Adding upstream version 18.2.2.upstream/18.2.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1017 insertions, 0 deletions

diff --git a/src/mount/mount.ceph.c b/src/mount/mount.ceph.c
new file mode 100644
index 000000000..631b0b3fc
--- /dev/null
+++ b/src/mount/mount.ceph.c
@@ -0,0 +1,1017 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <sys/mount.h>
+#include <stdbool.h>
+#include <sys/mman.h>
+#include <wait.h>
+#include <cap-ng.h>
+#include <getopt.h>
+
+#include "common/module.h"
+#include "common/secret.h"
+#include "include/addr_parsing.h"
+#include "mount.ceph.h"
+
+#ifndef MS_RELATIME
+# define MS_RELATIME (1<<21)
+#endif
+
+bool verboseflag = false;
+bool fakeflag = false;
+bool skip_mtab_flag = false;
+bool v2_addrs = true;
+bool no_fallback = false;
+bool ms_mode_specified = false;
+bool mon_addr_specified = false;
+static const char * const EMPTY_STRING = "";
+
+/* TODO duplicates logic from kernel */
+#define CEPH_AUTH_NAME_DEFAULT "guest"
+
+/* path to sysfs for ceph */
+#define CEPH_SYS_FS_PATH "/sys/module/ceph/"
+#define CEPH_SYS_FS_PARAM_PATH CEPH_SYS_FS_PATH"/parameters"
+
+/*
+ * mount support hint from kernel -- we only need to check
+ * v2 support for catching bugs.
+ */
+#define CEPH_V2_MOUNT_SUPPORT_PATH CEPH_SYS_FS_PARAM_PATH"/mount_syntax_v2"
+
+#define CEPH_DEFAULT_V2_MS_MODE "prefer-crc"
+
+#include "mtab.c"
+
+enum mount_dev_format {
+  MOUNT_DEV_FORMAT_OLD = 0,
+  MOUNT_DEV_FORMAT_NEW = 1,
+};
+
+struct ceph_mount_info {
+	unsigned long	cmi_flags;
+	char		*cmi_name;
+	char		*cmi_fsname;
+	char		*cmi_fsid;
+	char		*cmi_path;
+	char		*cmi_mons;
+	char		*cmi_conf;
+	char		*cmi_opts;
+	int		cmi_opts_len;
+	char 		cmi_secret[SECRET_BUFSIZE];
+
+	/* mount dev syntax format */
+	enum mount_dev_format format;
+};
+
+static void mon_addr_as_resolve_param(char *mon_addr)
+{
+	for (; *mon_addr; ++mon_addr)
+		if (*mon_addr == '/')
+			*mon_addr = ',';
+}
+
+static void resolved_mon_addr_as_mount_opt(char *mon_addr)
+{
+	for (; *mon_addr; ++mon_addr)
+		if (*mon_addr == ',')
+			*mon_addr = '/';
+}
+
+static void resolved_mon_addr_as_mount_dev(char *mon_addr)
+{
+	for (; *mon_addr; ++mon_addr)
+		if (*mon_addr == '/')
+			*mon_addr = ',';
+}
+
+static void block_signals (int how)
+{
+     sigset_t sigs;
+
+     sigfillset (&sigs);
+     sigdelset(&sigs, SIGTRAP);
+     sigdelset(&sigs, SIGSEGV);
+     sigprocmask (how, &sigs, (sigset_t *) 0);
+}
+
+void mount_ceph_debug(const char *fmt, ...)
+{
+	if (verboseflag) {
+		va_list args;
+
+		va_start(args, fmt);
+		vprintf(fmt, args);
+		va_end(args);
+	}
+}
+
+/*
+ * append a key value pair option to option string.
+ */
+static void append_opt(const char *key, const char *value,
+		       struct ceph_mount_info *cmi, int *pos)
+{
+	if (*pos != 0)
+		*pos = safe_cat(&cmi->cmi_opts, &cmi->cmi_opts_len, *pos, ",");
+
+	if (value) {
+		*pos = safe_cat(&cmi->cmi_opts, &cmi->cmi_opts_len, *pos, key);
+		*pos = safe_cat(&cmi->cmi_opts, &cmi->cmi_opts_len, *pos, "=");
+		*pos = safe_cat(&cmi->cmi_opts, &cmi->cmi_opts_len, *pos, value);
+	} else {
+		*pos = safe_cat(&cmi->cmi_opts, &cmi->cmi_opts_len, *pos, key);
+	}
+}
+
+/*
+ * remove a key value pair from option string. caller should ensure that the
+ * key value pair is separated by "=".
+ */
+static int remove_opt(struct ceph_mount_info *cmi, const char *key, char **value)
+{
+	char *key_start = strstr(cmi->cmi_opts, key);
+	if (!key_start) {
+		return -ENOENT;
+	}
+
+	/* key present -- try to split */
+	char *key_sep = strstr(key_start, "=");
+	if (!key_sep) {
+		return -ENOENT;
+	}
+
+	if (strncmp(key, key_start, key_sep - key_start) != 0) {
+		return -ENOENT;
+	}
+
+	++key_sep;
+	char *value_end = strstr(key_sep, ",");
+	if (!value_end)
+		value_end = key_sep + strlen(key_sep);
+
+	if (value_end != key_sep && value) {
+		size_t len1 = value_end - key_sep;
+		*value = strndup(key_sep, len1+1);
+		if (!*value)
+			return -ENOMEM;
+		(*value)[len1] = '\0';
+	}
+
+	/* purge it */
+	size_t len2 = strlen(value_end);
+	if (len2) {
+		++value_end;
+		memmove(key_start, value_end, len2);
+	} else {
+                /* last kv pair - swallow the comma */
+		if (*(key_start - 1) == ',') {
+			--key_start;
+		}
+		*key_start = '\0';
+	}
+
+	return 0;
+}
+
+static void record_name(const char *name, struct ceph_mount_info *cmi)
+{
+	int name_pos = 0;
+	int name_len = 0;
+
+	name_pos = safe_cat(&cmi->cmi_name, &name_len, name_pos, name);
+}
+
+/*
+ * parse old device string of format: <mon_addr>:/<path>
+ */
+static int parse_old_dev(const char *dev_str, struct ceph_mount_info *cmi,
+			 int *opt_pos)
+{
+	size_t len;
+	char *mount_path;
+
+	mount_path = strstr(dev_str, ":/");
+	if (!mount_path) {
+		fprintf(stderr, "source mount path was not specified\n");
+		return -EINVAL;
+	}
+
+	len = mount_path - dev_str;
+	if (len != 0) {
+		free(cmi->cmi_mons);
+		/* overrides mon_addr passed via mount option (if any) */
+		cmi->cmi_mons = strndup(dev_str, len);
+		if (!cmi->cmi_mons)
+			return -ENOMEM;
+		mon_addr_specified = true;
+	} else {
+		/* reset mon_addr=<> mount option */
+		mon_addr_specified = false;
+	}
+
+	mount_path++;
+	cmi->cmi_path = strdup(mount_path);
+	if (!cmi->cmi_path)
+		return -ENOMEM;
+	if (!cmi->cmi_name)
+		record_name(CEPH_AUTH_NAME_DEFAULT, cmi);
+
+	cmi->format = MOUNT_DEV_FORMAT_OLD;
+	return 0;
+}
+
+/*
+ * parse new device string of format: name@<fsid>.fs_name=/path
+ */
+static int parse_new_dev(const char *dev_str, struct ceph_mount_info *cmi,
+			 int *opt_pos)
+{
+	size_t len;
+	char *name;
+	char *name_end;
+	char *dot;
+	char *fs_name;
+
+	name_end = strstr(dev_str, "@");
+	if (!name_end) {
+		mount_ceph_debug("invalid new device string format\n");
+		return -ENODEV;
+	}
+
+	len = name_end - dev_str;
+	if (!len) {
+		fprintf(stderr, "missing <name> in device\n");
+		return -EINVAL;
+	}
+
+	name = (char *)alloca(len+1);
+	memcpy(name, dev_str, len);
+	name[len] = '\0';
+
+	if (cmi->cmi_name && strcmp(cmi->cmi_name, name)) {
+		fprintf(stderr, "mismatching ceph user in mount option and device string\n");
+		return -EINVAL;
+	}
+
+	/* record name and store in option string */
+	if (!cmi->cmi_name) {
+		record_name(name, cmi);
+		append_opt("name", name, cmi, opt_pos);
+	}
+
+	++name_end;
+	/* check if an fsid is included in the device string */
+	dot = strstr(name_end, ".");
+	if (!dot) {
+		fprintf(stderr, "invalid device string format\n");
+		return -EINVAL;
+	}
+	len = dot - name_end;
+	if (len) {
+		/* check if this _looks_ like a UUID */
+		if (len != CLUSTER_FSID_LEN - 1) {
+			fprintf(stderr, "invalid device string format\n");
+			return -EINVAL;
+		}
+
+		cmi->cmi_fsid = strndup(name_end, len);
+		if (!cmi->cmi_fsid)
+			return -ENOMEM;
+	}
+
+	++dot;
+	fs_name = strstr(dot, "=");
+	if (!fs_name) {
+		fprintf(stderr, "invalid device string format\n");
+		return -EINVAL;
+	}
+	len = fs_name - dot;
+	if (!len) {
+		fprintf(stderr, "missing <fs_name> in device\n");
+		return -EINVAL;
+	}
+	cmi->cmi_fsname = strndup(dot, len);
+	if (!cmi->cmi_fsname)
+		return -ENOMEM;
+
+	++fs_name;
+	if (strlen(fs_name)) {
+		cmi->cmi_path = strdup(fs_name);
+		if (!cmi->cmi_path)
+			return -ENOMEM;
+	}
+
+	/* new-style dev - force using v2 addrs first */
+	if (!ms_mode_specified && !mon_addr_specified)
+	  append_opt("ms_mode", CEPH_DEFAULT_V2_MS_MODE, cmi,
+		     opt_pos);
+
+	cmi->format = MOUNT_DEV_FORMAT_NEW;
+	return 0;
+}
+
+static int parse_dev(const char *dev_str, struct ceph_mount_info *cmi,
+		     int *opt_pos)
+{
+	int ret;
+
+	ret = parse_new_dev(dev_str, cmi, opt_pos);
+	if (ret < 0 && ret != -ENODEV)
+		return -EINVAL;
+	if (ret)
+		ret = parse_old_dev(dev_str, cmi, opt_pos);
+	if (ret < 0)
+		fprintf(stderr, "error parsing device string\n");
+	return ret;
+}
+
+/* resolve monitor host and optionally record in option string.
+ * use opt_pos to determine if the caller wants to record the
+ * resolved address in mount option (c.f., mount_old_device_format).
+ */
+static int finalize_src(struct ceph_mount_info *cmi, int *opt_pos,
+			char **resolved_addr)
+{
+	char *src;
+        size_t len = strlen(cmi->cmi_mons);
+        char *addr = alloca(len+1);
+
+        memcpy(addr, cmi->cmi_mons, len+1);
+        mon_addr_as_resolve_param(addr);
+
+	src = resolve_addrs(addr);
+	if (!src)
+		return -1;
+
+	mount_ceph_debug("mount.ceph: resolved to: \"%s\"\n", src);
+	if (opt_pos) {
+		resolved_mon_addr_as_mount_opt(src);
+		append_opt("mon_addr", src, cmi, opt_pos);
+	} else if (resolved_addr) {
+                *resolved_addr = strdup(src);
+        }
+	free(src);
+	return 0;
+}
+
+static int
+drop_capabilities()
+{
+	capng_setpid(getpid());
+	capng_clear(CAPNG_SELECT_BOTH);
+	if (capng_update(CAPNG_ADD, CAPNG_PERMITTED, CAP_DAC_READ_SEARCH)) {
+		fprintf(stderr, "Unable to update permitted capability set.\n");
+		return EX_SYSERR;
+	}
+	if (capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, CAP_DAC_READ_SEARCH)) {
+		fprintf(stderr, "Unable to update effective capability set.\n");
+		return EX_SYSERR;
+	}
+	if (capng_apply(CAPNG_SELECT_BOTH)) {
+		fprintf(stderr, "Unable to apply new capability set.\n");
+		return EX_SYSERR;
+	}
+	return 0;
+}
+
+/*
+ * Attempt to fetch info from the local config file, if one is present. Since
+ * this involves activity that may be dangerous for a privileged task, we
+ * fork(), have the child drop privileges and do the processing and then hand
+ * back the results via memory shared with the parent.
+ */
+static int fetch_config_info(struct ceph_mount_info *cmi)
+{
+	int ret = 0;
+	pid_t pid;
+	struct ceph_config_info *cci;
+
+	/* Don't do anything if we already have requisite info */
+	if (cmi->cmi_secret[0] && cmi->cmi_mons && cmi->cmi_fsid)
+		return 0;
+
+	cci = mmap((void *)0, sizeof(*cci), PROT_READ | PROT_WRITE,
+		   MAP_ANONYMOUS | MAP_SHARED, -1, 0);
+	if (cci == MAP_FAILED) {
+		mount_ceph_debug("Unable to allocate memory: %s\n",
+				 strerror(errno));
+		return EX_SYSERR;
+	}
+
+	pid = fork();
+	if (pid < 0) {
+		mount_ceph_debug("fork() failure: %s\n", strerror(errno));
+		ret = EX_SYSERR;
+		goto out;
+	}
+
+	if (pid == 0) {
+		char *entity_name = NULL;
+		int name_pos = 0;
+		int name_len = 0;
+
+		/* child */
+		ret = drop_capabilities();
+		if (ret)
+			exit(1);
+
+		name_pos = safe_cat(&entity_name, &name_len, name_pos, "client.");
+		name_pos = safe_cat(&entity_name, &name_len, name_pos, cmi->cmi_name);
+		mount_ceph_get_config_info(cmi->cmi_conf, entity_name, v2_addrs, cci);
+		free(entity_name);
+		exit(0);
+	} else {
+		/* parent */
+		pid = wait(&ret);
+		if (!WIFEXITED(ret)) {
+			mount_ceph_debug("Child process terminated abnormally.\n");
+			ret = EX_SYSERR;
+			goto out;
+		}
+		ret = WEXITSTATUS(ret);
+		if (ret) {
+			mount_ceph_debug("Child exited with status %d\n", ret);
+			ret = EX_SYSERR;
+			goto out;
+		}
+
+		/*
+		 * Copy values from MAP_SHARED buffer to cmi if we didn't
+		 * already find anything and we got something from the child.
+		 */
+		size_t len;
+		if (!cmi->cmi_secret[0] && cci->cci_secret[0]) {
+
+			len = strnlen(cci->cci_secret, SECRET_BUFSIZE);
+			if (len < SECRET_BUFSIZE) {
+				memcpy(cmi->cmi_secret, cci->cci_secret, len + 1);
+			} else {
+				mount_ceph_debug("secret is too long (len=%zu max=%zu)!\n", len, SECRET_BUFSIZE);
+			}
+		}
+		if (!cmi->cmi_mons && cci->cci_mons[0]) {
+			len = strnlen(cci->cci_mons, MON_LIST_BUFSIZE);
+			if (len < MON_LIST_BUFSIZE)
+				cmi->cmi_mons = strndup(cci->cci_mons, len + 1);
+		}
+		if (!cmi->cmi_fsid) {
+			len = strnlen(cci->cci_fsid, CLUSTER_FSID_LEN);
+			if (len < CLUSTER_FSID_LEN)
+				cmi->cmi_fsid = strndup(cci->cci_fsid, len + 1);
+		}
+	}
+out:
+	munmap(cci, sizeof(*cci));
+	return ret;
+}
+
+/*
+ * this one is partially based on parse_options() from cifs.mount.c
+ */
+static int parse_options(const char *data, struct ceph_mount_info *cmi,
+			 int *opt_pos)
+{
+	char * next_keyword = NULL;
+	char *name = NULL;
+
+	if (data == EMPTY_STRING)
+		goto out;
+
+	mount_ceph_debug("parsing options: %s\n", data);
+
+	do {
+		char * value = NULL;
+		bool skip = true;
+
+		/*  check if ends with trailing comma */
+		if(*data == 0)
+			break;
+		next_keyword = strchr(data,',');
+
+		/* temporarily null terminate end of keyword=value pair */
+		if(next_keyword)
+			*next_keyword++ = 0;
+
+		/* temporarily null terminate keyword to make keyword and value distinct */
+		if ((value = strchr(data, '=')) != NULL) {
+			*value = '\0';
+			value++;
+		}
+
+		if (strcmp(data, "ro") == 0) {
+			cmi->cmi_flags |= MS_RDONLY;
+		} else if (strcmp(data, "rw") == 0) {
+			cmi->cmi_flags &= ~MS_RDONLY;
+		} else if (strcmp(data, "nosuid") == 0) {
+			cmi->cmi_flags |= MS_NOSUID;
+		} else if (strcmp(data, "suid") == 0) {
+			cmi->cmi_flags &= ~MS_NOSUID;
+		} else if (strcmp(data, "dev") == 0) {
+			cmi->cmi_flags &= ~MS_NODEV;
+		} else if (strcmp(data, "nodev") == 0) {
+			cmi->cmi_flags |= MS_NODEV;
+		} else if (strcmp(data, "noexec") == 0) {
+			cmi->cmi_flags |= MS_NOEXEC;
+		} else if (strcmp(data, "exec") == 0) {
+			cmi->cmi_flags &= ~MS_NOEXEC;
+                } else if (strcmp(data, "sync") == 0) {
+                        cmi->cmi_flags |= MS_SYNCHRONOUS;
+                } else if (strcmp(data, "remount") == 0) {
+                        cmi->cmi_flags |= MS_REMOUNT;
+                } else if (strcmp(data, "mandlock") == 0) {
+                        cmi->cmi_flags |= MS_MANDLOCK;
+		} else if ((strcmp(data, "nobrl") == 0) ||
+			   (strcmp(data, "nolock") == 0)) {
+			cmi->cmi_flags &= ~MS_MANDLOCK;
+		} else if (strcmp(data, "noatime") == 0) {
+			cmi->cmi_flags |= MS_NOATIME;
+		} else if (strcmp(data, "nodiratime") == 0) {
+			cmi->cmi_flags |= MS_NODIRATIME;
+		} else if (strcmp(data, "relatime") == 0) {
+			cmi->cmi_flags |= MS_RELATIME;
+		} else if (strcmp(data, "strictatime") == 0) {
+			cmi->cmi_flags |= MS_STRICTATIME;
+		} else if (strcmp(data, "noauto") == 0) {
+			/* ignore */
+		} else if (strcmp(data, "_netdev") == 0) {
+			/* ignore */
+		} else if (strcmp(data, "nofail") == 0) {
+			/* ignore */
+		} else if (strcmp(data, "fs") == 0) {
+			if (!value || !*value) {
+				fprintf(stderr, "mount option fs requires a value.\n");
+				return -EINVAL;
+			}
+			data = "mds_namespace";
+			skip = false;
+		} else if (strcmp(data, "nofallback") == 0) {
+			no_fallback = true;
+		} else if (strcmp(data, "secretfile") == 0) {
+			int ret;
+
+			if (!value || !*value) {
+				fprintf(stderr, "keyword secretfile found, but no secret file specified\n");
+				return -EINVAL;
+			}
+			ret = read_secret_from_file(value, cmi->cmi_secret, sizeof(cmi->cmi_secret));
+			if (ret < 0) {
+				fprintf(stderr, "error reading secret file: %d\n", ret);
+				return ret;
+			}
+		} else if (strcmp(data, "secret") == 0) {
+			size_t len;
+
+			if (!value || !*value) {
+				fprintf(stderr, "mount option secret requires a value.\n");
+				return -EINVAL;
+			}
+
+			len = strnlen(value, sizeof(cmi->cmi_secret)) + 1;
+			if (len <= sizeof(cmi->cmi_secret))
+				memcpy(cmi->cmi_secret, value, len);
+		} else if (strcmp(data, "conf") == 0) {
+			if (!value || !*value) {
+				fprintf(stderr, "mount option conf requires a value.\n");
+				return -EINVAL;
+			}
+			/* keep pointer to value */
+			cmi->cmi_conf = strdup(value);
+			if (!cmi->cmi_conf)
+				return -ENOMEM;
+		} else if (strcmp(data, "name") == 0) {
+			if (!value || !*value) {
+				fprintf(stderr, "mount option name requires a value.\n");
+				return -EINVAL;
+			}
+			/* keep pointer to value */
+			name = value;
+			skip = false;
+		} else if (strcmp(data, "ms_mode") == 0) {
+			if (!value || !*value) {
+				fprintf(stderr, "mount option ms_mode requires a value.\n");
+				return -EINVAL;
+			}
+			/* Only legacy ms_mode needs v1 addrs */
+			v2_addrs = strcmp(value, "legacy");
+			skip = false;
+			ms_mode_specified = true;
+		} else if (strcmp(data, "mon_addr") == 0) {
+			/* monitor address to use for mounting */
+			if (!value || !*value) {
+				fprintf(stderr, "mount option mon_addr requires a value.\n");
+				return -EINVAL;
+			}
+			cmi->cmi_mons = strdup(value);
+			if (!cmi->cmi_mons)
+				return -ENOMEM;
+			mon_addr_specified = true;
+		} else {
+			/* unrecognized mount options, passing to kernel */
+			skip = false;
+		}
+
+		/* Copy (possibly modified) option to out */
+		if (!skip)
+                        append_opt(data, value, cmi, opt_pos);
+		data = next_keyword;
+	} while (data);
+
+out:
+	/*
+	 * set ->cmi_name conditionally -- this gets checked when parsing new
+	 * device format. for old device format, ->cmi_name is set to default
+	 * user name when name option is not passed in.
+	 */
+	if (name)
+		record_name(name, cmi);
+	if (cmi->cmi_opts)
+		mount_ceph_debug("mount.ceph: options \"%s\".\n",  cmi->cmi_opts);
+
+	if (!cmi->cmi_opts) {
+		cmi->cmi_opts = strdup(EMPTY_STRING);
+		if (!cmi->cmi_opts)
+			return -ENOMEM;
+	}
+	return 0;
+}
+
+
+static int parse_arguments(int argc, char *const *const argv,
+		const char **src, const char **node, const char **opts)
+{
+	int opt = 0;
+	static struct option long_options[] = {
+		{ "help",    no_argument,        0,  'h' },
+		{ "no-mtab", no_argument,        0,  'n' },
+		{ "verbose", no_argument,        0,  'v' },
+		{ "fake",    no_argument,        0,  'f' },
+		{ "options", required_argument,  0,  'o' },
+		{ 0,         0,                  0,  0   }
+	};
+
+	if (argc < 2) {
+		// There were no arguments. Just show the usage.
+		return 1;
+	}
+	if ((!strcmp(argv[1], "-h")) || (!strcmp(argv[1], "--help"))) {
+		// The user asked for help.
+		return 1;
+	}
+
+	// The first two arguments are positional
+	if (argc < 3)
+		return -EINVAL;
+	*src = argv[1];
+	*node = argv[2];
+
+	// Parse the remaining options
+	*opts = EMPTY_STRING;
+	while ((opt = getopt_long(argc, argv, "hnvfo:",
+					long_options, NULL)) != -1) {
+		switch (opt) {
+			case 'h' : // -h or --help
+				return 1;
+			case 'n' : // -n or --no-mtab
+				skip_mtab_flag = true;
+				break;
+			case 'v' : // -v or --verbose
+				verboseflag = true;
+				break;
+			case 'f' : // -f or --fake
+				fakeflag = true;
+				break;
+			case 'o' : // -o or --options
+				*opts = optarg;
+				break;
+			default:
+				return -EINVAL;
+		}
+	}
+	return 0;
+}
+
+/* modprobe failing doesn't necessarily prevent from working, so this
+   returns void */
+static void modprobe(void)
+{
+	int r;
+
+	r = module_load("ceph", NULL);
+	if (r)
+		printf("failed to load ceph kernel module (%d)\n", r);
+}
+
+static void usage(const char *prog_name)
+{
+	printf("usage: %s [src] [mount-point] [-n] [-v] [-o ceph-options]\n",
+		prog_name);
+	printf("options:\n");
+	printf("\t-h, --help\tPrint this help\n");
+	printf("\t-n, --no-mtab\tDo not update /etc/mtab\n");
+	printf("\t-v, --verbose\tVerbose\n");
+	printf("\t-f, --fake\tFake mount, do not actually mount\n");
+	printf("ceph-options: refer to mount.ceph(8)\n");
+	printf("\n");
+}
+
+/*
+ * The structure itself lives on the stack, so don't free it. Just the
+ * pointers inside.
+ */
+static void ceph_mount_info_free(struct ceph_mount_info *cmi)
+{
+	free(cmi->cmi_opts);
+	free(cmi->cmi_name);
+	free(cmi->cmi_fsname);
+	free(cmi->cmi_fsid);
+	free(cmi->cmi_path);
+	free(cmi->cmi_mons);
+	free(cmi->cmi_conf);
+}
+
+static int call_mount_system_call(const char *rsrc, const char *node, struct ceph_mount_info *cmi)
+{
+	int r = 0;
+	if (!fakeflag) {
+		r = mount(rsrc, node, "ceph", cmi->cmi_flags, cmi->cmi_opts);
+	}
+	return r;
+}
+
+static int mount_new_device_format(const char *node, struct ceph_mount_info *cmi)
+{
+	int r;
+	char *rsrc = NULL;
+	int pos = 0;
+	int len = 0;
+
+	if (!cmi->cmi_fsid) {
+		fprintf(stderr, "missing ceph cluster-id");
+		return -EINVAL;
+	}
+
+	pos = safe_cat(&rsrc, &len, pos, cmi->cmi_name);
+	pos = safe_cat(&rsrc, &len, pos, "@");
+	pos = safe_cat(&rsrc, &len, pos, cmi->cmi_fsid);
+	pos = safe_cat(&rsrc, &len, pos, ".");
+	pos = safe_cat(&rsrc, &len, pos, cmi->cmi_fsname);
+	pos = safe_cat(&rsrc, &len, pos, "=");
+	if (cmi->cmi_path)
+		safe_cat(&rsrc, &len, pos, cmi->cmi_path);
+
+	mount_ceph_debug("mount.ceph: trying mount with new device syntax: %s\n",
+			 rsrc);
+	if (cmi->cmi_opts)
+		mount_ceph_debug("mount.ceph: options \"%s\" will pass to kernel\n",
+				 cmi->cmi_opts);
+	r = call_mount_system_call(rsrc, node, cmi);
+	if (r)
+		r = -errno;
+	free(rsrc);
+	return r;
+}
+
+static int mount_old_device_format(const char *node, struct ceph_mount_info *cmi)
+{
+	int r;
+	int len = 0;
+	int pos = 0;
+	char *mon_addr = NULL;
+	char *rsrc = NULL;
+
+	r = remove_opt(cmi, "mon_addr", &mon_addr);
+	if (r) {
+		fprintf(stderr, "failed to switch using old device format\n");
+		return -EINVAL;
+	}
+
+	/* if we reach here and still have a v2 addr, we'd need to
+	 * refresh with v1 addrs, since we'll be not passing ms_mode
+	 * with the old syntax.
+	 */
+	if (v2_addrs && !ms_mode_specified && !mon_addr_specified) {
+		mount_ceph_debug("mount.ceph: switching to using v1 address with old syntax\n");
+		v2_addrs = false;
+		free(mon_addr);
+		free(cmi->cmi_mons);
+		mon_addr = NULL;
+		cmi->cmi_mons = NULL;
+		fetch_config_info(cmi);
+		if (!cmi->cmi_mons) {
+			fprintf(stderr, "unable to determine (v1) mon addresses\n");
+			return -EINVAL;
+		}
+		r = finalize_src(cmi, NULL, &mon_addr);
+		if (r) {
+			fprintf(stderr, "failed to resolve (v1) mon addresses\n");
+			return -EINVAL;
+		}
+		remove_opt(cmi, "ms_mode", NULL);
+	}
+
+	pos = strlen(cmi->cmi_opts);
+        if (cmi->cmi_fsname)
+                append_opt("mds_namespace", cmi->cmi_fsname, cmi, &pos);
+	if (cmi->cmi_fsid)
+		append_opt("fsid", cmi->cmi_fsid, cmi, &pos);
+
+	pos = 0;
+	resolved_mon_addr_as_mount_dev(mon_addr);
+	pos = safe_cat(&rsrc, &len, pos, mon_addr);
+	pos = safe_cat(&rsrc, &len, pos, ":");
+	if (cmi->cmi_path)
+		safe_cat(&rsrc, &len, pos, cmi->cmi_path);
+
+	mount_ceph_debug("mount.ceph: trying mount with old device syntax: %s\n",
+			 rsrc);
+	if (cmi->cmi_opts)
+		mount_ceph_debug("mount.ceph: options \"%s\" will pass to kernel\n",
+				 cmi->cmi_opts);
+
+	r = call_mount_system_call(rsrc, node, cmi);
+	free(mon_addr);
+	free(rsrc);
+
+	return r;
+}
+
+/*
+ * check whether to fall-back to using old-style mount syntax (called
+ * when new-style mount syntax fails). this is mostly to catch any
+ * new-style (v2) implementation bugs in the kernel and is primarly
+ * used in teuthology tests.
+ */
+static bool should_fallback()
+{
+	int ret;
+	struct stat stbuf;
+
+	if (!no_fallback)
+		return true;
+
+	ret = stat(CEPH_V2_MOUNT_SUPPORT_PATH, &stbuf);
+	if (ret) {
+		mount_ceph_debug("mount.ceph: v2 mount support check returned %d\n",
+				 errno);
+		if (errno == ENOENT)
+			mount_ceph_debug("mount.ceph: kernel does not support v2"
+					 " syntax\n");
+		/* fallback on *all* errors */
+		return true;
+	}
+
+	fprintf(stderr, "mount.ceph: kernel BUG!\n");
+	return false;
+}
+
+static int do_mount(const char *dev, const char *node,
+		    struct ceph_mount_info *cmi) {
+	int pos = 0;
+	int retval= -EINVAL;
+	bool fallback = true;
+
+        /* no v2 addresses available via config - try v1 addresses */
+	if (v2_addrs &&
+	    !cmi->cmi_mons &&
+	    !ms_mode_specified &&
+	    !mon_addr_specified) {
+		mount_ceph_debug("mount.ceph: switching to using v1 address\n");
+		v2_addrs = false;
+		fetch_config_info(cmi);
+		remove_opt(cmi, "ms_mode", NULL);
+	}
+
+	if (!cmi->cmi_mons) {
+		fprintf(stderr, "unable to determine mon addresses\n");
+		return -EINVAL;
+	}
+
+	pos = strlen(cmi->cmi_opts);
+	retval = finalize_src(cmi, &pos, NULL);
+	if (retval) {
+		fprintf(stderr, "failed to resolve source\n");
+		return -EINVAL;
+	}
+
+	retval = -1;
+	if (cmi->format == MOUNT_DEV_FORMAT_NEW) {
+		retval = mount_new_device_format(node, cmi);
+		if (retval)
+			fallback = (should_fallback() && retval == -EINVAL && cmi->cmi_fsid);
+	}
+
+	/* pass-through or fallback to old-style mount device */
+	if (retval && fallback)
+		retval = mount_old_device_format(node, cmi);
+	if (retval) {
+		retval = EX_FAIL;
+		switch (errno) {
+		case ENODEV:
+			fprintf(stderr, "mount error: ceph filesystem not supported by the system\n");
+			break;
+		case EHOSTUNREACH:
+			fprintf(stderr, "mount error: no mds server is up or the cluster is laggy\n");
+			break;
+		default:
+			fprintf(stderr, "mount error %d = %s\n", errno, strerror(errno));
+		}
+	}
+
+	if (!retval && !skip_mtab_flag) {
+		update_mtab_entry(dev, node, "ceph", cmi->cmi_opts, cmi->cmi_flags, 0, 0);
+	}
+
+	return retval;
+}
+
+static int append_key_or_secret_option(struct ceph_mount_info *cmi)
+{
+	int pos = strlen(cmi->cmi_opts);
+
+	if (!cmi->cmi_secret[0] && !is_kernel_secret(cmi->cmi_name))
+		return 0;
+
+	if (pos)
+		pos = safe_cat(&cmi->cmi_opts, &cmi->cmi_opts_len, pos, ",");
+
+	/* when parsing kernel options (-o remount) we get '<hidden>' as the secret */
+	if (cmi->cmi_secret[0] && (strcmp(cmi->cmi_secret, "<hidden>") != 0)) {
+		int ret = set_kernel_secret(cmi->cmi_secret, cmi->cmi_name);
+		if (ret < 0) {
+			if (ret == -ENODEV || ret == -ENOSYS) {
+				/* old kernel; fall back to secret= in options */
+				pos = safe_cat(&cmi->cmi_opts,
+					       &cmi->cmi_opts_len, pos,
+					       "secret=");
+				pos = safe_cat(&cmi->cmi_opts,
+					       &cmi->cmi_opts_len, pos,
+					       cmi->cmi_secret);
+				return 0;
+			}
+			fprintf(stderr, "adding ceph secret key to kernel failed: %s\n",
+				strerror(-ret));
+			return ret;
+		}
+	}
+
+	pos = safe_cat(&cmi->cmi_opts, &cmi->cmi_opts_len, pos, "key=");
+	pos = safe_cat(&cmi->cmi_opts, &cmi->cmi_opts_len, pos, cmi->cmi_name);
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	int opt_pos = 0;
+	const char *dev, *node, *opts;
+	int retval;
+	struct ceph_mount_info cmi = { 0 };
+
+	retval = parse_arguments(argc, argv, &dev, &node, &opts);
+	if (retval) {
+		usage(argv[0]);
+		retval = (retval > 0) ? 0 : EX_USAGE;
+		goto out;
+	}
+
+	retval = parse_options(opts, &cmi, &opt_pos);
+	if (retval) {
+		fprintf(stderr, "failed to parse ceph_options: %d\n", retval);
+		retval = EX_USAGE;
+		goto out;
+	}
+
+	retval = parse_dev(dev, &cmi, &opt_pos);
+	if (retval) {
+		fprintf(stderr, "unable to parse mount device string: %d\n", retval);
+		retval = EX_USAGE;
+		goto out;
+	}
+
+	/*
+	 * We don't care if this errors out, since this is best-effort.
+	 * note that this fetches v1 or v2 addr depending on @v2_addr
+	 * flag.
+	 */
+	fetch_config_info(&cmi);
+
+	/* Ensure the ceph key_type is available */
+	modprobe();
+
+	retval = append_key_or_secret_option(&cmi);
+	if (retval) {
+		fprintf(stderr, "couldn't append secret option: %d\n", retval);
+		retval = EX_USAGE;
+		goto out;
+	}
+
+	block_signals(SIG_BLOCK);
+	retval = do_mount(dev, node, &cmi);
+	block_signals(SIG_UNBLOCK);
+out:
+	ceph_mount_info_free(&cmi);
+	return retval;
+}
+