EL Fri, 7 Nov 2014 18:02:42 +0100
Miklos Szeredi <[email protected]> escrigué:
> This is the first iteration of the patch, and quite possibly buggy.
> Testing and review is welcome.
>
Hello,
I did light tests on this patch applied to kernel 3.18-rc3, it works.
Observations:
- option lowerdirs is an extended case of lowerdir,
then we can use only a name for that option and discard the other,
for compatibility with older versions may be lowerdir.
- overlayfs changes fast the mount options that we should specify,
an overlayfs version number will help the implementer to control it.
- limit filesystem depth by a kernel config parameter, allowing nomax.
- print more detailed error message
Following patches are included to better explain some points,
you can use the idea and make your best,
Regards,
Jordi Pujol
modinfo --field=version overlayfs
busybox modinfo -F version /lib/modules/$(uname -r)/kernel/fs/overlayfs.ko | awk '{print $NF}'
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -23,6 +23,7 @@
MODULE_AUTHOR("Miklos Szeredi <[email protected]>");
MODULE_DESCRIPTION("Overlay filesystem");
MODULE_LICENSE("GPL");
+MODULE_VERSION(OVERLAYFS_VERSION);
#define OVERLAYFS_SUPER_MAGIC 0x794c764f
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -9,6 +9,8 @@
#include <linux/kernel.h>
+#define OVERLAYFS_VERSION "25"
+
struct ovl_entry;
enum ovl_path_type {
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -728,7 +728,10 @@ static int ovl_fill_super(struct super_b
}
if (!ufs->config.upperdir &&
!ufs->config.lowerdir && !ufs->config.lowerdirs) {
- pr_err("overlayfs: no 'upperdir', 'lowerdir' or 'lowerdirs' specified\n");
+ pr_err("overlayfs: missing%s%s%s\n",
+ ufs->config.upperdir ? "" : " upperdir",
+ ufs->config.lowerdir ? "" : " lowerdir",
+ ufs->config.lowerdirs ? "" : " lowerdirs");
goto out_free_config;
}
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -246,12 +246,6 @@ struct iattr {
*/
#include <linux/quota.h>
-/*
- * Maximum number of layers of fs stack. Needs to be limited to
- * prevent kernel stack overflow
- */
-#define FILESYSTEM_MAX_STACK_DEPTH 2
-
/**
* enum positive_aop_returns - aop return codes with specific semantics
*
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -44,6 +44,12 @@ config INIT_ENV_ARG_LIMIT
Maximum of each of the number of arguments and environment
variables passed to init from the kernel command line.
+config FILESYSTEM_MAX_STACK_DEPTH
+ int "Maximum number of layers of fs stack"
+ default 2
+ help
+ Maximum number of layers of fs stack. Needs to be limited to
+ prevent kernel stack overflow. Set to 0 for no limit.
config CROSS_COMPILE
string "Cross-compiler tool prefix"
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -568,8 +568,9 @@ static struct dentry *ecryptfs_mount(str
s->s_magic = ECRYPTFS_SUPER_MAGIC;
s->s_stack_depth = path.dentry->d_sb->s_stack_depth + 1;
- rc = -EINVAL;
- if (s->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
+ if (CONFIG_FILESYSTEM_MAX_STACK_DEPTH > 0 &&
+ s->s_stack_depth > CONFIG_FILESYSTEM_MAX_STACK_DEPTH) {
+ rc = -EINVAL;
pr_err("eCryptfs: maximum fs stacking depth exceeded\n");
goto out_free;
}
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -818,7 +818,8 @@ static int ovl_fill_super(struct super_b
}
err = -EINVAL;
- if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
+ if (CONFIG_FILESYSTEM_MAX_STACK_DEPTH > 0 &&
+ sb->s_stack_depth > CONFIG_FILESYSTEM_MAX_STACK_DEPTH) {
pr_err("overlayfs: maximum fs stacking depth exceeded\n");
goto out_put_lowerpath;
}
