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Include process start time when doing polkit checks

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Since PIDs can be reused, polkit prefers to be given
a (PID,start time) pair. If given a PID on its own,
it will attempt to lookup the start time in /proc/pid/stat,
though this is subject to races.

It is safer if the client app resolves the PID start
time itself, because as long as the app has the client
socket open, the client PID won't be reused.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
(cherry picked from commit 979e9c56a7aadf2dcfbddd1abfbad594b78b4468)
Signed-off-by: Eric Blake <eblake@redhat.com>

Conflicts:
	src/libvirt_private.syms - not backported
	src/locking/lock_daemon.c - not backported
	src/rpc/virnetserverclient.c
	src/rpc/virnetsocket.c
	src/rpc/virnetsocket.h
	src/util/viridentity.h - not backported
	src/util/virprocess.c
	src/util/virprocess.h
	src/util/virstring.c
	src/util/virstring.h

Most conflicts were contextual (this patch adds new functions,
but upstream intermediate patches not backported here also added
new features, and the resolution was picking out just the portions
needed by this commit).  virnetsocket.c also had slightly
different locking semantics.
This commit is contained in:
Daniel P. Berrange 2013-04-25 17:05:00 +01:00 committed by Eric Blake
parent d0b0b052d3
commit cd03624eec
9 changed files with 167 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
daemon/remote.c
View File

@ -2351,6 +2351,7 @@ remoteDispatchAuthList(virNetServerPtr server ATTRIBUTE_UNUSED,
uid_t callerUid;
gid_t callerGid;
pid_t callerPid;
unsigned long long timestamp;
/* If the client is root then we want to bypass the
* policykit auth to avoid root being denied if
@ -2358,7 +2359,7 @@ remoteDispatchAuthList(virNetServerPtr server ATTRIBUTE_UNUSED,
*/
if (auth == VIR_NET_SERVER_SERVICE_AUTH_POLKIT) {
if (virNetServerClientGetUNIXIdentity(client, &callerUid, &callerGid,
&callerPid) < 0) {
&callerPid, &timestamp) < 0) {
/* Don't do anything on error - it'll be validated at next
* phase of auth anyway */
virResetLastError();
@ -2786,6 +2787,7 @@ remoteDispatchAuthPolkit(virNetServerPtr server ATTRIBUTE_UNUSED,
pid_t callerPid = -1;
gid_t callerGid = -1;
uid_t callerUid = -1;
unsigned long long timestamp;
const char *action;
int status = -1;
char *ident = NULL;
@ -2811,7 +2813,7 @@ remoteDispatchAuthPolkit(virNetServerPtr server ATTRIBUTE_UNUSED,
}
if (virNetServerClientGetUNIXIdentity(client, &callerUid, &callerGid,
&callerPid) < 0) {
&callerPid, &timestamp) < 0) {
goto authfail;
}
@ -2819,7 +2821,11 @@ remoteDispatchAuthPolkit(virNetServerPtr server ATTRIBUTE_UNUSED,
(long long) callerPid, callerUid);
virCommandAddArg(cmd, "--process");
virCommandAddArgFormat(cmd, "%lld", (long long) callerPid);
if (timestamp != 0) {
virCommandAddArgFormat(cmd, "%lld,%llu", (long long) callerPid, timestamp);
} else {
virCommandAddArgFormat(cmd, "%lld", (long long) callerPid);
}
virCommandAddArg(cmd, "--allow-user-interaction");
if (virAsprintf(&ident, "pid:%lld,uid:%d",

8
src/rpc/virnetserverclient.c
View File

@ -466,16 +466,20 @@ int virNetServerClientGetFD(virNetServerClientPtr client)
}
int virNetServerClientGetUNIXIdentity(virNetServerClientPtr client,
uid_t *uid, gid_t *gid, pid_t *pid)
uid_t *uid, gid_t *gid, pid_t *pid,
unsigned long long *timestamp)
{
int ret = -1;
virNetServerClientLock(client);
if (client->sock)
ret = virNetSocketGetUNIXIdentity(client->sock, uid, gid, pid);
ret = virNetSocketGetUNIXIdentity(client->sock,
uid, gid, pid,
timestamp);
virNetServerClientUnlock(client);
return ret;
}
bool virNetServerClientIsSecure(virNetServerClientPtr client)
{
bool secure = false;

3
src/rpc/virnetserverclient.h
View File

@ -78,7 +78,8 @@ int virNetServerClientSetIdentity(virNetServerClientPtr client,
const char *virNetServerClientGetIdentity(virNetServerClientPtr client);
int virNetServerClientGetUNIXIdentity(virNetServerClientPtr client,
uid_t *uid, gid_t *gid, pid_t *pid);
uid_t *uid, gid_t *gid, pid_t *pid,
unsigned long long *timestamp);
void *virNetServerClientGetPrivateData(virNetServerClientPtr client);

19
src/rpc/virnetsocket.c
View File

@ -987,31 +987,40 @@ int virNetSocketGetPort(virNetSocketPtr sock)
int virNetSocketGetUNIXIdentity(virNetSocketPtr sock,
uid_t *uid,
gid_t *gid,
pid_t *pid)
pid_t *pid,
unsigned long long *timestamp)
{
struct ucred cr;
socklen_t cr_len = sizeof(cr);
int ret = -1;
virMutexLock(&sock->lock);
if (getsockopt(sock->fd, SOL_SOCKET, SO_PEERCRED, &cr, &cr_len) < 0) {
virReportSystemError(errno, "%s",
_("Failed to get client socket identity"));
virMutexUnlock(&sock->lock);
return -1;
goto cleanup;
}
if (virProcessGetStartTime(cr.pid, timestamp) < 0)
goto cleanup;
*pid = cr.pid;
*uid = cr.uid;
*gid = cr.gid;
ret = 0;
cleanup:
virMutexUnlock(&sock->lock);
return 0;
return ret;
}
#else
int virNetSocketGetUNIXIdentity(virNetSocketPtr sock ATTRIBUTE_UNUSED,
uid_t *uid ATTRIBUTE_UNUSED,
gid_t *gid ATTRIBUTE_UNUSED,
pid_t *pid ATTRIBUTE_UNUSED)
pid_t *pid ATTRIBUTE_UNUSED,
unsigned long long *timestamp ATTRIBUTE_UNUSED)
{
/* XXX Many more OS support UNIX socket credentials we could port to. See dbus ....*/
virReportSystemError(ENOSYS, "%s",

3
src/rpc/virnetsocket.h
View File

@ -105,7 +105,8 @@ int virNetSocketGetPort(virNetSocketPtr sock);
int virNetSocketGetUNIXIdentity(virNetSocketPtr sock,
uid_t *uid,
gid_t *gid,
pid_t *pid);
pid_t *pid,
unsigned long long *timestamp);
int virNetSocketSetBlocking(virNetSocketPtr sock,
bool blocking);

118
src/util/virprocess.c
View File

@ -26,11 +26,19 @@
#include <errno.h>
#include <sys/wait.h>
#ifdef __FreeBSD__
# include <sys/param.h>
# include <sys/sysctl.h>
# include <sys/user.h>
#endif
#include "viratomic.h"
#include "virprocess.h"
#include "virterror_internal.h"
#include "memory.h"
#include "logging.h"
#include "util.h"
#include "virstring.h"
#define VIR_FROM_THIS VIR_FROM_NONE
@ -235,3 +243,113 @@ int virProcessKill(pid_t pid, int sig)
return kill(pid, sig);
#endif
}
#ifdef __linux__
/*
* Port of code from polkitunixprocess.c under terms
* of the LGPLv2+
*/
int virProcessGetStartTime(pid_t pid,
unsigned long long *timestamp)
{
char *filename = NULL;
char *buf = NULL;
char *tmp;
int ret = -1;
int len;
char **tokens = NULL;
if (virAsprintf(&filename, "/proc/%llu/stat",
(unsigned long long)pid) < 0) {
virReportOOMError();
return -1;
}
if ((len = virFileReadAll(filename, 1024, &buf)) < 0)
goto cleanup;
/* start time is the token at index 19 after the '(process name)' entry - since only this
* field can contain the ')' character, search backwards for this to avoid malicious
* processes trying to fool us
*/
if (!(tmp = strrchr(buf, ')'))) {
virReportError(VIR_ERR_INTERNAL_ERROR,
_("Cannot find start time in %s"),
filename);
goto cleanup;
}
tmp += 2; /* skip ') ' */
if ((tmp - buf) >= len) {
virReportError(VIR_ERR_INTERNAL_ERROR,
_("Cannot find start time in %s"),
filename);
goto cleanup;
}
tokens = virStringSplit(tmp, " ", 0);
if (virStringListLength(tokens) < 20) {
virReportError(VIR_ERR_INTERNAL_ERROR,
_("Cannot find start time in %s"),
filename);
goto cleanup;
}
if (virStrToLong_ull(tokens[19],
NULL,
10,
timestamp) < 0) {
virReportError(VIR_ERR_INTERNAL_ERROR,
_("Cannot parse start time %s in %s"),
tokens[19], filename);
goto cleanup;
}
ret = 0;
cleanup:
virStringFreeList(tokens);
VIR_FREE(filename);
VIR_FREE(buf);
return ret;
}
#elif defined(__FreeBSD__)
int virProcessGetStartTime(pid_t pid,
unsigned long long *timestamp)
{
struct kinfo_proc p;
int mib[4];
size_t len = 4;
sysctlnametomib("kern.proc.pid", mib, &len);
len = sizeof(struct kinfo_proc);
mib[3] = pid;
if (sysctl(mib, 4, &p, &len, NULL, 0) < 0) {
virReportSystemError(errno, "%s",
_("Unable to query process ID start time"));
return -1;
}
*timestamp = (unsigned long long)p.ki_start.tv_sec;
return 0;
}
#else
int virProcessGetStartTime(pid_t pid,
unsigned long long *timestamp)
{
static int warned = 0;
if (virAtomicIntInc(&warned) == 1) {
VIR_WARN("Process start time of pid %llu not available on this platform",
(unsigned long long)pid);
warned = true;
}
*timestamp = 0;
return 0;
}
#endif

3
src/util/virprocess.h
View File

@ -39,4 +39,7 @@ virProcessWait(pid_t pid, int *exitstatus)
int virProcessKill(pid_t pid, int sig);
int virProcessGetStartTime(pid_t pid,
unsigned long long *timestamp);
#endif /* __VIR_PROCESS_H__ */

11
src/util/virstring.c
View File

@ -166,3 +166,14 @@ void virStringFreeList(char **strings)
}
VIR_FREE(strings);
}
size_t virStringListLength(char **strings)
{
size_t i = 0;
while (strings && strings[i])
i++;
return i;
}

2
src/util/virstring.h
View File

@ -35,4 +35,6 @@ char *virStringJoin(const char **strings,
void virStringFreeList(char **strings);
size_t virStringListLength(char **strings);
#endif /* __VIR_STRING_H__ */