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authorLinus Torvalds <torvalds@linux-foundation.org>2016-01-21 23:20:46 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-01-21 23:20:46 +0300
commite9f57ebcba563e0cd532926cab83c92bb4d79360 (patch)
tree6cf11baa7851129145cc35f9218583287f41dd64
parent5c89e9ea7ef1feaa147325b2ab47a89a147fb903 (diff)
parent84889d49335627bc770b32787c1ef9ebad1da232 (diff)
downloadlinux-e9f57ebcba563e0cd532926cab83c92bb4d79360.tar.xz
Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs updates from Miklos Szeredi: "This contains several bug fixes and a new mount option 'default_permissions' that allows read-only exported NFS filesystems to be used as lower layer" * 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: ovl: check dentry positiveness in ovl_cleanup_whiteouts() ovl: setattr: check permissions before copy-up ovl: root: copy attr ovl: move super block magic number to magic.h ovl: use a minimal buffer in ovl_copy_xattr ovl: allow zero size xattr ovl: default permissions
-rw-r--r--fs/overlayfs/copy_up.c41
-rw-r--r--fs/overlayfs/inode.c36
-rw-r--r--fs/overlayfs/overlayfs.h3
-rw-r--r--fs/overlayfs/readdir.c3
-rw-r--r--fs/overlayfs/super.c35
-rw-r--r--include/uapi/linux/magic.h1
6 files changed, 101 insertions, 18 deletions
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 0a8983492d91..eff6319d5037 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -22,9 +22,9 @@
int ovl_copy_xattr(struct dentry *old, struct dentry *new)
{
- ssize_t list_size, size;
- char *buf, *name, *value;
- int error;
+ ssize_t list_size, size, value_size = 0;
+ char *buf, *name, *value = NULL;
+ int uninitialized_var(error);
if (!old->d_inode->i_op->getxattr ||
!new->d_inode->i_op->getxattr)
@@ -41,29 +41,40 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new)
if (!buf)
return -ENOMEM;
- error = -ENOMEM;
- value = kmalloc(XATTR_SIZE_MAX, GFP_KERNEL);
- if (!value)
- goto out;
-
list_size = vfs_listxattr(old, buf, list_size);
if (list_size <= 0) {
error = list_size;
- goto out_free_value;
+ goto out;
}
for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {
- size = vfs_getxattr(old, name, value, XATTR_SIZE_MAX);
- if (size <= 0) {
+retry:
+ size = vfs_getxattr(old, name, value, value_size);
+ if (size == -ERANGE)
+ size = vfs_getxattr(old, name, NULL, 0);
+
+ if (size < 0) {
error = size;
- goto out_free_value;
+ break;
+ }
+
+ if (size > value_size) {
+ void *new;
+
+ new = krealloc(value, size, GFP_KERNEL);
+ if (!new) {
+ error = -ENOMEM;
+ break;
+ }
+ value = new;
+ value_size = size;
+ goto retry;
}
+
error = vfs_setxattr(new, name, value, size, 0);
if (error)
- goto out_free_value;
+ break;
}
-
-out_free_value:
kfree(value);
out:
kfree(buf);
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 964a60fa7afc..bf996e574f3d 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -42,6 +42,19 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr)
int err;
struct dentry *upperdentry;
+ /*
+ * Check for permissions before trying to copy-up. This is redundant
+ * since it will be rechecked later by ->setattr() on upper dentry. But
+ * without this, copy-up can be triggered by just about anybody.
+ *
+ * We don't initialize inode->size, which just means that
+ * inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not
+ * check for a swapfile (which this won't be anyway).
+ */
+ err = inode_change_ok(dentry->d_inode, attr);
+ if (err)
+ return err;
+
err = ovl_want_write(dentry);
if (err)
goto out;
@@ -95,6 +108,29 @@ int ovl_permission(struct inode *inode, int mask)
realdentry = ovl_entry_real(oe, &is_upper);
+ if (ovl_is_default_permissions(inode)) {
+ struct kstat stat;
+ struct path realpath = { .dentry = realdentry };
+
+ if (mask & MAY_NOT_BLOCK)
+ return -ECHILD;
+
+ realpath.mnt = ovl_entry_mnt_real(oe, inode, is_upper);
+
+ err = vfs_getattr(&realpath, &stat);
+ if (err)
+ return err;
+
+ if ((stat.mode ^ inode->i_mode) & S_IFMT)
+ return -ESTALE;
+
+ inode->i_mode = stat.mode;
+ inode->i_uid = stat.uid;
+ inode->i_gid = stat.gid;
+
+ return generic_permission(inode, mask);
+ }
+
/* Careful in RCU walk mode */
realinode = ACCESS_ONCE(realdentry->d_inode);
if (!realinode) {
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index e17154aeaae4..99b4168c36ff 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -142,7 +142,10 @@ struct dentry *ovl_dentry_upper(struct dentry *dentry);
struct dentry *ovl_dentry_lower(struct dentry *dentry);
struct dentry *ovl_dentry_real(struct dentry *dentry);
struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper);
+struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode,
+ bool is_upper);
struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry);
+bool ovl_is_default_permissions(struct inode *inode);
void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache);
struct dentry *ovl_workdir(struct dentry *dentry);
int ovl_want_write(struct dentry *dentry);
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index 70e9af551600..adcb1398c481 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -571,7 +571,8 @@ void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list)
(int) PTR_ERR(dentry));
continue;
}
- ovl_cleanup(upper->d_inode, dentry);
+ if (dentry->d_inode)
+ ovl_cleanup(upper->d_inode, dentry);
dput(dentry);
}
mutex_unlock(&upper->d_inode->i_mutex);
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index e38ee0fed24a..a4cbdf9824c7 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -9,6 +9,7 @@
#include <linux/fs.h>
#include <linux/namei.h>
+#include <linux/pagemap.h>
#include <linux/xattr.h>
#include <linux/security.h>
#include <linux/mount.h>
@@ -24,12 +25,11 @@ MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
MODULE_DESCRIPTION("Overlay filesystem");
MODULE_LICENSE("GPL");
-#define OVERLAYFS_SUPER_MAGIC 0x794c7630
-
struct ovl_config {
char *lowerdir;
char *upperdir;
char *workdir;
+ bool default_permissions;
};
/* private information held for overlayfs's superblock */
@@ -154,6 +154,18 @@ struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper)
return realdentry;
}
+struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode,
+ bool is_upper)
+{
+ if (is_upper) {
+ struct ovl_fs *ofs = inode->i_sb->s_fs_info;
+
+ return ofs->upper_mnt;
+ } else {
+ return oe->numlower ? oe->lowerstack[0].mnt : NULL;
+ }
+}
+
struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry)
{
struct ovl_entry *oe = dentry->d_fsdata;
@@ -161,6 +173,13 @@ struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry)
return oe->cache;
}
+bool ovl_is_default_permissions(struct inode *inode)
+{
+ struct ovl_fs *ofs = inode->i_sb->s_fs_info;
+
+ return ofs->config.default_permissions;
+}
+
void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache)
{
struct ovl_entry *oe = dentry->d_fsdata;
@@ -594,6 +613,8 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
seq_show_option(m, "upperdir", ufs->config.upperdir);
seq_show_option(m, "workdir", ufs->config.workdir);
}
+ if (ufs->config.default_permissions)
+ seq_puts(m, ",default_permissions");
return 0;
}
@@ -618,6 +639,7 @@ enum {
OPT_LOWERDIR,
OPT_UPPERDIR,
OPT_WORKDIR,
+ OPT_DEFAULT_PERMISSIONS,
OPT_ERR,
};
@@ -625,6 +647,7 @@ static const match_table_t ovl_tokens = {
{OPT_LOWERDIR, "lowerdir=%s"},
{OPT_UPPERDIR, "upperdir=%s"},
{OPT_WORKDIR, "workdir=%s"},
+ {OPT_DEFAULT_PERMISSIONS, "default_permissions"},
{OPT_ERR, NULL}
};
@@ -685,6 +708,10 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config)
return -ENOMEM;
break;
+ case OPT_DEFAULT_PERMISSIONS:
+ config->default_permissions = true;
+ break;
+
default:
pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p);
return -EINVAL;
@@ -910,6 +937,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
}
sb->s_stack_depth = 0;
+ sb->s_maxbytes = MAX_LFS_FILESIZE;
if (ufs->config.upperdir) {
if (!ufs->config.workdir) {
pr_err("overlayfs: missing 'workdir'\n");
@@ -1053,6 +1081,9 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
root_dentry->d_fsdata = oe;
+ ovl_copyattr(ovl_dentry_real(root_dentry)->d_inode,
+ root_dentry->d_inode);
+
sb->s_magic = OVERLAYFS_SUPER_MAGIC;
sb->s_op = &ovl_super_operations;
sb->s_root = root_dentry;
diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h
index b283d56c1db9..0de181ad73d5 100644
--- a/include/uapi/linux/magic.h
+++ b/include/uapi/linux/magic.h
@@ -31,6 +31,7 @@
#define PSTOREFS_MAGIC 0x6165676C
#define EFIVARFS_MAGIC 0xde5e81e4
#define HOSTFS_SUPER_MAGIC 0x00c0ffee
+#define OVERLAYFS_SUPER_MAGIC 0x794c7630
#define MINIX_SUPER_MAGIC 0x137F /* minix v1 fs, 14 char names */
#define MINIX_SUPER_MAGIC2 0x138F /* minix v1 fs, 30 char names */