libringbuffer/shm.h

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-only
   3  *
   4  * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  */
   6
   7 #ifndef _LIBRINGBUFFER_SHM_H
   8 #define _LIBRINGBUFFER_SHM_H
   9
  10 #include <stddef.h>
  11 #include <stdint.h>
  12 #include <unistd.h>
  13 #include <usterr-signal-safe.h>
  14 #include <urcu/compiler.h>
  15 #include "shm_types.h"
  16
  17 /* channel_handle_create - for UST. */
  18 __attribute__((visibility("hidden")))
  19 extern
  20 struct lttng_ust_shm_handle *channel_handle_create(void *data,
  21                                 uint64_t memory_map_size, int wakeup_fd);
  22
  23 /* channel_handle_add_stream - for UST. */
  24 __attribute__((visibility("hidden")))
  25 extern
  26 int channel_handle_add_stream(struct lttng_ust_shm_handle *handle,
  27                 int shm_fd, int wakeup_fd, uint32_t stream_nr,
  28                 uint64_t memory_map_size);
  29
  30 __attribute__((visibility("hidden")))
  31 unsigned int channel_handle_get_nr_streams(struct lttng_ust_shm_handle *handle);
  32
  33 __attribute__((visibility("hidden")))
  34 extern
  35 void channel_destroy(struct lttng_ust_lib_ring_buffer_channel *chan,
  36                 struct lttng_ust_shm_handle *handle,
  37                 int consumer);
  38
  39 /*
  40  * Pointer dereferencing. We don't trust the shm_ref, so we validate
  41  * both the index and offset with known boundaries.
  42  *
  43  * "shmp" and "shmp_index" guarantee that it's safe to use the pointer
  44  * target type, even in the occurrence of shm_ref modification by an
  45  * untrusted process having write access to the shm_ref. We return a
  46  * NULL pointer if the ranges are invalid.
  47  */
  48 static inline
  49 char *_shmp_offset(struct shm_object_table *table, struct shm_ref *ref,
  50                    size_t idx, size_t elem_size)
  51 {
  52         struct shm_object *obj;
  53         size_t objindex, ref_offset;
  54
  55         objindex = (size_t) ref->index;
  56         if (caa_unlikely(objindex >= table->allocated_len))
  57                 return NULL;
  58         obj = &table->objects[objindex];
  59         ref_offset = (size_t) ref->offset;
  60         ref_offset += idx * elem_size;
  61         /* Check if part of the element returned would exceed the limits. */
  62         if (caa_unlikely(ref_offset + elem_size > obj->memory_map_size))
  63                 return NULL;
  64         return &obj->memory_map[ref_offset];
  65 }
  66
  67 #define shmp_index(handle, ref, index)  \
  68         ((__typeof__((ref)._type)) _shmp_offset((handle)->table, &(ref)._ref, index, sizeof(*((ref)._type))))
  69
  70 #define shmp(handle, ref)       shmp_index(handle, ref, 0)
  71
  72 static inline
  73 void _set_shmp(struct shm_ref *ref, struct shm_ref src)
  74 {
  75         *ref = src;
  76 }
  77
  78 #define set_shmp(ref, src)      _set_shmp(&(ref)._ref, src)
  79
  80 __attribute__((visibility("hidden")))
  81 struct shm_object_table *shm_object_table_create(size_t max_nb_obj);
  82
  83 __attribute__((visibility("hidden")))
  84 struct shm_object *shm_object_table_alloc(struct shm_object_table *table,
  85                         size_t memory_map_size,
  86                         enum shm_object_type type,
  87                         const int stream_fd,
  88                         int cpu);
  89
  90 __attribute__((visibility("hidden")))
  91 struct shm_object *shm_object_table_append_shm(struct shm_object_table *table,
  92                         int shm_fd, int wakeup_fd, uint32_t stream_nr,
  93                         size_t memory_map_size);
  94
  95 /* mem ownership is passed to shm_object_table_append_mem(). */
  96 __attribute__((visibility("hidden")))
  97 struct shm_object *shm_object_table_append_mem(struct shm_object_table *table,
  98                         void *mem, size_t memory_map_size, int wakeup_fd);
  99
 100 __attribute__((visibility("hidden")))
 101 void shm_object_table_destroy(struct shm_object_table *table, int consumer);
 102
 103 /*
 104  * zalloc_shm - allocate memory within a shm object.
 105  *
 106  * Shared memory is already zeroed by shmget.
 107  * *NOT* multithread-safe (should be protected by mutex).
 108  * Returns a -1, -1 tuple on error.
 109  */
 110 __attribute__((visibility("hidden")))
 111 struct shm_ref zalloc_shm(struct shm_object *obj, size_t len);
 112
 113 __attribute__((visibility("hidden")))
 114 void align_shm(struct shm_object *obj, size_t align);
 115
 116 static inline
 117 int shm_get_wait_fd(struct lttng_ust_shm_handle *handle, struct shm_ref *ref)
 118 {
 119         struct shm_object_table *table = handle->table;
 120         struct shm_object *obj;
 121         size_t index;
 122
 123         index = (size_t) ref->index;
 124         if (caa_unlikely(index >= table->allocated_len))
 125                 return -EPERM;
 126         obj = &table->objects[index];
 127         return obj->wait_fd[0];
 128 }
 129
 130 static inline
 131 int shm_get_wakeup_fd(struct lttng_ust_shm_handle *handle, struct shm_ref *ref)
 132 {
 133         struct shm_object_table *table = handle->table;
 134         struct shm_object *obj;
 135         size_t index;
 136
 137         index = (size_t) ref->index;
 138         if (caa_unlikely(index >= table->allocated_len))
 139                 return -EPERM;
 140         obj = &table->objects[index];
 141         return obj->wait_fd[1];
 142 }
 143
 144 static inline
 145 int shm_close_wait_fd(struct lttng_ust_shm_handle *handle,
 146                 struct shm_ref *ref)
 147 {
 148         struct shm_object_table *table = handle->table;
 149         struct shm_object *obj;
 150         int wait_fd;
 151         size_t index;
 152         int ret;
 153
 154         index = (size_t) ref->index;
 155         if (caa_unlikely(index >= table->allocated_len))
 156                 return -EPERM;
 157         obj = &table->objects[index];
 158         wait_fd = obj->wait_fd[0];
 159         if (wait_fd < 0)
 160                 return -ENOENT;
 161         obj->wait_fd[0] = -1;
 162         ret = close(wait_fd);
 163         if (ret) {
 164                 ret = -errno;
 165                 return ret;
 166         }
 167         return 0;
 168 }
 169
 170 static inline
 171 int shm_close_wakeup_fd(struct lttng_ust_shm_handle *handle,
 172                 struct shm_ref *ref)
 173 {
 174         struct shm_object_table *table = handle->table;
 175         struct shm_object *obj;
 176         int wakeup_fd;
 177         size_t index;
 178         int ret;
 179
 180         index = (size_t) ref->index;
 181         if (caa_unlikely(index >= table->allocated_len))
 182                 return -EPERM;
 183         obj = &table->objects[index];
 184         wakeup_fd = obj->wait_fd[1];
 185         if (wakeup_fd < 0)
 186                 return -ENOENT;
 187         obj->wait_fd[1] = -1;
 188         ret = close(wakeup_fd);
 189         if (ret) {
 190                 ret = -errno;
 191                 return ret;
 192         }
 193         return 0;
 194 }
 195
 196 static inline
 197 int shm_get_shm_fd(struct lttng_ust_shm_handle *handle, struct shm_ref *ref)
 198 {
 199         struct shm_object_table *table = handle->table;
 200         struct shm_object *obj;
 201         size_t index;
 202
 203         index = (size_t) ref->index;
 204         if (caa_unlikely(index >= table->allocated_len))
 205                 return -EPERM;
 206         obj = &table->objects[index];
 207         return obj->shm_fd;
 208 }
 209
 210
 211 static inline
 212 int shm_get_shm_size(struct lttng_ust_shm_handle *handle, struct shm_ref *ref,
 213                 uint64_t *size)
 214 {
 215         struct shm_object_table *table = handle->table;
 216         struct shm_object *obj;
 217         size_t index;
 218
 219         index = (size_t) ref->index;
 220         if (caa_unlikely(index >= table->allocated_len))
 221                 return -EPERM;
 222         obj = &table->objects[index];
 223         *size = obj->memory_map_size;
 224         return 0;
 225 }
 226
 227 #endif /* _LIBRINGBUFFER_SHM_H */