bpf, inode: add support for symlinks and fix mtime/ctime
While commit bb35a6ef ("bpf, inode: allow for rename and link ops") added support for hard links that can be used for prog and map nodes, this work adds simple symlink support, which can be used f.e. for directories also when unpriviledged and works with cmdline tooling that understands S_IFLNK anyway. Since the switch in e27f4a94 ("bpf: Use mount_nodev not mount_ns to mount the bpf filesystem"), there can be various mount instances with mount_nodev() and thus hierarchy can be flattened to facilitate object sharing. Thus, we can keep bpf tooling also working by repointing paths. Most of the functionality can be used from vfs library operations. The symlink is stored in the inode itself, that is in i_link, which is sufficient in our case as opposed to storing it in the page cache. While at it, I noticed that bpf_mkdir() and bpf_mkobj() don't update the directories mtime and ctime, so add a common helper for it called bpf_dentry_finalize() that takes care of it for all cases now. Signed-off-by:Daniel Borkmann <daniel@iogearbox.net> Acked-by:
Alexei Starovoitov <ast@kernel.org> Signed-off-by:
David S. Miller <davem@davemloft.net>
parent
8778b276
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