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bpf: Validate BPF object in BPF_OBJ_PIN before calling LSM

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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
This commit is contained in:
Andrii Nakryiko 2023-05-22 16:29:14 -07:00 committed by Daniel Borkmann
parent f46392ee3d
commit e7d85427ef
1 changed files with 5 additions and 6 deletions
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11
kernel/bpf/inode.c
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@ -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);