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Secure promiscuous mode for posix semaphores 

Adjusts the permissions of posix semaphores when promiscuous mode is enabled.

Note that changing permissions of semaphores is only supported on linux by
using the /dev/shm filesystem. As of now, linux does not use posix semaphores
anymore so this code is currently unsed.
This commit is contained in:
Cédric Schieli 2017-03-18 11:33:30 +01:00
parent 5d89eba8c7
commit d4f925c2ea
2 changed files with 26 additions and 3 deletions
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22
posix/JackPosixSemaphore.cpp
View File

@ -24,10 +24,22 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
#include <fcntl.h>
#include <stdio.h>
#include <sys/time.h>
#ifdef __linux__
#include "promiscuous.h"
#endif
namespace Jack
{
JackPosixSemaphore::JackPosixSemaphore() : JackSynchro(), fSemaphore(NULL)
{
const char* promiscuous = getenv("JACK_PROMISCUOUS_SERVER");
fPromiscuous = (promiscuous != NULL);
#ifdef __linux__
fPromiscuousGid = jack_group2gid(promiscuous);
#endif
}
void JackPosixSemaphore::BuildName(const char* client_name, const char* server_name, char* res, int size)
{
char ext_client_name[SYNC_MAX_NAME_SIZE + 1];
@ -35,7 +47,7 @@ void JackPosixSemaphore::BuildName(const char* client_name, const char* server_n
#if __APPLE__ // POSIX semaphore names are limited to 32 characters...
snprintf(res, 32, "js_%s", ext_client_name);
#else
if (getenv("JACK_PROMISCUOUS_SERVER")) {
if (fPromiscuous) {
snprintf(res, size, "jack_sem.%s_%s", server_name, ext_client_name);
} else {
snprintf(res, size, "jack_sem.%d_%s_%s", JackTools::GetUID(), server_name, ext_client_name);
@ -147,6 +159,14 @@ bool JackPosixSemaphore::Allocate(const char* name, const char* server_name, int
jack_error("Allocate: can't check in named semaphore name = %s err = %s", fName, strerror(errno));
return false;
} else {
#ifdef __linux__
if (fPromiscuous) {
char sempath[SYNC_MAX_NAME_SIZE+13];
snprintf(sempath, sizeof(sempath), "/dev/shm/sem.%s", fName);
if (jack_promiscuous_perms(-1, sempath, fPromiscuousGid) < 0)
return false;
}
#endif
return true;
}
}

7
posix/JackPosixSemaphore.h
View File

@ -39,6 +39,10 @@ class SERVER_EXPORT JackPosixSemaphore : public detail::JackSynchro
private:
sem_t* fSemaphore;
bool fPromiscuous;
#ifdef __linux__
int fPromiscuousGid;
#endif
protected:
@ -46,8 +50,7 @@ class SERVER_EXPORT JackPosixSemaphore : public detail::JackSynchro
public:
JackPosixSemaphore():JackSynchro(), fSemaphore(NULL)
{}
JackPosixSemaphore();
bool Signal();
bool SignalAll();