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-rw-r--r--include/linux/bpf.h11
-rw-r--r--include/linux/vmalloc.h1
-rw-r--r--include/uapi/linux/bpf.h3
-rw-r--r--kernel/bpf/arraymap.c58
-rw-r--r--kernel/bpf/syscall.c99
-rw-r--r--mm/vmalloc.c20
-rw-r--r--tools/include/uapi/linux/bpf.h3
7 files changed, 183 insertions, 12 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index fb606dc61a3a..e913dd5946ae 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -12,6 +12,7 @@
#include <linux/err.h>
#include <linux/rbtree_latch.h>
#include <linux/numa.h>
+#include <linux/mm_types.h>
#include <linux/wait.h>
#include <linux/u64_stats_sync.h>
#include <linux/refcount.h>
@@ -68,6 +69,7 @@ struct bpf_map_ops {
u64 *imm, u32 off);
int (*map_direct_value_meta)(const struct bpf_map *map,
u64 imm, u32 *off);
+ int (*map_mmap)(struct bpf_map *map, struct vm_area_struct *vma);
};
struct bpf_map_memory {
@@ -96,9 +98,10 @@ struct bpf_map {
u32 btf_value_type_id;
struct btf *btf;
struct bpf_map_memory memory;
+ char name[BPF_OBJ_NAME_LEN];
bool unpriv_array;
- bool frozen; /* write-once */
- /* 48 bytes hole */
+ bool frozen; /* write-once; write-protected by freeze_mutex */
+ /* 22 bytes hole */
/* The 3rd and 4th cacheline with misc members to avoid false sharing
* particularly with refcounting.
@@ -106,7 +109,8 @@ struct bpf_map {
atomic64_t refcnt ____cacheline_aligned;
atomic64_t usercnt;
struct work_struct work;
- char name[BPF_OBJ_NAME_LEN];
+ struct mutex freeze_mutex;
+ u64 writecnt; /* writable mmap cnt; protected by freeze_mutex */
};
static inline bool map_value_has_spin_lock(const struct bpf_map *map)
@@ -795,6 +799,7 @@ void bpf_map_charge_finish(struct bpf_map_memory *mem);
void bpf_map_charge_move(struct bpf_map_memory *dst,
struct bpf_map_memory *src);
void *bpf_map_area_alloc(size_t size, int numa_node);
+void *bpf_map_area_mmapable_alloc(size_t size, int numa_node);
void bpf_map_area_free(void *base);
void bpf_map_init_from_attr(struct bpf_map *map, union bpf_attr *attr);
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 4e7809408073..b4c58a191eb1 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -93,6 +93,7 @@ extern void *vzalloc(unsigned long size);
extern void *vmalloc_user(unsigned long size);
extern void *vmalloc_node(unsigned long size, int node);
extern void *vzalloc_node(unsigned long size, int node);
+extern void *vmalloc_user_node_flags(unsigned long size, int node, gfp_t flags);
extern void *vmalloc_exec(unsigned long size);
extern void *vmalloc_32(unsigned long size);
extern void *vmalloc_32_user(unsigned long size);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 4842a134b202..dbbcf0b02970 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -348,6 +348,9 @@ enum bpf_attach_type {
/* Clone map from listener for newly accepted socket */
#define BPF_F_CLONE (1U << 9)
+/* Enable memory-mapping BPF map */
+#define BPF_F_MMAPABLE (1U << 10)
+
/* flags for BPF_PROG_QUERY */
#define BPF_F_QUERY_EFFECTIVE (1U << 0)
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 1c65ce0098a9..a42097c36b0c 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -14,7 +14,7 @@
#include "map_in_map.h"
#define ARRAY_CREATE_FLAG_MASK \
- (BPF_F_NUMA_NODE | BPF_F_ACCESS_MASK)
+ (BPF_F_NUMA_NODE | BPF_F_MMAPABLE | BPF_F_ACCESS_MASK)
static void bpf_array_free_percpu(struct bpf_array *array)
{
@@ -59,6 +59,10 @@ int array_map_alloc_check(union bpf_attr *attr)
(percpu && numa_node != NUMA_NO_NODE))
return -EINVAL;
+ if (attr->map_type != BPF_MAP_TYPE_ARRAY &&
+ attr->map_flags & BPF_F_MMAPABLE)
+ return -EINVAL;
+
if (attr->value_size > KMALLOC_MAX_SIZE)
/* if value_size is bigger, the user space won't be able to
* access the elements.
@@ -102,10 +106,19 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
}
array_size = sizeof(*array);
- if (percpu)
+ if (percpu) {
array_size += (u64) max_entries * sizeof(void *);
- else
- array_size += (u64) max_entries * elem_size;
+ } else {
+ /* rely on vmalloc() to return page-aligned memory and
+ * ensure array->value is exactly page-aligned
+ */
+ if (attr->map_flags & BPF_F_MMAPABLE) {
+ array_size = PAGE_ALIGN(array_size);
+ array_size += PAGE_ALIGN((u64) max_entries * elem_size);
+ } else {
+ array_size += (u64) max_entries * elem_size;
+ }
+ }
/* make sure there is no u32 overflow later in round_up() */
cost = array_size;
@@ -117,7 +130,20 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
return ERR_PTR(ret);
/* allocate all map elements and zero-initialize them */
- array = bpf_map_area_alloc(array_size, numa_node);
+ if (attr->map_flags & BPF_F_MMAPABLE) {
+ void *data;
+
+ /* kmalloc'ed memory can't be mmap'ed, use explicit vmalloc */
+ data = bpf_map_area_mmapable_alloc(array_size, numa_node);
+ if (!data) {
+ bpf_map_charge_finish(&mem);
+ return ERR_PTR(-ENOMEM);
+ }
+ array = data + PAGE_ALIGN(sizeof(struct bpf_array))
+ - offsetof(struct bpf_array, value);
+ } else {
+ array = bpf_map_area_alloc(array_size, numa_node);
+ }
if (!array) {
bpf_map_charge_finish(&mem);
return ERR_PTR(-ENOMEM);
@@ -350,6 +376,11 @@ static int array_map_delete_elem(struct bpf_map *map, void *key)
return -EINVAL;
}
+static void *array_map_vmalloc_addr(struct bpf_array *array)
+{
+ return (void *)round_down((unsigned long)array, PAGE_SIZE);
+}
+
/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
static void array_map_free(struct bpf_map *map)
{
@@ -365,7 +396,10 @@ static void array_map_free(struct bpf_map *map)
if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
bpf_array_free_percpu(array);
- bpf_map_area_free(array);
+ if (array->map.map_flags & BPF_F_MMAPABLE)
+ bpf_map_area_free(array_map_vmalloc_addr(array));
+ else
+ bpf_map_area_free(array);
}
static void array_map_seq_show_elem(struct bpf_map *map, void *key,
@@ -444,6 +478,17 @@ static int array_map_check_btf(const struct bpf_map *map,
return 0;
}
+int array_map_mmap(struct bpf_map *map, struct vm_area_struct *vma)
+{
+ struct bpf_array *array = container_of(map, struct bpf_array, map);
+ pgoff_t pgoff = PAGE_ALIGN(sizeof(*array)) >> PAGE_SHIFT;
+
+ if (!(map->map_flags & BPF_F_MMAPABLE))
+ return -EINVAL;
+
+ return remap_vmalloc_range(vma, array_map_vmalloc_addr(array), pgoff);
+}
+
const struct bpf_map_ops array_map_ops = {
.map_alloc_check = array_map_alloc_check,
.map_alloc = array_map_alloc,
@@ -455,6 +500,7 @@ const struct bpf_map_ops array_map_ops = {
.map_gen_lookup = array_map_gen_lookup,
.map_direct_value_addr = array_map_direct_value_addr,
.map_direct_value_meta = array_map_direct_value_meta,
+ .map_mmap = array_map_mmap,
.map_seq_show_elem = array_map_seq_show_elem,
.map_check_btf = array_map_check_btf,
};
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 52fe4bacb330..bac3becf9f90 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -127,7 +127,7 @@ static struct bpf_map *find_and_alloc_map(union bpf_attr *attr)
return map;
}
-void *bpf_map_area_alloc(size_t size, int numa_node)
+static void *__bpf_map_area_alloc(size_t size, int numa_node, bool mmapable)
{
/* We really just want to fail instead of triggering OOM killer
* under memory pressure, therefore we set __GFP_NORETRY to kmalloc,
@@ -142,18 +142,33 @@ void *bpf_map_area_alloc(size_t size, int numa_node)
const gfp_t flags = __GFP_NOWARN | __GFP_ZERO;
void *area;
- if (size <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER)) {
+ /* kmalloc()'ed memory can't be mmap()'ed */
+ if (!mmapable && size <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER)) {
area = kmalloc_node(size, GFP_USER | __GFP_NORETRY | flags,
numa_node);
if (area != NULL)
return area;
}
-
+ if (mmapable) {
+ BUG_ON(!PAGE_ALIGNED(size));
+ return vmalloc_user_node_flags(size, numa_node, GFP_KERNEL |
+ __GFP_RETRY_MAYFAIL | flags);
+ }
return __vmalloc_node_flags_caller(size, numa_node,
GFP_KERNEL | __GFP_RETRY_MAYFAIL |
flags, __builtin_return_address(0));
}
+void *bpf_map_area_alloc(size_t size, int numa_node)
+{
+ return __bpf_map_area_alloc(size, numa_node, false);
+}
+
+void *bpf_map_area_mmapable_alloc(size_t size, int numa_node)
+{
+ return __bpf_map_area_alloc(size, numa_node, true);
+}
+
void bpf_map_area_free(void *area)
{
kvfree(area);
@@ -425,6 +440,74 @@ static ssize_t bpf_dummy_write(struct file *filp, const char __user *buf,
return -EINVAL;
}
+/* called for any extra memory-mapped regions (except initial) */
+static void bpf_map_mmap_open(struct vm_area_struct *vma)
+{
+ struct bpf_map *map = vma->vm_file->private_data;
+
+ bpf_map_inc_with_uref(map);
+
+ if (vma->vm_flags & VM_WRITE) {
+ mutex_lock(&map->freeze_mutex);
+ map->writecnt++;
+ mutex_unlock(&map->freeze_mutex);
+ }
+}
+
+/* called for all unmapped memory region (including initial) */
+static void bpf_map_mmap_close(struct vm_area_struct *vma)
+{
+ struct bpf_map *map = vma->vm_file->private_data;
+
+ if (vma->vm_flags & VM_WRITE) {
+ mutex_lock(&map->freeze_mutex);
+ map->writecnt--;
+ mutex_unlock(&map->freeze_mutex);
+ }
+
+ bpf_map_put_with_uref(map);
+}
+
+static const struct vm_operations_struct bpf_map_default_vmops = {
+ .open = bpf_map_mmap_open,
+ .close = bpf_map_mmap_close,
+};
+
+static int bpf_map_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+ struct bpf_map *map = filp->private_data;
+ int err;
+
+ if (!map->ops->map_mmap || map_value_has_spin_lock(map))
+ return -ENOTSUPP;
+
+ if (!(vma->vm_flags & VM_SHARED))
+ return -EINVAL;
+
+ mutex_lock(&map->freeze_mutex);
+
+ if ((vma->vm_flags & VM_WRITE) && map->frozen) {
+ err = -EPERM;
+ goto out;
+ }
+
+ /* set default open/close callbacks */
+ vma->vm_ops = &bpf_map_default_vmops;
+ vma->vm_private_data = map;
+
+ err = map->ops->map_mmap(map, vma);
+ if (err)
+ goto out;
+
+ bpf_map_inc_with_uref(map);
+
+ if (vma->vm_flags & VM_WRITE)
+ map->writecnt++;
+out:
+ mutex_unlock(&map->freeze_mutex);
+ return err;
+}
+
const struct file_operations bpf_map_fops = {
#ifdef CONFIG_PROC_FS
.show_fdinfo = bpf_map_show_fdinfo,
@@ -432,6 +515,7 @@ const struct file_operations bpf_map_fops = {
.release = bpf_map_release,
.read = bpf_dummy_read,
.write = bpf_dummy_write,
+ .mmap = bpf_map_mmap,
};
int bpf_map_new_fd(struct bpf_map *map, int flags)
@@ -577,6 +661,7 @@ static int map_create(union bpf_attr *attr)
atomic64_set(&map->refcnt, 1);
atomic64_set(&map->usercnt, 1);
+ mutex_init(&map->freeze_mutex);
if (attr->btf_key_type_id || attr->btf_value_type_id) {
struct btf *btf;
@@ -1163,6 +1248,13 @@ static int map_freeze(const union bpf_attr *attr)
map = __bpf_map_get(f);
if (IS_ERR(map))
return PTR_ERR(map);
+
+ mutex_lock(&map->freeze_mutex);
+
+ if (map->writecnt) {
+ err = -EBUSY;
+ goto err_put;
+ }
if (READ_ONCE(map->frozen)) {
err = -EBUSY;
goto err_put;
@@ -1174,6 +1266,7 @@ static int map_freeze(const union bpf_attr *attr)
WRITE_ONCE(map->frozen, true);
err_put:
+ mutex_unlock(&map->freeze_mutex);
fdput(f);
return err;
}
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index a3c70e275f4e..4a7d7459c4f9 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2672,6 +2672,26 @@ void *vzalloc_node(unsigned long size, int node)
EXPORT_SYMBOL(vzalloc_node);
/**
+ * vmalloc_user_node_flags - allocate memory for userspace on a specific node
+ * @size: allocation size
+ * @node: numa node
+ * @flags: flags for the page level allocator
+ *
+ * The resulting memory area is zeroed so it can be mapped to userspace
+ * without leaking data.
+ *
+ * Return: pointer to the allocated memory or %NULL on error
+ */
+void *vmalloc_user_node_flags(unsigned long size, int node, gfp_t flags)
+{
+ return __vmalloc_node_range(size, SHMLBA, VMALLOC_START, VMALLOC_END,
+ flags | __GFP_ZERO, PAGE_KERNEL,
+ VM_USERMAP, node,
+ __builtin_return_address(0));
+}
+EXPORT_SYMBOL(vmalloc_user_node_flags);
+
+/**
* vmalloc_exec - allocate virtually contiguous, executable memory
* @size: allocation size
*
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 4842a134b202..dbbcf0b02970 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -348,6 +348,9 @@ enum bpf_attach_type {
/* Clone map from listener for newly accepted socket */
#define BPF_F_CLONE (1U << 9)
+/* Enable memory-mapping BPF map */
+#define BPF_F_MMAPABLE (1U << 10)
+
/* flags for BPF_PROG_QUERY */
#define BPF_F_QUERY_EFFECTIVE (1U << 0)
generated by cgit (git 2.34.1) at 2024-06-26 23:50:28 +0000