[PATCH bpf-next v8 33/34] bpf: eliminate rlimit-based memory accounting for bpf progs

Roman Gushchin
2020-11-25T03:02:50Z

Do not use rlimit-based memory accounting for bpf progs. It has been
replaced with memcg-based memory accounting.

Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
---
include/linux/bpf.h | 11 -------
kernel/bpf/core.c | 12 ++------
kernel/bpf/syscall.c | 69 +++++++-------------------------------------
3 files changed, 12 insertions(+), 80 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index c9322adedd50..df5d5a8763db 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1201,8 +1201,6 @@ void bpf_prog_sub(struct bpf_prog *prog, int i);
void bpf_prog_inc(struct bpf_prog *prog);
struct bpf_prog * __must_check bpf_prog_inc_not_zero(struct bpf_prog *prog);
void bpf_prog_put(struct bpf_prog *prog);
-int __bpf_prog_charge(struct user_struct *user, u32 pages);
-void __bpf_prog_uncharge(struct user_struct *user, u32 pages);
void __bpf_free_used_maps(struct bpf_prog_aux *aux,
struct bpf_map **used_maps, u32 len);

@@ -1504,15 +1502,6 @@ bpf_prog_inc_not_zero(struct bpf_prog *prog)
return ERR_PTR(-EOPNOTSUPP);
}

-static inline int __bpf_prog_charge(struct user_struct *user, u32 pages)
-{
- return 0;
-}
-
-static inline void __bpf_prog_uncharge(struct user_struct *user, u32 pages)
-{
-}
-
static inline void bpf_link_init(struct bpf_link *link, enum bpf_link_type type,
const struct bpf_link_ops *ops,
struct bpf_prog *prog)
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 2921f58c03a8..261f8692d0d2 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -221,23 +221,15 @@ struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size,
{
gfp_t gfp_flags = GFP_KERNEL_ACCOUNT | __GFP_ZERO | gfp_extra_flags;
struct bpf_prog *fp;
- u32 pages, delta;
- int ret;
+ u32 pages;

size = round_up(size, PAGE_SIZE);
pages = size / PAGE_SIZE;
if (pages <= fp_old->pages)
return fp_old;

- delta = pages - fp_old->pages;
- ret = __bpf_prog_charge(fp_old->aux->user, delta);
- if (ret)
- return NULL;
-
fp = __vmalloc(size, gfp_flags);
- if (fp == NULL) {
- __bpf_prog_uncharge(fp_old->aux->user, delta);
- } else {
+ if (fp) {
memcpy(fp, fp_old, fp_old->pages * PAGE_SIZE);
fp->pages = pages;
fp->aux->prog = fp;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 3dadf34c3dd0..7cd5860098ee 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1641,51 +1641,6 @@ static void bpf_audit_prog(const struct bpf_prog *prog, unsigned int op)
audit_log_end(ab);
}

-int __bpf_prog_charge(struct user_struct *user, u32 pages)
-{
- unsigned long memlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
- unsigned long user_bufs;
-
- if (user) {
- user_bufs = atomic_long_add_return(pages, &user->locked_vm);
- if (user_bufs > memlock_limit) {
- atomic_long_sub(pages, &user->locked_vm);
- return -EPERM;
- }
- }
-
- return 0;
-}
-
-void __bpf_prog_uncharge(struct user_struct *user, u32 pages)
-{
- if (user)
- atomic_long_sub(pages, &user->locked_vm);
-}
-
-static int bpf_prog_charge_memlock(struct bpf_prog *prog)
-{
- struct user_struct *user = get_current_user();
- int ret;
-
- ret = __bpf_prog_charge(user, prog->pages);
- if (ret) {
- free_uid(user);
- return ret;
- }
-
- prog->aux->user = user;
- return 0;
-}
-
-static void bpf_prog_uncharge_memlock(struct bpf_prog *prog)
-{
- struct user_struct *user = prog->aux->user;
-
- __bpf_prog_uncharge(user, prog->pages);
- free_uid(user);
-}
-
static int bpf_prog_alloc_id(struct bpf_prog *prog)
{
int id;
@@ -1735,7 +1690,7 @@ static void __bpf_prog_put_rcu(struct rcu_head *rcu)

kvfree(aux->func_info);
kfree(aux->func_info_aux);
- bpf_prog_uncharge_memlock(aux->prog);
+ free_uid(aux->user);
security_bpf_prog_free(aux);
bpf_prog_free(aux->prog);
}
@@ -2173,7 +2128,7 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)
dst_prog = bpf_prog_get(attr->attach_prog_fd);
if (IS_ERR(dst_prog)) {
err = PTR_ERR(dst_prog);
- goto free_prog_nouncharge;
+ goto free_prog;
}
prog->aux->dst_prog = dst_prog;
}
@@ -2183,18 +2138,15 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)

err = security_bpf_prog_alloc(prog->aux);
if (err)
- goto free_prog_nouncharge;
-
- err = bpf_prog_charge_memlock(prog);
- if (err)
- goto free_prog_sec;
+ goto free_prog;

+ prog->aux->user = get_current_user();
prog->len = attr->insn_cnt;

err = -EFAULT;
if (copy_from_user(prog->insns, u64_to_user_ptr(attr->insns),
bpf_prog_insn_size(prog)) != 0)
- goto free_prog;
+ goto free_prog_sec;

prog->orig_prog = NULL;
prog->jited = 0;
@@ -2205,19 +2157,19 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)
if (bpf_prog_is_dev_bound(prog->aux)) {
err = bpf_prog_offload_init(prog, attr);
if (err)
- goto free_prog;
+ goto free_prog_sec;
}

/* find program type: socket_filter vs tracing_filter */
err = find_prog_type(type, prog);
if (err < 0)
- goto free_prog;
+ goto free_prog_sec;

prog->aux->load_time = ktime_get_boottime_ns();
err = bpf_obj_name_cpy(prog->aux->name, attr->prog_name,
sizeof(attr->prog_name));
if (err < 0)
- goto free_prog;
+ goto free_prog_sec;

/* run eBPF verifier */
err = bpf_check(&prog, attr, uattr);
@@ -2262,11 +2214,10 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)
*/
__bpf_prog_put_noref(prog, prog->aux->func_cnt);
return err;
-free_prog:
- bpf_prog_uncharge_memlock(prog);
free_prog_sec:
+ free_uid(prog->aux->user);
security_bpf_prog_free(prog->aux);
-free_prog_nouncharge:
+free_prog:
bpf_prog_free(prog);
return err;
}
--
2.26.2