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bpf: Add sockptr support for getsockopt 

The whole network stack uses sockptr, and while it doesn't move to
something more modern, let's use sockptr in getsockptr BPF hooks, so, it
could be used by other callers.

The main motivation for this change is to use it in the io_uring
{g,s}etsockopt(), which will use a userspace pointer for *optval, but, a
kernel value for optlen.

Link: https://lore.kernel.org/all/ZSArfLaaGcfd8LH8@gmail.com/

Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20231016134750.1381153-2-leitao@debian.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Breno Leitao 2023-10-16 06:47:39 -07:00 committed by Jens Axboe
parent 6ce4a93dbb
commit a615f67e1a
3 changed files with 17 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
include/linux/bpf-cgroup.h
View File

@ -139,9 +139,10 @@ int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
int __cgroup_bpf_run_filter_setsockopt(struct sock *sock, int *level,
int *optname, char __user *optval,
int *optlen, char **kernel_optval);
int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
int optname, char __user *optval,
int __user *optlen, int max_optlen,
int optname, sockptr_t optval,
sockptr_t optlen, int max_optlen,
int retval);
int __cgroup_bpf_run_filter_getsockopt_kern(struct sock *sk, int level,

20
kernel/bpf/cgroup.c
View File

@ -1875,8 +1875,8 @@ out:
}
int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
int optname, char __user *optval,
int __user *optlen, int max_optlen,
int optname, sockptr_t optval,
sockptr_t optlen, int max_optlen,
int retval)
{
struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
@ -1903,8 +1903,8 @@ int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
* one that kernel returned as well to let
* BPF programs inspect the value.
*/
if (get_user(ctx.optlen, optlen)) {
if (copy_from_sockptr(&ctx.optlen, optlen,
sizeof(ctx.optlen))) {
ret = -EFAULT;
goto out;
}
@ -1915,8 +1915,8 @@ int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
}
orig_optlen = ctx.optlen;
if (copy_from_user(ctx.optval, optval,
min(ctx.optlen, max_optlen)) != 0) {
if (copy_from_sockptr(ctx.optval, optval,
min(ctx.optlen, max_optlen))) {
ret = -EFAULT;
goto out;
}
@ -1930,7 +1930,8 @@ int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
if (ret < 0)
goto out;
if (optval && (ctx.optlen > max_optlen || ctx.optlen < 0)) {
if (!sockptr_is_null(optval) &&
(ctx.optlen > max_optlen || ctx.optlen < 0)) {
if (orig_optlen > PAGE_SIZE && ctx.optlen >= 0) {
pr_info_once("bpf getsockopt: ignoring program buffer with optlen=%d (max_optlen=%d)\n",
ctx.optlen, max_optlen);
@ -1942,11 +1943,12 @@ int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
}
if (ctx.optlen != 0) {
if (optval && copy_to_user(optval, ctx.optval, ctx.optlen)) {
if (!sockptr_is_null(optval) &&
copy_to_sockptr(optval, ctx.optval, ctx.optlen)) {
ret = -EFAULT;
goto out;
}
if (put_user(ctx.optlen, optlen)) {
if (copy_to_sockptr(optlen, &ctx.optlen, sizeof(ctx.optlen))) {
ret = -EFAULT;
goto out;
}

5
net/socket.c
View File

@ -2356,8 +2356,9 @@ int __sys_getsockopt(int fd, int level, int optname, char __user *optval,
if (!in_compat_syscall())
err = BPF_CGROUP_RUN_PROG_GETSOCKOPT(sock->sk, level, optname,
optval, optlen, max_optlen,
err);
USER_SOCKPTR(optval),
USER_SOCKPTR(optlen),
max_optlen, err);
out_put:
fput_light(sock->file, fput_needed);
return err;