diff options
Diffstat (limited to 'qemu/block/ssh.c')
| -rw-r--r-- | qemu/block/ssh.c | 1114 |
1 files changed, 1114 insertions, 0 deletions
diff --git a/qemu/block/ssh.c b/qemu/block/ssh.c new file mode 100644 index 000000000..8d0673903 --- /dev/null +++ b/qemu/block/ssh.c @@ -0,0 +1,1114 @@ +/* + * 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 = -EIO; + 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); |