diff options
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/meson.build | 17 | ||||
| -rw-r--r-- | tools/virtiofsd/helper.c | 8 | ||||
| -rw-r--r-- | tools/virtiofsd/passthrough_ll.c | 538 |
3 files changed, 552 insertions, 11 deletions
diff --git a/tools/meson.build b/tools/meson.build index 513bd2ff4f..76bf84df52 100644 --- a/tools/meson.build +++ b/tools/meson.build @@ -1,10 +1,23 @@ -have_virtiofsd = (have_system and +have_virtiofsd = (targetos == 'linux' and have_tools and - 'CONFIG_LINUX' in config_host and 'CONFIG_SECCOMP' in config_host and 'CONFIG_LIBCAP_NG' in config_host and 'CONFIG_VHOST_USER' in config_host) +if get_option('virtiofsd').enabled() + if not have_virtiofsd + if targetos != 'linux' + error('virtiofsd requires Linux') + elif 'CONFIG_SECCOMP' not in config_host or 'CONFIG_LIBCAP_NG' not in config_host + error('virtiofsd requires libcap-ng-devel and seccomp-devel') + elif not have_tools or 'CONFIG_VHOST_USER' not in config_host + error('virtiofsd needs tools and vhost-user support') + endif + endif +elif get_option('virtiofsd').disabled() or not have_system + have_virtiofsd = false +endif + if have_virtiofsd subdir('virtiofsd') endif diff --git a/tools/virtiofsd/helper.c b/tools/virtiofsd/helper.c index 85770d63f1..2e181a49b5 100644 --- a/tools/virtiofsd/helper.c +++ b/tools/virtiofsd/helper.c @@ -166,6 +166,14 @@ void fuse_cmdline_help(void) " enable/disable readirplus\n" " default: readdirplus except with " "cache=none\n" + " -o sandbox=namespace|chroot\n" + " sandboxing mode:\n" + " - namespace: mount, pid, and net\n" + " namespaces with pivot_root(2)\n" + " into shared directory\n" + " - chroot: chroot(2) into shared\n" + " directory (use in containers)\n" + " default: namespace\n" " -o timeout=<number> I/O timeout (seconds)\n" " default: depends on cache= option.\n" " -o writeback|no_writeback enable/disable writeback cache\n" diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index ff53df4451..a0beb986f3 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -64,6 +64,7 @@ #include <syslog.h> #include <unistd.h> +#include "qemu/cutils.h" #include "passthrough_helpers.h" #include "passthrough_seccomp.h" @@ -137,13 +138,26 @@ enum { CACHE_ALWAYS, }; +enum { + SANDBOX_NAMESPACE, + SANDBOX_CHROOT, +}; + +typedef struct xattr_map_entry { + char *key; + char *prepend; + unsigned int flags; +} XattrMapEntry; + struct lo_data { pthread_mutex_t mutex; + int sandbox; int debug; int writeback; int flock; int posix_lock; int xattr; + char *xattrmap; char *source; char *modcaps; double timeout; @@ -157,12 +171,20 @@ struct lo_data { struct lo_map ino_map; /* protected by lo->mutex */ struct lo_map dirp_map; /* protected by lo->mutex */ struct lo_map fd_map; /* protected by lo->mutex */ + XattrMapEntry *xattr_map_list; + size_t xattr_map_nentries; /* An O_PATH file descriptor to /proc/self/fd/ */ int proc_self_fd; }; static const struct fuse_opt lo_opts[] = { + { "sandbox=namespace", + offsetof(struct lo_data, sandbox), + SANDBOX_NAMESPACE }, + { "sandbox=chroot", + offsetof(struct lo_data, sandbox), + SANDBOX_CHROOT }, { "writeback", offsetof(struct lo_data, writeback), 1 }, { "no_writeback", offsetof(struct lo_data, writeback), 0 }, { "source=%s", offsetof(struct lo_data, source), 0 }, @@ -172,6 +194,7 @@ static const struct fuse_opt lo_opts[] = { { "no_posix_lock", offsetof(struct lo_data, posix_lock), 0 }, { "xattr", offsetof(struct lo_data, xattr), 1 }, { "no_xattr", offsetof(struct lo_data, xattr), 0 }, + { "xattrmap=%s", offsetof(struct lo_data, xattrmap), 0 }, { "modcaps=%s", offsetof(struct lo_data, modcaps), 0 }, { "timeout=%lf", offsetof(struct lo_data, timeout), 0 }, { "timeout=", offsetof(struct lo_data, timeout_set), 1 }, @@ -2010,20 +2033,383 @@ static void lo_flock(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi, fuse_reply_err(req, res == -1 ? errno : 0); } -static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name, +/* types */ +/* + * Exit; process attribute unmodified if matched. + * An empty key applies to all. + */ +#define XATTR_MAP_FLAG_OK (1 << 0) +/* + * The attribute is unwanted; + * EPERM on write, hidden on read. + */ +#define XATTR_MAP_FLAG_BAD (1 << 1) +/* + * For attr that start with 'key' prepend 'prepend' + * 'key' may be empty to prepend for all attrs + * key is defined from set/remove point of view. + * Automatically reversed on read + */ +#define XATTR_MAP_FLAG_PREFIX (1 << 2) + +/* scopes */ +/* Apply rule to get/set/remove */ +#define XATTR_MAP_FLAG_CLIENT (1 << 16) +/* Apply rule to list */ +#define XATTR_MAP_FLAG_SERVER (1 << 17) +/* Apply rule to all */ +#define XATTR_MAP_FLAG_ALL (XATTR_MAP_FLAG_SERVER | XATTR_MAP_FLAG_CLIENT) + +static void add_xattrmap_entry(struct lo_data *lo, + const XattrMapEntry *new_entry) +{ + XattrMapEntry *res = g_realloc_n(lo->xattr_map_list, + lo->xattr_map_nentries + 1, + sizeof(XattrMapEntry)); + res[lo->xattr_map_nentries++] = *new_entry; + + lo->xattr_map_list = res; +} + +static void free_xattrmap(struct lo_data *lo) +{ + XattrMapEntry *map = lo->xattr_map_list; + size_t i; + + if (!map) { + return; + } + + for (i = 0; i < lo->xattr_map_nentries; i++) { + g_free(map[i].key); + g_free(map[i].prepend); + }; + + g_free(map); + lo->xattr_map_list = NULL; + lo->xattr_map_nentries = -1; +} + +/* + * Handle the 'map' type, which is sugar for a set of commands + * for the common case of prefixing a subset or everything, + * and allowing anything not prefixed through. + * It must be the last entry in the stream, although there + * can be other entries before it. + * The form is: + * :map:key:prefix: + * + * key maybe empty in which case all entries are prefixed. + */ +static void parse_xattrmap_map(struct lo_data *lo, + const char *rule, char sep) +{ + const char *tmp; + char *key; + char *prefix; + XattrMapEntry tmp_entry; + + if (*rule != sep) { + fuse_log(FUSE_LOG_ERR, + "%s: Expecting '%c' after 'map' keyword, found '%c'\n", + __func__, sep, *rule); + exit(1); + } + + rule++; + + /* At start of 'key' field */ + tmp = strchr(rule, sep); + if (!tmp) { + fuse_log(FUSE_LOG_ERR, + "%s: Missing '%c' at end of key field in map rule\n", + __func__, sep); + exit(1); + } + + key = g_strndup(rule, tmp - rule); + rule = tmp + 1; + + /* At start of prefix field */ + tmp = strchr(rule, sep); + if (!tmp) { + fuse_log(FUSE_LOG_ERR, + "%s: Missing '%c' at end of prefix field in map rule\n", + __func__, sep); + exit(1); + } + + prefix = g_strndup(rule, tmp - rule); + rule = tmp + 1; + + /* + * This should be the end of the string, we don't allow + * any more commands after 'map'. + */ + if (*rule) { + fuse_log(FUSE_LOG_ERR, + "%s: Expecting end of command after map, found '%c'\n", + __func__, *rule); + exit(1); + } + + /* 1st: Prefix matches/everything */ + tmp_entry.flags = XATTR_MAP_FLAG_PREFIX | XATTR_MAP_FLAG_ALL; + tmp_entry.key = g_strdup(key); + tmp_entry.prepend = g_strdup(prefix); + add_xattrmap_entry(lo, &tmp_entry); + + if (!*key) { + /* Prefix all case */ + + /* 2nd: Hide any non-prefixed entries on the host */ + tmp_entry.flags = XATTR_MAP_FLAG_BAD | XATTR_MAP_FLAG_ALL; + tmp_entry.key = g_strdup(""); + tmp_entry.prepend = g_strdup(""); + add_xattrmap_entry(lo, &tmp_entry); + } else { + /* Prefix matching case */ + + /* 2nd: Hide non-prefixed but matching entries on the host */ + tmp_entry.flags = XATTR_MAP_FLAG_BAD | XATTR_MAP_FLAG_SERVER; + tmp_entry.key = g_strdup(""); /* Not used */ + tmp_entry.prepend = g_strdup(key); + add_xattrmap_entry(lo, &tmp_entry); + + /* 3rd: Stop the client accessing prefixed attributes directly */ + tmp_entry.flags = XATTR_MAP_FLAG_BAD | XATTR_MAP_FLAG_CLIENT; + tmp_entry.key = g_strdup(prefix); + tmp_entry.prepend = g_strdup(""); /* Not used */ + add_xattrmap_entry(lo, &tmp_entry); + + /* 4th: Everything else is OK */ + tmp_entry.flags = XATTR_MAP_FLAG_OK | XATTR_MAP_FLAG_ALL; + tmp_entry.key = g_strdup(""); + tmp_entry.prepend = g_strdup(""); + add_xattrmap_entry(lo, &tmp_entry); + } + + g_free(key); + g_free(prefix); +} + +static void parse_xattrmap(struct lo_data *lo) +{ + const char *map = lo->xattrmap; + const char *tmp; + + lo->xattr_map_nentries = 0; + while (*map) { + XattrMapEntry tmp_entry; + char sep; + + if (isspace(*map)) { + map++; + continue; + } + /* The separator is the first non-space of the rule */ + sep = *map++; + if (!sep) { + break; + } + + tmp_entry.flags = 0; + /* Start of 'type' */ + if (strstart(map, "prefix", &map)) { + tmp_entry.flags |= XATTR_MAP_FLAG_PREFIX; + } else if (strstart(map, "ok", &map)) { + tmp_entry.flags |= XATTR_MAP_FLAG_OK; + } else if (strstart(map, "bad", &map)) { + tmp_entry.flags |= XATTR_MAP_FLAG_BAD; + } else if (strstart(map, "map", &map)) { + /* + * map is sugar that adds a number of rules, and must be + * the last entry. + */ + parse_xattrmap_map(lo, map, sep); + return; + } else { + fuse_log(FUSE_LOG_ERR, + "%s: Unexpected type;" + "Expecting 'prefix', 'ok', 'bad' or 'map' in rule %zu\n", + __func__, lo->xattr_map_nentries); + exit(1); + } + + if (*map++ != sep) { + fuse_log(FUSE_LOG_ERR, + "%s: Missing '%c' at end of type field of rule %zu\n", + __func__, sep, lo->xattr_map_nentries); + exit(1); + } + + /* Start of 'scope' */ + if (strstart(map, "client", &map)) { + tmp_entry.flags |= XATTR_MAP_FLAG_CLIENT; + } else if (strstart(map, "server", &map)) { + tmp_entry.flags |= XATTR_MAP_FLAG_SERVER; + } else if (strstart(map, "all", &map)) { + tmp_entry.flags |= XATTR_MAP_FLAG_ALL; + } else { + fuse_log(FUSE_LOG_ERR, + "%s: Unexpected scope;" + " Expecting 'client', 'server', or 'all', in rule %zu\n", + __func__, lo->xattr_map_nentries); + exit(1); + } + + if (*map++ != sep) { + fuse_log(FUSE_LOG_ERR, + "%s: Expecting '%c' found '%c'" + " after scope in rule %zu\n", + __func__, sep, *map, lo->xattr_map_nentries); + exit(1); + } + + /* At start of 'key' field */ + tmp = strchr(map, sep); + if (!tmp) { + fuse_log(FUSE_LOG_ERR, + "%s: Missing '%c' at end of key field of rule %zu", + __func__, sep, lo->xattr_map_nentries); + exit(1); + } + tmp_entry.key = g_strndup(map, tmp - map); + map = tmp + 1; + + /* At start of 'prepend' field */ + tmp = strchr(map, sep); + if (!tmp) { + fuse_log(FUSE_LOG_ERR, + "%s: Missing '%c' at end of prepend field of rule %zu", + __func__, sep, lo->xattr_map_nentries); + exit(1); + } + tmp_entry.prepend = g_strndup(map, tmp - map); + map = tmp + 1; + + add_xattrmap_entry(lo, &tmp_entry); + /* End of rule - go around again for another rule */ + } + + if (!lo->xattr_map_nentries) { + fuse_log(FUSE_LOG_ERR, "Empty xattr map\n"); + exit(1); + } +} + +/* + * For use with getxattr/setxattr/removexattr, where the client + * gives us a name and we may need to choose a different one. + * Allocates a buffer for the result placing it in *out_name. + * If there's no change then *out_name is not set. + * Returns 0 on success + * Can return -EPERM to indicate we block a given attribute + * (in which case out_name is not allocated) + * Can return -ENOMEM to indicate out_name couldn't be allocated. + */ +static int xattr_map_client(const struct lo_data *lo, const char *client_name, + char **out_name) +{ + size_t i; + for (i = 0; i < lo->xattr_map_nentries; i++) { + const XattrMapEntry *cur_entry = lo->xattr_map_list + i; + + if ((cur_entry->flags & XATTR_MAP_FLAG_CLIENT) && + (strstart(client_name, cur_entry->key, NULL))) { + if (cur_entry->flags & XATTR_MAP_FLAG_BAD) { + return -EPERM; + } + if (cur_entry->flags & XATTR_MAP_FLAG_OK) { + /* Unmodified name */ + return 0; + } + if (cur_entry->flags & XATTR_MAP_FLAG_PREFIX) { + *out_name = g_try_malloc(strlen(client_name) + + strlen(cur_entry->prepend) + 1); + if (!*out_name) { + return -ENOMEM; + } + sprintf(*out_name, "%s%s", cur_entry->prepend, client_name); + return 0; + } + } + } + + return -EPERM; +} + +/* + * For use with listxattr where the server fs gives us a name and we may need + * to sanitize this for the client. + * Returns a pointer to the result in *out_name + * This is always the original string or the current string with some prefix + * removed; no reallocation is done. + * Returns 0 on success + * Can return -ENODATA to indicate the name should be dropped from the list. + */ +static int xattr_map_server(const struct lo_data *lo, const char *server_name, + const char **out_name) +{ + size_t i; + const char *end; + + for (i = 0; i < lo->xattr_map_nentries; i++) { + const XattrMapEntry *cur_entry = lo->xattr_map_list + i; + + if ((cur_entry->flags & XATTR_MAP_FLAG_SERVER) && + (strstart(server_name, cur_entry->prepend, &end))) { + if (cur_entry->flags & XATTR_MAP_FLAG_BAD) { + return -ENODATA; + } + if (cur_entry->flags & XATTR_MAP_FLAG_OK) { + *out_name = server_name; + return 0; + } + if (cur_entry->flags & XATTR_MAP_FLAG_PREFIX) { + /* Remove prefix */ + *out_name = end; + return 0; + } + } + } + + return -ENODATA; +} + +static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name, size_t size) { struct lo_data *lo = lo_data(req); char *value = NULL; char procname[64]; + const char *name; + char *mapped_name; struct lo_inode *inode; ssize_t ret; int saverr; int fd = -1; + mapped_name = NULL; + name = in_name; + if (lo->xattrmap) { + ret = xattr_map_client(lo, in_name, &mapped_name); + if (ret < 0) { + if (ret == -EPERM) { + ret = -ENODATA; + } + fuse_reply_err(req, -ret); + return; + } + if (mapped_name) { + name = mapped_name; + } + } + inode = lo_inode(req, ino); if (!inode) { fuse_reply_err(req, EBADF); + g_free(mapped_name); return; } @@ -2088,6 +2474,7 @@ out_err: saverr = errno; out: fuse_reply_err(req, saverr); + g_free(mapped_name); goto out_free; } @@ -2144,8 +2531,60 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) if (ret == 0) { goto out; } + + if (lo->xattr_map_list) { + /* + * Map the names back, some attributes might be dropped, + * some shortened, but not increased, so we shouldn't + * run out of room. + */ + size_t out_index, in_index; + out_index = 0; + in_index = 0; + while (in_index < ret) { + const char *map_out; + char *in_ptr = value + in_index; + /* Length of current attribute name */ + size_t in_len = strlen(value + in_index) + 1; + + int mapret = xattr_map_server(lo, in_ptr, &map_out); + if (mapret != -ENODATA && mapret != 0) { + /* Shouldn't happen */ + saverr = -mapret; + goto out; + } + if (mapret == 0) { + /* Either unchanged, or truncated */ + size_t out_len; + if (map_out != in_ptr) { + /* +1 copies the NIL */ + out_len = strlen(map_out) + 1; + } else { + /* No change */ + out_len = in_len; + } + /* + * Move result along, may still be needed for an unchanged + * entry if a previous entry was changed. + */ + memmove(value + out_index, map_out, out_len); + + out_index += out_len; + } + in_index += in_len; + } + ret = out_index; + if (ret == 0) { + goto out; + } + } fuse_reply_buf(req, value, ret); } else { + /* + * xattrmap only ever shortens the result, + * so we don't need to do anything clever with the + * allocation length here. + */ fuse_reply_xattr(req, ret); } out_free: @@ -2165,19 +2604,35 @@ out: goto out_free; } -static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *name, +static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name, const char *value, size_t size, int flags) { char procname[64]; + const char *name; + char *mapped_name; struct lo_data *lo = lo_data(req); struct lo_inode *inode; ssize_t ret; int saverr; int fd = -1; + mapped_name = NULL; + name = in_name; + if (lo->xattrmap) { + ret = xattr_map_client(lo, in_name, &mapped_name); + if (ret < 0) { + fuse_reply_err(req, -ret); + return; + } + if (mapped_name) { + name = mapped_name; + } + } + inode = lo_inode(req, ino); if (!inode) { fuse_reply_err(req, EBADF); + g_free(mapped_name); return; } @@ -2212,21 +2667,38 @@ out: } lo_inode_put(lo, &inode); + g_free(mapped_name); fuse_reply_err(req, saverr); } -static void lo_removexattr(fuse_req_t req, fuse_ino_t ino, const char *name) +static void lo_removexattr(fuse_req_t req, fuse_ino_t ino, const char *in_name) { char procname[64]; + const char *name; + char *mapped_name; struct lo_data *lo = lo_data(req); struct lo_inode *inode; ssize_t ret; int saverr; int fd = -1; + mapped_name = NULL; + name = in_name; + if (lo->xattrmap) { + ret = xattr_map_client(lo, in_name, &mapped_name); + if (ret < 0) { + fuse_reply_err(req, -ret); + return; + } + if (mapped_name) { + name = mapped_name; + } + } + inode = lo_inode(req, ino); if (!inode) { fuse_reply_err(req, EBADF); + g_free(mapped_name); return; } @@ -2261,6 +2733,7 @@ out: } lo_inode_put(lo, &inode); + g_free(mapped_name); fuse_reply_err(req, saverr); } @@ -2661,14 +3134,54 @@ static void setup_capabilities(char *modcaps_in) } /* + * Use chroot as a weaker sandbox for environments where the process is + * launched without CAP_SYS_ADMIN. + */ +static void setup_chroot(struct lo_data *lo) +{ + lo->proc_self_fd = open("/proc/self/fd", O_PATH); + if (lo->proc_self_fd == -1) { + fuse_log(FUSE_LOG_ERR, "open(\"/proc/self/fd\", O_PATH): %m\n"); + exit(1); + } + + /* + * Make the shared directory the file system root so that FUSE_OPEN + * (lo_open()) cannot escape the shared directory by opening a symlink. + * + * The chroot(2) syscall is later disabled by seccomp and the + * CAP_SYS_CHROOT capability is dropped so that tampering with the chroot + * is not possible. + * + * However, it's still possible to escape the chroot via lo->proc_self_fd + * but that requires first gaining control of the process. + */ + if (chroot(lo->source) != 0) { + fuse_log(FUSE_LOG_ERR, "chroot(\"%s\"): %m\n", lo->source); + exit(1); + } + + /* Move into the chroot */ + if (chdir("/") != 0) { + fuse_log(FUSE_LOG_ERR, "chdir(\"/\"): %m\n"); + exit(1); + } +} + +/* * Lock down this process to prevent access to other processes or files outside * source directory. This reduces the impact of arbitrary code execution bugs. */ static void setup_sandbox(struct lo_data *lo, struct fuse_session *se, bool enable_syslog) { - setup_namespaces(lo, se); - setup_mounts(lo->source); + if (lo->sandbox == SANDBOX_NAMESPACE) { + setup_namespaces(lo, se); + setup_mounts(lo->source); + } else { + setup_chroot(lo); + } + setup_seccomp(enable_syslog); setup_capabilities(g_strdup(lo->modcaps)); } @@ -2806,6 +3319,8 @@ static void fuse_lo_data_cleanup(struct lo_data *lo) close(lo->root.fd); } + free(lo->xattrmap); + free_xattrmap(lo); free(lo->source); } @@ -2815,6 +3330,7 @@ int main(int argc, char *argv[]) struct fuse_session *se; struct fuse_cmdline_opts opts; struct lo_data lo = { + .sandbox = SANDBOX_NAMESPACE, .debug = 0, .writeback = 0, .posix_lock = 0, @@ -2878,12 +3394,11 @@ int main(int argc, char *argv[]) goto err_out1; } - /* - * log_level is 0 if not configured via cmd options (0 is LOG_EMERG, - * and we don't use this log level). - */ if (opts.log_level != 0) { current_log_level = opts.log_level; + } else { + /* default log level is INFO */ + current_log_level = FUSE_LOG_INFO; } lo.debug = opts.debug; if (lo.debug) { @@ -2906,6 +3421,11 @@ int main(int argc, char *argv[]) } else { lo.source = strdup("/"); } + + if (lo.xattrmap) { + parse_xattrmap(&lo); + } + if (!lo.timeout_set) { switch (lo.cache) { case CACHE_NONE: |