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Linux/ipc/msgutil.c

  1 /*
  2  * linux/ipc/msgutil.c
  3  * Copyright (C) 1999, 2004 Manfred Spraul
  4  *
  5  * This file is released under GNU General Public Licence version 2 or
  6  * (at your option) any later version.
  7  *
  8  * See the file COPYING for more details.
  9  */
 10 
 11 #include <linux/spinlock.h>
 12 #include <linux/init.h>
 13 #include <linux/security.h>
 14 #include <linux/slab.h>
 15 #include <linux/ipc.h>
 16 #include <linux/msg.h>
 17 #include <linux/ipc_namespace.h>
 18 #include <linux/utsname.h>
 19 #include <linux/proc_ns.h>
 20 #include <linux/uaccess.h>
 21 
 22 #include "util.h"
 23 
 24 DEFINE_SPINLOCK(mq_lock);
 25 
 26 /*
 27  * The next 2 defines are here bc this is the only file
 28  * compiled when either CONFIG_SYSVIPC and CONFIG_POSIX_MQUEUE
 29  * and not CONFIG_IPC_NS.
 30  */
 31 struct ipc_namespace init_ipc_ns = {
 32         .count          = ATOMIC_INIT(1),
 33         .user_ns = &init_user_ns,
 34         .ns.inum = PROC_IPC_INIT_INO,
 35 #ifdef CONFIG_IPC_NS
 36         .ns.ops = &ipcns_operations,
 37 #endif
 38 };
 39 
 40 struct msg_msgseg {
 41         struct msg_msgseg *next;
 42         /* the next part of the message follows immediately */
 43 };
 44 
 45 #define DATALEN_MSG     ((size_t)PAGE_SIZE-sizeof(struct msg_msg))
 46 #define DATALEN_SEG     ((size_t)PAGE_SIZE-sizeof(struct msg_msgseg))
 47 
 48 
 49 static struct msg_msg *alloc_msg(size_t len)
 50 {
 51         struct msg_msg *msg;
 52         struct msg_msgseg **pseg;
 53         size_t alen;
 54 
 55         alen = min(len, DATALEN_MSG);
 56         msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL_ACCOUNT);
 57         if (msg == NULL)
 58                 return NULL;
 59 
 60         msg->next = NULL;
 61         msg->security = NULL;
 62 
 63         len -= alen;
 64         pseg = &msg->next;
 65         while (len > 0) {
 66                 struct msg_msgseg *seg;
 67                 alen = min(len, DATALEN_SEG);
 68                 seg = kmalloc(sizeof(*seg) + alen, GFP_KERNEL_ACCOUNT);
 69                 if (seg == NULL)
 70                         goto out_err;
 71                 *pseg = seg;
 72                 seg->next = NULL;
 73                 pseg = &seg->next;
 74                 len -= alen;
 75         }
 76 
 77         return msg;
 78 
 79 out_err:
 80         free_msg(msg);
 81         return NULL;
 82 }
 83 
 84 struct msg_msg *load_msg(const void __user *src, size_t len)
 85 {
 86         struct msg_msg *msg;
 87         struct msg_msgseg *seg;
 88         int err = -EFAULT;
 89         size_t alen;
 90 
 91         msg = alloc_msg(len);
 92         if (msg == NULL)
 93                 return ERR_PTR(-ENOMEM);
 94 
 95         alen = min(len, DATALEN_MSG);
 96         if (copy_from_user(msg + 1, src, alen))
 97                 goto out_err;
 98 
 99         for (seg = msg->next; seg != NULL; seg = seg->next) {
100                 len -= alen;
101                 src = (char __user *)src + alen;
102                 alen = min(len, DATALEN_SEG);
103                 if (copy_from_user(seg + 1, src, alen))
104                         goto out_err;
105         }
106 
107         err = security_msg_msg_alloc(msg);
108         if (err)
109                 goto out_err;
110 
111         return msg;
112 
113 out_err:
114         free_msg(msg);
115         return ERR_PTR(err);
116 }
117 #ifdef CONFIG_CHECKPOINT_RESTORE
118 struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
119 {
120         struct msg_msgseg *dst_pseg, *src_pseg;
121         size_t len = src->m_ts;
122         size_t alen;
123 
124         if (src->m_ts > dst->m_ts)
125                 return ERR_PTR(-EINVAL);
126 
127         alen = min(len, DATALEN_MSG);
128         memcpy(dst + 1, src + 1, alen);
129 
130         for (dst_pseg = dst->next, src_pseg = src->next;
131              src_pseg != NULL;
132              dst_pseg = dst_pseg->next, src_pseg = src_pseg->next) {
133 
134                 len -= alen;
135                 alen = min(len, DATALEN_SEG);
136                 memcpy(dst_pseg + 1, src_pseg + 1, alen);
137         }
138 
139         dst->m_type = src->m_type;
140         dst->m_ts = src->m_ts;
141 
142         return dst;
143 }
144 #else
145 struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
146 {
147         return ERR_PTR(-ENOSYS);
148 }
149 #endif
150 int store_msg(void __user *dest, struct msg_msg *msg, size_t len)
151 {
152         size_t alen;
153         struct msg_msgseg *seg;
154 
155         alen = min(len, DATALEN_MSG);
156         if (copy_to_user(dest, msg + 1, alen))
157                 return -1;
158 
159         for (seg = msg->next; seg != NULL; seg = seg->next) {
160                 len -= alen;
161                 dest = (char __user *)dest + alen;
162                 alen = min(len, DATALEN_SEG);
163                 if (copy_to_user(dest, seg + 1, alen))
164                         return -1;
165         }
166         return 0;
167 }
168 
169 void free_msg(struct msg_msg *msg)
170 {
171         struct msg_msgseg *seg;
172 
173         security_msg_msg_free(msg);
174 
175         seg = msg->next;
176         kfree(msg);
177         while (seg != NULL) {
178                 struct msg_msgseg *tmp = seg->next;
179                 kfree(seg);
180                 seg = tmp;
181         }
182 }
183 

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