Commit 6e71b04a authored by Chenbo Feng's avatar Chenbo Feng Committed by David S. Miller
Browse files

bpf: Add file mode configuration into bpf maps 



Introduce the map read/write flags to the eBPF syscalls that returns the
map fd. The flags is used to set up the file mode when construct a new
file descriptor for bpf maps. To not break the backward capability, the
f_flags is set to O_RDWR if the flag passed by syscall is 0. Otherwise
it should be O_RDONLY or O_WRONLY. When the userspace want to modify or
read the map content, it will check the file mode to see if it is
allowed to make the change.

Signed-off-by: default avatarChenbo Feng <fengc@google.com>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent aec72f33

include/linux/bpf.h

+5 −3
Original line number Diff line number Diff line
@@ -315,11 +315,11 @@ void bpf_map_area_free(void *base); 


extern int sysctl_unprivileged_bpf_disabled;



int bpf_map_new_fd(struct bpf_map *map);

int bpf_map_new_fd(struct bpf_map *map, int flags);

int bpf_prog_new_fd(struct bpf_prog *prog);



int bpf_obj_pin_user(u32 ufd, const char __user *pathname);

int bpf_obj_get_user(const char __user *pathname);

int bpf_obj_get_user(const char __user *pathname, int flags);



int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value);

int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value);
@@ -338,6 +338,8 @@ int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file, 
				void *key, void *value, u64 map_flags);

int bpf_fd_htab_map_lookup_elem(struct bpf_map *map, void *key, u32 *value);



int bpf_get_file_flag(int flags);



/* memcpy that is used with 8-byte aligned pointers, power-of-8 size and

 * forced to use 'long' read/writes to try to atomically copy long counters.

 * Best-effort only.  No barriers here, since it _will_ race with concurrent
@@ -421,7 +423,7 @@ static inline void __bpf_prog_uncharge(struct user_struct *user, u32 pages) 
{

}



static inline int bpf_obj_get_user(const char __user *pathname)

static inline int bpf_obj_get_user(const char __user *pathname, int flags)

{

	return -EOPNOTSUPP;

}

include/uapi/linux/bpf.h

+6 −0
Original line number Diff line number Diff line
@@ -218,6 +218,10 @@ enum bpf_attach_type { 


#define BPF_OBJ_NAME_LEN 16U



/* Flags for accessing BPF object */

#define BPF_F_RDONLY		(1U << 3)

#define BPF_F_WRONLY		(1U << 4)



union bpf_attr {

	struct { /* anonymous struct used by BPF_MAP_CREATE command */

		__u32	map_type;	/* one of enum bpf_map_type */
@@ -260,6 +264,7 @@ union bpf_attr { 
	struct { /* anonymous struct used by BPF_OBJ_* commands */

		__aligned_u64	pathname;

		__u32		bpf_fd;

		__u32		file_flags;

	};



	struct { /* anonymous struct used by BPF_PROG_ATTACH/DETACH commands */
@@ -287,6 +292,7 @@ union bpf_attr { 
			__u32		map_id;

		};

		__u32		next_id;

		__u32		open_flags;

	};



	struct { /* anonymous struct used by BPF_OBJ_GET_INFO_BY_FD */

kernel/bpf/arraymap.c

+5 −1
Original line number Diff line number Diff line
@@ -19,6 +19,9 @@ 


#include "map_in_map.h"



#define ARRAY_CREATE_FLAG_MASK \

	(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)



static void bpf_array_free_percpu(struct bpf_array *array)

{

	int i;
@@ -56,7 +59,8 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr) 


	/* check sanity of attributes */

	if (attr->max_entries == 0 || attr->key_size != 4 ||

	    attr->value_size == 0 || attr->map_flags & ~BPF_F_NUMA_NODE ||

	    attr->value_size == 0 ||

	    attr->map_flags & ~ARRAY_CREATE_FLAG_MASK ||

	    (percpu && numa_node != NUMA_NO_NODE))

		return ERR_PTR(-EINVAL);

kernel/bpf/devmap.c

+4 −1
Original line number Diff line number Diff line
@@ -50,6 +50,9 @@ 
#include <linux/bpf.h>

#include <linux/filter.h>



#define DEV_CREATE_FLAG_MASK \

	(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)



struct bpf_dtab_netdev {

	struct net_device *dev;

	struct bpf_dtab *dtab;
@@ -80,7 +83,7 @@ static struct bpf_map *dev_map_alloc(union bpf_attr *attr) 


	/* check sanity of attributes */

	if (attr->max_entries == 0 || attr->key_size != 4 ||

	    attr->value_size != 4 || attr->map_flags & ~BPF_F_NUMA_NODE)

	    attr->value_size != 4 || attr->map_flags & ~DEV_CREATE_FLAG_MASK)

		return ERR_PTR(-EINVAL);



	dtab = kzalloc(sizeof(*dtab), GFP_USER);

kernel/bpf/hashtab.c

+3 −2
Original line number Diff line number Diff line
@@ -19,7 +19,8 @@ 
#include "map_in_map.h"



#define HTAB_CREATE_FLAG_MASK						\

	(BPF_F_NO_PREALLOC | BPF_F_NO_COMMON_LRU | BPF_F_NUMA_NODE)

	(BPF_F_NO_PREALLOC | BPF_F_NO_COMMON_LRU | BPF_F_NUMA_NODE |	\

	 BPF_F_RDONLY | BPF_F_WRONLY)



struct bucket {

	struct hlist_nulls_head head;

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