bpf: Introduce bpf_sys_bpf() helper and program type.

Add placeholders for bpf_sys_bpf() helper and new program type.
Make sure to check that expected_attach_type is zero for future extensibility.
Allow tracing helper functions to be used in this program type, since they will
only execute from user context via bpf_prog_test_run.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210514003623.28033-2-alexei.starovoitov@gmail.com
This commit is contained in:
Alexei Starovoitov 2021-05-13 17:36:03 -07:00 committed by Daniel Borkmann
parent fa7b83bf3b
commit 79a7f8bdb1
7 changed files with 132 additions and 0 deletions

View File

@ -1826,6 +1826,9 @@ static inline bool bpf_map_is_dev_bound(struct bpf_map *map)
struct bpf_map *bpf_map_offload_map_alloc(union bpf_attr *attr);
void bpf_map_offload_map_free(struct bpf_map *map);
int bpf_prog_test_run_syscall(struct bpf_prog *prog,
const union bpf_attr *kattr,
union bpf_attr __user *uattr);
#else
static inline int bpf_prog_offload_init(struct bpf_prog *prog,
union bpf_attr *attr)
@ -1851,6 +1854,13 @@ static inline struct bpf_map *bpf_map_offload_map_alloc(union bpf_attr *attr)
static inline void bpf_map_offload_map_free(struct bpf_map *map)
{
}
static inline int bpf_prog_test_run_syscall(struct bpf_prog *prog,
const union bpf_attr *kattr,
union bpf_attr __user *uattr)
{
return -ENOTSUPP;
}
#endif /* CONFIG_NET && CONFIG_BPF_SYSCALL */
#if defined(CONFIG_INET) && defined(CONFIG_BPF_SYSCALL)

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@ -77,6 +77,8 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_LSM, lsm,
void *, void *)
#endif /* CONFIG_BPF_LSM */
#endif
BPF_PROG_TYPE(BPF_PROG_TYPE_SYSCALL, bpf_syscall,
void *, void *)
BPF_MAP_TYPE(BPF_MAP_TYPE_ARRAY, array_map_ops)
BPF_MAP_TYPE(BPF_MAP_TYPE_PERCPU_ARRAY, percpu_array_map_ops)

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@ -937,6 +937,7 @@ enum bpf_prog_type {
BPF_PROG_TYPE_EXT,
BPF_PROG_TYPE_LSM,
BPF_PROG_TYPE_SK_LOOKUP,
BPF_PROG_TYPE_SYSCALL, /* a program that can execute syscalls */
};
enum bpf_attach_type {
@ -4735,6 +4736,12 @@ union bpf_attr {
* be zero-terminated except when **str_size** is 0.
*
* Or **-EBUSY** if the per-CPU memory copy buffer is busy.
*
* long bpf_sys_bpf(u32 cmd, void *attr, u32 attr_size)
* Description
* Execute bpf syscall with given arguments.
* Return
* A syscall result.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@ -4903,6 +4910,7 @@ union bpf_attr {
FN(check_mtu), \
FN(for_each_map_elem), \
FN(snprintf), \
FN(sys_bpf), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper

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@ -2014,6 +2014,7 @@ bpf_prog_load_check_attach(enum bpf_prog_type prog_type,
if (expected_attach_type == BPF_SK_LOOKUP)
return 0;
return -EINVAL;
case BPF_PROG_TYPE_SYSCALL:
case BPF_PROG_TYPE_EXT:
if (expected_attach_type)
return -EINVAL;
@ -4508,3 +4509,55 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
return err;
}
static bool syscall_prog_is_valid_access(int off, int size,
enum bpf_access_type type,
const struct bpf_prog *prog,
struct bpf_insn_access_aux *info)
{
if (off < 0 || off >= U16_MAX)
return false;
if (off % size != 0)
return false;
return true;
}
BPF_CALL_3(bpf_sys_bpf, int, cmd, void *, attr, u32, attr_size)
{
return -EINVAL;
}
const struct bpf_func_proto bpf_sys_bpf_proto = {
.func = bpf_sys_bpf,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_ANYTHING,
.arg2_type = ARG_PTR_TO_MEM,
.arg3_type = ARG_CONST_SIZE,
};
const struct bpf_func_proto * __weak
tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
return bpf_base_func_proto(func_id);
}
static const struct bpf_func_proto *
syscall_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
switch (func_id) {
case BPF_FUNC_sys_bpf:
return &bpf_sys_bpf_proto;
default:
return tracing_prog_func_proto(func_id, prog);
}
}
const struct bpf_verifier_ops bpf_syscall_verifier_ops = {
.get_func_proto = syscall_prog_func_proto,
.is_valid_access = syscall_prog_is_valid_access,
};
const struct bpf_prog_ops bpf_syscall_prog_ops = {
.test_run = bpf_prog_test_run_syscall,
};

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@ -13196,6 +13196,14 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
int ret;
u64 key;
if (prog->type == BPF_PROG_TYPE_SYSCALL) {
if (prog->aux->sleepable)
/* attach_btf_id checked to be zero already */
return 0;
verbose(env, "Syscall programs can only be sleepable\n");
return -EINVAL;
}
if (prog->aux->sleepable && prog->type != BPF_PROG_TYPE_TRACING &&
prog->type != BPF_PROG_TYPE_LSM) {
verbose(env, "Only fentry/fexit/fmod_ret and lsm programs can be sleepable\n");

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@ -918,3 +918,46 @@ out:
kfree(user_ctx);
return ret;
}
int bpf_prog_test_run_syscall(struct bpf_prog *prog,
const union bpf_attr *kattr,
union bpf_attr __user *uattr)
{
void __user *ctx_in = u64_to_user_ptr(kattr->test.ctx_in);
__u32 ctx_size_in = kattr->test.ctx_size_in;
void *ctx = NULL;
u32 retval;
int err = 0;
/* doesn't support data_in/out, ctx_out, duration, or repeat or flags */
if (kattr->test.data_in || kattr->test.data_out ||
kattr->test.ctx_out || kattr->test.duration ||
kattr->test.repeat || kattr->test.flags)
return -EINVAL;
if (ctx_size_in < prog->aux->max_ctx_offset ||
ctx_size_in > U16_MAX)
return -EINVAL;
if (ctx_size_in) {
ctx = kzalloc(ctx_size_in, GFP_USER);
if (!ctx)
return -ENOMEM;
if (copy_from_user(ctx, ctx_in, ctx_size_in)) {
err = -EFAULT;
goto out;
}
}
retval = bpf_prog_run_pin_on_cpu(prog, ctx);
if (copy_to_user(&uattr->test.retval, &retval, sizeof(u32))) {
err = -EFAULT;
goto out;
}
if (ctx_size_in)
if (copy_to_user(ctx_in, ctx, ctx_size_in))
err = -EFAULT;
out:
kfree(ctx);
return err;
}

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@ -937,6 +937,7 @@ enum bpf_prog_type {
BPF_PROG_TYPE_EXT,
BPF_PROG_TYPE_LSM,
BPF_PROG_TYPE_SK_LOOKUP,
BPF_PROG_TYPE_SYSCALL, /* a program that can execute syscalls */
};
enum bpf_attach_type {
@ -4735,6 +4736,12 @@ union bpf_attr {
* be zero-terminated except when **str_size** is 0.
*
* Or **-EBUSY** if the per-CPU memory copy buffer is busy.
*
* long bpf_sys_bpf(u32 cmd, void *attr, u32 attr_size)
* Description
* Execute bpf syscall with given arguments.
* Return
* A syscall result.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@ -4903,6 +4910,7 @@ union bpf_attr {
FN(check_mtu), \
FN(for_each_map_elem), \
FN(snprintf), \
FN(sys_bpf), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper