_BPF_STACK + off + i];
+ slot->stype = STACK_MISC;
+ slot->reg_st.type = UNKNOWN_VALUE;
+ slot->reg_st.map_ptr = NULL;
+ }
+ }
+ return 0;
+}
+
+static int check_stack_read(struct verifier_state *state, int off, int size,
+ int value_regno)
+{
+ int i;
+ struct bpf_stack_slot *slot;
+
+ slot = &state->stack[MAX_BPF_STACK + off];
+
+ if (slot->stype == STACK_SPILL) {
+ if (size != 8) {
+ verbose("invalid size of register spill\n");
+ return -EACCES;
+ }
+ for (i = 1; i < 8; i++) {
+ if (state->stack[MAX_BPF_STACK + off + i].stype !=
+ STACK_SPILL_PART) {
+ verbose("corrupted spill memory\n");
+ return -EACCES;
+ }
+ }
+
+ if (value_regno >= 0)
+ /* restore register state from stack */
+ state->regs[value_regno] = slot->reg_st;
+ return 0;
+ } else {
+ for (i = 0; i < size; i++) {
+ if (state->stack[MAX_BPF_STACK + off + i].stype !=
+ STACK_MISC) {
+ verbose("invalid read from stack off %d+%d size %d\n",
+ off, i, size);
+ return -EACCES;
+ }
+ }
+ if (value_regno >= 0)
+ /* have read misc data from the stack */
+ mark_reg_unknown_value(state->regs, value_regno);
+ return 0;
+ }
+}
+
+/* check read/write into map element returned by bpf_map_lookup_elem() */
+static int check_map_access(struct verifier_env *env, u32 regno, int off,
+ int size)
+{
+ struct bpf_map *map = env->cur_state.regs[regno].map_ptr;
+
+ if (off < 0 || off + size > map->value_size) {
+ verbose("invalid access to map value, value_size=%d off=%d size=%d\n",
+ map->value_size, off, size);
+ return -EACCES;
+ }
+ return 0;
+}
+
+/* check access to 'struct bpf_context' fields */
+static int check_ctx_access(struct verifier_env *env, int off, int size,
+ enum bpf_access_type t)
+{
+ if (env->prog->aux->ops->is_valid_access &&
+ env->prog->aux->ops->is_valid_access(off, size, t))
+ return 0;
+
+ verbose("invalid bpf_context access off=%d size=%d\n", off, size);
+ return -EACCES;
+}
+
+/* check whether memory at (regno + off) is accessible for t = (read | write)
+ * if t==write, value_regno is a register which value is stored into memory
+ * if t==read, value_regno is a register which will receive the value from memory
+ * if t==write && value_regno==-1, some unknown value is stored into memory
+ * if t==read && value_regno==-1, don't care what we read from memory
+ */
+static int check_mem_access(struct verifier_env *env, u32 regno, int off,
+ int bpf_size, enum bpf_access_type t,
+ int value_regno)
+{
+ struct verifier_state *state = &env->cur_state;
+ int size, err = 0;
+
+ size = bpf_size_to_bytes(bpf_size);
+ if (size < 0)
+ return size;
+
+ if (off % size != 0) {
+ verbose("misaligned access off %d size %d\n", off, size);
+ return -EACCES;
+ }
+
+ if (state->regs[regno].type == PTR_TO_MAP_VALUE) {
+ err = check_map_access(env, regno, off, size);
+ if (!err && t == BPF_READ && value_regno >= 0)
+ mark_reg_unknown_value(state->regs, value_regno);
+
+ } else if (state->regs[regno].type == PTR_TO_CTX) {
+ err = check_ctx_access(env, off, size, t);
+ if (!err && t == BPF_READ && value_regno >= 0)
+ mark_reg_unknown_value(state->regs, value_regno);
+
+ } else if (state->regs[regno].type == FRAME_PTR) {
+ if (off >= 0 || off < -MAX_BPF_STACK) {
+ verbose("invalid stack off=%d size=%d\n", off, size);
+ return -EACCES;
+ }
+ if (t == BPF_WRITE)
+ err = check_stack_write(state, off, size, value_regno);
+ else
+ err = check_stack_read(state, off, size, value_regno);
+ } else {
+ verbose("R%d invalid mem access '%s'\n",
+ regno, reg_type_str[state->regs[regno].type]);
+ return -EACCES;
+ }
+ return err;
+}
+
+static int check_xadd(struct verifier_env *env, struct bpf_insn *insn)
+{
+ struct reg_state *regs = env->cur_state.regs;
+ int err;
+
+ if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) ||
+ insn->imm != 0) {
+ verbose("BPF_XADD uses reserved fields\n");
+ return -EINVAL;
+ }
+
+ /* check src1 operand */
+ err = check_reg_arg(regs, insn->src_reg, SRC_OP);
+ if (err)
+ return err;
+
+ /* check src2 operand */
+ err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
+ if (err)
+ return err;
+
+ /* check whether atomic_add can read the memory */
+ err = check_mem_access(env, insn->dst_reg, insn->off,
+ BPF_SIZE(insn->code), BPF_READ, -1);
+ if (err)
+ return err;
+
+ /* check whether atomic_add can write into the same memory */
+ return check_mem_access(env, insn->dst_reg, insn->off,
+ BPF_SIZE(insn->code), BPF_WRITE, -1);
+}
+
+/* when register 'regno' is passed into function that will read 'access_size'
+ * bytes from that pointer, make sure that it's within stack boundary
+ * and all elements of stack are initialized
+ */
+static int check_stack_boundary(struct verifier_env *env,
+ int regno, int access_size)
+{
+ struct verifier_state *state = &env->cur_state;
+ struct reg_state *regs = state->regs;
+ int off, i;
+
+ if (regs[regno].type != PTR_TO_STACK)
+ return -EACCES;
+
+ off = regs[regno].imm;
+ if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 ||
+ access_size <= 0) {
+ verbose("invalid stack type R%d off=%d access_size=%d\n",
+ regno, off, access_size);
+ return -EACCES;
+ }
+
+ for (i = 0; i < access_size; i++) {
+ if (state->stack[MAX_BPF_STACK + off + i].stype != STACK_MISC) {
+ verbose("invalid indirect read from stack off %d+%d size %d\n",
+ off, i, access_size);
+ return -EACCES;
+ }
+ }
+ return 0;
+}
+
+static int check_func_arg(struct verifier_env *env, u32 regno,
+ enum bpf_arg_type arg_type, struct bpf_map **mapp)
+{
+ struct reg_state *reg = env->cur_state.regs + regno;
+ enum bpf_reg_type expected_type;
+ int err = 0;
+
+ if (arg_type == ARG_ANYTHING)
+ return 0;
+
+ if (reg->type == NOT_INIT) {
+ verbose("R%d !read_ok\n", regno);
+ return -EACCES;
+ }
+
+ if (arg_type == ARG_PTR_TO_STACK || arg_type == ARG_PTR_TO_MAP_KEY ||
+ arg_type == ARG_PTR_TO_MAP_VALUE) {
+ expected_type = PTR_TO_STACK;
+ } else if (arg_type == ARG_CONST_STACK_SIZE) {
+ expected_type = CONST_IMM;
+ } else if (arg_type == ARG_CONST_MAP_PTR) {
+ expected_type = CONST_PTR_TO_MAP;
+ } else {
+ verbose("unsupported arg_type %d\n", arg_type);
+ return -EFAULT;
+ }
+
+ if (reg->type != expected_type) {
+ verbose("R%d type=%s expected=%s\n", regno,
+ reg_type_str[reg->type], reg_type_str[expected_type]);
+ return -EACCES;
+ }
+
+ if (arg_type == ARG_CONST_MAP_PTR) {
+ /* bpf_map_xxx(map_ptr) call: remember that map_ptr */
+ *mapp = reg->map_ptr;
+
+ } else if (arg_type == ARG_PTR_TO_MAP_KEY) {
+ /* bpf_map_xxx(..., map_ptr, ..., key) call:
+ * check that [key, key + map->key_size) are within
+ * stack limits and initialized
+ */
+ if (!*mapp) {
+ /* in function declaration map_ptr must come before
+ * map_key, so that it's verified and known before
+ * we have to check map_key here. Otherwise it means
+ * that kernel subsystem misconfigured verifier
+ */
+ verbose("invalid map_ptr to access map->key\n");
+ return -EACCES;
+ }
+ err = check_stack_boundary(env, regno, (*mapp)->key_size);
+
+ } else if (arg_type == ARG_PTR_TO_MAP_VALUE) {
+ /* bpf_map_xxx(..., map_ptr, ..., value) call:
+ * check [value, value + map->value_size) validity
+ */
+ if (!*mapp) {
+ /* kernel subsystem misconfigured verifier */
+ verbose("invalid map_ptr to access map->value\n");
+ return -EACCES;
+ }
+ err = check_stack_boundary(env, regno, (*mapp)->value_size);
+
+ } else if (arg_type == ARG_CONST_STACK_SIZE) {
+ /* bpf_xxx(..., buf, len) call will access 'len' bytes
+ * from stack pointer 'buf'. Check it
+ * note: regno == len, regno - 1 == buf
+ */
+ if (regno == 0) {
+ /* kernel subsystem misconfigured verifier */
+ verbose("ARG_CONST_STACK_SIZE cannot be first argument\n");
+ return -EACCES;
+ }
+ err = check_stack_boundary(env, regno - 1, reg->imm);
+ }
+
+ return err;
+}
+
+static int check_call(struct verifier_env *env, int func_id)
+{
+ struct verifier_state *state = &env->cur_state;
+ const struct bpf_func_proto *fn = NULL;
+ struct reg_state *regs = state->regs;
+ struct bpf_map *map = NULL;
+ struct reg_state *reg;
+ int i, err;
+
+ /* find function prototype */
+ if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) {
+ verbose("invalid func %d\n", func_id);
+ return -EINVAL;
+ }
+
+ if (env->prog->aux->ops->get_func_proto)
+ fn = env->prog->aux->ops->get_func_proto(func_id);
+
+ if (!fn) {
+ verbose("unknown func %d\n", func_id);
+ return -EINVAL;
+ }
+
+ /* eBPF programs must be GPL compatible to use GPL-ed functions */
+ if (!env->prog->aux->is_gpl_compatible && fn->gpl_only) {
+ verbose("cannot call GPL only function from proprietary program\n");
+ return -EINVAL;
+ }
+
+ /* check args */
+ err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &map);
+ if (err)
+ return err;
+ err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &map);
+ if (err)
+ return err;
+ err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &map);
+ if (err)
+ return err;
+ err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &map);
+ if (err)
+ return err;
+ err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &map);
+ if (err)
+ return err;
+
+ /* reset caller saved regs */
+ for (i = 0; i < CALLER_SAVED_REGS; i++) {
+ reg = regs + caller_saved[i];
+ reg->type = NOT_INIT;
+ reg->imm = 0;
+ }
+
+ /* update return register */
+ if (fn->ret_type == RET_INTEGER) {
+ regs[BPF_REG_0].type = UNKNOWN_VALUE;
+ } else if (fn->ret_type == RET_VOID) {
+ regs[BPF_REG_0].type = NOT_INIT;
+ } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) {
+ regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL;
+ /* remember map_ptr, so that check_map_access()
+ * can check 'value_size' boundary of memory access
+ * to map element returned from bpf_map_lookup_elem()
+ */
+ if (map == NULL) {
+ verbose("kernel subsystem misconfigured verifier\n");
+ return -EINVAL;
+ }
+ regs[BPF_REG_0].map_ptr = map;
+ } else {
+ verbose("unknown return type %d of func %d\n",
+ fn->ret_type, func_id);
+ return -EINVAL;
+ }
+ return 0;
+}
+
+/* check validity of 32-bit and 64-bit arithmetic operations */
+static int check_alu_op(struct reg_state *regs, struct bpf_insn *insn)
+{
+ u8 opcode = BPF_OP(insn->code);
+ int err;
+
+ if (opcode == BPF_END || opcode == BPF_NEG) {
+ if (opcode == BPF_NEG) {
+ if (BPF_SRC(insn->code) != 0 ||
+ insn->src_reg != BPF_REG_0 ||
+ insn->off != 0 || insn->imm != 0) {
+ verbose("BPF_NEG uses reserved fields\n");
+ return -EINVAL;
+ }
+ } else {
+ if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
+ (insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) {
+ verbose("BPF_END uses reserved fields\n");
+ return -EINVAL;
+ }
+ }
+
+ /* check src operand */
+ err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
+ if (err)
+ return err;
+
+ /* check dest operand */
+ err = check_reg_arg(regs, insn->dst_reg, DST_OP);
+ if (err)
+ return err;
+
+ } else if (opcode == BPF_MOV) {
+
+ if (BPF_SRC(insn->code) == BPF_X) {
+ if (insn->imm != 0 || insn->off != 0) {
+ verbose("BPF_MOV uses reserved fields\n");
+ return -EINVAL;
+ }
+
+ /* check src operand */
+ err = check_reg_arg(regs, insn->src_reg, SRC_OP);
+ if (err)
+ return err;
+ } else {
+ if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
+ verbose("BPF_MOV uses reserved fields\n");
+ return -EINVAL;
+ }
+ }
+
+ /* check dest operand */
+ err = check_reg_arg(regs, insn->dst_reg, DST_OP);
+ if (err)
+ return err;
+
+ if (BPF_SRC(insn->code) == BPF_X) {
+ if (BPF_CLASS(insn->code) == BPF_ALU64) {
+ /* case: R1 = R2
+ * copy register state to dest reg
+ */
+ regs[insn->dst_reg] = regs[insn->src_reg];
+ } else {
+ regs[insn->dst_reg].type = UNKNOWN_VALUE;
+ regs[insn->dst_reg].map_ptr = NULL;
+ }
+ } else {
+ /* case: R = imm
+ * remember the value we stored into this reg
+ */
+ regs[insn->dst_reg].type = CONST_IMM;
+ regs[insn->dst_reg].imm = insn->imm;
+ }
+
+ } else if (opcode > BPF_END) {
+ verbose("invalid BPF_ALU opcode %x\n", opcode);
+ return -EINVAL;
+
+ } else { /* all other ALU ops: and, sub, xor, add, ... */
+
+ bool stack_relative = false;
+
+ if (BPF_SRC(insn->code) == BPF_X) {
+ if (insn->imm != 0 || insn->off != 0) {
+ verbose("BPF_ALU uses reserved fields\n");
+ return -EINVAL;
+ }
+ /* check src1 operand */
+ err = check_reg_arg(regs, insn->src_reg, SRC_OP);
+ if (err)
+ return err;
+ } else {
+ if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
+ verbose("BPF_ALU uses reserved fields\n");
+ return -EINVAL;
+ }
+ }
+
+ /* check src2 operand */
+ err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
+ if (err)
+ return err;
+
+ if ((opcode == BPF_MOD || opcode == BPF_DIV) &&
+ BPF_SRC(insn->code) == BPF_K && insn->imm == 0) {
+ verbose("div by zero\n");
+ return -EINVAL;
+ }
+
+ /* pattern match 'bpf_add Rx, imm' instruction */
+ if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 &&
+ regs[insn->dst_reg].type == FRAME_PTR &&
+ BPF_SRC(insn->code) == BPF_K)
+ stack_relative = true;
+
+ /* check dest operand */
+ err = check_reg_arg(regs, insn->dst_reg, DST_OP);
+ if (err)
+ return err;
+
+ if (stack_relative) {
+ regs[insn->dst_reg].type = PTR_TO_STACK;
+ regs[insn->dst_reg].imm = insn->imm;
+ }
+ }
+
+ return 0;
+}
+
+static int check_cond_jmp_op(struct verifier_env *env,
+ struct bpf_insn *insn, int *insn_idx)
+{
+ struct reg_state *regs = env->cur_state.regs;
+ struct verifier_state *other_branch;
+ u8 opcode = BPF_OP(insn->code);
+ int err;
+
+ if (opcode > BPF_EXIT) {
+ verbose("invalid BPF_JMP opcode %x\n", opcode);
+ return -EINVAL;
+ }
+
+ if (BPF_SRC(insn->code) == BPF_X) {
+ if (insn->imm != 0) {
+ verbose("BPF_JMP uses reserved fields\n");
+ return -EINVAL;
+ }
+
+ /* check src1 operand */
+ err = check_reg_arg(regs, insn->src_reg, SRC_OP);
+ if (err)
+ return err;
+ } else {
+ if (insn->src_reg != BPF_REG_0) {
+ verbose("BPF_JMP uses reserved fields\n");
+ return -EINVAL;
+ }
+ }
+
+ /* check src2 operand */
+ err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
+ if (err)
+ return err;
+
+ /* detect if R == 0 where R was initialized to zero earlier */
+ if (BPF_SRC(insn->code) == BPF_K &&
+ (opcode == BPF_JEQ || opcode == BPF_JNE) &&
+ regs[insn->dst_reg].type == CONST_IMM &&
+ regs[insn->dst_reg].imm == insn->imm) {
+ if (opcode == BPF_JEQ) {
+ /* if (imm == imm) goto pc+off;
+ * only follow the goto, ignore fall-through
+ */
+ *insn_idx += insn->off;
+ return 0;
+ } else {
+ /* if (imm != imm) goto pc+off;
+ * only follow fall-through branch, since
+ * that's where the program will go
+ */
+ return 0;
+ }
+ }
+
+ other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx);
+ if (!other_branch)
+ return -EFAULT;
+
+ /* detect if R == 0 where R is returned value from bpf_map_lookup_elem() */
+ if (BPF_SRC(insn->code) == BPF_K &&
+ insn->imm == 0 && (opcode == BPF_JEQ ||
+ opcode == BPF_JNE) &&
+ regs[insn->dst_reg].type == PTR_TO_MAP_VALUE_OR_NULL) {
+ if (opcode == BPF_JEQ) {
+ /* next fallthrough insn can access memory via
+ * this register
+ */
+ regs[insn->dst_reg].type = PTR_TO_MAP_VALUE;
+ /* branch targer cannot access it, since reg == 0 */
+ other_branch->regs[insn->dst_reg].type = CONST_IMM;
+ other_branch->regs[insn->dst_reg].imm = 0;
+ } else {
+ other_branch->regs[insn->dst_reg].type = PTR_TO_MAP_VALUE;
+ regs[insn->dst_reg].type = CONST_IMM;
+ regs[insn->dst_reg].imm = 0;
+ }
+ } else if (BPF_SRC(insn->code) == BPF_K &&
+ (opcode == BPF_JEQ || opcode == BPF_JNE)) {
+
+ if (opcode == BPF_JEQ) {
+ /* detect if (R == imm) goto
+ * and in the target state recognize that R = imm
+ */
+ other_branch->regs[insn->dst_reg].type = CONST_IMM;
+ other_branch->regs[insn->dst_reg].imm = insn->imm;
+ } else {
+ /* detect if (R != imm) goto
+ * and in the fall-through state recognize that R = imm
+ */
+ regs[insn->dst_reg].type = CONST_IMM;
+ regs[insn->dst_reg].imm = insn->imm;
+ }
+ }
+ if (log_level)
+ print_verifier_state(env);
+ return 0;
+}
+
/* return the map pointer stored inside BPF_LD_IMM64 instruction */
static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn)
{
@@ -313,6 +1148,37 @@ static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn)
return (struct bpf_map *) (unsigned long) imm64;
}
+/* verify BPF_LD_IMM64 instruction */
+static int check_ld_imm(struct verifier_env *env, struct bpf_insn *insn)
+{
+ struct reg_state *regs = env->cur_state.regs;
+ int err;
+
+ if (BPF_SIZE(insn->code) != BPF_DW) {
+ verbose("invalid BPF_LD_IMM insn\n");
+ return -EINVAL;
+ }
+ if (insn->off != 0) {
+ verbose("BPF_LD_IMM64 uses reserved fields\n");
+ return -EINVAL;
+ }
+
+ err = check_reg_arg(regs, insn->dst_reg, DST_OP);
+ if (err)
+ return err;
+
+ if (insn->src_reg == 0)
+ /* generic move 64-bit immediate into a register */
+ return 0;
+
+ /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */
+ BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD);
+
+ regs[insn->dst_reg].type = CONST_PTR_TO_MAP;
+ regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn);
+ return 0;
+}
+
/* non-recursive DFS pseudo code
* 1 procedure DFS-iterative(G,v):
* 2 label v as discovered
@@ -498,6 +1364,212 @@ err_free:
return ret;
}
+static int do_check(struct verifier_env *env)
+{
+ struct verifier_state *state = &env->cur_state;
+ struct bpf_insn *insns = env->prog->insnsi;
+ struct reg_state *regs = state->regs;
+ int insn_cnt = env->prog->len;
+ int insn_idx, prev_insn_idx = 0;
+ int insn_processed = 0;
+ bool do_print_state = false;
+
+ init_reg_state(regs);
+ insn_idx = 0;
+ for (;;) {
+ struct bpf_insn *insn;
+ u8 class;
+ int err;
+
+ if (insn_idx >= insn_cnt) {
+ verbose("invalid insn idx %d insn_cnt %d\n",
+ insn_idx, insn_cnt);
+ return -EFAULT;
+ }
+
+ insn = &insns[insn_idx];
+ class = BPF_CLASS(insn->code);
+
+ if (++insn_processed > 32768) {
+ verbose("BPF program is too large. Proccessed %d insn\n",
+ insn_processed);
+ return -E2BIG;
+ }
+
+ if (log_level && do_print_state) {
+ verbose("\nfrom %d to %d:", prev_insn_idx, insn_idx);
+ print_verifier_state(env);
+ do_print_state = false;
+ }
+
+ if (log_level) {
+ verbose("%d: ", insn_idx);
+ print_bpf_insn(insn);
+ }
+
+ if (class == BPF_ALU || class == BPF_ALU64) {
+ err = check_alu_op(regs, insn);
+ if (err)
+ return err;
+
+ } else if (class == BPF_LDX) {
+ if (BPF_MODE(insn->code) != BPF_MEM ||
+ insn->imm != 0) {
+ verbose("BPF_LDX uses reserved fields\n");
+ return -EINVAL;
+ }
+ /* check src operand */
+ err = check_reg_arg(regs, insn->src_reg, SRC_OP);
+ if (err)
+ return err;
+
+ err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK);
+ if (err)
+ return err;
+
+ /* check that memory (src_reg + off) is readable,
+ * the state of dst_reg will be updated by this func
+ */
+ err = check_mem_access(env, insn->src_reg, insn->off,
+ BPF_SIZE(insn->code), BPF_READ,
+ insn->dst_reg);
+ if (err)
+ return err;
+
+ } else if (class == BPF_STX) {
+ if (BPF_MODE(insn->code) == BPF_XADD) {
+ err = check_xadd(env, insn);
+ if (err)
+ return err;
+ insn_idx++;
+ continue;
+ }
+
+ if (BPF_MODE(insn->code) != BPF_MEM ||
+ insn->imm != 0) {
+ verbose("BPF_STX uses reserved fields\n");
+ return -EINVAL;
+ }
+ /* check src1 operand */
+ err = check_reg_arg(regs, insn->src_reg, SRC_OP);
+ if (err)
+ return err;
+ /* check src2 operand */
+ err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
+ if (err)
+ return err;
+
+ /* check that memory (dst_reg + off) is writeable */
+ err = check_mem_access(env, insn->dst_reg, insn->off,
+ BPF_SIZE(insn->code), BPF_WRITE,
+ insn->src_reg);
+ if (err)
+ return err;
+
+ } else if (class == BPF_ST) {
+ if (BPF_MODE(insn->code) != BPF_MEM ||
+ insn->src_reg != BPF_REG_0) {
+ verbose("BPF_ST uses reserved fields\n");
+ return -EINVAL;
+ }
+ /* check src operand */
+ err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
+ if (err)
+ return err;
+
+ /* check that memory (dst_reg + off) is writeable */
+ err = check_mem_access(env, insn->dst_reg, insn->off,
+ BPF_SIZE(insn->code), BPF_WRITE,
+ -1);
+ if (err)
+ return err;
+
+ } else if (class == BPF_JMP) {
+ u8 opcode = BPF_OP(insn->code);
+
+ if (opcode == BPF_CALL) {
+ if (BPF_SRC(insn->code) != BPF_K ||
+ insn->off != 0 ||
+ insn->src_reg != BPF_REG_0 ||
+ insn->dst_reg != BPF_REG_0) {
+ verbose("BPF_CALL uses reserved fields\n");
+ return -EINVAL;
+ }
+
+ err = check_call(env, insn->imm);
+ if (err)
+ return err;
+
+ } else if (opcode == BPF_JA) {
+ if (BPF_SRC(insn->code) != BPF_K ||
+ insn->imm != 0 ||
+ insn->src_reg != BPF_REG_0 ||
+ insn->dst_reg != BPF_REG_0) {
+ verbose("BPF_JA uses reserved fields\n");
+ return -EINVAL;
+ }
+
+ insn_idx += insn->off + 1;
+ continue;
+
+ } else if (opcode == BPF_EXIT) {
+ if (BPF_SRC(insn->code) != BPF_K ||
+ insn->imm != 0 ||
+ insn->src_reg != BPF_REG_0 ||
+ insn->dst_reg != BPF_REG_0) {
+ verbose("BPF_EXIT uses reserved fields\n");
+ return -EINVAL;
+ }
+
+ /* eBPF calling convetion is such that R0 is used
+ * to return the value from eBPF program.
+ * Make sure that it's readable at this time
+ * of bpf_exit, which means that program wrote
+ * something into it earlier
+ */
+ err = check_reg_arg(regs, BPF_REG_0, SRC_OP);
+ if (err)
+ return err;
+
+ insn_idx = pop_stack(env, &prev_insn_idx);
+ if (insn_idx < 0) {
+ break;
+ } else {
+ do_print_state = true;
+ continue;
+ }
+ } else {
+ err = check_cond_jmp_op(env, insn, &insn_idx);
+ if (err)
+ return err;
+ }
+ } else if (class == BPF_LD) {
+ u8 mode = BPF_MODE(insn->code);
+
+ if (mode == BPF_ABS || mode == BPF_IND) {
+ verbose("LD_ABS is not supported yet\n");
+ return -EINVAL;
+ } else if (mode == BPF_IMM) {
+ err = check_ld_imm(env, insn);
+ if (err)
+ return err;
+
+ insn_idx++;
+ } else {
+ verbose("invalid BPF_LD mode\n");
+ return -EINVAL;
+ }
+ } else {
+ verbose("unknown insn class %d\n", class);
+ return -EINVAL;
+ }
+
+ insn_idx++;
+ }
+
+ return 0;
+}
+
/* look for pseudo eBPF instructions that access map FDs and
* replace them with actual map pointers
*/
@@ -651,9 +1723,10 @@ int bpf_check(struct bpf_prog *prog, union bpf_attr *attr)
if (ret < 0)
goto skip_full_check;
- /* ret = do_check(env); */
+ ret = do_check(env);
skip_full_check:
+ while (pop_stack(env, NULL) >= 0);
if (log_level && log_len >= log_size - 1) {
BUG_ON(log_len >= log_size);
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-18 10:47:21 +0100