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vlc/modules/access/sftp.c
Steve Lhomme df1ee8c9e5 sftp: fix usage of NULL config_GetUserDir result
2022-09-02 07:53:46 +00:00

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/*****************************************************************************
* sftp.c: SFTP input module
*****************************************************************************
* Copyright (C) 2009 VLC authors and VideoLAN
*
* Authors: Rémi Duraffort <ivoire@videolan.org>
* Petri Hintukainen <phintuka@gmail.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This program 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
*****************************************************************************/
/*****************************************************************************
* Preamble
*****************************************************************************/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <vlc_common.h>
#include <vlc_plugin.h>
#include <assert.h>
#include <vlc_access.h>
#include <vlc_input_item.h>
#include <vlc_network.h>
#include <vlc_url.h>
#include <vlc_keystore.h>
#include <libssh2.h>
#include <libssh2_sftp.h>
/*****************************************************************************
* Module descriptor
*****************************************************************************/
static int Open ( vlc_object_t* );
static void Close( vlc_object_t* );
#define PORT_TEXT N_("SFTP port")
#define PORT_LONGTEXT N_("SFTP port number to use on the server")
#define USER_TEXT N_("Username")
#define USER_LONGTEXT N_("Username that will be used for the connection, " \
"if no username is set in the URL.")
#define PASS_TEXT N_("Password")
#define PASS_LONGTEXT N_("Password that will be used for the connection, " \
"if no username or password are set in URL.")
#define PRIVATEKEY_TEXT N_("Private key file")
#define PRIVATEKEY_LONGTEXT N_("Private-key file used for SSH public key authentication. "\
"Public-key file is assumed to be in the same directory with '.pub' appended. "\
"If unset, standard key paths will be attempted (e.g. '~/.ssh/id_rsa').")
vlc_module_begin ()
set_shortname( "SFTP" )
set_description( N_("SFTP input") )
set_capability( "access", 0 )
set_subcategory( SUBCAT_INPUT_ACCESS )
add_integer( "sftp-port", 22, PORT_TEXT, PORT_LONGTEXT )
add_string( "sftp-user", NULL, USER_TEXT, USER_LONGTEXT )
add_password("sftp-pwd", NULL, PASS_TEXT, PASS_LONGTEXT)
add_loadfile("sftp-privatekey", NULL, PRIVATEKEY_TEXT, PRIVATEKEY_LONGTEXT)
add_shortcut( "sftp" )
set_callbacks( Open, Close )
vlc_module_end ()
/*****************************************************************************
* Local prototypes
*****************************************************************************/
static ssize_t Read( stream_t *, void *, size_t );
static int Seek( stream_t *, uint64_t );
static int Control( stream_t *, int, va_list );
static int DirRead( stream_t *, input_item_node_t * );
typedef struct
{
int i_socket;
LIBSSH2_SESSION* ssh_session;
LIBSSH2_SFTP* sftp_session;
LIBSSH2_SFTP_HANDLE* file;
uint64_t filesize;
char *psz_base_url;
} access_sys_t;
static int AuthKeyAgent( stream_t *p_access, const char *psz_username )
{
access_sys_t* p_sys = p_access->p_sys;
int i_result = VLC_EGENERIC;
LIBSSH2_AGENT *p_sshagent = NULL;
struct libssh2_agent_publickey *p_identity = NULL,
*p_prev_identity = NULL;
if( !psz_username || !psz_username[0] )
return i_result;
p_sshagent = libssh2_agent_init( p_sys->ssh_session );
if( !p_sshagent )
{
msg_Dbg( p_access, "Failed to initialize key agent" );
goto bailout;
}
if( libssh2_agent_connect( p_sshagent ) )
{
msg_Dbg( p_access, "Failed to connect key agent" );
goto bailout;
}
if( libssh2_agent_list_identities( p_sshagent ) )
{
msg_Dbg( p_access, "Failed to request identities" );
goto bailout;
}
while( libssh2_agent_get_identity( p_sshagent, &p_identity, p_prev_identity ) == 0 )
{
msg_Dbg( p_access, "Using key %s", p_identity->comment );
if( libssh2_agent_userauth( p_sshagent, psz_username, p_identity ) == 0 )
{
msg_Info( p_access, "Public key agent authentication succeeded" );
i_result = VLC_SUCCESS;
goto bailout;
}
msg_Dbg( p_access, "Public key agent authentication failed" );
p_prev_identity = p_identity;
}
bailout:
if( p_sshagent )
{
libssh2_agent_disconnect( p_sshagent );
libssh2_agent_free( p_sshagent );
}
return i_result;
}
static int AuthPublicKey( stream_t *p_access, const char *psz_home, const char *psz_username )
{
access_sys_t* p_sys = p_access->p_sys;
char *psz_keyfile1 = NULL;
char *psz_keyfile2 = NULL;
static const char defaultkeys[4][8] = {
"rsa", "ed25519", "ecdsa", "dsa"
};
if( !psz_username || !psz_username[0] )
return VLC_EGENERIC;
psz_keyfile2 = var_InheritString( p_access, "sftp-privatekey" );
/* Attempt public key authentication using user specified key, if specified. */
if ( psz_keyfile2 )
{
if( asprintf( &psz_keyfile1, "%s.pub", psz_keyfile2 ) == -1 )
{
free( psz_keyfile2 );
return VLC_EGENERIC;
}
msg_Dbg( p_access, "Trying paths %s (public) and %s (private) as a possible key pair", psz_keyfile1, psz_keyfile2 );
int res = libssh2_userauth_publickey_fromfile( p_sys->ssh_session, psz_username, psz_keyfile1, psz_keyfile2, NULL );
free( psz_keyfile1 );
free( psz_keyfile2 );
if( !res )
{
msg_Info( p_access, "Public key authentication succeeded" );
return VLC_SUCCESS;
}
msg_Err( p_access, "Public key authentication failed" );
return VLC_EGENERIC;
}
/* If no custom path is provided, try all standard key files. */
for( size_t i = 0; i < ARRAY_SIZE(defaultkeys); i++)
{
if( asprintf( &psz_keyfile1, "%s/.ssh/id_%s.pub", psz_home, defaultkeys[i] ) == -1 )
return VLC_EGENERIC;
if( asprintf( &psz_keyfile2, "%s/.ssh/id_%s", psz_home, defaultkeys[i] ) == -1 )
{
free( psz_keyfile1 );
return VLC_EGENERIC;
}
msg_Dbg( p_access, "Trying paths %s (public) and %s (private) as a possible key pair", psz_keyfile1, psz_keyfile2 );
int res = libssh2_userauth_publickey_fromfile( p_sys->ssh_session, psz_username, psz_keyfile1, psz_keyfile2, NULL );
free( psz_keyfile1 );
free( psz_keyfile2 );
if( !res )
{
msg_Info( p_access, "Public key authentication succeeded" );
return VLC_SUCCESS;
}
msg_Dbg( p_access, "Public key authentication failed" );
}
return VLC_EGENERIC;
}
static void SSHSessionDestroy( stream_t *p_access )
{
access_sys_t* p_sys = p_access->p_sys;
if( p_sys->ssh_session )
{
libssh2_session_free( p_sys->ssh_session );
p_sys->ssh_session = NULL;
}
if( p_sys->i_socket >= 0 )
{
net_Close( p_sys->i_socket );
p_sys->i_socket = -1;
}
}
static int SSHSessionInit( stream_t *p_access, const char *psz_host, int i_port )
{
access_sys_t* p_sys = p_access->p_sys;
/* Connect to the server using a regular socket */
assert( p_sys->i_socket == -1 );
p_sys->i_socket = net_Connect( p_access, psz_host, i_port, SOCK_STREAM,
0 );
if( p_sys->i_socket < 0 )
goto error;
/* Create the ssh connection and wait until the server answer */
p_sys->ssh_session = libssh2_session_init();
if( p_sys->ssh_session == NULL )
goto error;
int i_ret;
while( ( i_ret = libssh2_session_startup( p_sys->ssh_session, p_sys->i_socket ) )
== LIBSSH2_ERROR_EAGAIN );
if( i_ret != 0 )
goto error;
/* Set the socket in non-blocking mode */
libssh2_session_set_blocking( p_sys->ssh_session, 1 );
return VLC_SUCCESS;
error:
msg_Err( p_access, "Impossible to open the connection to %s:%i",
psz_host, i_port );
SSHSessionDestroy( p_access );
return VLC_EGENERIC;
}
/**
* Connect to the sftp server and ask for a file
* @param p_this: the vlc_object
* @return VLC_SUCCESS if everything was fine
*/
static int Open( vlc_object_t* p_this )
{
stream_t* p_access = (stream_t*)p_this;
access_sys_t* p_sys;
vlc_credential credential;
char* psz_path = NULL;
char *psz_session_username = NULL;
char* psz_home = NULL;
int i_port;
vlc_url_t url;
size_t i_len;
int i_type;
int i_result = VLC_EGENERIC;
if( !p_access->psz_location )
return VLC_EGENERIC;
p_sys = p_access->p_sys = vlc_obj_calloc( p_this, 1, sizeof( access_sys_t ) );
if( !p_sys ) return VLC_ENOMEM;
p_sys->i_socket = -1;
/* Parse the URL */
if( vlc_UrlParseFixup( &url, p_access->psz_url ) != 0 )
{
vlc_UrlClean( &url );
return VLC_EGENERIC;
}
vlc_credential_init( &credential, &url );
if( url.psz_path != NULL )
{
psz_path = vlc_uri_decode_duplicate( url.psz_path );
if( psz_path == NULL )
goto error;
}
/* Check for some parameters */
if( EMPTY_STR( url.psz_host ) )
{
msg_Err( p_access, "Unable to extract host from %s", p_access->psz_url );
goto error;
}
if( url.i_port <= 0 )
i_port = var_InheritInteger( p_access, "sftp-port" );
else
i_port = url.i_port;
/* Create the ssh connection and wait until the server answer */
if( SSHSessionInit( p_access, url.psz_host, i_port ) != VLC_SUCCESS )
goto error;
/* List the know hosts */
LIBSSH2_KNOWNHOSTS *ssh_knownhosts = libssh2_knownhost_init( p_sys->ssh_session );
if( !ssh_knownhosts )
goto error;
psz_home = config_GetUserDir( VLC_HOME_DIR );
if (likely(psz_home != NULL))
{
char *psz_knownhosts_file;
if( asprintf( &psz_knownhosts_file, "%s/.ssh/known_hosts", psz_home ) != -1 )
{
if( libssh2_knownhost_readfile( ssh_knownhosts, psz_knownhosts_file,
LIBSSH2_KNOWNHOST_FILE_OPENSSH ) < 0 )
msg_Err( p_access, "Failure reading known_hosts '%s'", psz_knownhosts_file );
free( psz_knownhosts_file );
}
free( psz_home );
}
const char *fingerprint = libssh2_session_hostkey( p_sys->ssh_session, &i_len, &i_type );
struct libssh2_knownhost *host;
int knownhost_fingerprint_algo;
switch( i_type )
{
case LIBSSH2_HOSTKEY_TYPE_RSA:
knownhost_fingerprint_algo = LIBSSH2_KNOWNHOST_KEY_SSHRSA;
break;
case LIBSSH2_HOSTKEY_TYPE_DSS:
knownhost_fingerprint_algo = LIBSSH2_KNOWNHOST_KEY_SSHDSS;
break;
#if LIBSSH2_VERSION_NUM >= 0x010900
case LIBSSH2_HOSTKEY_TYPE_ECDSA_256:
knownhost_fingerprint_algo = LIBSSH2_KNOWNHOST_KEY_ECDSA_256;
break;
case LIBSSH2_HOSTKEY_TYPE_ECDSA_384:
knownhost_fingerprint_algo = LIBSSH2_KNOWNHOST_KEY_ECDSA_384;
break;
case LIBSSH2_HOSTKEY_TYPE_ECDSA_521:
knownhost_fingerprint_algo = LIBSSH2_KNOWNHOST_KEY_ECDSA_521;
break;
case LIBSSH2_HOSTKEY_TYPE_ED25519:
knownhost_fingerprint_algo = LIBSSH2_KNOWNHOST_KEY_ED25519;
break;
#endif
default:
msg_Err( p_access, "Host uses unrecognized session-key algorithm" );
libssh2_knownhost_free( ssh_knownhosts );
goto error;
}
#if LIBSSH2_VERSION_NUM >= 0x010206
int check = libssh2_knownhost_checkp( ssh_knownhosts, url.psz_host, i_port,
fingerprint, i_len,
LIBSSH2_KNOWNHOST_TYPE_PLAIN |
LIBSSH2_KNOWNHOST_KEYENC_RAW |
knownhost_fingerprint_algo,
&host );
#else
int check = libssh2_knownhost_check( ssh_knownhosts, url.psz_host,
fingerprint, i_len,
LIBSSH2_KNOWNHOST_TYPE_PLAIN |
LIBSSH2_KNOWNHOST_KEYENC_RAW |
knownhost_fingerprint_algo,
&host );
#endif
libssh2_knownhost_free( ssh_knownhosts );
/* Check that it does match or at least that the host is unknown */
switch(check)
{
case LIBSSH2_KNOWNHOST_CHECK_FAILURE:
case LIBSSH2_KNOWNHOST_CHECK_NOTFOUND:
msg_Dbg( p_access, "Unable to check the remote host" );
break;
case LIBSSH2_KNOWNHOST_CHECK_MATCH:
msg_Dbg( p_access, "Successfully matched the host" );
break;
case LIBSSH2_KNOWNHOST_CHECK_MISMATCH:
msg_Err( p_access, "The host does not match !! The remote key changed !!" );
goto error;
}
if (vlc_credential_get( &credential, p_access, "sftp-user", "sftp-pwd",
NULL, NULL) == -EINTR)
goto error;
char* psz_userauthlist = NULL;
bool b_publickey_tried = false;
do
{
if (!credential.psz_username || !credential.psz_username[0])
continue;
if( !psz_session_username )
{
psz_session_username = strdup( credential.psz_username );
psz_userauthlist =
libssh2_userauth_list( p_sys->ssh_session, credential.psz_username,
strlen( credential.psz_username ) );
}
else if( strcmp( psz_session_username, credential.psz_username ) != 0 )
{
msg_Warn( p_access, "The username changed, starting a new ssh session" );
SSHSessionDestroy( p_access );
if( SSHSessionInit( p_access, url.psz_host, i_port ) != VLC_SUCCESS )
goto error;
b_publickey_tried = false;
free( psz_session_username );
psz_session_username = strdup( credential.psz_username );
psz_userauthlist =
libssh2_userauth_list( p_sys->ssh_session, credential.psz_username,
strlen( credential.psz_username ) );
}
if( !psz_session_username || !psz_userauthlist )
goto error;
/* TODO: Follow PreferredAuthentications in ssh_config */
if( strstr( psz_userauthlist, "publickey" ) != NULL && !b_publickey_tried )
{
/* Don't try public key multiple times to avoid getting black
* listed */
b_publickey_tried = true;
if( AuthKeyAgent( p_access, credential.psz_username ) == VLC_SUCCESS
|| AuthPublicKey( p_access, psz_home, credential.psz_username ) == VLC_SUCCESS )
break;
}
if( strstr( psz_userauthlist, "password" ) != NULL
&& credential.psz_password != NULL
&& libssh2_userauth_password( p_sys->ssh_session,
credential.psz_username,
credential.psz_password ) == 0 )
{
vlc_credential_store( &credential, p_access );
break;
}
msg_Warn( p_access, "sftp auth failed for %s", credential.psz_username );
} while( vlc_credential_get( &credential, p_access, "sftp-user", "sftp-pwd",
_("SFTP authentication"),
_("Please enter a valid login and password for "
"the SFTP connection to %s"), url.psz_host ) == 0 );
/* Create the sftp session */
p_sys->sftp_session = libssh2_sftp_init( p_sys->ssh_session );
if( !p_sys->sftp_session )
{
msg_Err( p_access, "Unable to initialize the SFTP session" );
goto error;
}
/* No path, default to user Home */
char *base_url_tmp;
if( !psz_path )
{
const size_t i_size = 1024;
int i_read;
char* psz_remote_home = malloc( i_size );
if( !psz_remote_home )
goto error;
i_read = libssh2_sftp_symlink_ex( p_sys->sftp_session, ".", 1,
psz_remote_home, i_size - 1,
LIBSSH2_SFTP_REALPATH );
if( i_read <= 0 )
{
msg_Err( p_access, "Impossible to get the Home directory" );
free( psz_remote_home );
goto error;
}
psz_remote_home[i_read] = '\0';
psz_path = psz_remote_home;
/* store base url for directory read */
char *base = vlc_path2uri( psz_path, "sftp" );
if( !base )
goto error;
if( -1 == asprintf( &base_url_tmp, "sftp://%s%s", p_access->psz_location, base + 7 ) )
{
free( base );
goto error;
}
p_sys->psz_base_url = base_url_tmp;
free( base );
}
/* Get some information */
LIBSSH2_SFTP_ATTRIBUTES attributes;
if( libssh2_sftp_stat( p_sys->sftp_session, psz_path, &attributes ) )
{
msg_Err( p_access, "Impossible to get information about the remote path %s", psz_path );
goto error;
}
if( !LIBSSH2_SFTP_S_ISDIR( attributes.permissions ))
{
/* Open the given file */
p_sys->file = libssh2_sftp_open( p_sys->sftp_session, psz_path, LIBSSH2_FXF_READ, 0 );
p_sys->filesize = attributes.filesize;
ACCESS_SET_CALLBACKS( Read, NULL, Control, Seek );
}
else
{
/* Open the given directory */
p_sys->file = libssh2_sftp_opendir( p_sys->sftp_session, psz_path );
p_access->pf_readdir = DirRead;
p_access->pf_control = access_vaDirectoryControlHelper;
if( !p_sys->psz_base_url )
{
if( asprintf( &base_url_tmp, "sftp://%s", p_access->psz_location ) == -1 )
goto error;
p_sys->psz_base_url = base_url_tmp;
/* trim trailing '/' */
size_t len = strlen( p_sys->psz_base_url );
if( len > 0 && p_sys->psz_base_url[ len - 1 ] == '/' )
p_sys->psz_base_url[ len - 1 ] = 0;
}
}
if( !p_sys->file )
{
msg_Err( p_access, "Unable to open the remote path %s", psz_path );
goto error;
}
i_result = VLC_SUCCESS;
error:
free( psz_session_username );
free( psz_path );
vlc_credential_clean( &credential );
vlc_UrlClean( &url );
if( i_result != VLC_SUCCESS ) {
Close( p_this );
}
return i_result;
}
/* Close: quit the module */
static void Close( vlc_object_t* p_this )
{
stream_t* p_access = (stream_t*)p_this;
access_sys_t* p_sys = p_access->p_sys;
if( p_sys->file )
libssh2_sftp_close_handle( p_sys->file );
if( p_sys->sftp_session )
libssh2_sftp_shutdown( p_sys->sftp_session );
SSHSessionDestroy( p_access );
free( p_sys->psz_base_url );
}
static ssize_t Read( stream_t *p_access, void *buf, size_t len )
{
access_sys_t *p_sys = p_access->p_sys;
ssize_t val = libssh2_sftp_read( p_sys->file, buf, len );
if( val < 0 )
{
msg_Err( p_access, "read failed" );
return 0;
}
return val;
}
static int Seek( stream_t* p_access, uint64_t i_pos )
{
access_sys_t *sys = p_access->p_sys;
libssh2_sftp_seek( sys->file, i_pos );
return VLC_SUCCESS;
}
static int Control( stream_t* p_access, int i_query, va_list args )
{
access_sys_t *sys = p_access->p_sys;
bool* pb_bool;
switch( i_query )
{
case STREAM_CAN_SEEK:
pb_bool = va_arg( args, bool * );
*pb_bool = true;
break;
case STREAM_CAN_FASTSEEK:
pb_bool = va_arg( args, bool * );
*pb_bool = false;
break;
case STREAM_CAN_PAUSE:
case STREAM_CAN_CONTROL_PACE:
pb_bool = va_arg( args, bool * );
*pb_bool = true;
break;
case STREAM_GET_SIZE:
if( p_access->pf_readdir != NULL )
return VLC_EGENERIC;
*va_arg( args, uint64_t * ) = sys->filesize;
break;
case STREAM_GET_PTS_DELAY:
*va_arg( args, vlc_tick_t * ) =
VLC_TICK_FROM_MS(var_InheritInteger( p_access, "network-caching" ));
break;
case STREAM_SET_PAUSE_STATE:
break;
default:
return VLC_EGENERIC;
}
return VLC_SUCCESS;
}
/*****************************************************************************
* Directory access
*****************************************************************************/
static int DirRead (stream_t *p_access, input_item_node_t *p_current_node)
{
access_sys_t *p_sys = p_access->p_sys;
LIBSSH2_SFTP_ATTRIBUTES attrs;
int i_ret = VLC_SUCCESS;
int err;
/* Allocate 1024 bytes for file name. Longer names are skipped.
* libssh2 does not support seeking in directory streams.
* Retrying with larger buffer is possible, but would require
* re-opening the directory stream.
*/
size_t i_size = 1024;
char *psz_file = malloc( i_size );
if( !psz_file )
return VLC_ENOMEM;
struct vlc_readdir_helper rdh;
vlc_readdir_helper_init( &rdh, p_access, p_current_node );
while( i_ret == VLC_SUCCESS
&& 0 != ( err = libssh2_sftp_readdir( p_sys->file, psz_file, i_size, &attrs ) ) )
{
if( err < 0 )
{
if( err == LIBSSH2_ERROR_BUFFER_TOO_SMALL )
{
/* seeking back is not possible ... */
msg_Dbg( p_access, "skipped too long file name" );
continue;
}
if( err == LIBSSH2_ERROR_EAGAIN )
{
continue;
}
msg_Err( p_access, "directory read failed" );
break;
}
/* Create an input item for the current entry */
char *psz_full_uri, *psz_uri;
psz_uri = vlc_uri_encode( psz_file );
if( psz_uri == NULL )
{
i_ret = VLC_ENOMEM;
break;
}
if( asprintf( &psz_full_uri, "%s/%s", p_sys->psz_base_url, psz_uri ) == -1 )
{
free( psz_uri );
i_ret = VLC_ENOMEM;
break;
}
free( psz_uri );
int i_type = LIBSSH2_SFTP_S_ISDIR( attrs.permissions ) ? ITEM_TYPE_DIRECTORY : ITEM_TYPE_FILE;
input_item_t *p_item;
i_ret = vlc_readdir_helper_additem( &rdh, psz_full_uri, NULL, psz_file,
i_type, ITEM_NET, &p_item );
if (i_ret == VLC_SUCCESS && p_item)
{
input_item_AddStat(p_item, "mtime", attrs.mtime);
input_item_AddStat(p_item, "size", attrs.filesize);
}
free( psz_full_uri );
}
vlc_readdir_helper_finish( &rdh, i_ret == VLC_SUCCESS );
free( psz_file );
return i_ret;
}
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