godzil/fusd
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add locking mechanism in the fusd_file_info_t structure to prevent potential race conditions.

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This commit is contained in:
Godzil 2012-07-10 14:00:05 +02:00
parent 542d87ea75
commit 0678a66b3c
2 changed files with 44 additions and 9 deletions
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9
include/fusd.h
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@ -66,6 +66,8 @@ __BEGIN_DECLS
#define FUSD_KOR_HACKED_VERSION #define FUSD_KOR_HACKED_VERSION
#ifndef __KERNEL__
struct fusd_file_info; /* forward decl */ struct fusd_file_info; /* forward decl */
typedef typedef
@ -105,6 +107,7 @@ struct fusd_file_info {
/* other info might be added later, e.g. state needed to complete /* other info might be added later, e.g. state needed to complete
operations... */ operations... */
pthread_mutex_t lock;
/* request message associated with this call */ /* request message associated with this call */
int fd; int fd;
@ -112,8 +115,8 @@ struct fusd_file_info {
} fusd_file_info_t; } fusd_file_info_t;
#define FILE_LOCK(__f) pthread_mutex_lock(&__f->lock)
#define FILE_UNLOCK(__f) pthread_mutex_unlock(&__f->lock)
/*************************** Library Functions ****************************/ /*************************** Library Functions ****************************/
@ -278,6 +281,8 @@ static inline int fusd_get_poll_diff_cached_state(struct fusd_file_info *file)
/* returns static string representing the flagset (e.g. RWE) */ /* returns static string representing the flagset (e.g. RWE) */
char *fusd_unparse_flags(int flags); char *fusd_unparse_flags(int flags);
#endif /* !__KERNEL__ */
#ifndef __KERNEL__ #ifndef __KERNEL__
__END_DECLS __END_DECLS
#endif #endif

44
libfusd/libfusd.c
View File

@ -53,6 +53,11 @@ char libfusd_c_id[] = "$Id: libfusd.c 12351 2007-01-19 07:22:54Z xiphmont $";
#include <string.h> #include <string.h>
#include <time.h> #include <time.h>
#include <pthread.h>
#include <unistd.h>
#include <sys/syscall.h>
#include "fusd.h" #include "fusd.h"
#include "fusd_msg.h" #include "fusd_msg.h"
@ -72,7 +77,7 @@ char *dev_root = NULL;
* struct for each fusd fd. * struct for each fusd fd.
*/ */
static fusd_file_operations_t fusd_fops_set[FD_SETSIZE]; static fusd_file_operations_t fusd_fops_set[FD_SETSIZE];
fusd_file_operations_t null_fops = { NULL }; fusd_file_operations_t null_fops = { NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL };
/* /*
* accessor macros * accessor macros
@ -389,6 +394,11 @@ static int fusd_dispatch_one(int fd, fusd_file_operations_t *fops)
/* fill the file info struct */ /* fill the file info struct */
memset(file, '\0', sizeof(fusd_file_info_t)); memset(file, '\0', sizeof(fusd_file_info_t));
pthread_mutex_init(&file->lock, NULL);
FILE_LOCK(file);
file->fd = fd; file->fd = fd;
file->device_info = msg->parm.fops_msg.device_info; file->device_info = msg->parm.fops_msg.device_info;
file->private_data = msg->parm.fops_msg.private_info; file->private_data = msg->parm.fops_msg.private_info;
@ -398,6 +408,8 @@ static int fusd_dispatch_one(int fd, fusd_file_operations_t *fops)
file->gid = msg->parm.fops_msg.gid; file->gid = msg->parm.fops_msg.gid;
file->fusd_msg = msg; file->fusd_msg = msg;
FILE_UNLOCK(file);
/* right now we only handle fops requests */ /* right now we only handle fops requests */
if (msg->cmd != FUSD_FOPS_CALL && msg->cmd != FUSD_FOPS_NONBLOCK && if (msg->cmd != FUSD_FOPS_CALL && msg->cmd != FUSD_FOPS_NONBLOCK &&
msg->cmd != FUSD_FOPS_CALL_DROPREPLY) { msg->cmd != FUSD_FOPS_CALL_DROPREPLY) {
@ -602,20 +614,28 @@ int fusd_return(fusd_file_info_t *file, ssize_t retval)
int driver_retval = 0; int driver_retval = 0;
struct iovec iov[2]; struct iovec iov[2];
if (file == NULL) { if (file == NULL)
{
fprintf(stderr, "fusd_return: NULL file\n"); fprintf(stderr, "fusd_return: NULL file\n");
return -EINVAL; ret = -EINVAL;
goto exit;
} }
FILE_LOCK(file);
fd = file->fd; fd = file->fd;
if (!FUSD_FD_VALID(fd)) { if (!FUSD_FD_VALID(fd))
{
fprintf(stderr, "fusd_return: badfd (fd %d)\n", fd); fprintf(stderr, "fusd_return: badfd (fd %d)\n", fd);
return -EBADF; ret = -EBADF;
goto exit_unlock;
} }
if ((msg = file->fusd_msg) == NULL) { if ((msg = file->fusd_msg) == NULL)
{
fprintf(stderr, "fusd_return: fusd_msg is gone\n"); fprintf(stderr, "fusd_return: fusd_msg is gone\n");
return -EINVAL; ret = -EINVAL;
goto exit_unlock;
} }
/* if this was a "DONTREPLY" message, just free the struct */ /* if this was a "DONTREPLY" message, just free the struct */
@ -668,13 +688,23 @@ int fusd_return(fusd_file_info_t *file, ssize_t retval)
driver_retval = write(fd, msg, sizeof(fusd_msg_t)); driver_retval = write(fd, msg, sizeof(fusd_msg_t));
} }
free_memory:
FILE_UNLOCK(file);
free_memory: free_memory:
fusd_destroy(file); fusd_destroy(file);
ret = 0;
if (driver_retval < 0) if (driver_retval < 0)
return -errno; return -errno;
else else
return 0; return 0;
goto exit;
exit_unlock:
FILE_UNLOCK(file);
exit:
return ret;
} }