From: Maciej Żenczykowski maze@google.com
[ Upstream commit 5dec6d96d12d33900ec315972c8e47a73bcc378d ]
This reverts commit d37300ed1821 ("bpf: program: Refuse non-O_RDWR flags in BPF_OBJ_GET"). It breaks Android userspace which expects to be able to fetch programs with just read permissions.
See: https://cs.android.com/android/platform/superproject/+/master:frameworks/lib...
Side-note: another option to fix it would be to extend bpf_prog_new_fd() and to pass in used file mode flags in the same way as we do for maps via bpf_map_new_fd(). Meaning, they'd end up in anon_inode_getfd() and thus would be retained for prog fd operations with bpf() syscall. Right now these flags are not checked with progs since they are immutable for their lifetime (as opposed to maps which can be updated from user space). In future this could potentially change with new features, but at that point it's still fine to do the bpf_prog_new_fd() extension when needed. For a simple stable fix, a revert is less churn.
Fixes: d37300ed1821 ("bpf: program: Refuse non-O_RDWR flags in BPF_OBJ_GET") Signed-off-by: Maciej Żenczykowski maze@google.com [ Daniel: added side-note to commit message ] Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Lorenz Bauer lmb@cloudflare.com Acked-by: Greg Kroah-Hartman gregkh@google.com Link: https://lore.kernel.org/bpf/20210618105526.265003-1-zenczykowski@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/bpf/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c index b4ebd60a6c16..80da1db47c68 100644 --- a/kernel/bpf/inode.c +++ b/kernel/bpf/inode.c @@ -543,7 +543,7 @@ int bpf_obj_get_user(const char __user *pathname, int flags) return PTR_ERR(raw);
if (type == BPF_TYPE_PROG) - ret = (f_flags != O_RDWR) ? -EINVAL : bpf_prog_new_fd(raw); + ret = bpf_prog_new_fd(raw); else if (type == BPF_TYPE_MAP) ret = bpf_map_new_fd(raw, f_flags); else if (type == BPF_TYPE_LINK)