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a766cfbbeb
LSM hooks such as security_path_mknod() and security_inode_rename() have access to newly allocated negative dentry, which has NULL d_inode. Therefore, it is necessary to do the NULL pointer check for d_inode. Also add selftests that checks the verifier enforces the NULL pointer check. Signed-off-by: Song Liu <song@kernel.org> Reviewed-by: Matt Bobrowski <mattbobrowski@google.com> Link: https://lore.kernel.org/r/20250613052857.1992233-1-song@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
103 lines
2.1 KiB
C
103 lines
2.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2024 Google LLC. */
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#include <vmlinux.h>
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#include <errno.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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#include "bpf_misc.h"
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#include "bpf_experimental.h"
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static char buf[64];
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SEC("lsm.s/file_open")
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__success
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int BPF_PROG(get_task_exe_file_and_put_kfunc_from_current_sleepable)
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{
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struct file *acquired;
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acquired = bpf_get_task_exe_file(bpf_get_current_task_btf());
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if (!acquired)
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return 0;
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bpf_put_file(acquired);
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return 0;
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}
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SEC("lsm/file_open")
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__success
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int BPF_PROG(get_task_exe_file_and_put_kfunc_from_current_non_sleepable, struct file *file)
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{
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struct file *acquired;
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acquired = bpf_get_task_exe_file(bpf_get_current_task_btf());
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if (!acquired)
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return 0;
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bpf_put_file(acquired);
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return 0;
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}
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SEC("lsm.s/task_alloc")
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__success
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int BPF_PROG(get_task_exe_file_and_put_kfunc_from_argument,
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struct task_struct *task)
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{
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struct file *acquired;
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acquired = bpf_get_task_exe_file(task);
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if (!acquired)
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return 0;
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bpf_put_file(acquired);
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return 0;
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}
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SEC("lsm.s/inode_getattr")
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__success
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int BPF_PROG(path_d_path_from_path_argument, struct path *path)
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{
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int ret;
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ret = bpf_path_d_path(path, buf, sizeof(buf));
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__sink(ret);
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return 0;
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}
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SEC("lsm.s/file_open")
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__success
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int BPF_PROG(path_d_path_from_file_argument, struct file *file)
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{
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int ret;
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struct path *path;
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/* The f_path member is a path which is embedded directly within a
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* file. Therefore, a pointer to such embedded members are still
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* recognized by the BPF verifier as being PTR_TRUSTED as it's
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* essentially PTR_TRUSTED w/ a non-zero fixed offset.
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*/
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path = &file->f_path;
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ret = bpf_path_d_path(path, buf, sizeof(buf));
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__sink(ret);
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return 0;
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}
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SEC("lsm.s/inode_rename")
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__success
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int BPF_PROG(inode_rename, struct inode *old_dir, struct dentry *old_dentry,
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struct inode *new_dir, struct dentry *new_dentry,
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unsigned int flags)
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{
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struct inode *inode = new_dentry->d_inode;
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ino_t ino;
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if (!inode)
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return 0;
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ino = inode->i_ino;
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if (ino == 0)
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return -EACCES;
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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