Messages in this thread | | | Date | Mon, 21 Aug 2023 13:25:25 -0700 | Subject | Re: [PATCH v3 8/9] io_uring/cmd: BPF hook for getsockopt cmd | From | Martin KaFai Lau <> |
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On 8/17/23 12:08 PM, Gabriel Krisman Bertazi wrote: > Breno Leitao <leitao@debian.org> writes: > >> Add BPF hook support for getsockopts io_uring command. So, BPF cgroups >> programs can run when SOCKET_URING_OP_GETSOCKOPT command is executed >> through io_uring. >> >> This implementation follows a similar approach to what >> __sys_getsockopt() does, but, using USER_SOCKPTR() for optval instead of >> kernel pointer. >> >> Signed-off-by: Breno Leitao <leitao@debian.org> >> --- >> io_uring/uring_cmd.c | 18 +++++++++++++----- >> 1 file changed, 13 insertions(+), 5 deletions(-) >> >> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c >> index a567dd32df00..9e08a14760c3 100644 >> --- a/io_uring/uring_cmd.c >> +++ b/io_uring/uring_cmd.c >> @@ -5,6 +5,8 @@ >> #include <linux/io_uring.h> >> #include <linux/security.h> >> #include <linux/nospec.h> >> +#include <linux/compat.h> >> +#include <linux/bpf-cgroup.h> >> >> #include <uapi/linux/io_uring.h> >> #include <uapi/asm-generic/ioctls.h> >> @@ -184,17 +186,23 @@ static inline int io_uring_cmd_getsockopt(struct socket *sock, >> if (err) >> return err; >> >> - if (level == SOL_SOCKET) { >> + err = -EOPNOTSUPP; >> + if (level == SOL_SOCKET) >> err = sk_getsockopt(sock->sk, level, optname, >> USER_SOCKPTR(optval), >> KERNEL_SOCKPTR(&optlen)); >> - if (err) >> - return err; >> >> + if (!(issue_flags & IO_URING_F_COMPAT)) >> + err = BPF_CGROUP_RUN_PROG_GETSOCKOPT(sock->sk, level, >> + optname, >> + USER_SOCKPTR(optval), >> + KERNEL_SOCKPTR(&optlen), >> + optlen, err); >> + >> + if (!err) >> return optlen; >> - } > > Shouldn't you call sock->ops->getsockopt for level!=SOL_SOCKET prior to > running the hook? Before this patch, it would bail out with EOPNOTSUPP, > but now the bpf hook gets called even for level!=SOL_SOCKET, which > doesn't fit __sys_getsockopt. Am I misreading the code? I agree it should not call into bpf if the io_uring cannot support non SOL_SOCKET optnames. Otherwise, the bpf prog will get different optval and optlen when running in _sys_getsockopt vs io_uring getsockopt (e.g. in regular _sys_getsockopt(SOL_TCP), bpf expects the optval returned from tcp_getsockopt).
I think __sys_getsockopt can also be refactored similar to __sys_setsockopt in patch 3. Yes, for non SOL_SOCKET it only supports __user *optval and __user *optlen but may be a WARN_ON_ONCE/BUG_ON(sockpt_is_kernel(optval)) can be added before calling ops->getsockopt()? Then this details can be hidden away from the io_uring.
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