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libc/winsup/cygserver/shm.cc

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/* cygserver_shm.cc: Single unix specification IPC interface for Cygwin
Copyright 2001 Red Hat, Inc.
Originally written by Robert Collins <robert.collins@hotmail.com>
This file is part of Cygwin.
This software is a copyrighted work licensed under the terms of the
Cygwin license. Please consult the file "CYGWIN_LICENSE" for
details. */
#ifdef __OUTSIDE_CYGWIN__
#undef __INSIDE_CYGWIN__
#else
#include "winsup.h"
#endif
#ifndef __INSIDE_CYGWIN__
#define DEBUG 0
#define system_printf printf
#define debug_printf if (DEBUG) printf
#define api_fatal printf
#include <stdio.h>
#include <windows.h>
#endif
#include <sys/stat.h>
#include <errno.h>
#include "cygerrno.h"
#include <unistd.h>
#include "security.h"
//#include "fhandler.h"
//#include "dtable.h"
//#include "cygheap.h"
#include <stdio.h>
//#include "thread.h"
#ifndef __INSIDE_CYGWIN__
#define __INSIDE_CYGWIN__
#include <sys/shm.h>
#undef __INSIDE_CYGWIN__
#else
#include <sys/shm.h>
#endif
//#include "perprocess.h"
#include <threaded_queue.h>
#include <cygwin/cygserver_process.h>
#include "cygserver_shm.h"
// FIXME IS THIS CORRECT
/* Implementation notes: We use two shared memory regions per key:
* One for the control structure, and one for the shared memory.
* While this has a higher overhead tham a single shared area,
* It allows more flexability. As the entire code is transparent to the user
* We can merge these in the future should it be needed.
* Also, IPC_PRIVATE keys create unique mappings each time. The shm_ids just
* keep monotonically incrementing - system wide.
*/
size_t
getsystemallocgranularity ()
{
SYSTEM_INFO sysinfo;
static size_t buffer_offset = 0;
if (buffer_offset)
return buffer_offset;
GetSystemInfo (&sysinfo);
buffer_offset = sysinfo.dwAllocationGranularity;
return buffer_offset;
}
client_request_shm::client_request_shm ():client_request (CYGSERVER_REQUEST_SHM_GET, sizeof (parameters))
{
buffer = (char *) &parameters;
}
/* FIXME: If building on a 64-bit compiler, the address->int typecast will fail.
* Solution: manually calculate the next id value
*/
#if 0
extern "C" void *
shmat (int shmid, const void *shmaddr, int parameters.in.shmflg)
{
class shmid_ds *shm = (class shmid_ds *) shmid; //FIXME: verifyable object test
if (shmaddr)
{
//FIXME: requested base address ?!
set_errno (EINVAL);
return (void *) -1;
}
void *rv = MapViewOfFile (shm->attachmap,
(parameters.in.shmflg & SHM_RDONLY) ?
FILE_MAP_READ : FILE_MAP_WRITE, 0,
0, 0);
if (!rv)
{
//FIXME: translate GetLastError()
set_errno (EACCES);
return (void *) -1;
}
/* FIXME: this needs to be globally protected to prevent a mismatch betwen
* attach count and attachees list
*/
InterlockedIncrement (&shm->shm_nattch);
_shmattach *attachnode = new _shmattach;
attachnode->data = rv;
attachnode->next =
(_shmattach *) InterlockedExchangePointer ((LONG *) & shm->attachhead,
(long int) attachnode);
return rv;
}
#endif
/* FIXME: evaluate getuid() and getgid() against the requested mode. Then
* choose PAGE_READWRITE | PAGE_READONLY and FILE_MAP_WRITE | FILE_MAP_READ
* appropriately
*/
/* Test result from openbsd: shm ids are persistent cross process if a handle is left
* open. This could lead to resource starvation: we're not copying that behaviour
* unless we have to. (It will involve acygwin1.dll gloal shared list :[ ).
*/
/* FIXME: shmid should be a verifyable object
*/
/* FIXME: on NT we should check everything against the SD. On 95 we just emulate.
*/
extern GENERIC_MAPPING access_mapping;
extern int
check_and_dup_handle (HANDLE from_process, HANDLE to_process,
HANDLE from_process_token,
DWORD access,
HANDLE from_handle,
HANDLE * to_handle_ptr, BOOL bInheritHandle);
//FIXME: where should this live
static shmnode *shm_head = NULL;
/* must be long for InterlockedIncrement */
static long new_id = 0;
static long new_private_key = 0;
void
client_request_shm::serve (transport_layer_base * conn,
process_cache * cache)
{
// DWORD sd_size = 4096;
// char sd_buf[4096];
PSECURITY_DESCRIPTOR psd = (PSECURITY_DESCRIPTOR) parameters.in.sd_buf;
// /* create a sd for our open requests based on shmflag & 0x01ff */
// psd = alloc_sd (getuid (), getgid (), cygheap->user.logsrv (),
// parameters.in.shmflg & 0x01ff, psd, &sd_size);
HANDLE from_process_handle = NULL;
HANDLE token_handle = NULL;
DWORD rc;
from_process_handle = cache->process (parameters.in.pid)->handle ();
/* possible TODO: reduce the access on the handle before we use it */
/* Note that unless we do this, we don't need to call CloseHandle - it's kept open
* by the process cache until the process terminates.
* We may need a refcount on the cache however...
*/
if (!from_process_handle)
{
debug_printf ("error opening process (%lu)\n", GetLastError ());
header.error_code = EACCES;
return;
}
conn->impersonate_client ();
rc = OpenThreadToken (GetCurrentThread (),
TOKEN_QUERY, TRUE, &token_handle);
conn->revert_to_self ();
if (!rc)
{
debug_printf ("error opening thread token (%lu)\n", GetLastError ());
header.error_code = EACCES;
CloseHandle (from_process_handle);
return;
}
/* we trust the clients request - we will be doing it as them, and
* the worst they can do is open their own permissions
*/
SECURITY_ATTRIBUTES sa;
sa.nLength = sizeof (sa);
sa.lpSecurityDescriptor = psd;
sa.bInheritHandle = TRUE; /* the memory structures inherit ok */
char *shmname = NULL, *shmaname = NULL;
char stringbuf[29], stringbuf1[29];
/* TODO: make this code block a function! */
if (parameters.in.type == SHM_REATTACH)
{
/* just find and fill out the existing shm_id */
shmnode *tempnode = shm_head;
while (tempnode)
{
if (tempnode->shm_id == parameters.in.shm_id)
{
parameters.out.shm_id = tempnode->shm_id;
parameters.out.key = tempnode->key;
if (check_and_dup_handle
(GetCurrentProcess (), from_process_handle, token_handle,
DUPLICATE_SAME_ACCESS, tempnode->filemap,
&parameters.out.filemap, TRUE) != 0)
{
debug_printf ("error duplicating filemap handle (%lu)\n",
GetLastError ());
header.error_code = EACCES;
}
if (check_and_dup_handle
(GetCurrentProcess (), from_process_handle, token_handle,
DUPLICATE_SAME_ACCESS, tempnode->attachmap,
&parameters.out.attachmap, TRUE) != 0)
{
debug_printf ("error duplicating attachmap handle (%lu)\n",
GetLastError ());
header.error_code = EACCES;
}
CloseHandle (token_handle);
return;
}
tempnode = tempnode->next;
}
header.error_code = EINVAL;
CloseHandle (token_handle);
return;
}
/* someone attached */
/* someone can send shm_id's they don't have and currently we will increment those
* attach counts. If someone wants to fix that, please go ahead.
* The problem is that shm_get has nothing to do with the ability to attach. Attach
* requires a permission check, which we get the OS to do in MapViewOfFile.
*/
if (parameters.in.type == SHM_ATTACH)
{
shmnode *tempnode = shm_head;
while (tempnode)
{
if (tempnode->shm_id == parameters.in.shm_id)
{
InterlockedIncrement (&tempnode->shmds->shm_nattch);
header.error_code = 0;
CloseHandle (token_handle);
return;
}
tempnode = tempnode->next;
}
header.error_code = EINVAL;
CloseHandle (token_handle);
return;
}
/* it's a original request from the users */
/* FIXME: enter the checking for existing keys mutex. This mutex _must_ be system wide
* to prevent races on shmget.
*/
if (parameters.in.key == IPC_PRIVATE)
{
/* create the mapping name (CYGWINSHMKPRIVATE_0x01234567 */
/* The K refers to Key, the actual mapped area has D */
long private_key = (int) InterlockedIncrement (&new_private_key);
snprintf (stringbuf, 29, "CYGWINSHMKPRIVATE_0x%0x", private_key);
shmname = stringbuf;
snprintf (stringbuf1, 29, "CYGWINSHMDPRIVATE_0x%0x", private_key);
shmaname = stringbuf1;
}
else
{
/* create the mapping name (CYGWINSHMK0x0123456789abcdef */
/* The K refers to Key, the actual mapped area has D */
snprintf (stringbuf, 29, "CYGWINSHMK0x%0qx", parameters.in.key);
shmname = stringbuf;
snprintf (stringbuf1, 29, "CYGWINSHMD0x%0qx", parameters.in.key);
shmaname = stringbuf1;
debug_printf ("system id strings are \n%s\n%s\n", shmname, shmaname);
debug_printf ("key input value is 0x%0qx\n", parameters.in.key);
}
/* attempt to open the key */
/* get an existing key */
/* On unix the same shmid identifier is returned on multiple calls to shm_get
* with the same key and size. Different modes is a ?.
*/
/* walk the list of known keys and return the id if found. remember, we are
* authoritative...
*/
shmnode *tempnode = shm_head;
while (tempnode)
{
if (tempnode->key == parameters.in.key
&& parameters.in.key != IPC_PRIVATE)
{
// FIXME: free the mutex
if (parameters.in.size
&& tempnode->shmds->shm_segsz < parameters.in.size)
{
header.error_code = EINVAL;
CloseHandle (token_handle);
return;
}
/* FIXME: can the same process call this twice without error ? test
* on unix
*/
if ((parameters.in.shmflg & IPC_CREAT)
&& (parameters.in.shmflg & IPC_EXCL))
{
header.error_code = EEXIST;
debug_printf
("attempt to exclusively create already created shm_area with key 0x%0qx\n",
parameters.in.key);
// FIXME: free the mutex
CloseHandle (token_handle);
return;
}
// FIXME: do we need to other tests of the requested mode with the
// tempnode->shm_id mode ? testcase on unix needed.
// FIXME how do we do the security test? or
// do we wait for shmat to bother with that?
/* One possibly solution: impersonate the client, and then test we can
* reopen the area. In fact we'll probably have to do that to get
* handles back to them, alternatively just tell them the id, and then
* let them attempt the open.
*/
parameters.out.shm_id = tempnode->shm_id;
if (check_and_dup_handle (GetCurrentProcess (), from_process_handle,
token_handle,
DUPLICATE_SAME_ACCESS,
tempnode->filemap,
&parameters.out.filemap, TRUE) != 0)
{
printf ("error duplicating filemap handle (%lu)\n",
GetLastError ());
header.error_code = EACCES;
/*mutex*/
CloseHandle (token_handle);
return;
}
if (check_and_dup_handle (GetCurrentProcess (), from_process_handle,
token_handle,
DUPLICATE_SAME_ACCESS,
tempnode->attachmap,
&parameters.out.attachmap, TRUE) != 0)
{
printf ("error duplicating attachmap handle (%lu)\n",
GetLastError ());
header.error_code = EACCES;
/*mutex*/
CloseHandle (token_handle);
return;
}
CloseHandle (token_handle);
return;
}
tempnode = tempnode->next;
}
/* couldn't find a currently open shm area. */
/* create one */
/* do this as the client */
conn->impersonate_client ();
/* This may need sh_none... it's only a control structure */
HANDLE filemap = CreateFileMapping (INVALID_HANDLE_VALUE, // system pagefile.
&sa,
PAGE_READWRITE, // protection
0x00000000,
getsystemallocgranularity (),
shmname // object name
);
int lasterr = GetLastError ();
conn->revert_to_self ();
if (filemap == NULL)
{
/* We failed to open the filemapping ? */
system_printf ("failed to open file mapping: %lu\n", GetLastError ());
// free the mutex
// we can assume that it exists, and that it was an access problem.
header.error_code = EACCES;
CloseHandle (token_handle);
return;
}
/* successfully opened the control region mapping */
/* did we create it ? */
int oldmapping = lasterr == ERROR_ALREADY_EXISTS;
if (oldmapping)
{
/* should never happen - we are the global daemon! */
#if 0
if ((parameters.in.shmflg & IPC_CREAT)
&& (parameters.in.shmflg & IPC_EXCL))
#endif
{
/* FIXME free mutex */
CloseHandle (filemap);
header.error_code = EEXIST;
CloseHandle (token_handle);
return;
}
}
/* we created a new mapping */
if (parameters.in.key != IPC_PRIVATE &&
(parameters.in.shmflg & IPC_CREAT) == 0)
{
CloseHandle (filemap);
/* FIXME free mutex */
header.error_code = ENOENT;
CloseHandle (token_handle);
return;
}
conn->impersonate_client ();
void *mapptr = MapViewOfFile (filemap, FILE_MAP_WRITE, 0, 0, 0);
conn->revert_to_self ();
if (!mapptr)
{
CloseHandle (filemap);
//FIXME: close filemap and free the mutex
/* we couldn't access the mapped area with the requested permissions */
header.error_code = EACCES;
CloseHandle (token_handle);
return;
}
conn->impersonate_client ();
/* Now get the user data */
HANDLE attachmap = CreateFileMapping (INVALID_HANDLE_VALUE, // system pagefile
&sa,
PAGE_READWRITE, // protection (FIXME)
0x00000000,
parameters.in.size +
parameters.in.size %
getsystemallocgranularity (),
shmaname // object name
);
conn->revert_to_self ();
if (attachmap == NULL)
{
system_printf ("failed to get shm attachmap\n");
header.error_code = ENOMEM;
UnmapViewOfFile (mapptr);
CloseHandle (filemap);
/* FIXME exit the mutex */
CloseHandle (token_handle);
return;
}
shmid_ds *shmtemp = new shmid_ds;
if (!shmtemp)
{
system_printf ("failed to malloc shm node\n");
header.error_code = ENOMEM;
UnmapViewOfFile (mapptr);
CloseHandle (filemap);
CloseHandle (attachmap);
/* FIXME exit mutex */
CloseHandle (token_handle);
return;
}
/* fill out the node data */
shmtemp->shm_perm.cuid = getuid ();
shmtemp->shm_perm.uid = shmtemp->shm_perm.cuid;
shmtemp->shm_perm.cgid = getgid ();
shmtemp->shm_perm.gid = shmtemp->shm_perm.cgid;
shmtemp->shm_perm.mode = parameters.in.shmflg & 0x01ff;
shmtemp->shm_lpid = 0;
shmtemp->shm_nattch = 0;
shmtemp->shm_atime = 0;
shmtemp->shm_dtime = 0;
shmtemp->shm_ctime = time (NULL);
shmtemp->shm_segsz = parameters.in.size;
*(shmid_ds *) mapptr = *shmtemp;
shmtemp->mapptr = mapptr;
/* no need for InterlockedExchange here, we're serialised by the global mutex */
tempnode = new shmnode;
tempnode->shmds = shmtemp;
tempnode->shm_id = (int) InterlockedIncrement (&new_id);
tempnode->key = parameters.in.key;
tempnode->filemap = filemap;
tempnode->attachmap = attachmap;
tempnode->next = shm_head;
shm_head = tempnode;
/* we now have the area in the daemon list, opened.
FIXME: leave the system wide shm mutex */
parameters.out.shm_id = tempnode->shm_id;
if (check_and_dup_handle (GetCurrentProcess (), from_process_handle,
token_handle,
DUPLICATE_SAME_ACCESS,
tempnode->filemap, &parameters.out.filemap,
TRUE) != 0)
{
printf ("error duplicating filemap handle (%lu)\n", GetLastError ());
header.error_code = EACCES;
CloseHandle (token_handle);
/* mutex et al */
return;
}
if (check_and_dup_handle (GetCurrentProcess (), from_process_handle,
token_handle,
DUPLICATE_SAME_ACCESS,
tempnode->attachmap, &parameters.out.attachmap,
TRUE) != 0)
{
printf ("error duplicating attachmap handle (%lu)\n", GetLastError ());
header.error_code = EACCES;
CloseHandle (from_process_handle);
CloseHandle (token_handle);
/* more cleanup... yay! */
return;
}
CloseHandle (token_handle);
return;
}
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