From 8db2a44c9438749be98d41fb309f10d5084805df Mon Sep 17 00:00:00 2001
From: Jeff Layton <jlayton@redhat.com>
Date: Fri, 17 Jan 2020 07:48:12 -0500
Subject: [PATCH] mount.ceph: remove arbitrary limit on size of name= option

Aaron was getting back -ERANGE errors when trying to mount using
a long name= option. The issue is that the destination buffer for the
"key=" string is not big enough to hold long names.

When I overhauled the mount.ceph code recently, I made this buffer much
smaller than before figuring that it didn't need to be any larger than
the length of "secret=<base64 encoded key>".

In the case where the secret is set in the keyring though, this buffer
needs to be able to hold a string like "key=client.<cephx name>". The
cephx name can be of arbitrary length, however.

Rework the code to just safe_cat the strings directly into the options
buffer, eliminating an extra copy and the need for an arbitrary limit.
This also allows us to remove get_secret_option() from the the common
code as well.

Fixes: https://tracker.ceph.com/issues/43649
Reported-by: Aaron <aarongmldt@gmail.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 src/common/secret.h    |  7 ------
 src/mount/mount.ceph.c | 45 ++++++++++++++++++++++++-------------
 src/mount/mount.ceph.h |  3 ---
 4 files changed, 30 insertions(+), 75 deletions(-)

diff --git a/src/common/secret.h b/src/common/secret.h
index b681fa1ec7..5d2ad179dd 100644
--- a/src/common/secret.h
+++ b/src/common/secret.h
@@ -7,13 +7,6 @@ extern "C" {
 
 int read_secret_from_file(const char *filename, char *secret, size_t max_len);
 
-/*
- * Attempts to add the secret to the kernel, but falls back to
- * the old secret= option if the kernel is too old.
- */
-int get_secret_option(const char *secret, const char *key_name,
-		      char *secret_option, size_t secret_option_len);
-
 int set_kernel_secret(const char *secret, const char *key_name);
 
 int is_kernel_secret(const char *key_name);
diff --git a/src/mount/mount.ceph.c b/src/mount/mount.ceph.c
index e970648c59..133bc554f5 100644
--- a/src/mount/mount.ceph.c
+++ b/src/mount/mount.ceph.c
@@ -425,24 +425,39 @@ static void ceph_mount_info_free(struct ceph_mount_info *cmi)
 	free(cmi->cmi_conf);
 }
 
-static int finalize_options(struct ceph_mount_info *cmi)
+static int append_key_or_secret_option(struct ceph_mount_info *cmi)
 {
-	int pos;
+	int pos = strlen(cmi->cmi_opts);
 
-	if (cmi->cmi_secret[0] || is_kernel_secret(cmi->cmi_name)) {
-		int ret;
-		char secret_option[SECRET_OPTION_BUFSIZE];
+	if (!cmi->cmi_secret[0] && !is_kernel_secret(cmi->cmi_name))
+		return 0;
 
-		ret = get_secret_option(cmi->cmi_secret, cmi->cmi_name,
-					secret_option, sizeof(secret_option));
-		if (ret < 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 = strlen(cmi->cmi_opts);
-		if (pos)
-			pos = safe_cat(&cmi->cmi_opts, &cmi->cmi_opts_len, pos, ",");
-		pos = safe_cat(&cmi->cmi_opts, &cmi->cmi_opts_len, pos, secret_option);
+		}
 	}
+
+	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;
 }
 
@@ -493,9 +508,9 @@ int main(int argc, char *argv[])
 	/* Ensure the ceph key_type is available */
 	modprobe();
 
-	retval = finalize_options(&cmi);
+	retval = append_key_or_secret_option(&cmi);
 	if (retval) {
-		fprintf(stderr, "couldn't finalize options: %d\n", retval);
+		fprintf(stderr, "couldn't append secret option: %d\n", retval);
 		retval = EX_USAGE;
 		goto out;
 	}
diff --git a/src/mount/mount.ceph.h b/src/mount/mount.ceph.h
index c563597c43..b61176923d 100644
--- a/src/mount/mount.ceph.h
+++ b/src/mount/mount.ceph.h
@@ -21,9 +21,6 @@ extern "C" {
 /* Max Including null terminator */
 #define SECRET_BUFSIZE (MAX_SECRET_LEN + 1)
 
-/* Buffer size for secret= option */
-#define SECRET_OPTION_BUFSIZE (sizeof("secret=") + MAX_SECRET_LEN + 1)
-
 /* 2k should be enough for anyone? */
 #define MON_LIST_BUFSIZE	2048
 
-- 
2.24.1