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Linux/ipc/msgutil.c

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  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         .proc_inum = PROC_IPC_INIT_INO,
 35 };
 36 
 37 atomic_t nr_ipc_ns = ATOMIC_INIT(1);
 38 
 39 struct msg_msgseg {
 40         struct msg_msgseg *next;
 41         /* the next part of the message follows immediately */
 42 };
 43 
 44 #define DATALEN_MSG     ((size_t)PAGE_SIZE-sizeof(struct msg_msg))
 45 #define DATALEN_SEG     ((size_t)PAGE_SIZE-sizeof(struct msg_msgseg))
 46 
 47 
 48 static struct msg_msg *alloc_msg(size_t len)
 49 {
 50         struct msg_msg *msg;
 51         struct msg_msgseg **pseg;
 52         size_t alen;
 53 
 54         alen = min(len, DATALEN_MSG);
 55         msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL);
 56         if (msg == NULL)
 57                 return NULL;
 58 
 59         msg->next = NULL;
 60         msg->security = NULL;
 61 
 62         len -= alen;
 63         pseg = &msg->next;
 64         while (len > 0) {
 65                 struct msg_msgseg *seg;
 66                 alen = min(len, DATALEN_SEG);
 67                 seg = kmalloc(sizeof(*seg) + alen, GFP_KERNEL);
 68                 if (seg == NULL)
 69                         goto out_err;
 70                 *pseg = seg;
 71                 seg->next = NULL;
 72                 pseg = &seg->next;
 73                 len -= alen;
 74         }
 75 
 76         return msg;
 77 
 78 out_err:
 79         free_msg(msg);
 80         return NULL;
 81 }
 82 
 83 struct msg_msg *load_msg(const void __user *src, size_t len)
 84 {
 85         struct msg_msg *msg;
 86         struct msg_msgseg *seg;
 87         int err = -EFAULT;
 88         size_t alen;
 89 
 90         msg = alloc_msg(len);
 91         if (msg == NULL)
 92                 return ERR_PTR(-ENOMEM);
 93 
 94         alen = min(len, DATALEN_MSG);
 95         if (copy_from_user(msg + 1, src, alen))
 96                 goto out_err;
 97 
 98         for (seg = msg->next; seg != NULL; seg = seg->next) {
 99                 len -= alen;
100                 src = (char __user *)src + alen;
101                 alen = min(len, DATALEN_SEG);
102                 if (copy_from_user(seg + 1, src, alen))
103                         goto out_err;
104         }
105 
106         err = security_msg_msg_alloc(msg);
107         if (err)
108                 goto out_err;
109 
110         return msg;
111 
112 out_err:
113         free_msg(msg);
114         return ERR_PTR(err);
115 }
116 #ifdef CONFIG_CHECKPOINT_RESTORE
117 struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
118 {
119         struct msg_msgseg *dst_pseg, *src_pseg;
120         size_t len = src->m_ts;
121         size_t alen;
122 
123         BUG_ON(dst == NULL);
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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