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bpf: centre subprog information fields

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It is better to centre all subprog information fields into one structure.
This structure could later serve as function node in call graph.

Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Jiong Wang 2018-05-02 16:17:18 -04:00 committed by Daniel Borkmann
parent f910cefa32
commit 9c8105bd44
2 changed files with 38 additions and 33 deletions
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9
include/linux/bpf_verifier.h
View File

@ -173,6 +173,11 @@ static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log)
#define BPF_MAX_SUBPROGS 256
struct bpf_subprog_info {
u32 start; /* insn idx of function entry point */
u16 stack_depth; /* max. stack depth used by this function */
};
/* single container for all structs
* one verifier_env per bpf_check() call
*/
@ -191,9 +196,7 @@ struct bpf_verifier_env {
bool seen_direct_write;
struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */
struct bpf_verifier_log log;
u32 subprog_starts[BPF_MAX_SUBPROGS + 1];
/* computes the stack depth of each bpf function */
u16 subprog_stack_depth[BPF_MAX_SUBPROGS + 1];
struct bpf_subprog_info subprog_info[BPF_MAX_SUBPROGS + 1];
u32 subprog_cnt;
};

62
kernel/bpf/verifier.c
View File

@ -741,18 +741,19 @@ enum reg_arg_type {
static int cmp_subprogs(const void *a, const void *b)
{
return *(int *)a - *(int *)b;
return ((struct bpf_subprog_info *)a)->start -
((struct bpf_subprog_info *)b)->start;
}
static int find_subprog(struct bpf_verifier_env *env, int off)
{
u32 *p;
struct bpf_subprog_info *p;
p = bsearch(&off, env->subprog_starts, env->subprog_cnt,
sizeof(env->subprog_starts[0]), cmp_subprogs);
p = bsearch(&off, env->subprog_info, env->subprog_cnt,
sizeof(env->subprog_info[0]), cmp_subprogs);
if (!p)
return -ENOENT;
return p - env->subprog_starts;
return p - env->subprog_info;
}
@ -772,15 +773,16 @@ static int add_subprog(struct bpf_verifier_env *env, int off)
verbose(env, "too many subprograms\n");
return -E2BIG;
}
env->subprog_starts[env->subprog_cnt++] = off;
sort(env->subprog_starts, env->subprog_cnt,
sizeof(env->subprog_starts[0]), cmp_subprogs, NULL);
env->subprog_info[env->subprog_cnt++].start = off;
sort(env->subprog_info, env->subprog_cnt,
sizeof(env->subprog_info[0]), cmp_subprogs, NULL);
return 0;
}
static int check_subprogs(struct bpf_verifier_env *env)
{
int i, ret, subprog_start, subprog_end, off, cur_subprog = 0;
struct bpf_subprog_info *subprog = env->subprog_info;
struct bpf_insn *insn = env->prog->insnsi;
int insn_cnt = env->prog->len;
@ -810,14 +812,14 @@ static int check_subprogs(struct bpf_verifier_env *env)
if (env->log.level > 1)
for (i = 0; i < env->subprog_cnt; i++)
verbose(env, "func#%d @%d\n", i, env->subprog_starts[i]);
verbose(env, "func#%d @%d\n", i, subprog[i].start);
/* now check that all jumps are within the same subprog */
subprog_start = 0;
if (env->subprog_cnt == cur_subprog + 1)
subprog_end = insn_cnt;
else
subprog_end = env->subprog_starts[cur_subprog + 1];
subprog_end = subprog[cur_subprog + 1].start;
for (i = 0; i < insn_cnt; i++) {
u8 code = insn[i].code;
@ -846,8 +848,7 @@ next:
if (env->subprog_cnt == cur_subprog + 1)
subprog_end = insn_cnt;
else
subprog_end =
env->subprog_starts[cur_subprog + 1];
subprog_end = subprog[cur_subprog + 1].start;
}
}
return 0;
@ -1480,13 +1481,13 @@ static int update_stack_depth(struct bpf_verifier_env *env,
const struct bpf_func_state *func,
int off)
{
u16 stack = env->subprog_stack_depth[func->subprogno];
u16 stack = env->subprog_info[func->subprogno].stack_depth;
if (stack >= -off)
return 0;
/* update known max for given subprogram */
env->subprog_stack_depth[func->subprogno] = -off;
env->subprog_info[func->subprogno].stack_depth = -off;
return 0;
}
@ -1498,7 +1499,8 @@ static int update_stack_depth(struct bpf_verifier_env *env,
*/
static int check_max_stack_depth(struct bpf_verifier_env *env)
{
int depth = 0, frame = 0, subprog = 0, i = 0, subprog_end;
int depth = 0, frame = 0, idx = 0, i = 0, subprog_end;
struct bpf_subprog_info *subprog = env->subprog_info;
struct bpf_insn *insn = env->prog->insnsi;
int insn_cnt = env->prog->len;
int ret_insn[MAX_CALL_FRAMES];
@ -1508,17 +1510,17 @@ process_func:
/* round up to 32-bytes, since this is granularity
* of interpreter stack size
*/
depth += round_up(max_t(u32, env->subprog_stack_depth[subprog], 1), 32);
depth += round_up(max_t(u32, subprog[idx].stack_depth, 1), 32);
if (depth > MAX_BPF_STACK) {
verbose(env, "combined stack size of %d calls is %d. Too large\n",
frame + 1, depth);
return -EACCES;
}
continue_func:
if (env->subprog_cnt == subprog + 1)
if (env->subprog_cnt == idx + 1)
subprog_end = insn_cnt;
else
subprog_end = env->subprog_starts[subprog + 1];
subprog_end = subprog[idx + 1].start;
for (; i < subprog_end; i++) {
if (insn[i].code != (BPF_JMP | BPF_CALL))
continue;
@ -1526,12 +1528,12 @@ continue_func:
continue;
/* remember insn and function to return to */
ret_insn[frame] = i + 1;
ret_prog[frame] = subprog;
ret_prog[frame] = idx;
/* find the callee */
i = i + insn[i].imm + 1;
subprog = find_subprog(env, i);
if (subprog < 0) {
idx = find_subprog(env, i);
if (idx < 0) {
WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
i);
return -EFAULT;
@ -1548,10 +1550,10 @@ continue_func:
*/
if (frame == 0)
return 0;
depth -= round_up(max_t(u32, env->subprog_stack_depth[subprog], 1), 32);
depth -= round_up(max_t(u32, subprog[idx].stack_depth, 1), 32);
frame--;
i = ret_insn[frame];
subprog = ret_prog[frame];
idx = ret_prog[frame];
goto continue_func;
}
@ -1567,7 +1569,7 @@ static int get_callee_stack_depth(struct bpf_verifier_env *env,
start);
return -EFAULT;
}
return env->subprog_stack_depth[subprog];
return env->subprog_info[subprog].stack_depth;
}
#endif
@ -4926,14 +4928,14 @@ process_bpf_exit:
verbose(env, "processed %d insns (limit %d), stack depth ",
insn_processed, BPF_COMPLEXITY_LIMIT_INSNS);
for (i = 0; i < env->subprog_cnt; i++) {
u32 depth = env->subprog_stack_depth[i];
u32 depth = env->subprog_info[i].stack_depth;
verbose(env, "%d", depth);
if (i + 1 < env->subprog_cnt)
verbose(env, "+");
}
verbose(env, "\n");
env->prog->aux->stack_depth = env->subprog_stack_depth[0];
env->prog->aux->stack_depth = env->subprog_info[0].stack_depth;
return 0;
}
@ -5140,9 +5142,9 @@ static void adjust_subprog_starts(struct bpf_verifier_env *env, u32 off, u32 len
if (len == 1)
return;
for (i = 0; i < env->subprog_cnt; i++) {
if (env->subprog_starts[i] < off)
if (env->subprog_info[i].start < off)
continue;
env->subprog_starts[i] += len - 1;
env->subprog_info[i].start += len - 1;
}
}
@ -5340,7 +5342,7 @@ static int jit_subprogs(struct bpf_verifier_env *env)
if (env->subprog_cnt == i + 1)
subprog_end = prog->len;
else
subprog_end = env->subprog_starts[i + 1];
subprog_end = env->subprog_info[i + 1].start;
len = subprog_end - subprog_start;
func[i] = bpf_prog_alloc(bpf_prog_size(len), GFP_USER);
@ -5357,7 +5359,7 @@ static int jit_subprogs(struct bpf_verifier_env *env)
* Long term would need debug info to populate names
*/
func[i]->aux->name[0] = 'F';
func[i]->aux->stack_depth = env->subprog_stack_depth[i];
func[i]->aux->stack_depth = env->subprog_info[i].stack_depth;
func[i]->jit_requested = 1;
func[i] = bpf_int_jit_compile(func[i]);
if (!func[i]->jited) {