Revision 11bbd8b416f8abf40900dc5041152892f873d915 authored by Michal Koutný on 01 June 2019, 05:30:16 UTC, committed by Linus Torvalds on 01 June 2019, 22:51:31 UTC
Despite comment of validate_prctl_map claims there are no capability checks, it is not completely true since commit 4d28df6152aa ("prctl: Allow local CAP_SYS_ADMIN changing exe_file"). Extract the check out of the function and make the function perform purely arithmetic checks. This patch should not change any behavior, it is mere refactoring for following patch. [akpm@linux-foundation.org: coding style fixes] Link: http://lkml.kernel.org/r/20190502125203.24014-2-mkoutny@suse.com Signed-off-by: Michal Koutný <mkoutny@suse.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Mateusz Guzik <mguzik@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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test_probe_write_user_kern.c
/* Copyright (c) 2016 Sargun Dhillon <sargun@sargun.me>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*/
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <uapi/linux/bpf.h>
#include <linux/version.h>
#include "bpf_helpers.h"
struct bpf_map_def SEC("maps") dnat_map = {
.type = BPF_MAP_TYPE_HASH,
.key_size = sizeof(struct sockaddr_in),
.value_size = sizeof(struct sockaddr_in),
.max_entries = 256,
};
/* kprobe is NOT a stable ABI
* kernel functions can be removed, renamed or completely change semantics.
* Number of arguments and their positions can change, etc.
* In such case this bpf+kprobe example will no longer be meaningful
*
* This example sits on a syscall, and the syscall ABI is relatively stable
* of course, across platforms, and over time, the ABI may change.
*/
SEC("kprobe/sys_connect")
int bpf_prog1(struct pt_regs *ctx)
{
struct sockaddr_in new_addr, orig_addr = {};
struct sockaddr_in *mapped_addr;
void *sockaddr_arg = (void *)PT_REGS_PARM2(ctx);
int sockaddr_len = (int)PT_REGS_PARM3(ctx);
if (sockaddr_len > sizeof(orig_addr))
return 0;
if (bpf_probe_read(&orig_addr, sizeof(orig_addr), sockaddr_arg) != 0)
return 0;
mapped_addr = bpf_map_lookup_elem(&dnat_map, &orig_addr);
if (mapped_addr != NULL) {
memcpy(&new_addr, mapped_addr, sizeof(new_addr));
bpf_probe_write_user(sockaddr_arg, &new_addr,
sizeof(new_addr));
}
return 0;
}
char _license[] SEC("license") = "GPL";
u32 _version SEC("version") = LINUX_VERSION_CODE;
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