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Include process start time when doing polkit checks 

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>
This commit is contained in:
Daniel P. Berrange 2013-04-25 17:05:00 +01:00
parent b1d753fe40
commit 979e9c56a7
12 changed files with 191 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
daemon/remote.c
View File

@ -2339,6 +2339,7 @@ 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
@ -2346,7 +2347,7 @@ 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();
@ -2772,6 +2773,7 @@ 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;
@ -2797,7 +2799,7 @@ remoteDispatchAuthPolkit(virNetServerPtr server ATTRIBUTE_UNUSED,
}
if (virNetServerClientGetUNIXIdentity(client, &callerUid, &callerGid,
&callerPid) < 0) {
&callerPid, &timestamp) < 0) {
goto authfail;
}
@ -2805,7 +2807,11 @@ 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",

1
src/libvirt_private.syms
View File

@ -1755,6 +1755,7 @@ virStrdup;
virStringArrayHasString;
virStringFreeList;
virStringJoin;
virStringListLength;
virStringSplit;
virStrncpy;
virStrndup;

4
src/locking/lock_daemon.c
View File

@ -783,6 +783,7 @@ virLockDaemonClientNew(virNetServerClientPtr client,
virLockDaemonClientPtr priv;
uid_t clientuid;
gid_t clientgid;
unsigned long long timestamp;
bool privileged = opaque != NULL;
if (VIR_ALLOC(priv) < 0) {
@ -799,7 +800,8 @@ virLockDaemonClientNew(virNetServerClientPtr client,
if (virNetServerClientGetUNIXIdentity(client,
&clientuid,
&clientgid,
&priv->clientPid) < 0)
&priv->clientPid,
&timestamp) < 0)
goto error;
VIR_DEBUG("New client pid %llu uid %llu",

28
src/rpc/virnetserverclient.c
View File

@ -636,12 +636,15 @@ bool virNetServerClientIsLocal(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;
virObjectLock(client);
if (client->sock)
ret = virNetSocketGetUNIXIdentity(client->sock, uid, gid, pid);
ret = virNetSocketGetUNIXIdentity(client->sock,
uid, gid, pid,
timestamp);
virObjectUnlock(client);
return ret;
}
@ -651,6 +654,7 @@ static virIdentityPtr
virNetServerClientCreateIdentity(virNetServerClientPtr client)
{
char *processid = NULL;
char *processtime = NULL;
char *username = NULL;
char *groupname = NULL;
#if WITH_SASL
@ -664,15 +668,23 @@ virNetServerClientCreateIdentity(virNetServerClientPtr client)
gid_t gid;
uid_t uid;
pid_t pid;
if (virNetSocketGetUNIXIdentity(client->sock, &uid, &gid, &pid) < 0)
unsigned long long timestamp;
if (virNetSocketGetUNIXIdentity(client->sock,
&uid, &gid, &pid,
&timestamp) < 0)
goto cleanup;
if (!(username = virGetUserName(uid)))
goto cleanup;
if (!(groupname = virGetGroupName(gid)))
goto cleanup;
if (virAsprintf(&processid, "%lld",
(long long)pid) < 0) {
if (virAsprintf(&processid, "%llu",
(unsigned long long)pid) < 0) {
virReportOOMError();
goto cleanup;
}
if (virAsprintf(&processtime, "%llu",
timestamp) < 0) {
virReportOOMError();
goto cleanup;
}
@ -722,6 +734,11 @@ virNetServerClientCreateIdentity(virNetServerClientPtr client)
VIR_IDENTITY_ATTR_UNIX_PROCESS_ID,
processid) < 0)
goto error;
if (processtime &&
virIdentitySetAttr(ret,
VIR_IDENTITY_ATTR_UNIX_PROCESS_TIME,
processtime) < 0)
goto error;
#if HAVE_SASL
if (saslname &&
virIdentitySetAttr(ret,
@ -744,6 +761,7 @@ cleanup:
VIR_FREE(username);
VIR_FREE(groupname);
VIR_FREE(processid);
VIR_FREE(processtime);
VIR_FREE(seccontext);
#if HAVE_SASL
VIR_FREE(saslname);

3
src/rpc/virnetserverclient.h
View File

@ -99,7 +99,8 @@ bool virNetServerClientIsSecure(virNetServerClientPtr client);
bool virNetServerClientIsLocal(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 virNetServerClientGetSELinuxContext(virNetServerClientPtr client,
char **context);

23
src/rpc/virnetsocket.c
View File

@ -1103,31 +1103,41 @@ 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;
virObjectLock(sock);
if (getsockopt(sock->fd, SOL_SOCKET, SO_PEERCRED, &cr, &cr_len) < 0) {
virReportSystemError(errno, "%s",
_("Failed to get client socket identity"));
virObjectUnlock(sock);
return -1;
goto cleanup;
}
if (virProcessGetStartTime(cr.pid, timestamp) < 0)
goto cleanup;
*pid = cr.pid;
*uid = cr.uid;
*gid = cr.gid;
ret = 0;
cleanup:
virObjectUnlock(sock);
return 0;
return ret;
}
#elif defined(LOCAL_PEERCRED)
int virNetSocketGetUNIXIdentity(virNetSocketPtr sock,
uid_t *uid,
gid_t *gid,
pid_t *pid)
pid_t *pid,
unsigned long long *timestamp ATTRIBUTE_UNUSED)
{
struct xucred cr;
socklen_t cr_len = sizeof(cr);
@ -1151,7 +1161,8 @@ int virNetSocketGetUNIXIdentity(virNetSocketPtr sock,
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

@ -113,7 +113,8 @@ 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 virNetSocketGetSELinuxContext(virNetSocketPtr sock,
char **context);

1
src/util/viridentity.h
View File

@ -31,6 +31,7 @@ typedef enum {
VIR_IDENTITY_ATTR_UNIX_USER_NAME,
VIR_IDENTITY_ATTR_UNIX_GROUP_NAME,
VIR_IDENTITY_ATTR_UNIX_PROCESS_ID,
VIR_IDENTITY_ATTR_UNIX_PROCESS_TIME,
VIR_IDENTITY_ATTR_SASL_USER_NAME,
VIR_IDENTITY_ATTR_X509_DISTINGUISHED_NAME,
VIR_IDENTITY_ATTR_SELINUX_CONTEXT,

116
src/util/virprocess.c
View File

@ -33,6 +33,13 @@
#endif
#include <sched.h>
#ifdef __FreeBSD__
# include <sys/param.h>
# include <sys/sysctl.h>
# include <sys/user.h>
#endif
#include "viratomic.h"
#include "virprocess.h"
#include "virerror.h"
#include "viralloc.h"
@ -756,3 +763,112 @@ virProcessSetMaxFiles(pid_t pid ATTRIBUTE_UNUSED, unsigned int files)
return -1;
}
#endif /* ! (HAVE_SETRLIMIT && defined(RLIMIT_NOFILE)) */
#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

@ -47,6 +47,9 @@ int virProcessGetAffinity(pid_t pid,
virBitmapPtr *map,
int maxcpu);
int virProcessGetStartTime(pid_t pid,
unsigned long long *timestamp);
int virProcessGetNamespaces(pid_t pid,
size_t *nfdlist,
int **fdlist);

11
src/util/virstring.c
View File

@ -593,3 +593,14 @@ virStrndup(char **dest,
return 1;
}
size_t virStringListLength(char **strings)
{
size_t i = 0;
while (strings && strings[i])
i++;
return i;
}

4
src/util/virstring.h
View File

@ -88,7 +88,6 @@ char *virStrcpy(char *dest, const char *src, size_t destbytes)
ATTRIBUTE_RETURN_CHECK;
# define virStrcpyStatic(dest, src) virStrcpy((dest), (src), sizeof(dest))
/* Don't call these directly - use the macros below */
int virStrdup(char **dest, const char *src, bool report, int domcode,
const char *filename, const char *funcname, size_t linenr)
@ -159,4 +158,7 @@ int virStrndup(char **dest, const char *src, size_t n, bool report, int domcode,
*/
# define VIR_STRNDUP_QUIET(dst, src, n) virStrndup(&(dst), src, n, false, \
0, NULL, NULL, 0)
size_t virStringListLength(char **strings);
#endif /* __VIR_STRING_H__ */