[PATCH bpf-next v2 1/2] bpf: use kvmalloc for map values in syscall

Subsystems: bpf [core], bpf [general] (safe dynamic programs and tools), the rest

STALE1815d

6 messages, 3 authors, 2021-08-18 · open the first message on its own page

[PATCH bpf-next v2 1/2] bpf: use kvmalloc for map values in syscall

From: Stanislav Fomichev <hidden>
Date: 2021-08-17 15:46:00

Use kvmalloc/kvfree for temporary value when manipulating a map via
syscall. kmalloc might not be sufficient for percpu maps where the value
is big (and further multiplied by hundreds of CPUs).

Can be reproduced with netcnt test on qemu with "-smp 255".

Signed-off-by: Stanislav Fomichev <redacted>
---
 kernel/bpf/syscall.c | 28 +++++++++++-----------------
 1 file changed, 11 insertions(+), 17 deletions(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 7420e1334ab2..075f650d297a 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c

@@ -1076,7 +1076,7 @@ static int map_lookup_elem(union bpf_attr *attr)
 	value_size = bpf_map_value_size(map);
 
 	err = -ENOMEM;
-	value = kmalloc(value_size, GFP_USER | __GFP_NOWARN);
+	value = kvmalloc(value_size, GFP_USER | __GFP_NOWARN);
 	if (!value)
 		goto free_key;

@@ -1091,7 +1091,7 @@ static int map_lookup_elem(union bpf_attr *attr)
 	err = 0;
 
 free_value:
-	kfree(value);
+	kvfree(value);
 free_key:
 	kfree(key);
 err_put:

@@ -1137,16 +1137,10 @@ static int map_update_elem(union bpf_attr *attr, bpfptr_t uattr)
 		goto err_put;
 	}
 
-	if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
-	    map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH ||
-	    map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY ||
-	    map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE)
-		value_size = round_up(map->value_size, 8) * num_possible_cpus();
-	else
-		value_size = map->value_size;
+	value_size = bpf_map_value_size(map);
 
 	err = -ENOMEM;
-	value = kmalloc(value_size, GFP_USER | __GFP_NOWARN);
+	value = kvmalloc(value_size, GFP_USER | __GFP_NOWARN);
 	if (!value)
 		goto free_key;

@@ -1157,7 +1151,7 @@ static int map_update_elem(union bpf_attr *attr, bpfptr_t uattr)
 	err = bpf_map_update_value(map, f, key, value, attr->flags);
 
 free_value:
-	kfree(value);
+	kvfree(value);
 free_key:
 	kfree(key);
 err_put:

@@ -1367,7 +1361,7 @@ int generic_map_update_batch(struct bpf_map *map,
 	if (!key)
 		return -ENOMEM;
 
-	value = kmalloc(value_size, GFP_USER | __GFP_NOWARN);
+	value = kvmalloc(value_size, GFP_USER | __GFP_NOWARN);
 	if (!value) {
 		kfree(key);
 		return -ENOMEM;

@@ -1390,7 +1384,7 @@ int generic_map_update_batch(struct bpf_map *map,
 	if (copy_to_user(&uattr->batch.count, &cp, sizeof(cp)))
 		err = -EFAULT;
 
-	kfree(value);
+	kvfree(value);
 	kfree(key);
 	return err;
 }

@@ -1429,7 +1423,7 @@ int generic_map_lookup_batch(struct bpf_map *map,
 	if (!buf_prevkey)
 		return -ENOMEM;
 
-	buf = kmalloc(map->key_size + value_size, GFP_USER | __GFP_NOWARN);
+	buf = kvmalloc(map->key_size + value_size, GFP_USER | __GFP_NOWARN);
 	if (!buf) {
 		kfree(buf_prevkey);
 		return -ENOMEM;

@@ -1492,7 +1486,7 @@ int generic_map_lookup_batch(struct bpf_map *map,
 
 free_buf:
 	kfree(buf_prevkey);
-	kfree(buf);
+	kvfree(buf);
 	return err;
 }

@@ -1547,7 +1541,7 @@ static int map_lookup_and_delete_elem(union bpf_attr *attr)
 	value_size = bpf_map_value_size(map);
 
 	err = -ENOMEM;
-	value = kmalloc(value_size, GFP_USER | __GFP_NOWARN);
+	value = kvmalloc(value_size, GFP_USER | __GFP_NOWARN);
 	if (!value)
 		goto free_key;

@@ -1579,7 +1573,7 @@ static int map_lookup_and_delete_elem(union bpf_attr *attr)
 	err = 0;
 
 free_value:
-	kfree(value);
+	kvfree(value);
 free_key:
 	kfree(key);
 err_put:

-- 
2.33.0.rc1.237.g0d66db33f3-goog

[PATCH bpf-next v2 2/2] bpf: use kvmalloc for map keys in syscalls

From: Stanislav Fomichev <hidden>
Date: 2021-08-17 15:46:05

Same as previous patch but for the keys. memdup_bpfptr is renamed
to vmemdup_bpfptr (and converted to kvmalloc).

Signed-off-by: Stanislav Fomichev <redacted>
---
 include/linux/bpfptr.h | 12 ++++++++++--
 kernel/bpf/syscall.c   | 34 +++++++++++++++++-----------------
 2 files changed, 27 insertions(+), 19 deletions(-)

diff --git a/include/linux/bpfptr.h b/include/linux/bpfptr.h
index 5cdeab497cb3..84eeffb4316a 100644
--- a/include/linux/bpfptr.h
+++ b/include/linux/bpfptr.h

@@ -62,9 +62,17 @@ static inline int copy_to_bpfptr_offset(bpfptr_t dst, size_t offset,
 	return copy_to_sockptr_offset((sockptr_t) dst, offset, src, size);
 }
 
-static inline void *memdup_bpfptr(bpfptr_t src, size_t len)
+static inline void *vmemdup_bpfptr(bpfptr_t src, size_t len)
 {
-	return memdup_sockptr((sockptr_t) src, len);
+	void *p = kvmalloc(len, GFP_USER | __GFP_NOWARN);
+
+	if (!p)
+		return ERR_PTR(-ENOMEM);
+	if (copy_from_sockptr(p, (sockptr_t) src, len)) {
+		kvfree(p);
+		return ERR_PTR(-EFAULT);
+	}
+	return p;
 }
 
 static inline long strncpy_from_bpfptr(char *dst, bpfptr_t src, size_t count)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 075f650d297a..ac230f4234cd 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c

@@ -1013,7 +1013,7 @@ int __weak bpf_stackmap_copy(struct bpf_map *map, void *key, void *value)
 static void *__bpf_copy_key(void __user *ukey, u64 key_size)
 {
 	if (key_size)
-		return memdup_user(ukey, key_size);
+		return vmemdup_user(ukey, key_size);
 
 	if (ukey)
 		return ERR_PTR(-EINVAL);

@@ -1024,7 +1024,7 @@ static void *__bpf_copy_key(void __user *ukey, u64 key_size)
 static void *___bpf_copy_key(bpfptr_t ukey, u64 key_size)
 {
 	if (key_size)
-		return memdup_bpfptr(ukey, key_size);
+		return vmemdup_bpfptr(ukey, key_size);
 
 	if (!bpfptr_is_null(ukey))
 		return ERR_PTR(-EINVAL);

@@ -1093,7 +1093,7 @@ static int map_lookup_elem(union bpf_attr *attr)
 free_value:
 	kvfree(value);
 free_key:
-	kfree(key);
+	kvfree(key);
 err_put:
 	fdput(f);
 	return err;

@@ -1153,7 +1153,7 @@ static int map_update_elem(union bpf_attr *attr, bpfptr_t uattr)
 free_value:
 	kvfree(value);
 free_key:
-	kfree(key);
+	kvfree(key);
 err_put:
 	fdput(f);
 	return err;

@@ -1205,7 +1205,7 @@ static int map_delete_elem(union bpf_attr *attr)
 	bpf_enable_instrumentation();
 	maybe_wait_bpf_programs(map);
 out:
-	kfree(key);
+	kvfree(key);
 err_put:
 	fdput(f);
 	return err;

@@ -1247,7 +1247,7 @@ static int map_get_next_key(union bpf_attr *attr)
 	}
 
 	err = -ENOMEM;
-	next_key = kmalloc(map->key_size, GFP_USER);
+	next_key = kvmalloc(map->key_size, GFP_USER);
 	if (!next_key)
 		goto free_key;

@@ -1270,9 +1270,9 @@ static int map_get_next_key(union bpf_attr *attr)
 	err = 0;
 
 free_next_key:
-	kfree(next_key);
+	kvfree(next_key);
 free_key:
-	kfree(key);
+	kvfree(key);
 err_put:
 	fdput(f);
 	return err;

@@ -1299,7 +1299,7 @@ int generic_map_delete_batch(struct bpf_map *map,
 	if (!max_count)
 		return 0;
 
-	key = kmalloc(map->key_size, GFP_USER | __GFP_NOWARN);
+	key = kvmalloc(map->key_size, GFP_USER | __GFP_NOWARN);
 	if (!key)
 		return -ENOMEM;

@@ -1326,7 +1326,7 @@ int generic_map_delete_batch(struct bpf_map *map,
 	if (copy_to_user(&uattr->batch.count, &cp, sizeof(cp)))
 		err = -EFAULT;
 
-	kfree(key);
+	kvfree(key);
 	return err;
 }

@@ -1357,13 +1357,13 @@ int generic_map_update_batch(struct bpf_map *map,
 	if (!max_count)
 		return 0;
 
-	key = kmalloc(map->key_size, GFP_USER | __GFP_NOWARN);
+	key = kvmalloc(map->key_size, GFP_USER | __GFP_NOWARN);
 	if (!key)
 		return -ENOMEM;
 
 	value = kvmalloc(value_size, GFP_USER | __GFP_NOWARN);
 	if (!value) {
-		kfree(key);
+		kvfree(key);
 		return -ENOMEM;
 	}

@@ -1385,7 +1385,7 @@ int generic_map_update_batch(struct bpf_map *map,
 		err = -EFAULT;
 
 	kvfree(value);
-	kfree(key);
+	kvfree(key);
 	return err;
 }

@@ -1419,13 +1419,13 @@ int generic_map_lookup_batch(struct bpf_map *map,
 	if (put_user(0, &uattr->batch.count))
 		return -EFAULT;
 
-	buf_prevkey = kmalloc(map->key_size, GFP_USER | __GFP_NOWARN);
+	buf_prevkey = kvmalloc(map->key_size, GFP_USER | __GFP_NOWARN);
 	if (!buf_prevkey)
 		return -ENOMEM;
 
 	buf = kvmalloc(map->key_size + value_size, GFP_USER | __GFP_NOWARN);
 	if (!buf) {
-		kfree(buf_prevkey);
+		kvfree(buf_prevkey);
 		return -ENOMEM;
 	}

@@ -1485,7 +1485,7 @@ int generic_map_lookup_batch(struct bpf_map *map,
 		err = -EFAULT;
 
 free_buf:
-	kfree(buf_prevkey);
+	kvfree(buf_prevkey);
 	kvfree(buf);
 	return err;
 }

@@ -1575,7 +1575,7 @@ static int map_lookup_and_delete_elem(union bpf_attr *attr)
 free_value:
 	kvfree(value);
 free_key:
-	kfree(key);
+	kvfree(key);
 err_put:
 	fdput(f);
 	return err;

-- 
2.33.0.rc1.237.g0d66db33f3-goog

Re: [PATCH bpf-next v2 1/2] bpf: use kvmalloc for map values in syscall

From: Song Liu <song@kernel.org>
Date: 2021-08-17 16:19:43

On Tue, Aug 17, 2021 at 8:46 AM Stanislav Fomichev [off-list ref] wrote:

Use kvmalloc/kvfree for temporary value when manipulating a map via
syscall. kmalloc might not be sufficient for percpu maps where the value
is big (and further multiplied by hundreds of CPUs).

Can be reproduced with netcnt test on qemu with "-smp 255".

Signed-off-by: Stanislav Fomichev <redacted>

Acked-by: Song Liu <redacted>

Re: [PATCH bpf-next v2 2/2] bpf: use kvmalloc for map keys in syscalls

From: Song Liu <song@kernel.org>
Date: 2021-08-17 16:26:19

On Tue, Aug 17, 2021 at 8:46 AM Stanislav Fomichev [off-list ref] wrote:

Same as previous patch but for the keys. memdup_bpfptr is renamed
to vmemdup_bpfptr (and converted to kvmalloc).

Signed-off-by: Stanislav Fomichev <redacted>

Acked-by: Song Liu <redacted>

Re: [PATCH bpf-next v2 2/2] bpf: use kvmalloc for map keys in syscalls

From: Daniel Borkmann <daniel@iogearbox.net>
Date: 2021-08-18 22:24:45

On 8/17/21 5:45 PM, Stanislav Fomichev wrote:

quoted hunk

Same as previous patch but for the keys. memdup_bpfptr is renamed
to vmemdup_bpfptr (and converted to kvmalloc).

Signed-off-by: Stanislav Fomichev <redacted>
---
  include/linux/bpfptr.h | 12 ++++++++++--
  kernel/bpf/syscall.c   | 34 +++++++++++++++++-----------------
  2 files changed, 27 insertions(+), 19 deletions(-)

diff --git a/include/linux/bpfptr.h b/include/linux/bpfptr.h
index 5cdeab497cb3..84eeffb4316a 100644
--- a/include/linux/bpfptr.h
+++ b/include/linux/bpfptr.h

@@ -62,9 +62,17 @@ static inline int copy_to_bpfptr_offset(bpfptr_t dst, size_t offset,
  	return copy_to_sockptr_offset((sockptr_t) dst, offset, src, size);
  }
  
-static inline void *memdup_bpfptr(bpfptr_t src, size_t len)
+static inline void *vmemdup_bpfptr(bpfptr_t src, size_t len)

nit: should we just name it kvmemdup_bpfptr() in that case?

  {
-	return memdup_sockptr((sockptr_t) src, len);
+	void *p = kvmalloc(len, GFP_USER | __GFP_NOWARN);
+
+	if (!p)
+		return ERR_PTR(-ENOMEM);
+	if (copy_from_sockptr(p, (sockptr_t) src, len)) {

Also, I think this one should rather use copy_from_bpfptr() here.

+		kvfree(p);
+		return ERR_PTR(-EFAULT);
+	}
+	return p;
  }

Rest lgtm, thanks!

Re: [PATCH bpf-next v2 2/2] bpf: use kvmalloc for map keys in syscalls

From: <hidden>
Date: 2021-08-18 23:02:27

On 08/19, Daniel Borkmann wrote:

On 8/17/21 5:45 PM, Stanislav Fomichev wrote:

quoted

Same as previous patch but for the keys. memdup_bpfptr is renamed
to vmemdup_bpfptr (and converted to kvmalloc).

Signed-off-by: Stanislav Fomichev <redacted>
---
  include/linux/bpfptr.h | 12 ++++++++++--
  kernel/bpf/syscall.c   | 34 +++++++++++++++++-----------------
  2 files changed, 27 insertions(+), 19 deletions(-)

diff --git a/include/linux/bpfptr.h b/include/linux/bpfptr.h
index 5cdeab497cb3..84eeffb4316a 100644
--- a/include/linux/bpfptr.h
+++ b/include/linux/bpfptr.h

@@ -62,9 +62,17 @@ static inline int copy_to_bpfptr_offset(bpfptr_t

dst, size_t offset,

quoted

  	return copy_to_sockptr_offset((sockptr_t) dst, offset, src, size);
  }
-static inline void *memdup_bpfptr(bpfptr_t src, size_t len)
+static inline void *vmemdup_bpfptr(bpfptr_t src, size_t len)

nit: should we just name it kvmemdup_bpfptr() in that case?

Sounds good!

quoted

  {
-	return memdup_sockptr((sockptr_t) src, len);
+	void *p = kvmalloc(len, GFP_USER | __GFP_NOWARN);
+
+	if (!p)
+		return ERR_PTR(-ENOMEM);
+	if (copy_from_sockptr(p, (sockptr_t) src, len)) {

Also, I think this one should rather use copy_from_bpfptr() here.

Ah, missed that one, thanks!

quoted

+		kvfree(p);
+		return ERR_PTR(-EFAULT);
+	}
+	return p;
  }

Rest lgtm, thanks!

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