netdev - Re: [PATCH net-next v2 1/5] bpf: Add file mode configuration into bpf maps

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Message-ID: <CAMOXUJ=vvY6jY9CMuS4Q9vUi_EKF+g+hoRq69twRK3fvwqs_+A@mail.gmail.com>
Date:   Mon, 9 Oct 2017 16:31:35 -0700
From:   Chenbo Feng <fengc@...gle.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Chenbo Feng <chenbofeng.kernel@...il.com>,
        linux-security-module@...r.kernel.org, netdev@...r.kernel.org,
        SELinux <Selinux@...ho.nsa.gov>,
        Jeffrey Vander Stoep <jeffv@...gle.com>,
        Lorenzo Colitti <lorenzo@...gle.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Stephen Smalley <sds@...ho.nsa.gov>
Subject: Re: [PATCH net-next v2 1/5] bpf: Add file mode configuration into bpf maps

On Mon, Oct 9, 2017 at 4:07 PM, Alexei Starovoitov
<alexei.starovoitov@...il.com> wrote:
> On Mon, Oct 09, 2017 at 03:20:24PM -0700, Chenbo Feng wrote:
>> From: Chenbo Feng <fengc@...gle.com>
>>
>> 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: Chenbo Feng <fengc@...gle.com>
>> Acked-by: Alexei Starovoitov <ast@...nel.org>
>> ---
>>  include/linux/bpf.h      |  6 ++--
>>  include/uapi/linux/bpf.h |  6 ++++
>>  kernel/bpf/arraymap.c    |  7 +++--
>>  kernel/bpf/devmap.c      |  5 ++-
>>  kernel/bpf/hashtab.c     |  5 +--
>>  kernel/bpf/inode.c       | 15 ++++++---
>>  kernel/bpf/lpm_trie.c    |  3 +-
>>  kernel/bpf/sockmap.c     |  5 ++-
>>  kernel/bpf/stackmap.c    |  5 ++-
>>  kernel/bpf/syscall.c     | 80 +++++++++++++++++++++++++++++++++++++++++++-----
>>  10 files changed, 114 insertions(+), 23 deletions(-)
>>
>> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
>> index bc7da2ddfcaf..0e9ca2555d7f 100644
>> --- a/include/linux/bpf.h
>> +++ b/include/linux/bpf.h
>> @@ -308,11 +308,11 @@ 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);
>> @@ -331,6 +331,8 @@ 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
>> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
>> index 6db9e1d679cd..9cb50a228c39 100644
>> --- a/include/uapi/linux/bpf.h
>> +++ b/include/uapi/linux/bpf.h
>> @@ -217,6 +217,10 @@ 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 */
>> @@ -259,6 +263,7 @@ 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 */
>> @@ -286,6 +291,7 @@ union bpf_attr {
>>                       __u32           map_id;
>>               };
>>               __u32           next_id;
>> +             __u32           open_flags;
>>       };
>>
>>       struct { /* anonymous struct used by BPF_OBJ_GET_INFO_BY_FD */
>> diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
>> index 68d866628be0..f869e48ef2f6 100644
>> --- a/kernel/bpf/arraymap.c
>> +++ b/kernel/bpf/arraymap.c
>> @@ -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;
>> @@ -56,8 +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 ||
>> -         (percpu && numa_node != NUMA_NO_NODE))
>> +         attr->value_size == 0 || attr->map_flags &
>> +         ~ARRAY_CREATE_FLAG_MASK || (percpu && numa_node != NUMA_NO_NODE))
>
> that's very non-standard way of breaking lines.
> Did you run checkpatch ? did it complain?
>
Will fix in next revision, checkpatch didn't say anything about
this....0 error and 0 warning for this patch series.