diff mbox series

[v3,bpf-next,01/10] bpf: fail BPF_TOKEN_CREATE if no delegation option was set on BPF FS

Message ID 20231213190842.3844987-2-andrii@kernel.org (mailing list archive)
State Accepted
Commit f5fdb51fb980077a4c6c78f3f775821f611fb38b
Delegated to: BPF
Headers show
Series BPF token support in libbpf's BPF object | expand

Checks

Context Check Description
bpf/vmtest-bpf-next-PR fail merge-conflict
bpf/vmtest-bpf-next-VM_Test-43 success Logs for x86_64-llvm-18 / test (test_progs, false, 360) / test_progs on x86_64 with llvm-18
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bpf/vmtest-bpf-next-VM_Test-21 success Logs for x86_64-gcc / test (test_maps, false, 360) / test_maps on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-22 success Logs for x86_64-gcc / test (test_progs, false, 360) / test_progs on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-23 success Logs for x86_64-gcc / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-24 success Logs for x86_64-gcc / test (test_progs_no_alu32_parallel, true, 30) / test_progs_no_alu32_parallel on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-25 success Logs for x86_64-gcc / test (test_progs_parallel, true, 30) / test_progs_parallel on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-26 success Logs for x86_64-gcc / test (test_verifier, false, 360) / test_verifier on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-27 success Logs for x86_64-gcc / veristat / veristat on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-30 success Logs for x86_64-llvm-17 / test (test_maps, false, 360) / test_maps on x86_64 with llvm-17
bpf/vmtest-bpf-next-VM_Test-33 success Logs for x86_64-llvm-17 / test (test_verifier, false, 360) / test_verifier on x86_64 with llvm-17
bpf/vmtest-bpf-next-VM_Test-37 success Logs for x86_64-llvm-18 / test (test_maps, false, 360) / test_maps on x86_64 with llvm-18
bpf/vmtest-bpf-next-VM_Test-41 success Logs for x86_64-llvm-18 / test (test_verifier, false, 360) / test_verifier on x86_64 with llvm-18
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bpf/vmtest-bpf-next-VM_Test-38 success Logs for x86_64-llvm-18 / test (test_progs, false, 360) / test_progs on x86_64 with llvm-18
bpf/vmtest-bpf-next-VM_Test-39 success Logs for x86_64-llvm-18 / test (test_progs_cpuv4, false, 360) / test_progs_cpuv4 on x86_64 with llvm-18
bpf/vmtest-bpf-next-VM_Test-40 success Logs for x86_64-llvm-18 / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on x86_64 with llvm-18
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next
netdev/ynl success SINGLE THREAD; Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1117 this patch: 1117
netdev/cc_maintainers warning 7 maintainers not CCed: kpsingh@kernel.org haoluo@google.com yonghong.song@linux.dev martin.lau@linux.dev jolsa@kernel.org sdf@google.com song@kernel.org
netdev/build_clang success Errors and warnings before: 1143 this patch: 1143
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1144 this patch: 1144
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 22 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-next-VM_Test-16 success Logs for s390x-gcc / test (test_verifier, false, 360) / test_verifier on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-14 success Logs for s390x-gcc / test (test_progs, false, 360) / test_progs on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-15 success Logs for s390x-gcc / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on s390x with gcc
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bpf/vmtest-bpf-next-VM_Test-10 success Logs for x86_64-gcc / build-release

Commit Message

Andrii Nakryiko Dec. 13, 2023, 7:08 p.m. UTC 
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>
---
 kernel/bpf/token.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)
diff mbox series

Patch

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;