diff options
Diffstat (limited to 'tools/blktap/lib/xenbus.c')
| -rw-r--r-- | tools/blktap/lib/xenbus.c | 150 |
1 files changed, 148 insertions, 2 deletions
diff --git a/tools/blktap/lib/xenbus.c b/tools/blktap/lib/xenbus.c index 4fc56d661b..bf17d0b7a0 100644 --- a/tools/blktap/lib/xenbus.c +++ b/tools/blktap/lib/xenbus.c @@ -48,6 +48,7 @@ #include <poll.h> #include <time.h> #include <sys/time.h> +#include <unistd.h> #include "blktaplib.h" #include "list.h" #include "xs_api.h" @@ -149,6 +150,137 @@ static int backend_remove(struct xs_handle *h, struct backend_info *be) return 0; } +static int check_sharing(struct xs_handle *h, struct backend_info *be) +{ + char *dom_uuid; + char *cur_dom_uuid; + char *path; + char *mode; + char *params; + char **domains; + char **devices; + int i, j; + unsigned int num_dom, num_dev; + blkif_info_t *info; + int ret = 0; + + /* If the mode contains '!' or doesn't contain 'w' don't check anything */ + xs_gather(h, be->backpath, "mode", NULL, &mode, NULL); + if (strchr(mode, '!')) + goto out; + if (strchr(mode, 'w') == NULL) + goto out; + + /* Get the UUID of the domain we want to attach to */ + if (asprintf(&path, "/local/domain/%ld", be->frontend_id) == -1) + goto fail; + xs_gather(h, path, "vm", NULL, &dom_uuid, NULL); + free(path); + + /* Iterate through the devices of all VMs */ + domains = xs_directory(h, XBT_NULL, "backend/tap", &num_dom); + if (domains == NULL) + num_dom = 0; + + for (i = 0; !ret && (i < num_dom); i++) { + + /* If it's the same VM, no action needed */ + if (asprintf(&path, "/local/domain/%s", domains[i]) == -1) { + ret = -1; + break; + } + xs_gather(h, path, "vm", NULL, &cur_dom_uuid, NULL); + free(path); + + if (!strcmp(cur_dom_uuid, dom_uuid)) { + free(cur_dom_uuid); + continue; + } + + /* Check the devices */ + if (asprintf(&path, "backend/tap/%s", domains[i]) == -1) { + ret = -1; + free(cur_dom_uuid); + break; + } + devices = xs_directory(h, XBT_NULL, path, &num_dev); + if (devices == NULL) + num_dev = 0; + free(path); + + for (j = 0; !ret && (j < num_dev); j++) { + if (asprintf(&path, "backend/tap/%s/%s", domains[i], devices[j]) == -1) { + ret = -1; + break; + } + xs_gather(h, path, "params", NULL, ¶ms, NULL); + free(path); + + info = be->blkif->info; + if (strcmp(params, info->params)) { + ret = -1; + } + + free(params); + } + + free(cur_dom_uuid); + free(devices); + } + free(domains); + free(dom_uuid); + goto out; + +fail: + ret = -1; +out: + free(mode); + return ret; +} + +static int check_image(struct xs_handle *h, struct backend_info *be, + const char** errmsg) +{ + const char *tmp; + const char *path; + int mode; + blkif_t *blkif = be->blkif; + blkif_info_t *info = blkif->info; + + /* Strip off the image type */ + path = info->params; + + if (!strncmp(path, "tapdisk:", strlen("tapdisk:"))) { + path += strlen("tapdisk:"); + } else if (!strncmp(path, "ioemu:", strlen("ioemu:"))) { + path += strlen("ioemu:"); + } + + tmp = strchr(path, ':'); + if (tmp != NULL) + path = tmp + 1; + + /* Check if the image exists and access is permitted */ + mode = R_OK; + if (!be->readonly) + mode |= W_OK; + if (access(path, mode)) { + if (errno == ENOENT) + *errmsg = "File not found."; + else + *errmsg = "Insufficient file permissions."; + return -1; + } + + /* Check that the image is not attached to a different VM */ + if (check_sharing(h, be)) { + *errmsg = "File already in use by other domain"; + return -1; + } + + return 0; +} + static void ueblktap_setup(struct xs_handle *h, char *bepath) { struct backend_info *be; @@ -156,6 +288,7 @@ static void ueblktap_setup(struct xs_handle *h, char *bepath) int len, er, deverr; long int pdev = 0, handle; blkif_info_t *blk; + const char* errmsg = NULL; be = be_lookup_be(bepath); if (be == NULL) @@ -211,6 +344,9 @@ static void ueblktap_setup(struct xs_handle *h, char *bepath) be->pdev = pdev; } + if (check_image(h, be, &errmsg)) + goto fail; + er = blkif_init(be->blkif, handle, be->pdev, be->readonly); if (er != 0) { DPRINTF("Unable to open device %s\n",blk->params); @@ -246,12 +382,21 @@ static void ueblktap_setup(struct xs_handle *h, char *bepath) } be->blkif->state = CONNECTED; + xs_printf(h, be->backpath, "hotplug-status", "connected"); + DPRINTF("[SETUP] Complete\n\n"); goto close; fail: - if ( (be != NULL) && (be->blkif != NULL) ) + if (be) { + if (errmsg == NULL) + errmsg = "Setting up the backend failed. See the log " + "files in /var/log/xen/ for details."; + xs_printf(h, be->backpath, "hotplug-error", errmsg); + xs_printf(h, be->backpath, "hotplug-status", "error"); + backend_remove(h, be); + } close: if (path) free(path); @@ -286,7 +431,8 @@ static void ueblktap_probe(struct xs_handle *h, struct xenbus_watch *w, len = strsep_len(bepath, '/', 7); if (len < 0) goto free_be; - bepath[len] = '\0'; + if (bepath[len] != '\0') + goto free_be; be = malloc(sizeof(*be)); if (!be) { |