22ed8d5a46
We add 2 new kfuncs that are following the RET_PTR_TO_MEM
capability from the previous commit.
Then we test them in selftests:
the first tests are testing valid case, and are not failing,
and the later ones are actually preventing the program to be loaded
because they are wrong.
To work around that, we mark the failing ones as not autoloaded
(with SEC("?tc")), and we manually enable them one by one, ensuring
the verifier rejects them.
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Link: https://lore.kernel.org/r/20220906151303.2780789-8-benjamin.tissoires@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
160 lines
3.6 KiB
C
160 lines
3.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2021 Facebook */
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#include <vmlinux.h>
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#include <bpf/bpf_helpers.h>
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extern struct prog_test_ref_kfunc *bpf_kfunc_call_test_acquire(unsigned long *sp) __ksym;
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extern void bpf_kfunc_call_test_release(struct prog_test_ref_kfunc *p) __ksym;
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extern void bpf_kfunc_call_test_mem_len_pass1(void *mem, int len) __ksym;
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extern int *bpf_kfunc_call_test_get_rdwr_mem(struct prog_test_ref_kfunc *p, const int rdwr_buf_size) __ksym;
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extern int *bpf_kfunc_call_test_get_rdonly_mem(struct prog_test_ref_kfunc *p, const int rdonly_buf_size) __ksym;
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extern int *bpf_kfunc_call_test_acq_rdonly_mem(struct prog_test_ref_kfunc *p, const int rdonly_buf_size) __ksym;
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extern void bpf_kfunc_call_int_mem_release(int *p) __ksym;
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struct syscall_test_args {
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__u8 data[16];
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size_t size;
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};
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SEC("?syscall")
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int kfunc_syscall_test_fail(struct syscall_test_args *args)
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{
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bpf_kfunc_call_test_mem_len_pass1(&args->data, sizeof(*args) + 1);
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return 0;
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}
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SEC("?syscall")
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int kfunc_syscall_test_null_fail(struct syscall_test_args *args)
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{
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/* Must be called with args as a NULL pointer
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* we do not check for it to have the verifier consider that
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* the pointer might not be null, and so we can load it.
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*
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* So the following can not be added:
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*
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* if (args)
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* return -22;
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*/
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bpf_kfunc_call_test_mem_len_pass1(args, sizeof(*args));
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return 0;
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}
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SEC("?tc")
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int kfunc_call_test_get_mem_fail_rdonly(struct __sk_buff *skb)
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{
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struct prog_test_ref_kfunc *pt;
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unsigned long s = 0;
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int *p = NULL;
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int ret = 0;
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pt = bpf_kfunc_call_test_acquire(&s);
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if (pt) {
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p = bpf_kfunc_call_test_get_rdonly_mem(pt, 2 * sizeof(int));
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if (p)
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p[0] = 42; /* this is a read-only buffer, so -EACCES */
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else
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ret = -1;
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bpf_kfunc_call_test_release(pt);
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}
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return ret;
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}
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SEC("?tc")
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int kfunc_call_test_get_mem_fail_use_after_free(struct __sk_buff *skb)
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{
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struct prog_test_ref_kfunc *pt;
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unsigned long s = 0;
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int *p = NULL;
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int ret = 0;
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pt = bpf_kfunc_call_test_acquire(&s);
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if (pt) {
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p = bpf_kfunc_call_test_get_rdwr_mem(pt, 2 * sizeof(int));
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if (p) {
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p[0] = 42;
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ret = p[1]; /* 108 */
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} else {
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ret = -1;
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}
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bpf_kfunc_call_test_release(pt);
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}
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if (p)
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ret = p[0]; /* p is not valid anymore */
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return ret;
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}
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SEC("?tc")
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int kfunc_call_test_get_mem_fail_oob(struct __sk_buff *skb)
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{
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struct prog_test_ref_kfunc *pt;
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unsigned long s = 0;
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int *p = NULL;
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int ret = 0;
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pt = bpf_kfunc_call_test_acquire(&s);
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if (pt) {
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p = bpf_kfunc_call_test_get_rdonly_mem(pt, 2 * sizeof(int));
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if (p)
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ret = p[2 * sizeof(int)]; /* oob access, so -EACCES */
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else
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ret = -1;
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bpf_kfunc_call_test_release(pt);
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}
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return ret;
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}
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int not_const_size = 2 * sizeof(int);
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SEC("?tc")
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int kfunc_call_test_get_mem_fail_not_const(struct __sk_buff *skb)
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{
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struct prog_test_ref_kfunc *pt;
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unsigned long s = 0;
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int *p = NULL;
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int ret = 0;
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pt = bpf_kfunc_call_test_acquire(&s);
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if (pt) {
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p = bpf_kfunc_call_test_get_rdonly_mem(pt, not_const_size); /* non const size, -EINVAL */
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if (p)
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ret = p[0];
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else
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ret = -1;
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bpf_kfunc_call_test_release(pt);
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}
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return ret;
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}
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SEC("?tc")
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int kfunc_call_test_mem_acquire_fail(struct __sk_buff *skb)
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{
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struct prog_test_ref_kfunc *pt;
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unsigned long s = 0;
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int *p = NULL;
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int ret = 0;
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pt = bpf_kfunc_call_test_acquire(&s);
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if (pt) {
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/* we are failing on this one, because we are not acquiring a PTR_TO_BTF_ID (a struct ptr) */
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p = bpf_kfunc_call_test_acq_rdonly_mem(pt, 2 * sizeof(int));
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if (p)
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ret = p[0];
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else
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ret = -1;
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bpf_kfunc_call_int_mem_release(p);
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bpf_kfunc_call_test_release(pt);
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}
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return ret;
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}
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char _license[] SEC("license") = "GPL";
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