mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-09-24 11:25:43 +00:00
Code Issues Releases Wiki Activity

bpf: Align CAP_NET_ADMIN checks with bpf_capable() approach

Browse source 
Within BPF syscall handling code CAP_NET_ADMIN checks stand out a bit
compared to CAP_BPF and CAP_PERFMON checks. For the latter, CAP_BPF or
CAP_PERFMON are checked first, but if they are not set, CAP_SYS_ADMIN
takes over and grants whatever part of BPF syscall is required.

Similar kind of checks that involve CAP_NET_ADMIN are not so consistent.
One out of four uses does follow CAP_BPF/CAP_PERFMON model: during
BPF_PROG_LOAD, if the type of BPF program is "network-related" either
CAP_NET_ADMIN or CAP_SYS_ADMIN is required to proceed.

But in three other cases CAP_NET_ADMIN is required even if CAP_SYS_ADMIN
is set:
  - when creating DEVMAP/XDKMAP/CPU_MAP maps;
  - when attaching CGROUP_SKB programs;
  - when handling BPF_PROG_QUERY command.

This patch is changing the latter three cases to follow BPF_PROG_LOAD
model, that is allowing to proceed under either CAP_NET_ADMIN or
CAP_SYS_ADMIN.

This also makes it cleaner in subsequent BPF token patches to switch
wholesomely to a generic bpf_token_capable(int cap) check, that always
falls back to CAP_SYS_ADMIN if requested capability is missing.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/bpf/20240124022127.2379740-2-andrii@kernel.org
This commit is contained in:
Andrii Nakryiko 2024-01-23 18:20:58 -08:00 committed by Alexei Starovoitov
parent c9f1155645
commit ed1ad5a741
1 changed files with 9 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

13
kernel/bpf/syscall.c
View file

@ -1123,6 +1123,11 @@ static int map_check_btf(struct bpf_map *map, const struct btf *btf,
return ret;
}
static bool bpf_net_capable(void)
{
return capable(CAP_NET_ADMIN) || capable(CAP_SYS_ADMIN);
}
#define BPF_MAP_CREATE_LAST_FIELD value_type_btf_obj_fd
/* called via syscall */
static int map_create(union bpf_attr *attr)
@ -1226,7 +1231,7 @@ static int map_create(union bpf_attr *attr)
case BPF_MAP_TYPE_DEVMAP:
case BPF_MAP_TYPE_DEVMAP_HASH:
case BPF_MAP_TYPE_XSKMAP:
if (!capable(CAP_NET_ADMIN))
if (!bpf_net_capable())
return -EPERM;
break;
default:
@ -2636,7 +2641,7 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
!bpf_capable())
return -EPERM;
if (is_net_admin_prog_type(type) && !capable(CAP_NET_ADMIN) && !capable(CAP_SYS_ADMIN))
if (is_net_admin_prog_type(type) && !bpf_net_capable())
return -EPERM;
if (is_perfmon_prog_type(type) && !perfmon_capable())
return -EPERM;
@ -3822,7 +3827,7 @@ static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog,
case BPF_PROG_TYPE_SK_LOOKUP:
return attach_type == prog->expected_attach_type ? 0 : -EINVAL;
case BPF_PROG_TYPE_CGROUP_SKB:
if (!capable(CAP_NET_ADMIN))
if (!bpf_net_capable())
/* cg-skb progs can be loaded by unpriv user.
* check permissions at attach time.
*/
@ -4025,7 +4030,7 @@ static int bpf_prog_detach(const union bpf_attr *attr)
static int bpf_prog_query(const union bpf_attr *attr,
union bpf_attr __user *uattr)
{
if (!capable(CAP_NET_ADMIN))
if (!bpf_net_capable())
return -EPERM;
if (CHECK_ATTR(BPF_PROG_QUERY))
return -EINVAL;