Subject: [PATCH bpf-next v9 33/34] bpf: eliminate rlimit-based memory accounting for bpf progs

From: Roman Gushchin <[email-masked]>
Date: Tue, 1 Dec 2020 13:58:59 -0800

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

Signed-off-by: Roman Gushchin <[email-masked]>
Acked-by: Song Liu <[email-masked]>
---
 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 61331a148cde..a9de5711b23f 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1202,8 +1202,6 @@ 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);
 
@@ -1512,15 +1510,6 @@ 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 29096d96d989..d16dd4945100 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1632,51 +1632,6 @@ 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;
@@ -1726,7 +1681,7 @@ 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);
 }
@@ -2164,7 +2119,7 @@ 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;
 	}
@@ -2174,18 +2129,15 @@ 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;
@@ -2196,19 +2148,19 @@ 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);
@@ -2253,11 +2205,10 @@ 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