forked from luck/tmp_suning_uos_patched
bpf: verifier (add ability to receive verification log)
add optional attributes for BPF_PROG_LOAD syscall:
union bpf_attr {
struct {
...
__u32 log_level; /* verbosity level of eBPF verifier */
__u32 log_size; /* size of user buffer */
__aligned_u64 log_buf; /* user supplied 'char *buffer' */
};
};
when log_level > 0 the verifier will return its verification log in the user
supplied buffer 'log_buf' which can be used by program author to analyze why
verifier rejected given program.
'Understanding eBPF verifier messages' section of Documentation/networking/filter.txt
provides several examples of these messages, like the program:
BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
BPF_LD_MAP_FD(BPF_REG_1, 0),
BPF_CALL_FUNC(BPF_FUNC_map_lookup_elem),
BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1),
BPF_ST_MEM(BPF_DW, BPF_REG_0, 4, 0),
BPF_EXIT_INSN(),
will be rejected with the following multi-line message in log_buf:
0: (7a) *(u64 *)(r10 -8) = 0
1: (bf) r2 = r10
2: (07) r2 += -8
3: (b7) r1 = 0
4: (85) call 1
5: (15) if r0 == 0x0 goto pc+1
R0=map_ptr R10=fp
6: (7a) *(u64 *)(r0 +4) = 0
misaligned access off 4 size 8
The format of the output can change at any time as verifier evolves.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov
David S. Miller
parent
51580e798c
commit
cbd3570086
|
|
@ -138,6 +138,9 @@ union bpf_attr {
|
|||
__u32 insn_cnt;
|
||||
__aligned_u64 insns;
|
||||
__aligned_u64 license;
|
||||
__u32 log_level; /* verbosity level of verifier */
|
||||
__u32 log_size; /* size of user buffer */
|
||||
__aligned_u64 log_buf; /* user supplied buffer */
|
||||
};
|
||||
} __attribute__((aligned(8)));
|
||||
|
||||
|
|
|
|||
|
|
@ -458,7 +458,7 @@ struct bpf_prog *bpf_prog_get(u32 ufd)
|
|||
}
|
||||
|
||||
/* last field in 'union bpf_attr' used by this command */
|
||||
#define BPF_PROG_LOAD_LAST_FIELD license
|
||||
#define BPF_PROG_LOAD_LAST_FIELD log_buf
|
||||
|
||||
static int bpf_prog_load(union bpf_attr *attr)
|
||||
{
|
||||
|
|
|
|||
|
|
@ -125,9 +125,244 @@
|
|||
* are set to NOT_INIT to indicate that they are no longer readable.
|
||||
*/
|
||||
|
||||
/* single container for all structs
|
||||
* one verifier_env per bpf_check() call
|
||||
*/
|
||||
struct verifier_env {
|
||||
};
|
||||
|
||||
/* verbose verifier prints what it's seeing
|
||||
* bpf_check() is called under lock, so no race to access these global vars
|
||||
*/
|
||||
static u32 log_level, log_size, log_len;
|
||||
static char *log_buf;
|
||||
|
||||
static DEFINE_MUTEX(bpf_verifier_lock);
|
||||
|
||||
/* log_level controls verbosity level of eBPF verifier.
|
||||
* verbose() is used to dump the verification trace to the log, so the user
|
||||
* can figure out what's wrong with the program
|
||||
*/
|
||||
static void verbose(const char *fmt, ...)
|
||||
{
|
||||
va_list args;
|
||||
|
||||
if (log_level == 0 || log_len >= log_size - 1)
|
||||
return;
|
||||
|
||||
va_start(args, fmt);
|
||||
log_len += vscnprintf(log_buf + log_len, log_size - log_len, fmt, args);
|
||||
va_end(args);
|
||||
}
|
||||
|
||||
static const char *const bpf_class_string[] = {
|
||||
[BPF_LD] = "ld",
|
||||
[BPF_LDX] = "ldx",
|
||||
[BPF_ST] = "st",
|
||||
[BPF_STX] = "stx",
|
||||
[BPF_ALU] = "alu",
|
||||
[BPF_JMP] = "jmp",
|
||||
[BPF_RET] = "BUG",
|
||||
[BPF_ALU64] = "alu64",
|
||||
};
|
||||
|
||||
static const char *const bpf_alu_string[] = {
|
||||
[BPF_ADD >> 4] = "+=",
|
||||
[BPF_SUB >> 4] = "-=",
|
||||
[BPF_MUL >> 4] = "*=",
|
||||
[BPF_DIV >> 4] = "/=",
|
||||
[BPF_OR >> 4] = "|=",
|
||||
[BPF_AND >> 4] = "&=",
|
||||
[BPF_LSH >> 4] = "<<=",
|
||||
[BPF_RSH >> 4] = ">>=",
|
||||
[BPF_NEG >> 4] = "neg",
|
||||
[BPF_MOD >> 4] = "%=",
|
||||
[BPF_XOR >> 4] = "^=",
|
||||
[BPF_MOV >> 4] = "=",
|
||||
[BPF_ARSH >> 4] = "s>>=",
|
||||
[BPF_END >> 4] = "endian",
|
||||
};
|
||||
|
||||
static const char *const bpf_ldst_string[] = {
|
||||
[BPF_W >> 3] = "u32",
|
||||
[BPF_H >> 3] = "u16",
|
||||
[BPF_B >> 3] = "u8",
|
||||
[BPF_DW >> 3] = "u64",
|
||||
};
|
||||
|
||||
static const char *const bpf_jmp_string[] = {
|
||||
[BPF_JA >> 4] = "jmp",
|
||||
[BPF_JEQ >> 4] = "==",
|
||||
[BPF_JGT >> 4] = ">",
|
||||
[BPF_JGE >> 4] = ">=",
|
||||
[BPF_JSET >> 4] = "&",
|
||||
[BPF_JNE >> 4] = "!=",
|
||||
[BPF_JSGT >> 4] = "s>",
|
||||
[BPF_JSGE >> 4] = "s>=",
|
||||
[BPF_CALL >> 4] = "call",
|
||||
[BPF_EXIT >> 4] = "exit",
|
||||
};
|
||||
|
||||
static void print_bpf_insn(struct bpf_insn *insn)
|
||||
{
|
||||
u8 class = BPF_CLASS(insn->code);
|
||||
|
||||
if (class == BPF_ALU || class == BPF_ALU64) {
|
||||
if (BPF_SRC(insn->code) == BPF_X)
|
||||
verbose("(%02x) %sr%d %s %sr%d\n",
|
||||
insn->code, class == BPF_ALU ? "(u32) " : "",
|
||||
insn->dst_reg,
|
||||
bpf_alu_string[BPF_OP(insn->code) >> 4],
|
||||
class == BPF_ALU ? "(u32) " : "",
|
||||
insn->src_reg);
|
||||
else
|
||||
verbose("(%02x) %sr%d %s %s%d\n",
|
||||
insn->code, class == BPF_ALU ? "(u32) " : "",
|
||||
insn->dst_reg,
|
||||
bpf_alu_string[BPF_OP(insn->code) >> 4],
|
||||
class == BPF_ALU ? "(u32) " : "",
|
||||
insn->imm);
|
||||
} else if (class == BPF_STX) {
|
||||
if (BPF_MODE(insn->code) == BPF_MEM)
|
||||
verbose("(%02x) *(%s *)(r%d %+d) = r%d\n",
|
||||
insn->code,
|
||||
bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
|
||||
insn->dst_reg,
|
||||
insn->off, insn->src_reg);
|
||||
else if (BPF_MODE(insn->code) == BPF_XADD)
|
||||
verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n",
|
||||
insn->code,
|
||||
bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
|
||||
insn->dst_reg, insn->off,
|
||||
insn->src_reg);
|
||||
else
|
||||
verbose("BUG_%02x\n", insn->code);
|
||||
} else if (class == BPF_ST) {
|
||||
if (BPF_MODE(insn->code) != BPF_MEM) {
|
||||
verbose("BUG_st_%02x\n", insn->code);
|
||||
return;
|
||||
}
|
||||
verbose("(%02x) *(%s *)(r%d %+d) = %d\n",
|
||||
insn->code,
|
||||
bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
|
||||
insn->dst_reg,
|
||||
insn->off, insn->imm);
|
||||
} else if (class == BPF_LDX) {
|
||||
if (BPF_MODE(insn->code) != BPF_MEM) {
|
||||
verbose("BUG_ldx_%02x\n", insn->code);
|
||||
return;
|
||||
}
|
||||
verbose("(%02x) r%d = *(%s *)(r%d %+d)\n",
|
||||
insn->code, insn->dst_reg,
|
||||
bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
|
||||
insn->src_reg, insn->off);
|
||||
} else if (class == BPF_LD) {
|
||||
if (BPF_MODE(insn->code) == BPF_ABS) {
|
||||
verbose("(%02x) r0 = *(%s *)skb[%d]\n",
|
||||
insn->code,
|
||||
bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
|
||||
insn->imm);
|
||||
} else if (BPF_MODE(insn->code) == BPF_IND) {
|
||||
verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n",
|
||||
insn->code,
|
||||
bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
|
||||
insn->src_reg, insn->imm);
|
||||
} else if (BPF_MODE(insn->code) == BPF_IMM) {
|
||||
verbose("(%02x) r%d = 0x%x\n",
|
||||
insn->code, insn->dst_reg, insn->imm);
|
||||
} else {
|
||||
verbose("BUG_ld_%02x\n", insn->code);
|
||||
return;
|
||||
}
|
||||
} else if (class == BPF_JMP) {
|
||||
u8 opcode = BPF_OP(insn->code);
|
||||
|
||||
if (opcode == BPF_CALL) {
|
||||
verbose("(%02x) call %d\n", insn->code, insn->imm);
|
||||
} else if (insn->code == (BPF_JMP | BPF_JA)) {
|
||||
verbose("(%02x) goto pc%+d\n",
|
||||
insn->code, insn->off);
|
||||
} else if (insn->code == (BPF_JMP | BPF_EXIT)) {
|
||||
verbose("(%02x) exit\n", insn->code);
|
||||
} else if (BPF_SRC(insn->code) == BPF_X) {
|
||||
verbose("(%02x) if r%d %s r%d goto pc%+d\n",
|
||||
insn->code, insn->dst_reg,
|
||||
bpf_jmp_string[BPF_OP(insn->code) >> 4],
|
||||
insn->src_reg, insn->off);
|
||||
} else {
|
||||
verbose("(%02x) if r%d %s 0x%x goto pc%+d\n",
|
||||
insn->code, insn->dst_reg,
|
||||
bpf_jmp_string[BPF_OP(insn->code) >> 4],
|
||||
insn->imm, insn->off);
|
||||
}
|
||||
} else {
|
||||
verbose("(%02x) %s\n", insn->code, bpf_class_string[class]);
|
||||
}
|
||||
}
|
||||
|
||||
int bpf_check(struct bpf_prog *prog, union bpf_attr *attr)
|
||||
{
|
||||
char __user *log_ubuf = NULL;
|
||||
struct verifier_env *env;
|
||||
int ret = -EINVAL;
|
||||
|
||||
if (prog->len <= 0 || prog->len > BPF_MAXINSNS)
|
||||
return -E2BIG;
|
||||
|
||||
/* 'struct verifier_env' can be global, but since it's not small,
|
||||
* allocate/free it every time bpf_check() is called
|
||||
*/
|
||||
env = kzalloc(sizeof(struct verifier_env), GFP_KERNEL);
|
||||
if (!env)
|
||||
return -ENOMEM;
|
||||
|
||||
/* grab the mutex to protect few globals used by verifier */
|
||||
mutex_lock(&bpf_verifier_lock);
|
||||
|
||||
if (attr->log_level || attr->log_buf || attr->log_size) {
|
||||
/* user requested verbose verifier output
|
||||
* and supplied buffer to store the verification trace
|
||||
*/
|
||||
log_level = attr->log_level;
|
||||
log_ubuf = (char __user *) (unsigned long) attr->log_buf;
|
||||
log_size = attr->log_size;
|
||||
log_len = 0;
|
||||
|
||||
ret = -EINVAL;
|
||||
/* log_* values have to be sane */
|
||||
if (log_size < 128 || log_size > UINT_MAX >> 8 ||
|
||||
log_level == 0 || log_ubuf == NULL)
|
||||
goto free_env;
|
||||
|
||||
ret = -ENOMEM;
|
||||
log_buf = vmalloc(log_size);
|
||||
if (!log_buf)
|
||||
goto free_env;
|
||||
} else {
|
||||
log_level = 0;
|
||||
}
|
||||
|
||||
/* ret = do_check(env); */
|
||||
|
||||
if (log_level && log_len >= log_size - 1) {
|
||||
BUG_ON(log_len >= log_size);
|
||||
/* verifier log exceeded user supplied buffer */
|
||||
ret = -ENOSPC;
|
||||
/* fall through to return what was recorded */
|
||||
}
|
||||
|
||||
/* copy verifier log back to user space including trailing zero */
|
||||
if (log_level && copy_to_user(log_ubuf, log_buf, log_len + 1) != 0) {
|
||||
ret = -EFAULT;
|
||||
goto free_log_buf;
|
||||
}
|
||||
|
||||
|
||||
free_log_buf:
|
||||
if (log_level)
|
||||
vfree(log_buf);
|
||||
free_env:
|
||||
kfree(env);
|
||||
mutex_unlock(&bpf_verifier_lock);
|
||||
return ret;
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in New Issue
Block a user