diff options
| author | Kui-Feng Lee <thinker.li@gmail.com> | 2024-01-19 14:50:00 -0800 |
|---|---|---|
| committer | Martin KaFai Lau <martin.lau@kernel.org> | 2024-01-23 16:37:44 -0800 |
| commit | e3f87fdfed7b770dd7066b02262b12747881e76d (patch) | |
| tree | aba3b44c97564fd8d0e61f4b1eec1b90d7b13ee2 /kernel/bpf/verifier.c | |
| parent | fcc2c1fb0651477c8ed78a3a293c175ccd70697a (diff) | |
bpf: hold module refcnt in bpf_struct_ops map creation and prog verification.
To ensure that a module remains accessible whenever a struct_ops object of
a struct_ops type provided by the module is still in use.
struct bpf_struct_ops_map doesn't hold a refcnt to btf anymore since a
module will hold a refcnt to it's btf already. But, struct_ops programs are
different. They hold their associated btf, not the module since they need
only btf to assure their types (signatures).
However, verifier holds the refcnt of the associated module of a struct_ops
type temporarily when verify a struct_ops prog. Verifier needs the help
from the verifier operators (struct bpf_verifier_ops) provided by the owner
module to verify data access of a prog, provide information, and generate
code.
This patch also add a count of links (links_cnt) to bpf_struct_ops_map. It
avoids bpf_struct_ops_map_put_progs() from accessing btf after calling
module_put() in bpf_struct_ops_map_free().
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240119225005.668602-10-thinker.li@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Diffstat (limited to 'kernel/bpf/verifier.c')
| -rw-r--r-- | kernel/bpf/verifier.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 6081512deb79..f31868ba0c2d 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -20299,6 +20299,15 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env) } btf = prog->aux->attach_btf ?: bpf_get_btf_vmlinux(); + if (btf_is_module(btf)) { + /* Make sure st_ops is valid through the lifetime of env */ + env->attach_btf_mod = btf_try_get_module(btf); + if (!env->attach_btf_mod) { + verbose(env, "struct_ops module %s is not found\n", + btf_get_name(btf)); + return -ENOTSUPP; + } + } btf_id = prog->aux->attach_btf_id; st_ops_desc = bpf_struct_ops_find(btf, btf_id); @@ -21024,6 +21033,8 @@ err_release_maps: env->prog->expected_attach_type = 0; *prog = env->prog; + + module_put(env->attach_btf_mod); err_unlock: if (!is_priv) mutex_unlock(&bpf_verifier_lock); |