diff options
| author | Andrii Nakryiko <andrii@kernel.org> | 2023-12-13 11:08:33 -0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2023-12-13 15:47:04 -0800 |
| commit | f5fdb51fb980077a4c6c78f3f775821f611fb38b (patch) | |
| tree | fa1e7a72820564b8bab55f1c448f446d68b0c41f /kernel/bpf | |
| parent | f04f2ce6018f3cb33ac96270b9153c2920ead190 (diff) | |
bpf: fail BPF_TOKEN_CREATE if no delegation option was set on BPF FS
It's quite confusing in practice when it's possible to successfully
create a BPF token from BPF FS that didn't have any of delegate_xxx
mount options set up. While it's not wrong, it's actually more
meaningful to reject BPF_TOKEN_CREATE with specific error code (-ENOENT)
to let user-space know that no token delegation is setup up.
So, instead of creating empty BPF token that will be always ignored
because it doesn't have any of the allow_xxx bits set, reject it with
-ENOENT. If we ever need empty BPF token to be possible, we can support
that with extra flag passed into BPF_TOKEN_CREATE.
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231213190842.3844987-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/token.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/kernel/bpf/token.c b/kernel/bpf/token.c index 17212efcde60..a86fccd57e2d 100644 --- a/kernel/bpf/token.c +++ b/kernel/bpf/token.c @@ -152,6 +152,15 @@ int bpf_token_create(union bpf_attr *attr) goto out_path; } + mnt_opts = path.dentry->d_sb->s_fs_info; + if (mnt_opts->delegate_cmds == 0 && + mnt_opts->delegate_maps == 0 && + mnt_opts->delegate_progs == 0 && + mnt_opts->delegate_attachs == 0) { + err = -ENOENT; /* no BPF token delegation is set up */ + goto out_path; + } + mode = S_IFREG | ((S_IRUSR | S_IWUSR) & ~current_umask()); inode = bpf_get_inode(path.mnt->mnt_sb, NULL, mode); if (IS_ERR(inode)) { @@ -181,7 +190,6 @@ int bpf_token_create(union bpf_attr *attr) /* remember bpffs owning userns for future ns_capable() checks */ token->userns = get_user_ns(userns); - mnt_opts = path.dentry->d_sb->s_fs_info; token->allowed_cmds = mnt_opts->delegate_cmds; token->allowed_maps = mnt_opts->delegate_maps; token->allowed_progs = mnt_opts->delegate_progs; |