mq_open_tests.c

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/*
 * This application is Copyright 2012 Red Hat, Inc.
 *  Doug Ledford <[email protected]>
 *
 * mq_open_tests is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, version 3.
 *
 * mq_open_tests is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * For the full text of the license, see <http://www.gnu.org/licenses/>.
 *
 * mq_open_tests.c
 *   Tests the various situations that should either succeed or fail to
 *   open a posix message queue and then reports whether or not they
 *   did as they were supposed to.
 *
 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <limits.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <mqueue.h>

static char *usage =
"Usage:\n"
"  %s path\n"
"\n"
"   path    Path name of the message queue to create\n"
"\n"
"   Note: this program must be run as root in order to enable all tests\n"
"\n";

char *DEF_MSGS = "/proc/sys/fs/mqueue/msg_default";
char *DEF_MSGSIZE = "/proc/sys/fs/mqueue/msgsize_default";
char *MAX_MSGS = "/proc/sys/fs/mqueue/msg_max";
char *MAX_MSGSIZE = "/proc/sys/fs/mqueue/msgsize_max";

int default_settings;
struct rlimit saved_limits, cur_limits;
int saved_def_msgs, saved_def_msgsize, saved_max_msgs, saved_max_msgsize;
int cur_def_msgs, cur_def_msgsize, cur_max_msgs, cur_max_msgsize;
FILE *def_msgs, *def_msgsize, *max_msgs, *max_msgsize;
char *queue_path;
mqd_t queue = -1;

static inline void __set(FILE *stream, int value, char *err_msg);
void shutdown(int exit_val, char *err_cause, int line_no);
static inline int get(FILE *stream);
static inline void set(FILE *stream, int value);
static inline void getr(int type, struct rlimit *rlim);
static inline void setr(int type, struct rlimit *rlim);
void validate_current_settings();
static inline void test_queue(struct mq_attr *attr, struct mq_attr *result);
static inline int test_queue_fail(struct mq_attr *attr, struct mq_attr *result);

static inline void __set(FILE *stream, int value, char *err_msg)
{
    rewind(stream);
    if (fprintf(stream, "%d", value) < 0)
        perror(err_msg);
}


void shutdown(int exit_val, char *err_cause, int line_no)
{
    static int in_shutdown = 0;

    /* In case we get called recursively by a set() call below */
    if (in_shutdown++)
        return;

    seteuid(0);

    if (queue != -1)
        if (mq_close(queue))
            perror("mq_close() during shutdown");
    if (queue_path)
        /*
         * Be silent if this fails, if we cleaned up already it's
         * expected to fail
         */
        mq_unlink(queue_path);
    if (default_settings) {
        if (saved_def_msgs)
            __set(def_msgs, saved_def_msgs,
                  "failed to restore saved_def_msgs");
        if (saved_def_msgsize)
            __set(def_msgsize, saved_def_msgsize,
                  "failed to restore saved_def_msgsize");
    }
    if (saved_max_msgs)
        __set(max_msgs, saved_max_msgs,
              "failed to restore saved_max_msgs");
    if (saved_max_msgsize)
        __set(max_msgsize, saved_max_msgsize,
              "failed to restore saved_max_msgsize");
    if (exit_val)
        error(exit_val, errno, "%s at %d", err_cause, line_no);
    exit(0);
}

static inline int get(FILE *stream)
{
    int value;
    rewind(stream);
    if (fscanf(stream, "%d", &value) != 1)
        shutdown(4, "Error reading /proc entry", __LINE__ - 1);
    return value;
}

static inline void set(FILE *stream, int value)
{
    int new_value;

    rewind(stream);
    if (fprintf(stream, "%d", value) < 0)
        return shutdown(5, "Failed writing to /proc file",
                __LINE__ - 1);
    new_value = get(stream);
    if (new_value != value)
        return shutdown(5, "We didn't get what we wrote to /proc back",
                __LINE__ - 1);
}

static inline void getr(int type, struct rlimit *rlim)
{
    if (getrlimit(type, rlim))
        shutdown(6, "getrlimit()", __LINE__ - 1);
}

static inline void setr(int type, struct rlimit *rlim)
{
    if (setrlimit(type, rlim))
        shutdown(7, "setrlimit()", __LINE__ - 1);
}

void validate_current_settings()
{
    int rlim_needed;

    if (cur_limits.rlim_cur < 4096) {
        printf("Current rlimit value for POSIX message queue bytes is "
               "unreasonably low,\nincreasing.\n\n");
        cur_limits.rlim_cur = 8192;
        cur_limits.rlim_max = 16384;
        setr(RLIMIT_MSGQUEUE, &cur_limits);
    }

    if (default_settings) {
        rlim_needed = (cur_def_msgs + 1) * (cur_def_msgsize + 1 +
                            2 * sizeof(void *));
        if (rlim_needed > cur_limits.rlim_cur) {
            printf("Temporarily lowering default queue parameters "
                   "to something that will work\n"
                   "with the current rlimit values.\n\n");
            set(def_msgs, 10);
            cur_def_msgs = 10;
            set(def_msgsize, 128);
            cur_def_msgsize = 128;
        }
    } else {
        rlim_needed = (cur_max_msgs + 1) * (cur_max_msgsize + 1 +
                            2 * sizeof(void *));
        if (rlim_needed > cur_limits.rlim_cur) {
            printf("Temporarily lowering maximum queue parameters "
                   "to something that will work\n"
                   "with the current rlimit values in case this is "
                   "a kernel that ties the default\n"
                   "queue parameters to the maximum queue "
                   "parameters.\n\n");
            set(max_msgs, 10);
            cur_max_msgs = 10;
            set(max_msgsize, 128);
            cur_max_msgsize = 128;
        }
    }
}

/*
 * test_queue - Test opening a queue, shutdown if we fail.  This should
 * only be called in situations that should never fail.  We clean up
 * after ourselves and return the queue attributes in *result.
 */
static inline void test_queue(struct mq_attr *attr, struct mq_attr *result)
{
    int flags = O_RDWR | O_EXCL | O_CREAT;
    int perms = DEFFILEMODE;

    if ((queue = mq_open(queue_path, flags, perms, attr)) == -1)
        shutdown(1, "mq_open()", __LINE__);
    if (mq_getattr(queue, result))
        shutdown(1, "mq_getattr()", __LINE__);
    if (mq_close(queue))
        shutdown(1, "mq_close()", __LINE__);
    queue = -1;
    if (mq_unlink(queue_path))
        shutdown(1, "mq_unlink()", __LINE__);
}

/*
 * Same as test_queue above, but failure is not fatal.
 * Returns:
 * 0 - Failed to create a queue
 * 1 - Created a queue, attributes in *result
 */
static inline int test_queue_fail(struct mq_attr *attr, struct mq_attr *result)
{
    int flags = O_RDWR | O_EXCL | O_CREAT;
    int perms = DEFFILEMODE;

    if ((queue = mq_open(queue_path, flags, perms, attr)) == -1)
        return 0;
    if (mq_getattr(queue, result))
        shutdown(1, "mq_getattr()", __LINE__);
    if (mq_close(queue))
        shutdown(1, "mq_close()", __LINE__);
    queue = -1;
    if (mq_unlink(queue_path))
        shutdown(1, "mq_unlink()", __LINE__);
    return 1;
}

int main(int argc, char *argv[])
{
    struct mq_attr attr, result;

    if (argc != 2) {
        fprintf(stderr, "Must pass a valid queue name\n\n");
        fprintf(stderr, usage, argv[0]);
        exit(1);
    }

    /*
     * Although we can create a msg queue with a non-absolute path name,
     * unlink will fail.  So, if the name doesn't start with a /, add one
     * when we save it.
     */
    if (*argv[1] == '/')
        queue_path = strdup(argv[1]);
    else {
        queue_path = malloc(strlen(argv[1]) + 2);
        if (!queue_path) {
            perror("malloc()");
            exit(1);
        }
        queue_path[0] = '/';
        queue_path[1] = 0;
        strcat(queue_path, argv[1]);
    }

    if (getuid() != 0) {
        fprintf(stderr, "Not running as root, but almost all tests "
            "require root in order to modify\nsystem settings.  "
            "Exiting.\n");
        exit(1);
    }

    /* Find out what files there are for us to make tweaks in */
    def_msgs = fopen(DEF_MSGS, "r+");
    def_msgsize = fopen(DEF_MSGSIZE, "r+");
    max_msgs = fopen(MAX_MSGS, "r+");
    max_msgsize = fopen(MAX_MSGSIZE, "r+");

    if (!max_msgs)
        shutdown(2, "Failed to open msg_max", __LINE__);
    if (!max_msgsize)
        shutdown(2, "Failed to open msgsize_max", __LINE__);
    if (def_msgs || def_msgsize)
        default_settings = 1;

    /* Load up the current system values for everything we can */
    getr(RLIMIT_MSGQUEUE, &saved_limits);
    cur_limits = saved_limits;
    if (default_settings) {
        saved_def_msgs = cur_def_msgs = get(def_msgs);
        saved_def_msgsize = cur_def_msgsize = get(def_msgsize);
    }
    saved_max_msgs = cur_max_msgs = get(max_msgs);
    saved_max_msgsize = cur_max_msgsize = get(max_msgsize);

    /* Tell the user our initial state */
    printf("\nInitial system state:\n");
    printf("\tUsing queue path:\t\t%s\n", queue_path);
    printf("\tRLIMIT_MSGQUEUE(soft):\t\t%d\n", saved_limits.rlim_cur);
    printf("\tRLIMIT_MSGQUEUE(hard):\t\t%d\n", saved_limits.rlim_max);
    printf("\tMaximum Message Size:\t\t%d\n", saved_max_msgsize);
    printf("\tMaximum Queue Size:\t\t%d\n", saved_max_msgs);
    if (default_settings) {
        printf("\tDefault Message Size:\t\t%d\n", saved_def_msgsize);
        printf("\tDefault Queue Size:\t\t%d\n", saved_def_msgs);
    } else {
        printf("\tDefault Message Size:\t\tNot Supported\n");
        printf("\tDefault Queue Size:\t\tNot Supported\n");
    }
    printf("\n");

    validate_current_settings();

    printf("Adjusted system state for testing:\n");
    printf("\tRLIMIT_MSGQUEUE(soft):\t\t%d\n", cur_limits.rlim_cur);
    printf("\tRLIMIT_MSGQUEUE(hard):\t\t%d\n", cur_limits.rlim_max);
    printf("\tMaximum Message Size:\t\t%d\n", cur_max_msgsize);
    printf("\tMaximum Queue Size:\t\t%d\n", cur_max_msgs);
    if (default_settings) {
        printf("\tDefault Message Size:\t\t%d\n", cur_def_msgsize);
        printf("\tDefault Queue Size:\t\t%d\n", cur_def_msgs);
    }

    printf("\n\nTest series 1, behavior when no attr struct "
           "passed to mq_open:\n");
    if (!default_settings) {
        test_queue(NULL, &result);
        printf("Given sane system settings, mq_open without an attr "
               "struct succeeds:\tPASS\n");
        if (result.mq_maxmsg != cur_max_msgs ||
            result.mq_msgsize != cur_max_msgsize) {
            printf("Kernel does not support setting the default "
                   "mq attributes,\nbut also doesn't tie the "
                   "defaults to the maximums:\t\t\tPASS\n");
        } else {
            set(max_msgs, ++cur_max_msgs);
            set(max_msgsize, ++cur_max_msgsize);
            test_queue(NULL, &result);
            if (result.mq_maxmsg == cur_max_msgs &&
                result.mq_msgsize == cur_max_msgsize)
                printf("Kernel does not support setting the "
                       "default mq attributes and\n"
                       "also ties system wide defaults to "
                       "the system wide maximums:\t\t"
                       "FAIL\n");
            else
                printf("Kernel does not support setting the "
                       "default mq attributes,\n"
                       "but also doesn't tie the defaults to "
                       "the maximums:\t\t\tPASS\n");
        }
    } else {
        printf("Kernel supports setting defaults separately from "
               "maximums:\t\tPASS\n");
        /*
         * While we are here, go ahead and test that the kernel
         * properly follows the default settings
         */
        test_queue(NULL, &result);
        printf("Given sane values, mq_open without an attr struct "
               "succeeds:\t\tPASS\n");
        if (result.mq_maxmsg != cur_def_msgs ||
            result.mq_msgsize != cur_def_msgsize)
            printf("Kernel supports setting defaults, but does "
                   "not actually honor them:\tFAIL\n\n");
        else {
            set(def_msgs, ++cur_def_msgs);
            set(def_msgsize, ++cur_def_msgsize);
            /* In case max was the same as the default */
            set(max_msgs, ++cur_max_msgs);
            set(max_msgsize, ++cur_max_msgsize);
            test_queue(NULL, &result);
            if (result.mq_maxmsg != cur_def_msgs ||
                result.mq_msgsize != cur_def_msgsize)
                printf("Kernel supports setting defaults, but "
                       "does not actually honor them:\t"
                       "FAIL\n");
            else
                printf("Kernel properly honors default setting "
                       "knobs:\t\t\t\tPASS\n");
        }
        set(def_msgs, cur_max_msgs + 1);
        cur_def_msgs = cur_max_msgs + 1;
        set(def_msgsize, cur_max_msgsize + 1);
        cur_def_msgsize = cur_max_msgsize + 1;
        if (cur_def_msgs * (cur_def_msgsize + 2 * sizeof(void *)) >=
            cur_limits.rlim_cur) {
            cur_limits.rlim_cur = (cur_def_msgs + 2) *
                (cur_def_msgsize + 2 * sizeof(void *));
            cur_limits.rlim_max = 2 * cur_limits.rlim_cur;
            setr(RLIMIT_MSGQUEUE, &cur_limits);
        }
        if (test_queue_fail(NULL, &result)) {
            if (result.mq_maxmsg == cur_max_msgs &&
                result.mq_msgsize == cur_max_msgsize)
                printf("Kernel properly limits default values "
                       "to lesser of default/max:\t\tPASS\n");
            else
                printf("Kernel does not properly set default "
                       "queue parameters when\ndefaults > "
                       "max:\t\t\t\t\t\t\t\tFAIL\n");
        } else
            printf("Kernel fails to open mq because defaults are "
                   "greater than maximums:\tFAIL\n");
        set(def_msgs, --cur_def_msgs);
        set(def_msgsize, --cur_def_msgsize);
        cur_limits.rlim_cur = cur_limits.rlim_max = cur_def_msgs *
            cur_def_msgsize;
        setr(RLIMIT_MSGQUEUE, &cur_limits);
        if (test_queue_fail(NULL, &result))
            printf("Kernel creates queue even though defaults "
                   "would exceed\nrlimit setting:"
                   "\t\t\t\t\t\t\t\tFAIL\n");
        else
            printf("Kernel properly fails to create queue when "
                   "defaults would\nexceed rlimit:"
                   "\t\t\t\t\t\t\t\tPASS\n");
    }

    /*
     * Test #2 - open with an attr struct that exceeds rlimit
     */
    printf("\n\nTest series 2, behavior when attr struct is "
           "passed to mq_open:\n");
    cur_max_msgs = 32;
    cur_max_msgsize = cur_limits.rlim_max >> 4;
    set(max_msgs, cur_max_msgs);
    set(max_msgsize, cur_max_msgsize);
    attr.mq_maxmsg = cur_max_msgs;
    attr.mq_msgsize = cur_max_msgsize;
    if (test_queue_fail(&attr, &result))
        printf("Queue open in excess of rlimit max when euid = 0 "
               "succeeded:\t\tFAIL\n");
    else
        printf("Queue open in excess of rlimit max when euid = 0 "
               "failed:\t\tPASS\n");
    attr.mq_maxmsg = cur_max_msgs + 1;
    attr.mq_msgsize = 10;
    if (test_queue_fail(&attr, &result))
        printf("Queue open with mq_maxmsg > limit when euid = 0 "
               "succeeded:\t\tPASS\n");
    else
        printf("Queue open with mq_maxmsg > limit when euid = 0 "
               "failed:\t\tFAIL\n");
    attr.mq_maxmsg = 1;
    attr.mq_msgsize = cur_max_msgsize + 1;
    if (test_queue_fail(&attr, &result))
        printf("Queue open with mq_msgsize > limit when euid = 0 "
               "succeeded:\t\tPASS\n");
    else
        printf("Queue open with mq_msgsize > limit when euid = 0 "
               "failed:\t\tFAIL\n");
    attr.mq_maxmsg = 65536;
    attr.mq_msgsize = 65536;
    if (test_queue_fail(&attr, &result))
        printf("Queue open with total size > 2GB when euid = 0 "
               "succeeded:\t\tFAIL\n");
    else
        printf("Queue open with total size > 2GB when euid = 0 "
               "failed:\t\t\tPASS\n");
    seteuid(99);
    attr.mq_maxmsg = cur_max_msgs;
    attr.mq_msgsize = cur_max_msgsize;
    if (test_queue_fail(&attr, &result))
        printf("Queue open in excess of rlimit max when euid = 99 "
               "succeeded:\t\tFAIL\n");
    else
        printf("Queue open in excess of rlimit max when euid = 99 "
               "failed:\t\tPASS\n");
    attr.mq_maxmsg = cur_max_msgs + 1;
    attr.mq_msgsize = 10;
    if (test_queue_fail(&attr, &result))
        printf("Queue open with mq_maxmsg > limit when euid = 99 "
               "succeeded:\t\tFAIL\n");
    else
        printf("Queue open with mq_maxmsg > limit when euid = 99 "
               "failed:\t\tPASS\n");
    attr.mq_maxmsg = 1;
    attr.mq_msgsize = cur_max_msgsize + 1;
    if (test_queue_fail(&attr, &result))
        printf("Queue open with mq_msgsize > limit when euid = 99 "
               "succeeded:\t\tFAIL\n");
    else
        printf("Queue open with mq_msgsize > limit when euid = 99 "
               "failed:\t\tPASS\n");
    attr.mq_maxmsg = 65536;
    attr.mq_msgsize = 65536;
    if (test_queue_fail(&attr, &result))
        printf("Queue open with total size > 2GB when euid = 99 "
               "succeeded:\t\tFAIL\n");
    else
        printf("Queue open with total size > 2GB when euid = 99 "
               "failed:\t\t\tPASS\n");

    shutdown(0,"",0);
}