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bpf: Move unprivileged checks into map_create() and bpf_prog_load()

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Make each bpf() syscall command a bit more self-contained, making it
easier to further enhance it. We move sysctl_unprivileged_bpf_disabled
handling down to map_create() and bpf_prog_load(), two special commands
in this regard.

Also swap the order of checks, calling bpf_capable() only if
sysctl_unprivileged_bpf_disabled is true, avoiding unnecessary audit
messages.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20230613223533.3689589-2-andrii@kernel.org
This commit is contained in:
Andrii Nakryiko 2023-06-13 15:35:30 -07:00 committed by Daniel Borkmann
parent ab5d47bd41
commit 1d28635abc
1 changed files with 19 additions and 15 deletions
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34
kernel/bpf/syscall.c
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@ -1157,6 +1157,15 @@ static int map_create(union bpf_attr *attr)
!node_online(numa_node)))
return -EINVAL;
/* Intent here is for unprivileged_bpf_disabled to block BPF map
* creation for unprivileged users; other actions depend
* on fd availability and access to bpffs, so are dependent on
* object creation success. Even with unprivileged BPF disabled,
* capability checks are still carried out.
*/
if (sysctl_unprivileged_bpf_disabled && !bpf_capable())
return -EPERM;
/* find map type and init map: hashtable vs rbtree vs bloom vs ... */
map = find_and_alloc_map(attr);
if (IS_ERR(map))
@ -2532,6 +2541,16 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
/* eBPF programs must be GPL compatible to use GPL-ed functions */
is_gpl = license_is_gpl_compatible(license);
/* Intent here is for unprivileged_bpf_disabled to block BPF program
* creation for unprivileged users; other actions depend
* on fd availability and access to bpffs, so are dependent on
* object creation success. Even with unprivileged BPF disabled,
* capability checks are still carried out for these
* and other operations.
*/
if (sysctl_unprivileged_bpf_disabled && !bpf_capable())
return -EPERM;
if (attr->insn_cnt == 0 ||
attr->insn_cnt > (bpf_capable() ? BPF_COMPLEXITY_LIMIT_INSNS : BPF_MAXINSNS))
return -E2BIG;
@ -5030,23 +5049,8 @@ out_prog_put:
static int __sys_bpf(int cmd, bpfptr_t uattr, unsigned int size)
{
union bpf_attr attr;
bool capable;
int err;
capable = bpf_capable() || !sysctl_unprivileged_bpf_disabled;
/* Intent here is for unprivileged_bpf_disabled to block key object
* creation commands for unprivileged users; other actions depend
* of fd availability and access to bpffs, so are dependent on
* object creation success. Capabilities are later verified for
* operations such as load and map create, so even with unprivileged
* BPF disabled, capability checks are still carried out for these
* and other operations.
*/
if (!capable &&
(cmd == BPF_MAP_CREATE || cmd == BPF_PROG_LOAD))
return -EPERM;
err = bpf_check_uarg_tail_zero(uattr, sizeof(attr), size);
if (err)
return err;