| /* |
| * Secure Shell (ssh) backend for QEMU. |
| * |
| * Copyright (C) 2013 Red Hat Inc., Richard W.M. Jones <rjones@redhat.com> |
| * |
| * 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. |
| */ |
| |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <stdarg.h> |
| |
| #include <libssh2.h> |
| #include <libssh2_sftp.h> |
| |
| #include "block/block_int.h" |
| #include "qemu/error-report.h" |
| #include "qemu/sockets.h" |
| #include "qemu/uri.h" |
| #include "qapi/qmp/qint.h" |
| #include "qapi/qmp/qstring.h" |
| |
| /* DEBUG_SSH=1 enables the DPRINTF (debugging printf) statements in |
| * this block driver code. |
| * |
| * TRACE_LIBSSH2=<bitmask> enables tracing in libssh2 itself. Note |
| * that this requires that libssh2 was specially compiled with the |
| * `./configure --enable-debug' option, so most likely you will have |
| * to compile it yourself. The meaning of <bitmask> is described |
| * here: http://www.libssh2.org/libssh2_trace.html |
| */ |
| #define DEBUG_SSH 0 |
| #define TRACE_LIBSSH2 0 /* or try: LIBSSH2_TRACE_SFTP */ |
| |
| #define DPRINTF(fmt, ...) \ |
| do { \ |
| if (DEBUG_SSH) { \ |
| fprintf(stderr, "ssh: %-15s " fmt "\n", \ |
| __func__, ##__VA_ARGS__); \ |
| } \ |
| } while (0) |
| |
| typedef struct BDRVSSHState { |
| /* Coroutine. */ |
| CoMutex lock; |
| |
| /* SSH connection. */ |
| int sock; /* socket */ |
| LIBSSH2_SESSION *session; /* ssh session */ |
| LIBSSH2_SFTP *sftp; /* sftp session */ |
| LIBSSH2_SFTP_HANDLE *sftp_handle; /* sftp remote file handle */ |
| |
| /* See ssh_seek() function below. */ |
| int64_t offset; |
| bool offset_op_read; |
| |
| /* File attributes at open. We try to keep the .filesize field |
| * updated if it changes (eg by writing at the end of the file). |
| */ |
| LIBSSH2_SFTP_ATTRIBUTES attrs; |
| |
| /* Used to warn if 'flush' is not supported. */ |
| char *hostport; |
| bool unsafe_flush_warning; |
| } BDRVSSHState; |
| |
| static void ssh_state_init(BDRVSSHState *s) |
| { |
| memset(s, 0, sizeof *s); |
| s->sock = -1; |
| s->offset = -1; |
| qemu_co_mutex_init(&s->lock); |
| } |
| |
| static void ssh_state_free(BDRVSSHState *s) |
| { |
| g_free(s->hostport); |
| if (s->sftp_handle) { |
| libssh2_sftp_close(s->sftp_handle); |
| } |
| if (s->sftp) { |
| libssh2_sftp_shutdown(s->sftp); |
| } |
| if (s->session) { |
| libssh2_session_disconnect(s->session, |
| "from qemu ssh client: " |
| "user closed the connection"); |
| libssh2_session_free(s->session); |
| } |
| if (s->sock >= 0) { |
| close(s->sock); |
| } |
| } |
| |
| static void GCC_FMT_ATTR(3, 4) |
| session_error_setg(Error **errp, BDRVSSHState *s, const char *fs, ...) |
| { |
| va_list args; |
| char *msg; |
| |
| va_start(args, fs); |
| msg = g_strdup_vprintf(fs, args); |
| va_end(args); |
| |
| if (s->session) { |
| char *ssh_err; |
| int ssh_err_code; |
| |
| /* This is not an errno. See <libssh2.h>. */ |
| ssh_err_code = libssh2_session_last_error(s->session, |
| &ssh_err, NULL, 0); |
| error_setg(errp, "%s: %s (libssh2 error code: %d)", |
| msg, ssh_err, ssh_err_code); |
| } else { |
| error_setg(errp, "%s", msg); |
| } |
| g_free(msg); |
| } |
| |
| static void GCC_FMT_ATTR(3, 4) |
| sftp_error_setg(Error **errp, BDRVSSHState *s, const char *fs, ...) |
| { |
| va_list args; |
| char *msg; |
| |
| va_start(args, fs); |
| msg = g_strdup_vprintf(fs, args); |
| va_end(args); |
| |
| if (s->sftp) { |
| char *ssh_err; |
| int ssh_err_code; |
| unsigned long sftp_err_code; |
| |
| /* This is not an errno. See <libssh2.h>. */ |
| ssh_err_code = libssh2_session_last_error(s->session, |
| &ssh_err, NULL, 0); |
| /* See <libssh2_sftp.h>. */ |
| sftp_err_code = libssh2_sftp_last_error((s)->sftp); |
| |
| error_setg(errp, |
| "%s: %s (libssh2 error code: %d, sftp error code: %lu)", |
| msg, ssh_err, ssh_err_code, sftp_err_code); |
| } else { |
| error_setg(errp, "%s", msg); |
| } |
| g_free(msg); |
| } |
| |
| static void GCC_FMT_ATTR(2, 3) |
| sftp_error_report(BDRVSSHState *s, const char *fs, ...) |
| { |
| va_list args; |
| |
| va_start(args, fs); |
| error_vprintf(fs, args); |
| |
| if ((s)->sftp) { |
| char *ssh_err; |
| int ssh_err_code; |
| unsigned long sftp_err_code; |
| |
| /* This is not an errno. See <libssh2.h>. */ |
| ssh_err_code = libssh2_session_last_error(s->session, |
| &ssh_err, NULL, 0); |
| /* See <libssh2_sftp.h>. */ |
| sftp_err_code = libssh2_sftp_last_error((s)->sftp); |
| |
| error_printf(": %s (libssh2 error code: %d, sftp error code: %lu)", |
| ssh_err, ssh_err_code, sftp_err_code); |
| } |
| |
| va_end(args); |
| error_printf("\n"); |
| } |
| |
| static int parse_uri(const char *filename, QDict *options, Error **errp) |
| { |
| URI *uri = NULL; |
| QueryParams *qp = NULL; |
| int i; |
| |
| uri = uri_parse(filename); |
| if (!uri) { |
| return -EINVAL; |
| } |
| |
| if (strcmp(uri->scheme, "ssh") != 0) { |
| error_setg(errp, "URI scheme must be 'ssh'"); |
| goto err; |
| } |
| |
| if (!uri->server || strcmp(uri->server, "") == 0) { |
| error_setg(errp, "missing hostname in URI"); |
| goto err; |
| } |
| |
| if (!uri->path || strcmp(uri->path, "") == 0) { |
| error_setg(errp, "missing remote path in URI"); |
| goto err; |
| } |
| |
| qp = query_params_parse(uri->query); |
| if (!qp) { |
| error_setg(errp, "could not parse query parameters"); |
| goto err; |
| } |
| |
| if(uri->user && strcmp(uri->user, "") != 0) { |
| qdict_put(options, "user", qstring_from_str(uri->user)); |
| } |
| |
| qdict_put(options, "host", qstring_from_str(uri->server)); |
| |
| if (uri->port) { |
| qdict_put(options, "port", qint_from_int(uri->port)); |
| } |
| |
| qdict_put(options, "path", qstring_from_str(uri->path)); |
| |
| /* Pick out any query parameters that we understand, and ignore |
| * the rest. |
| */ |
| for (i = 0; i < qp->n; ++i) { |
| if (strcmp(qp->p[i].name, "host_key_check") == 0) { |
| qdict_put(options, "host_key_check", |
| qstring_from_str(qp->p[i].value)); |
| } |
| } |
| |
| query_params_free(qp); |
| uri_free(uri); |
| return 0; |
| |
| err: |
| if (qp) { |
| query_params_free(qp); |
| } |
| if (uri) { |
| uri_free(uri); |
| } |
| return -EINVAL; |
| } |
| |
| static void ssh_parse_filename(const char *filename, QDict *options, |
| Error **errp) |
| { |
| if (qdict_haskey(options, "user") || |
| qdict_haskey(options, "host") || |
| qdict_haskey(options, "port") || |
| qdict_haskey(options, "path") || |
| qdict_haskey(options, "host_key_check")) { |
| error_setg(errp, "user, host, port, path, host_key_check cannot be used at the same time as a file option"); |
| return; |
| } |
| |
| parse_uri(filename, options, errp); |
| } |
| |
| static int check_host_key_knownhosts(BDRVSSHState *s, |
| const char *host, int port, Error **errp) |
| { |
| const char *home; |
| char *knh_file = NULL; |
| LIBSSH2_KNOWNHOSTS *knh = NULL; |
| struct libssh2_knownhost *found; |
| int ret, r; |
| const char *hostkey; |
| size_t len; |
| int type; |
| |
| hostkey = libssh2_session_hostkey(s->session, &len, &type); |
| if (!hostkey) { |
| ret = -EINVAL; |
| session_error_setg(errp, s, "failed to read remote host key"); |
| goto out; |
| } |
| |
| knh = libssh2_knownhost_init(s->session); |
| if (!knh) { |
| ret = -EINVAL; |
| session_error_setg(errp, s, |
| "failed to initialize known hosts support"); |
| goto out; |
| } |
| |
| home = getenv("HOME"); |
| if (home) { |
| knh_file = g_strdup_printf("%s/.ssh/known_hosts", home); |
| } else { |
| knh_file = g_strdup_printf("/root/.ssh/known_hosts"); |
| } |
| |
| /* Read all known hosts from OpenSSH-style known_hosts file. */ |
| libssh2_knownhost_readfile(knh, knh_file, LIBSSH2_KNOWNHOST_FILE_OPENSSH); |
| |
| r = libssh2_knownhost_checkp(knh, host, port, hostkey, len, |
| LIBSSH2_KNOWNHOST_TYPE_PLAIN| |
| LIBSSH2_KNOWNHOST_KEYENC_RAW, |
| &found); |
| switch (r) { |
| case LIBSSH2_KNOWNHOST_CHECK_MATCH: |
| /* OK */ |
| DPRINTF("host key OK: %s", found->key); |
| break; |
| case LIBSSH2_KNOWNHOST_CHECK_MISMATCH: |
| ret = -EINVAL; |
| session_error_setg(errp, s, |
| "host key does not match the one in known_hosts" |
| " (found key %s)", found->key); |
| goto out; |
| case LIBSSH2_KNOWNHOST_CHECK_NOTFOUND: |
| ret = -EINVAL; |
| session_error_setg(errp, s, "no host key was found in known_hosts"); |
| goto out; |
| case LIBSSH2_KNOWNHOST_CHECK_FAILURE: |
| ret = -EINVAL; |
| session_error_setg(errp, s, |
| "failure matching the host key with known_hosts"); |
| goto out; |
| default: |
| ret = -EINVAL; |
| session_error_setg(errp, s, "unknown error matching the host key" |
| " with known_hosts (%d)", r); |
| goto out; |
| } |
| |
| /* known_hosts checking successful. */ |
| ret = 0; |
| |
| out: |
| if (knh != NULL) { |
| libssh2_knownhost_free(knh); |
| } |
| g_free(knh_file); |
| return ret; |
| } |
| |
| static unsigned hex2decimal(char ch) |
| { |
| if (ch >= '0' && ch <= '9') { |
| return (ch - '0'); |
| } else if (ch >= 'a' && ch <= 'f') { |
| return 10 + (ch - 'a'); |
| } else if (ch >= 'A' && ch <= 'F') { |
| return 10 + (ch - 'A'); |
| } |
| |
| return -1; |
| } |
| |
| /* Compare the binary fingerprint (hash of host key) with the |
| * host_key_check parameter. |
| */ |
| static int compare_fingerprint(const unsigned char *fingerprint, size_t len, |
| const char *host_key_check) |
| { |
| unsigned c; |
| |
| while (len > 0) { |
| while (*host_key_check == ':') |
| host_key_check++; |
| if (!qemu_isxdigit(host_key_check[0]) || |
| !qemu_isxdigit(host_key_check[1])) |
| return 1; |
| c = hex2decimal(host_key_check[0]) * 16 + |
| hex2decimal(host_key_check[1]); |
| if (c - *fingerprint != 0) |
| return c - *fingerprint; |
| fingerprint++; |
| len--; |
| host_key_check += 2; |
| } |
| return *host_key_check - '\0'; |
| } |
| |
| static int |
| check_host_key_hash(BDRVSSHState *s, const char *hash, |
| int hash_type, size_t fingerprint_len, Error **errp) |
| { |
| const char *fingerprint; |
| |
| fingerprint = libssh2_hostkey_hash(s->session, hash_type); |
| if (!fingerprint) { |
| session_error_setg(errp, s, "failed to read remote host key"); |
| return -EINVAL; |
| } |
| |
| if(compare_fingerprint((unsigned char *) fingerprint, fingerprint_len, |
| hash) != 0) { |
| error_setg(errp, "remote host key does not match host_key_check '%s'", |
| hash); |
| return -EPERM; |
| } |
| |
| return 0; |
| } |
| |
| static int check_host_key(BDRVSSHState *s, const char *host, int port, |
| const char *host_key_check, Error **errp) |
| { |
| /* host_key_check=no */ |
| if (strcmp(host_key_check, "no") == 0) { |
| return 0; |
| } |
| |
| /* host_key_check=md5:xx:yy:zz:... */ |
| if (strncmp(host_key_check, "md5:", 4) == 0) { |
| return check_host_key_hash(s, &host_key_check[4], |
| LIBSSH2_HOSTKEY_HASH_MD5, 16, errp); |
| } |
| |
| /* host_key_check=sha1:xx:yy:zz:... */ |
| if (strncmp(host_key_check, "sha1:", 5) == 0) { |
| return check_host_key_hash(s, &host_key_check[5], |
| LIBSSH2_HOSTKEY_HASH_SHA1, 20, errp); |
| } |
| |
| /* host_key_check=yes */ |
| if (strcmp(host_key_check, "yes") == 0) { |
| return check_host_key_knownhosts(s, host, port, errp); |
| } |
| |
| error_setg(errp, "unknown host_key_check setting (%s)", host_key_check); |
| return -EINVAL; |
| } |
| |
| static int authenticate(BDRVSSHState *s, const char *user, Error **errp) |
| { |
| int r, ret; |
| const char *userauthlist; |
| LIBSSH2_AGENT *agent = NULL; |
| struct libssh2_agent_publickey *identity; |
| struct libssh2_agent_publickey *prev_identity = NULL; |
| |
| userauthlist = libssh2_userauth_list(s->session, user, strlen(user)); |
| if (strstr(userauthlist, "publickey") == NULL) { |
| ret = -EPERM; |
| error_setg(errp, |
| "remote server does not support \"publickey\" authentication"); |
| goto out; |
| } |
| |
| /* Connect to ssh-agent and try each identity in turn. */ |
| agent = libssh2_agent_init(s->session); |
| if (!agent) { |
| ret = -EINVAL; |
| session_error_setg(errp, s, "failed to initialize ssh-agent support"); |
| goto out; |
| } |
| if (libssh2_agent_connect(agent)) { |
| ret = -ECONNREFUSED; |
| session_error_setg(errp, s, "failed to connect to ssh-agent"); |
| goto out; |
| } |
| if (libssh2_agent_list_identities(agent)) { |
| ret = -EINVAL; |
| session_error_setg(errp, s, |
| "failed requesting identities from ssh-agent"); |
| goto out; |
| } |
| |
| for(;;) { |
| r = libssh2_agent_get_identity(agent, &identity, prev_identity); |
| if (r == 1) { /* end of list */ |
| break; |
| } |
| if (r < 0) { |
| ret = -EINVAL; |
| session_error_setg(errp, s, |
| "failed to obtain identity from ssh-agent"); |
| goto out; |
| } |
| r = libssh2_agent_userauth(agent, user, identity); |
| if (r == 0) { |
| /* Authenticated! */ |
| ret = 0; |
| goto out; |
| } |
| /* Failed to authenticate with this identity, try the next one. */ |
| prev_identity = identity; |
| } |
| |
| ret = -EPERM; |
| error_setg(errp, "failed to authenticate using publickey authentication " |
| "and the identities held by your ssh-agent"); |
| |
| out: |
| if (agent != NULL) { |
| /* Note: libssh2 implementation implicitly calls |
| * libssh2_agent_disconnect if necessary. |
| */ |
| libssh2_agent_free(agent); |
| } |
| |
| return ret; |
| } |
| |
| static int connect_to_ssh(BDRVSSHState *s, QDict *options, |
| int ssh_flags, int creat_mode, Error **errp) |
| { |
| int r, ret; |
| const char *host, *user, *path, *host_key_check; |
| int port; |
| |
| if (!qdict_haskey(options, "host")) { |
| ret = -EINVAL; |
| error_setg(errp, "No hostname was specified"); |
| goto err; |
| } |
| host = qdict_get_str(options, "host"); |
| |
| if (qdict_haskey(options, "port")) { |
| port = qdict_get_int(options, "port"); |
| } else { |
| port = 22; |
| } |
| |
| if (!qdict_haskey(options, "path")) { |
| ret = -EINVAL; |
| error_setg(errp, "No path was specified"); |
| goto err; |
| } |
| path = qdict_get_str(options, "path"); |
| |
| if (qdict_haskey(options, "user")) { |
| user = qdict_get_str(options, "user"); |
| } else { |
| user = g_get_user_name(); |
| if (!user) { |
| error_setg_errno(errp, errno, "Can't get user name"); |
| ret = -errno; |
| goto err; |
| } |
| } |
| |
| if (qdict_haskey(options, "host_key_check")) { |
| host_key_check = qdict_get_str(options, "host_key_check"); |
| } else { |
| host_key_check = "yes"; |
| } |
| |
| /* Construct the host:port name for inet_connect. */ |
| g_free(s->hostport); |
| s->hostport = g_strdup_printf("%s:%d", host, port); |
| |
| /* Open the socket and connect. */ |
| s->sock = inet_connect(s->hostport, errp); |
| if (s->sock < 0) { |
| ret = -errno; |
| goto err; |
| } |
| |
| /* Create SSH session. */ |
| s->session = libssh2_session_init(); |
| if (!s->session) { |
| ret = -EINVAL; |
| session_error_setg(errp, s, "failed to initialize libssh2 session"); |
| goto err; |
| } |
| |
| #if TRACE_LIBSSH2 != 0 |
| libssh2_trace(s->session, TRACE_LIBSSH2); |
| #endif |
| |
| r = libssh2_session_handshake(s->session, s->sock); |
| if (r != 0) { |
| ret = -EINVAL; |
| session_error_setg(errp, s, "failed to establish SSH session"); |
| goto err; |
| } |
| |
| /* Check the remote host's key against known_hosts. */ |
| ret = check_host_key(s, host, port, host_key_check, errp); |
| if (ret < 0) { |
| goto err; |
| } |
| |
| /* Authenticate. */ |
| ret = authenticate(s, user, errp); |
| if (ret < 0) { |
| goto err; |
| } |
| |
| /* Start SFTP. */ |
| s->sftp = libssh2_sftp_init(s->session); |
| if (!s->sftp) { |
| session_error_setg(errp, s, "failed to initialize sftp handle"); |
| ret = -EINVAL; |
| goto err; |
| } |
| |
| /* Open the remote file. */ |
| DPRINTF("opening file %s flags=0x%x creat_mode=0%o", |
| path, ssh_flags, creat_mode); |
| s->sftp_handle = libssh2_sftp_open(s->sftp, path, ssh_flags, creat_mode); |
| if (!s->sftp_handle) { |
| session_error_setg(errp, s, "failed to open remote file '%s'", path); |
| ret = -EINVAL; |
| goto err; |
| } |
| |
| r = libssh2_sftp_fstat(s->sftp_handle, &s->attrs); |
| if (r < 0) { |
| sftp_error_setg(errp, s, "failed to read file attributes"); |
| return -EINVAL; |
| } |
| |
| /* Delete the options we've used; any not deleted will cause the |
| * block layer to give an error about unused options. |
| */ |
| qdict_del(options, "host"); |
| qdict_del(options, "port"); |
| qdict_del(options, "user"); |
| qdict_del(options, "path"); |
| qdict_del(options, "host_key_check"); |
| |
| return 0; |
| |
| err: |
| if (s->sftp_handle) { |
| libssh2_sftp_close(s->sftp_handle); |
| } |
| s->sftp_handle = NULL; |
| if (s->sftp) { |
| libssh2_sftp_shutdown(s->sftp); |
| } |
| s->sftp = NULL; |
| if (s->session) { |
| libssh2_session_disconnect(s->session, |
| "from qemu ssh client: " |
| "error opening connection"); |
| libssh2_session_free(s->session); |
| } |
| s->session = NULL; |
| |
| return ret; |
| } |
| |
| static int ssh_file_open(BlockDriverState *bs, QDict *options, int bdrv_flags, |
| Error **errp) |
| { |
| BDRVSSHState *s = bs->opaque; |
| int ret; |
| int ssh_flags; |
| |
| ssh_state_init(s); |
| |
| ssh_flags = LIBSSH2_FXF_READ; |
| if (bdrv_flags & BDRV_O_RDWR) { |
| ssh_flags |= LIBSSH2_FXF_WRITE; |
| } |
| |
| /* Start up SSH. */ |
| ret = connect_to_ssh(s, options, ssh_flags, 0, errp); |
| if (ret < 0) { |
| goto err; |
| } |
| |
| /* Go non-blocking. */ |
| libssh2_session_set_blocking(s->session, 0); |
| |
| return 0; |
| |
| err: |
| if (s->sock >= 0) { |
| close(s->sock); |
| } |
| s->sock = -1; |
| |
| return ret; |
| } |
| |
| static QemuOptsList ssh_create_opts = { |
| .name = "ssh-create-opts", |
| .head = QTAILQ_HEAD_INITIALIZER(ssh_create_opts.head), |
| .desc = { |
| { |
| .name = BLOCK_OPT_SIZE, |
| .type = QEMU_OPT_SIZE, |
| .help = "Virtual disk size" |
| }, |
| { /* end of list */ } |
| } |
| }; |
| |
| static int ssh_create(const char *filename, QemuOpts *opts, Error **errp) |
| { |
| int r, ret; |
| int64_t total_size = 0; |
| QDict *uri_options = NULL; |
| BDRVSSHState s; |
| ssize_t r2; |
| char c[1] = { '\0' }; |
| |
| ssh_state_init(&s); |
| |
| /* Get desired file size. */ |
| total_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0), |
| BDRV_SECTOR_SIZE); |
| DPRINTF("total_size=%" PRIi64, total_size); |
| |
| uri_options = qdict_new(); |
| r = parse_uri(filename, uri_options, errp); |
| if (r < 0) { |
| ret = r; |
| goto out; |
| } |
| |
| r = connect_to_ssh(&s, uri_options, |
| LIBSSH2_FXF_READ|LIBSSH2_FXF_WRITE| |
| LIBSSH2_FXF_CREAT|LIBSSH2_FXF_TRUNC, |
| 0644, errp); |
| if (r < 0) { |
| ret = r; |
| goto out; |
| } |
| |
| if (total_size > 0) { |
| libssh2_sftp_seek64(s.sftp_handle, total_size-1); |
| r2 = libssh2_sftp_write(s.sftp_handle, c, 1); |
| if (r2 < 0) { |
| sftp_error_setg(errp, &s, "truncate failed"); |
| ret = -EINVAL; |
| goto out; |
| } |
| s.attrs.filesize = total_size; |
| } |
| |
| ret = 0; |
| |
| out: |
| ssh_state_free(&s); |
| if (uri_options != NULL) { |
| QDECREF(uri_options); |
| } |
| return ret; |
| } |
| |
| static void ssh_close(BlockDriverState *bs) |
| { |
| BDRVSSHState *s = bs->opaque; |
| |
| ssh_state_free(s); |
| } |
| |
| static int ssh_has_zero_init(BlockDriverState *bs) |
| { |
| BDRVSSHState *s = bs->opaque; |
| /* Assume false, unless we can positively prove it's true. */ |
| int has_zero_init = 0; |
| |
| if (s->attrs.flags & LIBSSH2_SFTP_ATTR_PERMISSIONS) { |
| if (s->attrs.permissions & LIBSSH2_SFTP_S_IFREG) { |
| has_zero_init = 1; |
| } |
| } |
| |
| return has_zero_init; |
| } |
| |
| static void restart_coroutine(void *opaque) |
| { |
| Coroutine *co = opaque; |
| |
| DPRINTF("co=%p", co); |
| |
| qemu_coroutine_enter(co, NULL); |
| } |
| |
| static coroutine_fn void set_fd_handler(BDRVSSHState *s, BlockDriverState *bs) |
| { |
| int r; |
| IOHandler *rd_handler = NULL, *wr_handler = NULL; |
| Coroutine *co = qemu_coroutine_self(); |
| |
| r = libssh2_session_block_directions(s->session); |
| |
| if (r & LIBSSH2_SESSION_BLOCK_INBOUND) { |
| rd_handler = restart_coroutine; |
| } |
| if (r & LIBSSH2_SESSION_BLOCK_OUTBOUND) { |
| wr_handler = restart_coroutine; |
| } |
| |
| DPRINTF("s->sock=%d rd_handler=%p wr_handler=%p", s->sock, |
| rd_handler, wr_handler); |
| |
| aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock, |
| rd_handler, wr_handler, co); |
| } |
| |
| static coroutine_fn void clear_fd_handler(BDRVSSHState *s, |
| BlockDriverState *bs) |
| { |
| DPRINTF("s->sock=%d", s->sock); |
| aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock, NULL, NULL, NULL); |
| } |
| |
| /* A non-blocking call returned EAGAIN, so yield, ensuring the |
| * handlers are set up so that we'll be rescheduled when there is an |
| * interesting event on the socket. |
| */ |
| static coroutine_fn void co_yield(BDRVSSHState *s, BlockDriverState *bs) |
| { |
| set_fd_handler(s, bs); |
| qemu_coroutine_yield(); |
| clear_fd_handler(s, bs); |
| } |
| |
| /* SFTP has a function `libssh2_sftp_seek64' which seeks to a position |
| * in the remote file. Notice that it just updates a field in the |
| * sftp_handle structure, so there is no network traffic and it cannot |
| * fail. |
| * |
| * However, `libssh2_sftp_seek64' does have a catastrophic effect on |
| * performance since it causes the handle to throw away all in-flight |
| * reads and buffered readahead data. Therefore this function tries |
| * to be intelligent about when to call the underlying libssh2 function. |
| */ |
| #define SSH_SEEK_WRITE 0 |
| #define SSH_SEEK_READ 1 |
| #define SSH_SEEK_FORCE 2 |
| |
| static void ssh_seek(BDRVSSHState *s, int64_t offset, int flags) |
| { |
| bool op_read = (flags & SSH_SEEK_READ) != 0; |
| bool force = (flags & SSH_SEEK_FORCE) != 0; |
| |
| if (force || op_read != s->offset_op_read || offset != s->offset) { |
| DPRINTF("seeking to offset=%" PRIi64, offset); |
| libssh2_sftp_seek64(s->sftp_handle, offset); |
| s->offset = offset; |
| s->offset_op_read = op_read; |
| } |
| } |
| |
| static coroutine_fn int ssh_read(BDRVSSHState *s, BlockDriverState *bs, |
| int64_t offset, size_t size, |
| QEMUIOVector *qiov) |
| { |
| ssize_t r; |
| size_t got; |
| char *buf, *end_of_vec; |
| struct iovec *i; |
| |
| DPRINTF("offset=%" PRIi64 " size=%zu", offset, size); |
| |
| ssh_seek(s, offset, SSH_SEEK_READ); |
| |
| /* This keeps track of the current iovec element ('i'), where we |
| * will write to next ('buf'), and the end of the current iovec |
| * ('end_of_vec'). |
| */ |
| i = &qiov->iov[0]; |
| buf = i->iov_base; |
| end_of_vec = i->iov_base + i->iov_len; |
| |
| /* libssh2 has a hard-coded limit of 2000 bytes per request, |
| * although it will also do readahead behind our backs. Therefore |
| * we may have to do repeated reads here until we have read 'size' |
| * bytes. |
| */ |
| for (got = 0; got < size; ) { |
| again: |
| DPRINTF("sftp_read buf=%p size=%zu", buf, end_of_vec - buf); |
| r = libssh2_sftp_read(s->sftp_handle, buf, end_of_vec - buf); |
| DPRINTF("sftp_read returned %zd", r); |
| |
| if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) { |
| co_yield(s, bs); |
| goto again; |
| } |
| if (r < 0) { |
| sftp_error_report(s, "read failed"); |
| s->offset = -1; |
| return -EIO; |
| } |
| if (r == 0) { |
| /* EOF: Short read so pad the buffer with zeroes and return it. */ |
| qemu_iovec_memset(qiov, got, 0, size - got); |
| return 0; |
| } |
| |
| got += r; |
| buf += r; |
| s->offset += r; |
| if (buf >= end_of_vec && got < size) { |
| i++; |
| buf = i->iov_base; |
| end_of_vec = i->iov_base + i->iov_len; |
| } |
| } |
| |
| return 0; |
| } |
| |
| static coroutine_fn int ssh_co_readv(BlockDriverState *bs, |
| int64_t sector_num, |
| int nb_sectors, QEMUIOVector *qiov) |
| { |
| BDRVSSHState *s = bs->opaque; |
| int ret; |
| |
| qemu_co_mutex_lock(&s->lock); |
| ret = ssh_read(s, bs, sector_num * BDRV_SECTOR_SIZE, |
| nb_sectors * BDRV_SECTOR_SIZE, qiov); |
| qemu_co_mutex_unlock(&s->lock); |
| |
| return ret; |
| } |
| |
| static int ssh_write(BDRVSSHState *s, BlockDriverState *bs, |
| int64_t offset, size_t size, |
| QEMUIOVector *qiov) |
| { |
| ssize_t r; |
| size_t written; |
| char *buf, *end_of_vec; |
| struct iovec *i; |
| |
| DPRINTF("offset=%" PRIi64 " size=%zu", offset, size); |
| |
| ssh_seek(s, offset, SSH_SEEK_WRITE); |
| |
| /* This keeps track of the current iovec element ('i'), where we |
| * will read from next ('buf'), and the end of the current iovec |
| * ('end_of_vec'). |
| */ |
| i = &qiov->iov[0]; |
| buf = i->iov_base; |
| end_of_vec = i->iov_base + i->iov_len; |
| |
| for (written = 0; written < size; ) { |
| again: |
| DPRINTF("sftp_write buf=%p size=%zu", buf, end_of_vec - buf); |
| r = libssh2_sftp_write(s->sftp_handle, buf, end_of_vec - buf); |
| DPRINTF("sftp_write returned %zd", r); |
| |
| if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) { |
| co_yield(s, bs); |
| goto again; |
| } |
| if (r < 0) { |
| sftp_error_report(s, "write failed"); |
| s->offset = -1; |
| return -EIO; |
| } |
| /* The libssh2 API is very unclear about this. A comment in |
| * the code says "nothing was acked, and no EAGAIN was |
| * received!" which apparently means that no data got sent |
| * out, and the underlying channel didn't return any EAGAIN |
| * indication. I think this is a bug in either libssh2 or |
| * OpenSSH (server-side). In any case, forcing a seek (to |
| * discard libssh2 internal buffers), and then trying again |
| * works for me. |
| */ |
| if (r == 0) { |
| ssh_seek(s, offset + written, SSH_SEEK_WRITE|SSH_SEEK_FORCE); |
| co_yield(s, bs); |
| goto again; |
| } |
| |
| written += r; |
| buf += r; |
| s->offset += r; |
| if (buf >= end_of_vec && written < size) { |
| i++; |
| buf = i->iov_base; |
| end_of_vec = i->iov_base + i->iov_len; |
| } |
| |
| if (offset + written > s->attrs.filesize) |
| s->attrs.filesize = offset + written; |
| } |
| |
| return 0; |
| } |
| |
| static coroutine_fn int ssh_co_writev(BlockDriverState *bs, |
| int64_t sector_num, |
| int nb_sectors, QEMUIOVector *qiov) |
| { |
| BDRVSSHState *s = bs->opaque; |
| int ret; |
| |
| qemu_co_mutex_lock(&s->lock); |
| ret = ssh_write(s, bs, sector_num * BDRV_SECTOR_SIZE, |
| nb_sectors * BDRV_SECTOR_SIZE, qiov); |
| qemu_co_mutex_unlock(&s->lock); |
| |
| return ret; |
| } |
| |
| static void unsafe_flush_warning(BDRVSSHState *s, const char *what) |
| { |
| if (!s->unsafe_flush_warning) { |
| error_report("warning: ssh server %s does not support fsync", |
| s->hostport); |
| if (what) { |
| error_report("to support fsync, you need %s", what); |
| } |
| s->unsafe_flush_warning = true; |
| } |
| } |
| |
| #ifdef HAS_LIBSSH2_SFTP_FSYNC |
| |
| static coroutine_fn int ssh_flush(BDRVSSHState *s, BlockDriverState *bs) |
| { |
| int r; |
| |
| DPRINTF("fsync"); |
| again: |
| r = libssh2_sftp_fsync(s->sftp_handle); |
| if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) { |
| co_yield(s, bs); |
| goto again; |
| } |
| if (r == LIBSSH2_ERROR_SFTP_PROTOCOL && |
| libssh2_sftp_last_error(s->sftp) == LIBSSH2_FX_OP_UNSUPPORTED) { |
| unsafe_flush_warning(s, "OpenSSH >= 6.3"); |
| return 0; |
| } |
| if (r < 0) { |
| sftp_error_report(s, "fsync failed"); |
| return -EIO; |
| } |
| |
| return 0; |
| } |
| |
| static coroutine_fn int ssh_co_flush(BlockDriverState *bs) |
| { |
| BDRVSSHState *s = bs->opaque; |
| int ret; |
| |
| qemu_co_mutex_lock(&s->lock); |
| ret = ssh_flush(s, bs); |
| qemu_co_mutex_unlock(&s->lock); |
| |
| return ret; |
| } |
| |
| #else /* !HAS_LIBSSH2_SFTP_FSYNC */ |
| |
| static coroutine_fn int ssh_co_flush(BlockDriverState *bs) |
| { |
| BDRVSSHState *s = bs->opaque; |
| |
| unsafe_flush_warning(s, "libssh2 >= 1.4.4"); |
| return 0; |
| } |
| |
| #endif /* !HAS_LIBSSH2_SFTP_FSYNC */ |
| |
| static int64_t ssh_getlength(BlockDriverState *bs) |
| { |
| BDRVSSHState *s = bs->opaque; |
| int64_t length; |
| |
| /* Note we cannot make a libssh2 call here. */ |
| length = (int64_t) s->attrs.filesize; |
| DPRINTF("length=%" PRIi64, length); |
| |
| return length; |
| } |
| |
| static BlockDriver bdrv_ssh = { |
| .format_name = "ssh", |
| .protocol_name = "ssh", |
| .instance_size = sizeof(BDRVSSHState), |
| .bdrv_parse_filename = ssh_parse_filename, |
| .bdrv_file_open = ssh_file_open, |
| .bdrv_create = ssh_create, |
| .bdrv_close = ssh_close, |
| .bdrv_has_zero_init = ssh_has_zero_init, |
| .bdrv_co_readv = ssh_co_readv, |
| .bdrv_co_writev = ssh_co_writev, |
| .bdrv_getlength = ssh_getlength, |
| .bdrv_co_flush_to_disk = ssh_co_flush, |
| .create_opts = &ssh_create_opts, |
| }; |
| |
| static void bdrv_ssh_init(void) |
| { |
| int r; |
| |
| r = libssh2_init(0); |
| if (r != 0) { |
| fprintf(stderr, "libssh2 initialization failed, %d\n", r); |
| exit(EXIT_FAILURE); |
| } |
| |
| bdrv_register(&bdrv_ssh); |
| } |
| |
| block_init(bdrv_ssh_init); |