diff options
| author | Dave Marchevsky <davemarchevsky@fb.com> | 2023-08-21 22:33:09 +0300 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2023-08-25 19:23:16 +0300 |
| commit | 0816b8c6bf7fc87cec4273dc199e8f0764b9e7b1 (patch) | |
| tree | 1bdb64aaeb54516f7cced49453b9737921093546 /include/linux/bpf.h | |
| parent | ba2464c86f182c6fdb69fe2f77a3d04c19a72357 (diff) | |
| download | linux-0816b8c6bf7fc87cec4273dc199e8f0764b9e7b1.tar.xz | |
bpf: Consider non-owning refs to refcounted nodes RCU protected
An earlier patch in the series ensures that the underlying memory of
nodes with bpf_refcount - which can have multiple owners - is not reused
until RCU grace period has elapsed. This prevents
use-after-free with non-owning references that may point to
recently-freed memory. While RCU read lock is held, it's safe to
dereference such a non-owning ref, as by definition RCU GP couldn't have
elapsed and therefore underlying memory couldn't have been reused.
From the perspective of verifier "trustedness" non-owning refs to
refcounted nodes are now trusted only in RCU CS and therefore should no
longer pass is_trusted_reg, but rather is_rcu_reg. Let's mark them
MEM_RCU in order to reflect this new state.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230821193311.3290257-6-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'include/linux/bpf.h')
| -rw-r--r-- | include/linux/bpf.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index eced6400f778..12596af59c00 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -653,7 +653,8 @@ enum bpf_type_flag { MEM_RCU = BIT(13 + BPF_BASE_TYPE_BITS), /* Used to tag PTR_TO_BTF_ID | MEM_ALLOC references which are non-owning. - * Currently only valid for linked-list and rbtree nodes. + * Currently only valid for linked-list and rbtree nodes. If the nodes + * have a bpf_refcount_field, they must be tagged MEM_RCU as well. */ NON_OWN_REF = BIT(14 + BPF_BASE_TYPE_BITS), |