1 files changed, 49 insertions, 12 deletions

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 7c25426d3cf5..ab94d304a634 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -53,9 +53,10 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
 {
         bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
         int numa_node = bpf_map_attr_numa_node(attr);
+        u32 elem_size, index_mask, max_entries;
+        bool unpriv = !capable(CAP_SYS_ADMIN);
         struct bpf_array *array;
-        u64 array_size;
-        u32 elem_size;
+        u64 array_size, mask64;
 
         /* check sanity of attributes */
         if (attr->max_entries == 0 || attr->key_size != 4 ||
@@ -72,11 +73,32 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
 
         elem_size = round_up(attr->value_size, 8);
 
+        max_entries = attr->max_entries;
+
+        /* On 32 bit archs roundup_pow_of_two() with max_entries that has
+         * upper most bit set in u32 space is undefined behavior due to
+         * resulting 1U << 32, so do it manually here in u64 space.
+         */
+        mask64 = fls_long(max_entries - 1);
+        mask64 = 1ULL << mask64;
+        mask64 -= 1;
+
+        index_mask = mask64;
+        if (unpriv) {
+                /* round up array size to nearest power of 2,
+                 * since cpu will speculate within index_mask limits
+                 */
+                max_entries = index_mask + 1;
+                /* Check for overflows. */
+                if (max_entries < attr->max_entries)
+                        return ERR_PTR(-E2BIG);
+        }
+
         array_size = sizeof(*array);
         if (percpu)
-                array_size += (u64) attr->max_entries * sizeof(void *);
+                array_size += (u64) max_entries * sizeof(void *);
         else
-                array_size += (u64) attr->max_entries * elem_size;
+                array_size += (u64) max_entries * elem_size;
 
         /* make sure there is no u32 overflow later in round_up() */
         if (array_size >= U32_MAX - PAGE_SIZE)
@@ -86,6 +108,8 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
         array = bpf_map_area_alloc(array_size, numa_node);
         if (!array)
                 return ERR_PTR(-ENOMEM);
+        array->index_mask = index_mask;
+        array->map.unpriv_array = unpriv;
 
         /* copy mandatory map attributes */
         array->map.map_type = attr->map_type;
@@ -121,12 +145,13 @@ static void *array_map_lookup_elem(struct bpf_map *map, void *key)
         if (unlikely(index >= array->map.max_entries))
                 return NULL;
 
-        return array->value + array->elem_size * index;
+        return array->value + array->elem_size * (index & array->index_mask);
 }
 
 /* emit BPF instructions equivalent to C code of array_map_lookup_elem() */
 static u32 array_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
 {
+        struct bpf_array *array = container_of(map, struct bpf_array, map);
         struct bpf_insn *insn = insn_buf;
         u32 elem_size = round_up(map->value_size, 8);
         const int ret = BPF_REG_0;
@@ -135,7 +160,12 @@ static u32 array_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
 
         *insn++ = BPF_ALU64_IMM(BPF_ADD, map_ptr, offsetof(struct bpf_array, value));
         *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
-        *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 3);
+        if (map->unpriv_array) {
+                *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 4);
+                *insn++ = BPF_ALU32_IMM(BPF_AND, ret, array->index_mask);
+        } else {
+                *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 3);
+        }
 
         if (is_power_of_2(elem_size)) {
                 *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(elem_size));
@@ -157,7 +187,7 @@ static void *percpu_array_map_lookup_elem(struct bpf_map *map, void *key)
         if (unlikely(index >= array->map.max_entries))
                 return NULL;
 
-        return this_cpu_ptr(array->pptrs[index]);
+        return this_cpu_ptr(array->pptrs[index & array->index_mask]);
 }
 
 int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
@@ -177,7 +207,7 @@ int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
          */
         size = round_up(map->value_size, 8);
         rcu_read_lock();
-        pptr = array->pptrs[index];
+        pptr = array->pptrs[index & array->index_mask];
         for_each_possible_cpu(cpu) {
                 bpf_long_memcpy(value + off, per_cpu_ptr(pptr, cpu), size);
                 off += size;
@@ -225,10 +255,11 @@ static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
                 return -EEXIST;
 
         if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
-                memcpy(this_cpu_ptr(array->pptrs[index]),
+                memcpy(this_cpu_ptr(array->pptrs[index & array->index_mask]),
                        value, map->value_size);
         else
-                memcpy(array->value + array->elem_size * index,
+                memcpy(array->value +
+                       array->elem_size * (index & array->index_mask),
                        value, map->value_size);
         return 0;
 }
@@ -262,7 +293,7 @@ int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
          */
         size = round_up(map->value_size, 8);
         rcu_read_lock();
-        pptr = array->pptrs[index];
+        pptr = array->pptrs[index & array->index_mask];
         for_each_possible_cpu(cpu) {
                 bpf_long_memcpy(per_cpu_ptr(pptr, cpu), value + off, size);
                 off += size;
@@ -613,6 +644,7 @@ static void *array_of_map_lookup_elem(struct bpf_map *map, void *key)
 static u32 array_of_map_gen_lookup(struct bpf_map *map,
                                    struct bpf_insn *insn_buf)
 {
+        struct bpf_array *array = container_of(map, struct bpf_array, map);
         u32 elem_size = round_up(map->value_size, 8);
         struct bpf_insn *insn = insn_buf;
         const int ret = BPF_REG_0;
@@ -621,7 +653,12 @@ static u32 array_of_map_gen_lookup(struct bpf_map *map,
 
         *insn++ = BPF_ALU64_IMM(BPF_ADD, map_ptr, offsetof(struct bpf_array, value));
         *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
-        *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5);
+        if (map->unpriv_array) {
+                *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 6);
+                *insn++ = BPF_ALU32_IMM(BPF_AND, ret, array->index_mask);
+        } else {
+                *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5);
+        }
         if (is_power_of_2(elem_size))
                 *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(elem_size));
         else