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GUACAMOLE-303: Merge Allow root directory of SFTP filesystem to be configured.

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This commit is contained in:
Nick Couchman 2017-07-03 17:47:05 -04:00
commit 07db9808a0
11 changed files with 332 additions and 18 deletions
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21
src/common-ssh/common-ssh/sftp.h
View File

@ -33,6 +33,11 @@
*/
#define GUAC_COMMON_SSH_SFTP_MAX_PATH 2048
/**
* Maximum number of path components per path.
*/
#define GUAC_COMMON_SSH_SFTP_MAX_DEPTH 1024
/**
* Representation of an SFTP-driven filesystem object. Unlike guac_object, this
* structure is not tied to any particular user.
@ -54,6 +59,11 @@ typedef struct guac_common_ssh_sftp_filesystem {
*/
LIBSSH2_SFTP* sftp_session;
/**
* The path to the directory to expose to the user as a filesystem object.
*/
char root_path[GUAC_COMMON_SSH_SFTP_MAX_PATH];
/**
* The path files will be sent to, if uploaded directly via a "file"
* instruction.
@ -103,15 +113,22 @@ typedef struct guac_common_ssh_sftp_ls_state {
* The session to use to provide SFTP. This session will automatically be
* destroyed when this filesystem is destroyed.
*
* @param root_path
* The path accessible via SFTP to consider the root path of the filesystem
* exposed to the user. Only the contents of this path will be available
* via the filesystem object.
*
* @param name
* The name to send as the name of the filesystem whenever it is exposed
* to a user.
* to a user, or NULL to automatically generate a name from the provided
* root_path.
*
* @return
* A new SFTP filesystem object, not yet exposed to users.
*/
guac_common_ssh_sftp_filesystem* guac_common_ssh_create_sftp_filesystem(
guac_common_ssh_session* session, const char* name);
guac_common_ssh_session* session, const char* root_path,
const char* name);
/**
* Destroys the given filesystem object, disconnecting from SFTP and freeing

259
src/common-ssh/sftp.c
View File

@ -32,6 +32,111 @@
#include <stdlib.h>
#include <string.h>
/**
* Given an arbitrary absolute path, which may contain "..", ".", and
* backslashes, creates an equivalent absolute path which does NOT contain
* relative path components (".." or "."), backslashes, or empty path
* components. With the exception of paths referring to the root directory, the
* resulting path is guaranteed to not contain trailing slashes.
*
* Normalization will fail if the given path is not absolute, is too long, or
* contains more than GUAC_COMMON_SSH_SFTP_MAX_DEPTH path components.
*
* @param fullpath
* The buffer to populate with the normalized path. The normalized path
* will not contain relative path components like ".." or ".", nor will it
* contain backslashes. This buffer MUST be at least
* GUAC_COMMON_SSH_SFTP_MAX_PATH bytes in size.
*
* @param path
* The absolute path to normalize.
*
* @return
* Non-zero if normalization succeeded, zero otherwise.
*/
static int guac_common_ssh_sftp_normalize_path(char* fullpath,
const char* path) {
int i;
int path_depth = 0;
char path_component_data[GUAC_COMMON_SSH_SFTP_MAX_PATH];
const char* path_components[GUAC_COMMON_SSH_SFTP_MAX_DEPTH];
const char** current_path_component = &(path_components[0]);
const char* current_path_component_data = &(path_component_data[0]);
/* If original path is not absolute, normalization fails */
if (path[0] != '\\' && path[0] != '/')
return 1;
/* Skip past leading slash */
path++;
/* Copy path into component data for parsing */
strncpy(path_component_data, path, sizeof(path_component_data) - 1);
/* Find path components within path */
for (i = 0; i < sizeof(path_component_data); i++) {
/* If current character is a path separator, parse as component */
char c = path_component_data[i];
if (c == '/' || c == '\\' || c == '\0') {
/* Terminate current component */
path_component_data[i] = '\0';
/* If component refers to parent, just move up in depth */
if (strcmp(current_path_component_data, "..") == 0) {
if (path_depth > 0)
path_depth--;
}
/* Otherwise, if component not current directory, add to list */
else if (strcmp(current_path_component_data, ".") != 0
&& strcmp(current_path_component_data, "") != 0)
path_components[path_depth++] = current_path_component_data;
/* If end of string, stop */
if (c == '\0')
break;
/* Update start of next component */
current_path_component_data = &(path_component_data[i+1]);
} /* end if separator */
} /* end for each character */
/* If no components, the path is simply root */
if (path_depth == 0) {
strcpy(fullpath, "/");
return 1;
}
/* Ensure last component is null-terminated */
path_component_data[i] = 0;
/* Convert components back into path */
for (; path_depth > 0; path_depth--) {
const char* filename = *(current_path_component++);
/* Add separator */
*(fullpath++) = '/';
/* Copy string */
while (*filename != 0)
*(fullpath++) = *(filename++);
}
/* Terminate absolute path */
*(fullpath++) = 0;
return 1;
}
/**
* Translates the last error message received by the SFTP layer of an SSH
* session into a Guacamole protocol status code.
@ -183,6 +288,73 @@ static int guac_ssh_append_filename(char* fullpath, const char* path,
}
/**
* Concatenates the given paths, separating the two with a single forward
* slash. The full result must be no more than GUAC_COMMON_SSH_SFTP_MAX_PATH
* bytes long, counting null terminator.
*
* @param fullpath
* The buffer to store the result within. This buffer must be at least
* GUAC_COMMON_SSH_SFTP_MAX_PATH bytes long.
*
* @param path_a
* The path to place at the beginning of the resulting path.
*
* @param path_b
* The path to append after path_a within the resulting path.
*
* @return
* Non-zero if the paths were successfully concatenated together, zero
* otherwise.
*/
static int guac_ssh_append_path(char* fullpath, const char* path_a,
const char* path_b) {
int i;
/* Copy path, appending a trailing slash */
for (i = 0; i < GUAC_COMMON_SSH_SFTP_MAX_PATH; i++) {
char c = path_a[i];
if (c == '\0') {
if (i > 0 && path_a[i-1] != '/')
fullpath[i++] = '/';
break;
}
/* Copy character if not end of string */
fullpath[i] = c;
}
/* Skip past leading slashes in second path */
while (*path_b == '/')
path_b++;
/* Append path */
for (; i < GUAC_COMMON_SSH_SFTP_MAX_PATH; i++) {
char c = *(path_b++);
if (c == '\0')
break;
/* Append each character within path */
fullpath[i] = c;
}
/* Verify path length is within maximum */
if (i == GUAC_COMMON_SSH_SFTP_MAX_PATH)
return 0;
/* Terminate path string */
fullpath[i] = '\0';
/* Append was successful */
return 1;
}
/**
* Handler for blob messages which continue an inbound SFTP data transfer
* (upload). The data associated with the given stream is expected to be a
@ -567,6 +739,38 @@ static int guac_common_ssh_sftp_ls_ack_handler(guac_user* user,
}
/**
* Translates a stream name for the given SFTP filesystem object into the
* absolute path corresponding to the actual file it represents.
*
* @param fullpath
* The buffer to populate with the translated path. This buffer MUST be at
* least GUAC_COMMON_SSH_SFTP_MAX_PATH bytes in size.
*
* @param object
* The Guacamole protocol object associated with the SFTP filesystem.
*
* @param name
* The name of the stream (file) to translate into an absolute path.
*
* @return
* Non-zero if translation succeeded, zero otherwise.
*/
static int guac_common_ssh_sftp_translate_name(char* fullpath,
guac_object* object, char* name) {
char normalized_name[GUAC_COMMON_SSH_SFTP_MAX_PATH];
guac_common_ssh_sftp_filesystem* filesystem =
(guac_common_ssh_sftp_filesystem*) object->data;
/* Normalize stream name into a path, and append to the root path */
return guac_common_ssh_sftp_normalize_path(normalized_name, name)
&& guac_ssh_append_path(fullpath, filesystem->root_path,
normalized_name);
}
/**
* Handler for get messages. In context of SFTP and the filesystem exposed via
* the Guacamole protocol, get messages request the body of a file within the
@ -587,16 +791,25 @@ static int guac_common_ssh_sftp_ls_ack_handler(guac_user* user,
static int guac_common_ssh_sftp_get_handler(guac_user* user,
guac_object* object, char* name) {
char fullpath[GUAC_COMMON_SSH_SFTP_MAX_PATH];
guac_common_ssh_sftp_filesystem* filesystem =
(guac_common_ssh_sftp_filesystem*) object->data;
LIBSSH2_SFTP* sftp = filesystem->sftp_session;
LIBSSH2_SFTP_ATTRIBUTES attributes;
/* Translate stream name into filesystem path */
if (!guac_common_ssh_sftp_translate_name(fullpath, object, name)) {
guac_user_log(user, GUAC_LOG_INFO, "Unable to generate real path "
"for stream \"%s\"", name);
return 0;
}
/* Attempt to read file information */
if (libssh2_sftp_stat(sftp, name, &attributes)) {
if (libssh2_sftp_stat(sftp, fullpath, &attributes)) {
guac_user_log(user, GUAC_LOG_INFO, "Unable to read file \"%s\"",
name);
fullpath);
return 0;
}
@ -604,10 +817,10 @@ static int guac_common_ssh_sftp_get_handler(guac_user* user,
if (LIBSSH2_SFTP_S_ISDIR(attributes.permissions)) {
/* Open as directory */
LIBSSH2_SFTP_HANDLE* dir = libssh2_sftp_opendir(sftp, name);
LIBSSH2_SFTP_HANDLE* dir = libssh2_sftp_opendir(sftp, fullpath);
if (dir == NULL) {
guac_user_log(user, GUAC_LOG_INFO,
"Unable to read directory \"%s\"", name);
"Unable to read directory \"%s\"", fullpath);
return 0;
}
@ -638,11 +851,11 @@ static int guac_common_ssh_sftp_get_handler(guac_user* user,
else {
/* Open as normal file */
LIBSSH2_SFTP_HANDLE* file = libssh2_sftp_open(sftp, name,
LIBSSH2_SFTP_HANDLE* file = libssh2_sftp_open(sftp, fullpath,
LIBSSH2_FXF_READ, 0);
if (file == NULL) {
guac_user_log(user, GUAC_LOG_INFO,
"Unable to read file \"%s\"", name);
"Unable to read file \"%s\"", fullpath);
return 0;
}
@ -688,19 +901,28 @@ static int guac_common_ssh_sftp_get_handler(guac_user* user,
static int guac_common_ssh_sftp_put_handler(guac_user* user,
guac_object* object, guac_stream* stream, char* mimetype, char* name) {
char fullpath[GUAC_COMMON_SSH_SFTP_MAX_PATH];
guac_common_ssh_sftp_filesystem* filesystem =
(guac_common_ssh_sftp_filesystem*) object->data;
LIBSSH2_SFTP* sftp = filesystem->sftp_session;
/* Translate stream name into filesystem path */
if (!guac_common_ssh_sftp_translate_name(fullpath, object, name)) {
guac_user_log(user, GUAC_LOG_INFO, "Unable to generate real path "
"for stream \"%s\"", name);
return 0;
}
/* Open file via SFTP */
LIBSSH2_SFTP_HANDLE* file = libssh2_sftp_open(sftp, name,
LIBSSH2_SFTP_HANDLE* file = libssh2_sftp_open(sftp, fullpath,
LIBSSH2_FXF_WRITE | LIBSSH2_FXF_CREAT | LIBSSH2_FXF_TRUNC,
S_IRUSR | S_IWUSR);
/* Acknowledge stream if successful */
if (file != NULL) {
guac_user_log(user, GUAC_LOG_DEBUG, "File \"%s\" opened", name);
guac_user_log(user, GUAC_LOG_DEBUG, "File \"%s\" opened", fullpath);
guac_protocol_send_ack(user->socket, stream, "SFTP: File opened",
GUAC_PROTOCOL_STATUS_SUCCESS);
}
@ -708,7 +930,7 @@ static int guac_common_ssh_sftp_put_handler(guac_user* user,
/* Abort on failure */
else {
guac_user_log(user, GUAC_LOG_INFO,
"Unable to open file \"%s\"", name);
"Unable to open file \"%s\"", fullpath);
guac_protocol_send_ack(user->socket, stream, "SFTP: Open failed",
guac_sftp_get_status(filesystem));
}
@ -756,7 +978,8 @@ guac_object* guac_common_ssh_alloc_sftp_filesystem_object(
}
guac_common_ssh_sftp_filesystem* guac_common_ssh_create_sftp_filesystem(
guac_common_ssh_session* session, const char* name) {
guac_common_ssh_session* session, const char* root_path,
const char* name) {
/* Request SFTP */
LIBSSH2_SFTP* sftp_session = libssh2_sftp_init(session->session);
@ -768,10 +991,24 @@ guac_common_ssh_sftp_filesystem* guac_common_ssh_create_sftp_filesystem(
malloc(sizeof(guac_common_ssh_sftp_filesystem));
/* Associate SSH session with SFTP data and user */
filesystem->name = strdup(name);
filesystem->ssh_session = session;
filesystem->sftp_session = sftp_session;
/* Normalize and store the provided root path */
if (!guac_common_ssh_sftp_normalize_path(filesystem->root_path,
root_path)) {
guac_client_log(session->client, GUAC_LOG_WARNING, "Cannot create "
"SFTP filesystem - \"%s\" is not a valid path.", root_path);
free(filesystem);
return NULL;
}
/* Generate filesystem name from root path if no name is provided */
if (name != NULL)
filesystem->name = strdup(name);
else
filesystem->name = strdup(filesystem->root_path);
/* Initially upload files to current directory */
strcpy(filesystem->upload_path, ".");

4
src/protocols/rdp/rdp.c
View File

@ -987,8 +987,8 @@ void* guac_rdp_client_thread(void* data) {
/* Load and expose filesystem */
rdp_client->sftp_filesystem =
guac_common_ssh_create_sftp_filesystem(
rdp_client->sftp_session, "/");
guac_common_ssh_create_sftp_filesystem(rdp_client->sftp_session,
settings->sftp_root_directory, NULL);
/* Expose filesystem to connection owner */
guac_client_for_owner(client,

13
src/protocols/rdp/rdp_settings.c
View File

@ -84,6 +84,7 @@ const char* GUAC_RDP_CLIENT_ARGS[] = {
"sftp-private-key",
"sftp-passphrase",
"sftp-directory",
"sftp-root-directory",
"sftp-server-alive-interval",
#endif
@ -367,6 +368,12 @@ enum RDP_ARGS_IDX {
*/
IDX_SFTP_DIRECTORY,
/**
* The path of the directory within the SSH server to expose as a
* filesystem guac_object. If omitted, "/" will be used by default.
*/
IDX_SFTP_ROOT_DIRECTORY,
/**
* The interval at which SSH keepalive messages are sent to the server for
* SFTP connections. The default is 0 (disabling keepalives), and a value
@ -784,6 +791,11 @@ guac_rdp_settings* guac_rdp_parse_args(guac_user* user,
guac_user_parse_args_string(user, GUAC_RDP_CLIENT_ARGS, argv,
IDX_SFTP_DIRECTORY, NULL);
/* SFTP root directory */
settings->sftp_root_directory =
guac_user_parse_args_string(user, GUAC_RDP_CLIENT_ARGS, argv,
IDX_SFTP_ROOT_DIRECTORY, "/");
/* Default keepalive value */
settings->sftp_server_alive_interval =
guac_user_parse_args_int(user, GUAC_RDP_CLIENT_ARGS, argv,
@ -909,6 +921,7 @@ void guac_rdp_settings_free(guac_rdp_settings* settings) {
#ifdef ENABLE_COMMON_SSH
/* Free SFTP settings */
free(settings->sftp_directory);
free(settings->sftp_root_directory);
free(settings->sftp_hostname);
free(settings->sftp_passphrase);
free(settings->sftp_password);

6
src/protocols/rdp/rdp_settings.h
View File

@ -360,6 +360,12 @@ typedef struct guac_rdp_settings {
*/
char* sftp_directory;
/**
* The path of the directory within the SSH server to expose as a
* filesystem guac_object.
*/
char* sftp_root_directory;
/**
* The interval at which SSH keepalive messages are sent to the server for
* SFTP connections. The default is 0 (disabling keepalives), and a value

15
src/protocols/ssh/settings.c
View File

@ -37,6 +37,7 @@ const char* GUAC_SSH_CLIENT_ARGS[] = {
"font-name",
"font-size",
"enable-sftp",
"sftp-root-directory",
"private-key",
"passphrase",
#ifdef ENABLE_SSH_AGENT
@ -92,6 +93,12 @@ enum SSH_ARGS_IDX {
*/
IDX_ENABLE_SFTP,
/**
* The path of the directory within the SSH server to expose as a
* filesystem guac_object. If omitted, "/" will be used by default.
*/
IDX_SFTP_ROOT_DIRECTORY,
/**
* The private key to use for authentication, if any.
*/
@ -236,6 +243,11 @@ guac_ssh_settings* guac_ssh_parse_args(guac_user* user,
guac_user_parse_args_boolean(user, GUAC_SSH_CLIENT_ARGS, argv,
IDX_ENABLE_SFTP, false);
/* SFTP root directory */
settings->sftp_root_directory =
guac_user_parse_args_string(user, GUAC_SSH_CLIENT_ARGS, argv,
IDX_SFTP_ROOT_DIRECTORY, "/");
#ifdef ENABLE_SSH_AGENT
settings->enable_agent =
guac_user_parse_args_boolean(user, GUAC_SSH_CLIENT_ARGS, argv,
@ -316,6 +328,9 @@ void guac_ssh_settings_free(guac_ssh_settings* settings) {
/* Free requested command */
free(settings->command);
/* Free SFTP settings */
free(settings->sftp_root_directory);
/* Free typescript settings */
free(settings->typescript_name);
free(settings->typescript_path);

6
src/protocols/ssh/settings.h
View File

@ -145,6 +145,12 @@ typedef struct guac_ssh_settings {
*/
bool enable_sftp;
/**
* The path of the directory within the SSH server to expose as a
* filesystem guac_object.
*/
char* sftp_root_directory;
#ifdef ENABLE_SSH_AGENT
/**
* Whether the SSH agent is enabled.

3
src/protocols/ssh/ssh.c
View File

@ -266,7 +266,8 @@ void* ssh_client_thread(void* data) {
/* Request SFTP */
ssh_client->sftp_filesystem = guac_common_ssh_create_sftp_filesystem(
ssh_client->sftp_session, "/");
ssh_client->sftp_session, settings->sftp_root_directory,
NULL);
/* Expose filesystem to connection owner */
guac_client_for_owner(client,

13
src/protocols/vnc/settings.c
View File

@ -66,6 +66,7 @@ const char* GUAC_VNC_CLIENT_ARGS[] = {
"sftp-private-key",
"sftp-passphrase",
"sftp-directory",
"sftp-root-directory",
"sftp-server-alive-interval",
#endif
@ -229,6 +230,12 @@ enum VNC_ARGS_IDX {
*/
IDX_SFTP_DIRECTORY,
/**
* The path of the directory within the SSH server to expose as a
* filesystem guac_object. If omitted, "/" will be used by default.
*/
IDX_SFTP_ROOT_DIRECTORY,
/**
* The interval at which SSH keepalive messages are sent to the server for
* SFTP connections. The default is 0 (disabling keepalives), and a value
@ -405,6 +412,11 @@ guac_vnc_settings* guac_vnc_parse_args(guac_user* user,
guac_user_parse_args_string(user, GUAC_VNC_CLIENT_ARGS, argv,
IDX_SFTP_DIRECTORY, NULL);
/* SFTP root directory */
settings->sftp_root_directory =
guac_user_parse_args_string(user, GUAC_VNC_CLIENT_ARGS, argv,
IDX_SFTP_ROOT_DIRECTORY, "/");
/* Default keepalive value */
settings->sftp_server_alive_interval =
guac_user_parse_args_int(user, GUAC_VNC_CLIENT_ARGS, argv,
@ -447,6 +459,7 @@ void guac_vnc_settings_free(guac_vnc_settings* settings) {
#ifdef ENABLE_COMMON_SSH
/* Free SFTP settings */
free(settings->sftp_directory);
free(settings->sftp_root_directory);
free(settings->sftp_hostname);
free(settings->sftp_passphrase);
free(settings->sftp_password);

6
src/protocols/vnc/settings.h
View File

@ -174,6 +174,12 @@ typedef struct guac_vnc_settings {
*/
char* sftp_directory;
/**
* The path of the directory within the SSH server to expose as a
* filesystem guac_object.
*/
char* sftp_root_directory;
/**
* The interval at which SSH keepalive messages are sent to the server for
* SFTP connections. The default is 0 (disabling keepalives), and a value

4
src/protocols/vnc/vnc.c
View File

@ -271,8 +271,8 @@ void* guac_vnc_client_thread(void* data) {
/* Load filesystem */
vnc_client->sftp_filesystem =
guac_common_ssh_create_sftp_filesystem(
vnc_client->sftp_session, "/");
guac_common_ssh_create_sftp_filesystem(vnc_client->sftp_session,
settings->sftp_root_directory, NULL);
/* Expose filesystem to connection owner */
guac_client_for_owner(client,