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