On Wed, Jul 21, 2021 at 10:01 PM Hengqi Chen <hengqi.chen@xxxxxxxxx> wrote: > > > > On 2021/7/20 3:02 AM, Andrii Nakryiko wrote: > > On Mon, Jul 19, 2021 at 8:18 AM Hengqi Chen <hengqi.chen@xxxxxxxxx> wrote: > >> > >> Add vfs_* and security_* to bpf_d_path allowlist, so that we can use > >> bpf_d_path helper to extract full file path from these functions' > >> `struct path *` and `struct file *` arguments. This will help tools > >> like IOVisor's filetop[2]/filelife to get full file path. > >> > >> Changes since v1: [1] > >> - Alexei and Yonghong suggested that bpf_d_path helper could also > >> apply to vfs_* and security_file_* kernel functions. Added them. > >> > >> [1] https://lore.kernel.org/bpf/20210712162424.2034006-1-hengqi.chen@xxxxxxxxx/ > >> [2] https://github.com/iovisor/bcc/issues/3527 > >> > >> Signed-off-by: Hengqi Chen <hengqi.chen@xxxxxxxxx> > >> --- > >> kernel/trace/bpf_trace.c | 50 ++++++++++++++++++++++++++++++++++++++-- > >> 1 file changed, 48 insertions(+), 2 deletions(-) > >> > >> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > >> index 08906007306d..c784f3c7143f 100644 > >> --- a/kernel/trace/bpf_trace.c > >> +++ b/kernel/trace/bpf_trace.c > >> @@ -850,16 +850,62 @@ BPF_CALL_3(bpf_d_path, struct path *, path, char *, buf, u32, sz) > >> BTF_SET_START(btf_allowlist_d_path) > >> #ifdef CONFIG_SECURITY > >> BTF_ID(func, security_file_permission) > >> -BTF_ID(func, security_inode_getattr) > >> BTF_ID(func, security_file_open) > >> +BTF_ID(func, security_file_ioctl) > >> +BTF_ID(func, security_file_free) > >> +BTF_ID(func, security_file_alloc) > >> +BTF_ID(func, security_file_lock) > >> +BTF_ID(func, security_file_fcntl) > >> +BTF_ID(func, security_file_set_fowner) > >> +BTF_ID(func, security_file_receive) > >> +BTF_ID(func, security_inode_getattr) > >> #endif > >> #ifdef CONFIG_SECURITY_PATH > >> BTF_ID(func, security_path_truncate) > >> +BTF_ID(func, security_path_notify) > >> +BTF_ID(func, security_path_unlink) > >> +BTF_ID(func, security_path_mkdir) > >> +BTF_ID(func, security_path_rmdir) > >> +BTF_ID(func, security_path_mknod) > >> +BTF_ID(func, security_path_symlink) > >> +BTF_ID(func, security_path_link) > >> +BTF_ID(func, security_path_rename) > >> +BTF_ID(func, security_path_chmod) > >> +BTF_ID(func, security_path_chown) > >> +BTF_ID(func, security_path_chroot) > >> #endif > >> BTF_ID(func, vfs_truncate) > >> BTF_ID(func, vfs_fallocate) > >> -BTF_ID(func, dentry_open) > >> BTF_ID(func, vfs_getattr) > >> +BTF_ID(func, vfs_fadvise) > >> +BTF_ID(func, vfs_fchmod) > >> +BTF_ID(func, vfs_fchown) > >> +BTF_ID(func, vfs_open) > >> +BTF_ID(func, vfs_setpos) > >> +BTF_ID(func, vfs_llseek) > >> +BTF_ID(func, vfs_read) > >> +BTF_ID(func, vfs_write) > >> +BTF_ID(func, vfs_iocb_iter_read) > >> +BTF_ID(func, vfs_iter_read) > >> +BTF_ID(func, vfs_readv) > >> +BTF_ID(func, vfs_iocb_iter_write) > >> +BTF_ID(func, vfs_iter_write) > >> +BTF_ID(func, vfs_writev) > >> +BTF_ID(func, vfs_copy_file_range) > >> +BTF_ID(func, vfs_getattr_nosec) > >> +BTF_ID(func, vfs_ioctl) > >> +BTF_ID(func, vfs_fsync_range) > >> +BTF_ID(func, vfs_fsync) > >> +BTF_ID(func, vfs_utimes) > >> +BTF_ID(func, vfs_statfs) > >> +BTF_ID(func, vfs_dedupe_file_range_one) > >> +BTF_ID(func, vfs_dedupe_file_range) > >> +BTF_ID(func, vfs_clone_file_range) > >> +BTF_ID(func, vfs_cancel_lock) > >> +BTF_ID(func, vfs_test_lock) > >> +BTF_ID(func, vfs_setlease) > >> +BTF_ID(func, vfs_lock_file) > >> +BTF_ID(func, dentry_open) > >> BTF_ID(func, filp_close) > >> BTF_SET_END(btf_allowlist_d_path) > >> > > > > Before we lend this expanded list of allowed functions, I think we > > should address an issue that comes up from time to time with .BTF_ids. > > Sometimes the referenced function can be changed from global to static > > and get inlined by the compiler, and thus disappears from BTF > > altogether. This will result in kernel build failure causing a lot of > > confusion, because the change might be done by people unfamiliar with > > the BTF_ID() stuff and not even aware of it. > > > > Thanks for the detailed background. > I was able to reproduce this kernel build failure. > > > This came up a few times before and it's frustrating for everyone > > involved. Before we proceed with extending the list further, let's > > teach resolve_btfids to warn on such missing function (so that we are > > at least aware) but otherwise ignore it (probably leaving ID as zero, > > but let's also confirm that all the users of BTF_ID() stuff handle > > those zeros correctly). > > > > Do you mean that resolve_btfids should be updated to emit warning messages > instead of aborting the build process ? Yes. Just double-check that unresolved BTF IDs are filled out as zeros and don't break anything. > > >> -- > >> 2.25.1 > >>
