diff mbox series

[v4,bpf-next,1/4] bpf: Validate BPF object in BPF_OBJ_PIN before calling LSM

Message ID 20230523170013.728457-2-andrii@kernel.org (mailing list archive)
State Not Applicable
Delegated to: BPF
Headers show
Series Add O_PATH-based BPF_OBJ_PIN and BPF_OBJ_GET support | expand

Checks

Context Check Description
bpf/vmtest-bpf-next-PR success PR summary
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netdev/tree_selection success Clearly marked for bpf-next, async
netdev/apply fail Patch does not apply to bpf-next
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bpf/vmtest-bpf-next-VM_Test-13 fail Logs for test_progs on x86_64 with gcc
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bpf/vmtest-bpf-next-VM_Test-12 fail Logs for test_progs on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-8 success Logs for test_maps on s390x with gcc

Commit Message

Andrii Nakryiko May 23, 2023, 5 p.m. UTC 
Do a sanity check whether provided file-to-be-pinned is actually a BPF
object (prog, map, btf) before calling security_path_mknod LSM hook. If
it's not, LSM hook doesn't have to be triggered, as the operation has no
chance of succeeding anyways.

Suggested-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/bpf/20230522232917.2454595-2-andrii@kernel.org
---
 kernel/bpf/inode.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
index 9948b542a470..329f27d5cacf 100644
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -448,18 +448,17 @@  static int bpf_obj_do_pin(const char __user *pathname, void *raw,
 	if (IS_ERR(dentry))
 		return PTR_ERR(dentry);
 
-	mode = S_IFREG | ((S_IRUSR | S_IWUSR) & ~current_umask());
-
-	ret = security_path_mknod(&path, dentry, mode, 0);
-	if (ret)
-		goto out;
-
 	dir = d_inode(path.dentry);
 	if (dir->i_op != &bpf_dir_iops) {
 		ret = -EPERM;
 		goto out;
 	}
 
+	mode = S_IFREG | ((S_IRUSR | S_IWUSR) & ~current_umask());
+	ret = security_path_mknod(&path, dentry, mode, 0);
+	if (ret)
+		goto out;
+
 	switch (type) {
 	case BPF_TYPE_PROG:
 		ret = vfs_mkobj(dentry, mode, bpf_mkprog, raw);