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etsalKernel Patches Daemon
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selftests/bpf: add selftests for bpf_arena_guard_pages
Add selftests for the new bpf_arena_guard_pages kfunc. Signed-off-by: Emil Tsalapatis <[email protected]>
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3 files changed

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‎tools/testing/selftests/bpf/bpf_arena_common.h

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -46,8 +46,11 @@
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void __arena* bpf_arena_alloc_pages(void *map, void __arena *addr, __u32 page_cnt,
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int node_id, __u64 flags) __ksym __weak;
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int bpf_arena_guard_pages(void *map, void __arena *addr, __u32 page_cnt) __ksym __weak;
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void bpf_arena_free_pages(void *map, void __arena *ptr, __u32 page_cnt) __ksym __weak;
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#define arena_base(map) ((void __arena *)((struct bpf_arena *)(map))->user_vm_start)
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#else /* when compiled as user space code */
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#define __arena

‎tools/testing/selftests/bpf/progs/verifier_arena.c

Lines changed: 106 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -114,6 +114,112 @@ int basic_alloc3(void *ctx)
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return 0;
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}
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SEC("syscall")
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__success __retval(0)
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int basic_guard1(void *ctx)
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{
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#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
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char __arena *page;
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int ret;
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page = bpf_arena_alloc_pages(&arena, NULL, 1, NUMA_NO_NODE, 0);
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if (!page)
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return 1;
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page += __PAGE_SIZE;
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/* Guard the second page */
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ret = bpf_arena_guard_pages(&arena, page, 1);
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if (ret)
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return 2;
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/* Try to explicitly allocate the guarded page. */
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page = bpf_arena_alloc_pages(&arena, page, 1, NUMA_NO_NODE, 0);
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if (page)
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return 3;
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/* Try to implicitly allocate the page (since there's only 2 of them). */
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page = bpf_arena_alloc_pages(&arena, NULL, 1, NUMA_NO_NODE, 0);
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if (page)
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return 4;
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#endif
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return 0;
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}
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SEC("syscall")
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__success __retval(0)
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int basic_guard2(void *ctx)
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{
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#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
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char __arena *page;
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int ret;
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page = arena_base(&arena);
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ret = bpf_arena_guard_pages(&arena, page, 1);
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if (ret)
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return 1;
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page = bpf_arena_alloc_pages(&arena, page, 1, NUMA_NO_NODE, 0);
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if ((u64)page)
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return 2;
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#endif
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return 0;
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}
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/* Guard the same page twice, should return -EALREADY. */
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SEC("syscall")
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__success __retval(0)
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int guard_twice(void *ctx)
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{
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#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
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char __arena *page;
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int ret;
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page = arena_base(&arena);
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ret = bpf_arena_guard_pages(&arena, page, 1);
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if (ret)
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return 1;
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/* Should be -EALREADY. */
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ret = bpf_arena_guard_pages(&arena, page, 1);
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if (ret != -114)
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return 2;
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#endif
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return 0;
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}
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/* Try to add a guard past the end of the arena. */
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SEC("syscall")
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__success __retval(0)
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int guard_invalid_region(void *ctx)
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{
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#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
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char __arena *page;
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int ret;
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/* Try a NULL pointer. */
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ret = bpf_arena_guard_pages(&arena, NULL, 3);
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if (ret != -22)
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return 1;
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page = arena_base(&arena);
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ret = bpf_arena_guard_pages(&arena, page, 3);
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if (ret != -22)
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return 2;
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ret = bpf_arena_guard_pages(&arena, page, 4096);
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if (ret != -22)
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return 3;
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ret = bpf_arena_guard_pages(&arena, page, (1ULL << 32) - 1);
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if (ret != -22)
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return 4;
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#endif
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return 0;
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}
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SEC("iter.s/bpf_map")
118224
__success __log_level(2)
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int iter_maps1(struct bpf_iter__bpf_map *ctx)

‎tools/testing/selftests/bpf/progs/verifier_arena_large.c

Lines changed: 93 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -67,6 +67,99 @@ int big_alloc1(void *ctx)
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return 0;
6868
}
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/* Try to access a guarded page. Behavior should be identical with accessing unallocated pages. */
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SEC("syscall")
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__success __retval(0)
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int access_guarded(void *ctx)
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{
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#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
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volatile char __arena *page;
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char __arena *base;
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const size_t len = 4;
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int ret, i;
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/* Get a separate region of the arena. */
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page = base = arena_base(&arena) + 16384 * PAGE_SIZE;
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ret = bpf_arena_guard_pages(&arena, base, len);
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if (ret)
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return 1;
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/* Try to dirty guarded memory. */
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for (i = 0; i < len && can_loop; i++)
90+
*page = 0x5a;
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for (i = 0; i < len && can_loop; i++) {
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page = (volatile char __arena *)(base + i * PAGE_SIZE);
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/*
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* Error out in case either the write went through,
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* or the address has random garbage.
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*/
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if (*page == 0x5a)
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return 2 + 2 * i;
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if (*page)
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return 2 + 2 * i + 1;
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}
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#endif
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return 0;
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}
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/* Try to allocate a region overlapping with a guard. */
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SEC("syscall")
111+
__success __retval(0)
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int request_partially_guarded(void *ctx)
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{
114+
#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
115+
volatile char __arena *page;
116+
char __arena *base;
117+
int ret;
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119+
/* Add an arbitrary page offset. */
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page = base = arena_base(&arena) + 4096 * __PAGE_SIZE;
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122+
ret = bpf_arena_guard_pages(&arena, base + 3 * __PAGE_SIZE, 4);
123+
if (ret)
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return 1;
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126+
page = bpf_arena_alloc_pages(&arena, base, 5, NUMA_NO_NODE, 0);
127+
if ((u64)page != 0ULL)
128+
return 2;
129+
#endif
130+
return 0;
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}
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133+
SEC("syscall")
134+
__success __retval(0)
135+
int free_guarded(void *ctx)
136+
{
137+
#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
138+
char __arena *addr;
139+
char __arena *page;
140+
int ret;
141+
142+
/* Add an arbitrary page offset. */
143+
addr = arena_base(&arena) + 32768 * __PAGE_SIZE;
144+
145+
page = bpf_arena_alloc_pages(&arena, addr, 4, NUMA_NO_NODE, 0);
146+
if (!page)
147+
return 1;
148+
149+
ret = bpf_arena_guard_pages(&arena, addr + 4 * __PAGE_SIZE, 4);
150+
if (ret)
151+
return 2;
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153+
bpf_arena_free_pages(&arena, addr + 3 * __PAGE_SIZE, 2);
154+
155+
/* The free pages call above should have failed, so this allocation should fail too. */
156+
page = bpf_arena_alloc_pages(&arena, addr + 3 * __PAGE_SIZE, 1, NUMA_NO_NODE, 0);
157+
if (page)
158+
return 3;
159+
#endif
160+
return 0;
161+
}
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70163
#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
71164
#define PAGE_CNT 100
72165
__u8 __arena * __arena page[PAGE_CNT]; /* occupies the first page */

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