Apache2 can't load mod_dav_fs.so #2479

flxchn · 2018-06-01T02:24:14Z

Clean install apache2.
Open /data/data/com.termux/files/usr/etc/apache2/httpd.conf
Change

#LoadModule dav_module libexec/apache2/mod_dav.so
#LoadModule dav_fs_module libexec/apache2/mod_dav_fs.so
#LoadModule dav_lock_module libexec/apache2/mod_dav_lock.so

To

LoadModule dav_module libexec/apache2/mod_dav.so
LoadModule dav_fs_module libexec/apache2/mod_dav_fs.so
LoadModule dav_lock_module libexec/apache2/mod_dav_lock.so

Save, Run

$ httpd -t
httpd: Syntax error on line 168 of /data/data/com.termux/files/usr/etc/apache2/httpd.conf: Cannot load libexec/apache2/mod_dav_fs.so into server: dlopen failed: cannot locate symbol "dav_hook_gather_propsets" referenced by "mod_dav_fs.so"...

fornwall · 2018-06-06T01:28:48Z

Thanks for reporting! Which Android version are you running?

flxchn · 2018-06-06T11:40:45Z

I'm running android 5.1.1

$ uname
Linux localhost 3.14.29 #2 SMP PREEMPT Sat May 7 19:48:29 CST 2016 aarch64 GNU/Linux
$ getprop
[ro.product.cpu.abi2]: [armeabi]
[ro.product.cpu.abi]: [armeabi-v7a]
[ro.product.cpu.abilist32]: [armeabi-v7a,armeabi]
[ro.product.cpu.abilist64]: []
[ro.product.cpu.abilist]: [armeabi-v7a,armeabi]
[ro.product.device]: [p201]
[ro.product.locale.language]: [en]
[ro.product.locale.region]: [US]
[ro.product.manufacturer]: [amlogic]
[ro.product.model]: [MXQPRO]
[ro.product.name]: [p201]

And found other problem.
Apache2 and nginx do not correctly display files larger than 2 GB. I looked up the previous issue, #902, does nginx and Apache2 need update?

fornwall · 2018-06-07T22:59:48Z

Seems to be a problem also on Android 8.1. dav_hook_gather_propsets should be provided by libexec/apache2/mod_dav.so.

Apache2 and nginx do not correctly display files larger than 2 GB. I looked up the previous issue, #902, does nginx and Apache2 need update?

It's a problem with -D_FILE_OFFSET_BITS=64 not working on 32-bit Android prior to Android 7.0, so the packages are not yet built with that enabled.

tomty89 · 2018-06-07T23:31:19Z

It's just android/ndk#201 again.

$ sed -i "s/#LoadModule dav_lock_module/LoadModule dav_lock_module/" ../usr/etc/apache2/httpd.conf
$ httpd                                                                            
httpd: Syntax error on line 170 of /data/data/com.termux/files/usr/etc/apache2/httpd.conf: Cannot load libexec/apache2/mod_dav_lock.so into server: dlopen failed: cannot locate symbol "dav_new_error" referenced by "/data/data/com.termux/files/usr/libexec/apache2/mod_dav_lock.so"...
$ sed -i "s/#LoadModule dav_fs_module/LoadModule dav_fs_module/" ../usr/etc/apache2/httpd.conf
$ httpd                                                                            
httpd: Syntax error on line 169 of /data/data/com.termux/files/usr/etc/apache2/httpd.conf: Cannot load libexec/apache2/mod_dav_fs.so into server: dlopen failed: cannot locate symbol "dav_hook_gather_propsets" referenced by "/data/data/com.termux/files/usr/libexec/apache2/mod_dav_fs.so"...
$ LD_PRELOAD=$PREFIX/libexec/apache2/mod_dav.so httpd                              
AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1. Set the 'ServerName' directive globally to suppress this message
$ curl http://localhost:8080                                                       
<html><body><h1>It works!</h1></body></html>
$

fornwall · 2018-06-08T00:03:28Z

@tomty89 But android/ndk#201 is about On Android only the main executable and LD_PRELOADs are considered to be RTLD_GLOBAL, all the dependencies of the main executable remain RTLD_LOCAL - and in this case mod_dav.so contains the symbol, which is not a dependency of the main exectable, right?

So if mod_dav.so is dlopen:ed with RTLD_GLOBAL its symbol should be available for the later dlopen:ed mod_dav_lock.so (at least on Android 6.0+, which supports RTLD_GLOBAL), or am i missing what is happening here?

fornwall · 2018-06-08T00:18:17Z

From looking at apache2 sources, it seems that modules/core/mod_so.c does the module loading:

static const char *dso_load(cmd_parms *cmd, apr_dso_handle_t **modhandlep,
                            const char *filename, const char **used_filename)
{   
    int retry = 0;
    const char *fullname = ap_server_root_relative(cmd->temp_pool, filename);
    char my_error[256];
    if (filename != NULL && ap_strchr_c(filename, '/') == NULL) {
        /* retry on error without path to use dlopen()'s search path */
        retry = 1;
    }
    
    if (fullname == NULL && !retry) {
        return apr_psprintf(cmd->temp_pool, "Invalid %s path %s",
                            cmd->cmd->name, filename);
    }
    *used_filename = fullname;
    if (apr_dso_load(modhandlep, fullname, cmd->pool) == APR_SUCCESS) {
        return NULL;
    }
    if (retry) {
        *used_filename = filename;
        if (apr_dso_load(modhandlep, filename, cmd->pool) == APR_SUCCESS)
            return NULL;
    }
    
    return apr_pstrcat(cmd->temp_pool, "Cannot load ", filename,
                        " into server: ",
                        apr_dso_error(*modhandlep, my_error, sizeof(my_error)),
                        NULL);
}

Here we can see the Cannot load $filename into server: log message. So it loads the module with apr_dso_load() from apr, which there is defined in dso/unix/dso.c to use RTLD_GLOBAL as:

APR_DECLARE(apr_status_t) apr_dso_load(apr_dso_handle_t **res_handle,·
                                       const char *path, apr_pool_t *pool)
{
#if defined(DSO_USE_SHL)
    shl_t os_handle = shl_load(path, BIND_IMMEDIATE, 0L);

#elif defined(DSO_USE_DYLD)
    [...]
#elif defined(DSO_USE_DLFCN)
#if defined(OSF1) || defined(SEQUENT) || defined(SNI) ||\
    (defined(__FreeBSD_version) && (__FreeBSD_version >= 220000)) ||\
    defined(__DragonFly__)
    void *os_handle = dlopen((char *)path, RTLD_NOW | RTLD_GLOBAL);

#else
    int flags = RTLD_NOW | RTLD_GLOBAL;
    void *os_handle;
#ifdef _AIX
    if (strchr(path + 1, '(') && path[strlen(path) - 1] == ')')
    {
        /* This special archive.a(dso.so) syntax is required for
         * the way libtool likes to build shared libraries on AIX.
         * dlopen() support for such a library requires that the
         * RTLD_MEMBER flag be enabled.
         */
        flags |= RTLD_MEMBER;
    }
#endif
    os_handle = dlopen(path, flags);
#endif····
#endif /* DSO_USE_x */

    *res_handle = apr_pcalloc(pool, sizeof(**res_handle));

    if(os_handle == NULL) {
#if defined(DSO_USE_SHL)
        (*res_handle)->errormsg = strerror(errno);
        return APR_EDSOOPEN;
#elif defined(DSO_USE_DYLD)
        (*res_handle)->errormsg = (err_msg) ? err_msg : "link failed";
        return APR_EDSOOPEN;
#elif defined(DSO_USE_DLFCN)
        (*res_handle)->errormsg = dlerror();
        return APR_EDSOOPEN;
#endif
    }

    (*res_handle)->handle = (void*)os_handle;
    (*res_handle)->pool = pool;
    (*res_handle)->errormsg = NULL;

    apr_pool_cleanup_register(pool, *res_handle, dso_cleanup, apr_pool_cleanup_null);

    return APR_SUCCESS;
}

vishalbiswas · 2018-06-08T03:56:18Z

3 options:

LD_PRELOAD the dependency
Use patchelf to explicitly state dependency.
Use static modules.

PS: This is exactly what's happening to php modules.

stale · 2021-11-18T18:55:42Z

This issue/PR has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

xtkoba · 2021-11-22T21:10:19Z

Another option will be to complement DT_NEEDED and DT_RUNPATH with ld options --as-needed and -rpath respectively. The effect should be the same as when using patchelf.

xtkoba · 2021-11-22T22:48:17Z

Other dependencies for currently built modules:

mod_cache_*.so needs mod_cache.so
mod_dav_*.so needs mod_dav.so
mod_heartbeat.so needs mod_watchdog.so
mod_proxy_*.so needs mod_proxy.so
mod_session_*.so needs mod_session.so

xtkoba · 2021-11-24T00:30:50Z

PR #8049 is based on #2479 (comment) and is rather hacky, but at least it works:

$ readelf -Wa libexec/apache2/mod_dav_fs.so | egrep '(RUNPATH|NEEDED)'
 0x000000000000001d (RUNPATH)            Library runpath: [/data/data/com.termux/files/usr/lib:/data/data/com.termux/files/usr/libexec/apache2]
 0x0000000000000001 (NEEDED)             Shared library: [libandroid-support.so]
 0x0000000000000001 (NEEDED)             Shared library: [libapr-1.so]
 0x0000000000000001 (NEEDED)             Shared library: [libaprutil-1.so]
 0x0000000000000001 (NEEDED)             Shared library: [mod_dav.so]
 0x0000000000000001 (NEEDED)             Shared library: [libc.so]

fornwall added the bug report Something is not working properly label Jun 8, 2018

ghost added the help wanted Help is wanted in order to solve the issue label May 6, 2020

This was referenced Jul 21, 2020

apache2 forward proxy #5166

Closed

Apache Unable to load PHP OPCache extension #5482

Closed

stale bot added the wontfix Issue won't be fixed label Nov 18, 2021

stale bot removed the wontfix Issue won't be fixed label Nov 22, 2021

This was referenced Nov 22, 2021

apache2: Set DT_NEEDED for modules #8043

Closed

apache2: Fix DT_NEEDED and DT_RUNPATH for modules #8049

Merged

Grimler91 closed this as completed in #8049 Nov 25, 2021

annpocoyo mentioned this issue Nov 19, 2022

[Bug]: Apache2: PHP: Cannot load extensions without being in LD_PRELOAD #13256

Closed

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Apache2 can't load mod_dav_fs.so #2479

Apache2 can't load mod_dav_fs.so #2479

flxchn commented Jun 1, 2018

fornwall commented Jun 6, 2018

flxchn commented Jun 6, 2018

fornwall commented Jun 7, 2018

tomty89 commented Jun 7, 2018

fornwall commented Jun 8, 2018

fornwall commented Jun 8, 2018

vishalbiswas commented Jun 8, 2018 •

edited

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stale bot commented Nov 18, 2021

xtkoba commented Nov 22, 2021

xtkoba commented Nov 22, 2021

xtkoba commented Nov 24, 2021

Apache2 can't load mod_dav_fs.so #2479

Apache2 can't load mod_dav_fs.so #2479

Comments

flxchn commented Jun 1, 2018

fornwall commented Jun 6, 2018

flxchn commented Jun 6, 2018

fornwall commented Jun 7, 2018

tomty89 commented Jun 7, 2018

fornwall commented Jun 8, 2018

fornwall commented Jun 8, 2018

vishalbiswas commented Jun 8, 2018 • edited Loading

stale bot commented Nov 18, 2021

xtkoba commented Nov 22, 2021

xtkoba commented Nov 22, 2021

xtkoba commented Nov 24, 2021

vishalbiswas commented Jun 8, 2018 •

edited

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