net: filter: cleanup invocation of internal BPF

Kernel API for classic BPF socket filters is:

sk_unattached_filter_create() - validate classic BPF, convert, JIT
SK_RUN_FILTER() - run it
sk_unattached_filter_destroy() - destroy socket filter

Cleanup internal BPF kernel API as following:

sk_filter_select_runtime() - final step of internal BPF creation.
  Try to JIT internal BPF program, if JIT is not available select interpreter
SK_RUN_FILTER() - run it
sk_filter_free() - free internal BPF program

Disallow direct calls to BPF interpreter. Execution of the BPF program should
be done with SK_RUN_FILTER() macro.

Example of internal BPF create, run, destroy:

  struct sk_filter *fp;

  fp = kzalloc(sk_filter_size(prog_len), GFP_KERNEL);
  memcpy(fp->insni, prog, prog_len * sizeof(fp->insni[0]));
  fp->len = prog_len;

  sk_filter_select_runtime(fp);

  SK_RUN_FILTER(fp, ctx);

  sk_filter_free(fp);

Sockets, seccomp, testsuite, tracing are using different ways to populate
sk_filter, so first steps of program creation are not common.

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov 2014-05-19 14:56:14 -07:00 committed by David S. Miller
parent 21ea04fa2d
commit 5fe821a9de
4 changed files with 34 additions and 26 deletions

View File

@ -184,10 +184,8 @@ static inline unsigned int sk_filter_size(unsigned int proglen)
int sk_filter(struct sock *sk, struct sk_buff *skb);
u32 sk_run_filter_int_seccomp(const struct seccomp_data *ctx,
const struct sock_filter_int *insni);
u32 sk_run_filter_int_skb(const struct sk_buff *ctx,
const struct sock_filter_int *insni);
void sk_filter_select_runtime(struct sk_filter *fp);
void sk_filter_free(struct sk_filter *fp);
int sk_convert_filter(struct sock_filter *prog, int len,
struct sock_filter_int *new_prog, int *new_len);

View File

@ -273,10 +273,8 @@ static long seccomp_attach_filter(struct sock_fprog *fprog)
atomic_set(&filter->usage, 1);
filter->prog->len = new_len;
filter->prog->bpf_func = (void *)sk_run_filter_int_seccomp;
/* JIT internal BPF into native HW instructions */
bpf_int_jit_compile(filter->prog);
sk_filter_select_runtime(filter->prog);
/*
* If there is an existing filter, make it the prev and don't drop its
@ -340,7 +338,7 @@ void put_seccomp_filter(struct task_struct *tsk)
while (orig && atomic_dec_and_test(&orig->usage)) {
struct seccomp_filter *freeme = orig;
orig = orig->prev;
bpf_jit_free(freeme->prog);
sk_filter_free(freeme->prog);
kfree(freeme);
}
}

View File

@ -1489,7 +1489,7 @@ static __init int test_bpf(void)
memcpy(fp_ext->insns, tests[i].insns_int,
fprog.len * 8);
fp->len = fprog.len;
fp->bpf_func = sk_run_filter_int_skb;
sk_filter_select_runtime(fp);
} else {
err = sk_unattached_filter_create(&fp, &fprog);
if (tests[i].data_type == EXPECTED_FAIL) {
@ -1516,7 +1516,7 @@ static __init int test_bpf(void)
if (tests[i].data_type != SKB_INT)
sk_unattached_filter_destroy(fp);
else
kfree(fp);
sk_filter_free(fp);
if (err) {
pr_cont("FAIL %d\n", err);

View File

@ -153,7 +153,7 @@ noinline u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
* keep, 0 for none. @ctx is the data we are operating on, @insn is the
* array of filter instructions.
*/
unsigned int __sk_run_filter(void *ctx, const struct sock_filter_int *insn)
static unsigned int __sk_run_filter(void *ctx, const struct sock_filter_int *insn)
{
u64 stack[MAX_BPF_STACK / sizeof(u64)];
u64 regs[MAX_BPF_REG], tmp;
@ -571,15 +571,6 @@ load_byte:
return 0;
}
u32 sk_run_filter_int_seccomp(const struct seccomp_data *ctx,
const struct sock_filter_int *insni)
__attribute__ ((alias ("__sk_run_filter")));
u32 sk_run_filter_int_skb(const struct sk_buff *ctx,
const struct sock_filter_int *insni)
__attribute__ ((alias ("__sk_run_filter")));
EXPORT_SYMBOL_GPL(sk_run_filter_int_skb);
/* Helper to find the offset of pkt_type in sk_buff structure. We want
* to make sure its still a 3bit field starting at a byte boundary;
* taken from arch/x86/net/bpf_jit_comp.c.
@ -1397,7 +1388,7 @@ static void sk_filter_release_rcu(struct rcu_head *rcu)
struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu);
sk_release_orig_filter(fp);
bpf_jit_free(fp);
sk_filter_free(fp);
}
/**
@ -1497,7 +1488,6 @@ static struct sk_filter *__sk_migrate_filter(struct sk_filter *fp,
goto out_err_free;
}
fp->bpf_func = sk_run_filter_int_skb;
fp->len = new_len;
/* 2nd pass: remap sock_filter insns into sock_filter_int insns. */
@ -1510,6 +1500,8 @@ static struct sk_filter *__sk_migrate_filter(struct sk_filter *fp,
*/
goto out_err_free;
sk_filter_select_runtime(fp);
kfree(old_prog);
return fp;
@ -1528,6 +1520,29 @@ void __weak bpf_int_jit_compile(struct sk_filter *prog)
{
}
/**
* sk_filter_select_runtime - select execution runtime for BPF program
* @fp: sk_filter populated with internal BPF program
*
* try to JIT internal BPF program, if JIT is not available select interpreter
* BPF program will be executed via SK_RUN_FILTER() macro
*/
void sk_filter_select_runtime(struct sk_filter *fp)
{
fp->bpf_func = (void *) __sk_run_filter;
/* Probe if internal BPF can be JITed */
bpf_int_jit_compile(fp);
}
EXPORT_SYMBOL_GPL(sk_filter_select_runtime);
/* free internal BPF program */
void sk_filter_free(struct sk_filter *fp)
{
bpf_jit_free(fp);
}
EXPORT_SYMBOL_GPL(sk_filter_free);
static struct sk_filter *__sk_prepare_filter(struct sk_filter *fp,
struct sock *sk)
{
@ -1548,12 +1563,9 @@ static struct sk_filter *__sk_prepare_filter(struct sk_filter *fp,
/* JIT compiler couldn't process this filter, so do the
* internal BPF translation for the optimized interpreter.
*/
if (!fp->jited) {
if (!fp->jited)
fp = __sk_migrate_filter(fp, sk);
/* Probe if internal BPF can be jit-ed */
bpf_int_jit_compile(fp);
}
return fp;
}