os: Add facilities for client ID tracking.

An interface is provided for figuring out the PID and process name of
a client. Make some existing functionality from SELinux and IA
extensions available for general use.

Signed-off-by: Rami Ylimäki <rami.ylimaki@vincit.fi>
Reviewed-by: Tiago Vignatti <tiago.vignatti@nokia.com>

1 files changed, 310 insertions, 0 deletions

diff --git a/os/client.c b/os/client.c
new file mode 100644
index 000000000..1311855d5
--- /dev/null
+++ b/os/client.c
@@ -0,0 +1,310 @@
+/*
+ * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies). All
+ * rights reserved.
+ * Copyright (c) 1993, 2010, Oracle and/or its affiliates. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+/**
+ * @file
+ *
+ * This file contains functionality for identifying clients by various
+ * means. The primary purpose of identification is to simply aid in
+ * finding out which clients are using X server and how they are using
+ * it. For example, it's often necessary to monitor what requests
+ * clients are executing (to spot bad behaviour) and how they are
+ * allocating resources in X server (to spot excessive resource
+ * usage).
+ *
+ * This framework automatically allocates information, that can be
+ * used for client identification, when a client connects to the
+ * server. The information is freed when the client disconnects. The
+ * allocated information is just a collection of various IDs, such as
+ * PID and process name for local clients, that are likely to be
+ * useful in analyzing X server usage.
+ *
+ * Users of the framework can query ID information about clients at
+ * any time. To avoid repeated polling of IDs the users can also
+ * subscribe for notifications about the availability of ID
+ * information. IDs have been allocated before ClientStateCallback is
+ * called with ClientStateInitial state. Similarly the IDs will be
+ * released after ClientStateCallback is called with ClientStateGone
+ * state.
+ *
+ * Author: Rami Ylimäki <rami.ylimaki@vincit.fi>
+ */
+
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include "client.h"
+#include "os.h"
+#include "dixstruct.h"
+
+/**
+ * Try to determine a PID for a client from its connection
+ * information. This should be called only once when new client has
+ * connected, use GetClientPid to determine the PID at other times.
+ *
+ * @param[in] client Connection linked to some process.
+ *
+ * @return PID of the client. Error (-1) if PID can't be determined
+ *         for the client.
+ *
+ * @see GetClientPid
+ */
+pid_t DetermineClientPid(struct _Client *client)
+{
+    LocalClientCredRec *lcc = NULL;
+    pid_t pid = -1;
+
+    if (client == NullClient)
+        return pid;
+
+    if (client == serverClient)
+        return getpid();
+
+    if (GetLocalClientCreds(client, &lcc) != -1)
+    {
+        if (lcc->fieldsSet & LCC_PID_SET)
+            pid = lcc->pid;
+        FreeLocalClientCreds(lcc);
+    }
+
+    return pid;
+}
+
+/**
+ * Try to determine a command line string for a client based on its
+ * PID. Note that mapping PID to a command hasn't been implemented for
+ * some operating systems. This should be called only once when a new
+ * client has connected, use GetClientCmdName/Args to determine the
+ * string at other times.
+ *
+ * @param[in]  pid     Process ID of a client.
+
+ * @param[out] cmdname Client process name without arguments. You must
+ *                     release this by calling free. On error NULL is
+ *                     returned. Pass NULL if you aren't interested in
+ *                     this value.
+ * @param[out] cmdargs Arguments to client process. Useful for
+ *                     identifying a client that is executed from a
+ *                     launcher program. You must release this by
+ *                     calling free. On error NULL is returned. Pass
+ *                     NULL if you aren't interested in this value.
+ *
+ * @see GetClientCmdName/Args
+ */
+void DetermineClientCmd(pid_t pid, const char **cmdname, const char **cmdargs)
+{
+    char path[PATH_MAX + 1];
+    int totsize = 0;
+    int cmdsize = 0;
+    int argsize = 0;
+    int fd = 0;
+
+    if (cmdname)
+        *cmdname = NULL;
+    if (cmdargs)
+        *cmdargs = NULL;
+
+    if (pid == -1)
+        return;
+
+    /* Check if /proc/pid/cmdline exists. It's not supported on all
+     * operating systems. */
+    if (snprintf(path, sizeof(path), "/proc/%d/cmdline", pid) < 0)
+        return;
+    fd = open(path, O_RDONLY);
+    if (fd < 0)
+        return;
+
+    /* Read the contents of /proc/pid/cmdline. It should contain the
+     * process name and arguments. */
+    totsize = read(fd, path, sizeof(path));
+    if (totsize <= 0)
+        return;
+    if (close(fd) < 0)
+        return;
+    path[totsize - 1] = '\0';
+
+    /* Contruct the process name without arguments. */
+    cmdsize = strlen(path) + 1;
+    if (cmdname)
+    {
+        char *name = malloc(cmdsize);
+        if (name)
+        {
+            strncpy(name, path, cmdsize);
+            name[cmdsize - 1] = '\0';
+            *cmdname = name;
+        }
+    }
+
+    /* Construct the arguments for client process. */
+    argsize = totsize - cmdsize;
+    if (cmdargs && (argsize > 0))
+    {
+        char *args = malloc(argsize);
+        if (args)
+        {
+            int i = 0;
+            for (i = 0; i < (argsize - 1); ++i)
+            {
+                const char c = path[cmdsize + i];
+                args[i] = (c == '\0') ? ' ' : c;
+            }
+            args[argsize - 1] = '\0';
+            *cmdargs = args;
+        }
+    }
+}
+
+/**
+ * Called when a new client connects. Allocates client ID information.
+ *
+ * @param[in] client Recently connected client.
+ */
+void ReserveClientIds(struct _Client *client)
+{
+#ifdef CLIENTIDS
+    if (client == NullClient)
+        return;
+
+    assert(!client->clientIds);
+    client->clientIds = calloc(1, sizeof(ClientIdRec));
+    if (!client->clientIds)
+        return;
+
+    client->clientIds->pid = DetermineClientPid(client);
+    if (client->clientIds->pid != -1)
+        DetermineClientCmd(client->clientIds->pid, &client->clientIds->cmdname, &client->clientIds->cmdargs);
+
+    DebugF("client(%lx): Reserved pid(%d).\n",
+           client->clientAsMask, client->clientIds->pid);
+    DebugF("client(%lx): Reserved cmdname(%s) and cmdargs(%s).\n",
+           client->clientAsMask,
+           client->clientIds->cmdname ? client->clientIds->cmdname : "NULL",
+           client->clientIds->cmdargs ? client->clientIds->cmdargs : "NULL");
+#endif /* CLIENTIDS */
+}
+
+/**
+ * Called when an existing client disconnects. Frees client ID
+ * information.
+ *
+ * @param[in] client Recently disconnected client.
+ */
+void ReleaseClientIds(struct _Client *client)
+{
+#ifdef CLIENTIDS
+    if (client == NullClient)
+        return;
+
+    if (!client->clientIds)
+        return;
+
+    DebugF("client(%lx): Released pid(%d).\n",
+           client->clientAsMask, client->clientIds->pid);
+    DebugF("client(%lx): Released cmdline(%s) and cmdargs(%s).\n",
+           client->clientAsMask,
+           client->clientIds->cmdname ? client->clientIds->cmdname : "NULL",
+           client->clientIds->cmdargs ? client->clientIds->cmdargs : "NULL");
+
+    free((void *) client->clientIds->cmdname); /* const char * */
+    free((void *) client->clientIds->cmdargs); /* const char * */
+    free(client->clientIds);
+    client->clientIds = NULL;
+#endif /* CLIENTIDS */
+}
+
+/**
+ * Get cached PID of a client.
+ *
+ * param[in] client Client whose PID has been already cached.
+ *
+ * @return Cached client PID. Error (-1) if called:
+ *         - before ClientStateInitial client state notification
+ *         - after ClientStateGone client state notification
+ *         - for remote clients
+ *
+ * @see DetermineClientPid
+ */
+pid_t GetClientPid(struct _Client *client)
+{
+    if (client == NullClient)
+        return -1;
+
+    if (!client->clientIds)
+        return -1;
+
+    return client->clientIds->pid;
+}
+
+/**
+ * Get cached command name string of a client.
+ *
+ * param[in] client Client whose command line string has been already
+ *                  cached.
+ *
+ * @return Cached client command name. Error (NULL) if called:
+ *         - before ClientStateInitial client state notification
+ *         - after ClientStateGone client state notification
+ *         - for remote clients
+ *         - on OS that doesn't support mapping of PID to command line
+ *
+ * @see DetermineClientCmd
+ */
+const char *GetClientCmdName(struct _Client *client)
+{
+    if (client == NullClient)
+        return NULL;
+
+    if (!client->clientIds)
+        return NULL;
+
+    return client->clientIds->cmdname;
+}
+
+/**
+ * Get cached command arguments string of a client.
+ *
+ * param[in] client Client whose command line string has been already
+ *                  cached.
+ *
+ * @return Cached client command arguments. Error (NULL) if called:
+ *         - before ClientStateInitial client state notification
+ *         - after ClientStateGone client state notification
+ *         - for remote clients
+ *         - on OS that doesn't support mapping of PID to command line
+ *
+ * @see DetermineClientCmd
+ */
+const char *GetClientCmdArgs(struct _Client *client)
+{
+    if (client == NullClient)
+        return NULL;
+
+    if (!client->clientIds)
+        return NULL;
+
+    return client->clientIds->cmdargs;
+}