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ovl: Move xattr support to new xattrs.c file
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This moves the code from super.c and inode.c, and makes ovl_xattr_get/set()
static.

This is in preparation for doing more work on xattrs support.

Signed-off-by: Alexander Larsson <alexl@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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Amir Goldstein committed Oct 30, 2023
1 parent 5b02bfc commit 420a62d
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Showing 5 changed files with 207 additions and 196 deletions.
2 changes: 1 addition & 1 deletion fs/overlayfs/Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -6,4 +6,4 @@
obj-$(CONFIG_OVERLAY_FS) += overlay.o

overlay-objs := super.o namei.o util.o inode.o file.o dir.o readdir.o \
copy_up.o export.o params.o
copy_up.o export.o params.o xattrs.o
122 changes: 0 additions & 122 deletions fs/overlayfs/inode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -339,128 +339,6 @@ static const char *ovl_get_link(struct dentry *dentry,
return p;
}

bool ovl_is_private_xattr(struct super_block *sb, const char *name)
{
struct ovl_fs *ofs = OVL_FS(sb);

if (ofs->config.userxattr)
return strncmp(name, OVL_XATTR_USER_PREFIX,
sizeof(OVL_XATTR_USER_PREFIX) - 1) == 0;
else
return strncmp(name, OVL_XATTR_TRUSTED_PREFIX,
sizeof(OVL_XATTR_TRUSTED_PREFIX) - 1) == 0;
}

int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
const void *value, size_t size, int flags)
{
int err;
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
struct dentry *upperdentry = ovl_i_dentry_upper(inode);
struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry);
struct path realpath;
const struct cred *old_cred;

if (!value && !upperdentry) {
ovl_path_lower(dentry, &realpath);
old_cred = ovl_override_creds(dentry->d_sb);
err = vfs_getxattr(mnt_idmap(realpath.mnt), realdentry, name, NULL, 0);
revert_creds(old_cred);
if (err < 0)
goto out;
}

if (!upperdentry) {
err = ovl_copy_up(dentry);
if (err)
goto out;

realdentry = ovl_dentry_upper(dentry);
}

err = ovl_want_write(dentry);
if (err)
goto out;

old_cred = ovl_override_creds(dentry->d_sb);
if (value) {
err = ovl_do_setxattr(ofs, realdentry, name, value, size,
flags);
} else {
WARN_ON(flags != XATTR_REPLACE);
err = ovl_do_removexattr(ofs, realdentry, name);
}
revert_creds(old_cred);
ovl_drop_write(dentry);

/* copy c/mtime */
ovl_copyattr(inode);
out:
return err;
}

int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
void *value, size_t size)
{
ssize_t res;
const struct cred *old_cred;
struct path realpath;

ovl_i_path_real(inode, &realpath);
old_cred = ovl_override_creds(dentry->d_sb);
res = vfs_getxattr(mnt_idmap(realpath.mnt), realpath.dentry, name, value, size);
revert_creds(old_cred);
return res;
}

static bool ovl_can_list(struct super_block *sb, const char *s)
{
/* Never list private (.overlay) */
if (ovl_is_private_xattr(sb, s))
return false;

/* List all non-trusted xattrs */
if (strncmp(s, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) != 0)
return true;

/* list other trusted for superuser only */
return ns_capable_noaudit(&init_user_ns, CAP_SYS_ADMIN);
}

ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
{
struct dentry *realdentry = ovl_dentry_real(dentry);
ssize_t res;
size_t len;
char *s;
const struct cred *old_cred;

old_cred = ovl_override_creds(dentry->d_sb);
res = vfs_listxattr(realdentry, list, size);
revert_creds(old_cred);
if (res <= 0 || size == 0)
return res;

/* filter out private xattrs */
for (s = list, len = res; len;) {
size_t slen = strnlen(s, len) + 1;

/* underlying fs providing us with an broken xattr list? */
if (WARN_ON(slen > len))
return -EIO;

len -= slen;
if (!ovl_can_list(dentry->d_sb, s)) {
res -= slen;
memmove(s, s + slen, len);
} else {
s += slen;
}
}

return res;
}

#ifdef CONFIG_FS_POSIX_ACL
/*
* Apply the idmapping of the layer to POSIX ACLs. The caller must pass a clone
Expand Down
18 changes: 9 additions & 9 deletions fs/overlayfs/overlayfs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -699,17 +699,8 @@ int ovl_set_nlink_lower(struct dentry *dentry);
unsigned int ovl_get_nlink(struct ovl_fs *ofs, struct dentry *lowerdentry,
struct dentry *upperdentry,
unsigned int fallback);
int ovl_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
struct iattr *attr);
int ovl_getattr(struct mnt_idmap *idmap, const struct path *path,
struct kstat *stat, u32 request_mask, unsigned int flags);
int ovl_permission(struct mnt_idmap *idmap, struct inode *inode,
int mask);
int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
const void *value, size_t size, int flags);
int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
void *value, size_t size);
ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);

#ifdef CONFIG_FS_POSIX_ACL
struct posix_acl *do_ovl_get_acl(struct mnt_idmap *idmap,
Expand Down Expand Up @@ -846,3 +837,12 @@ static inline bool ovl_force_readonly(struct ovl_fs *ofs)
{
return (!ovl_upper_mnt(ofs) || !ofs->workdir);
}

/* xattr.c */

const struct xattr_handler * const *ovl_xattr_handlers(struct ovl_fs *ofs);
int ovl_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
struct iattr *attr);
int ovl_getattr(struct mnt_idmap *idmap, const struct path *path,
struct kstat *stat, u32 request_mask, unsigned int flags);
ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
65 changes: 1 addition & 64 deletions fs/overlayfs/super.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -445,68 +445,6 @@ static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
return ok;
}

static int ovl_own_xattr_get(const struct xattr_handler *handler,
struct dentry *dentry, struct inode *inode,
const char *name, void *buffer, size_t size)
{
return -EOPNOTSUPP;
}

static int ovl_own_xattr_set(const struct xattr_handler *handler,
struct mnt_idmap *idmap,
struct dentry *dentry, struct inode *inode,
const char *name, const void *value,
size_t size, int flags)
{
return -EOPNOTSUPP;
}

static int ovl_other_xattr_get(const struct xattr_handler *handler,
struct dentry *dentry, struct inode *inode,
const char *name, void *buffer, size_t size)
{
return ovl_xattr_get(dentry, inode, name, buffer, size);
}

static int ovl_other_xattr_set(const struct xattr_handler *handler,
struct mnt_idmap *idmap,
struct dentry *dentry, struct inode *inode,
const char *name, const void *value,
size_t size, int flags)
{
return ovl_xattr_set(dentry, inode, name, value, size, flags);
}

static const struct xattr_handler ovl_own_trusted_xattr_handler = {
.prefix = OVL_XATTR_TRUSTED_PREFIX,
.get = ovl_own_xattr_get,
.set = ovl_own_xattr_set,
};

static const struct xattr_handler ovl_own_user_xattr_handler = {
.prefix = OVL_XATTR_USER_PREFIX,
.get = ovl_own_xattr_get,
.set = ovl_own_xattr_set,
};

static const struct xattr_handler ovl_other_xattr_handler = {
.prefix = "", /* catch all */
.get = ovl_other_xattr_get,
.set = ovl_other_xattr_set,
};

static const struct xattr_handler * const ovl_trusted_xattr_handlers[] = {
&ovl_own_trusted_xattr_handler,
&ovl_other_xattr_handler,
NULL
};

static const struct xattr_handler * const ovl_user_xattr_handlers[] = {
&ovl_own_user_xattr_handler,
&ovl_other_xattr_handler,
NULL
};

static int ovl_setup_trap(struct super_block *sb, struct dentry *dir,
struct inode **ptrap, const char *name)
{
Expand Down Expand Up @@ -1501,8 +1439,7 @@ int ovl_fill_super(struct super_block *sb, struct fs_context *fc)
cap_lower(cred->cap_effective, CAP_SYS_RESOURCE);

sb->s_magic = OVERLAYFS_SUPER_MAGIC;
sb->s_xattr = ofs->config.userxattr ? ovl_user_xattr_handlers :
ovl_trusted_xattr_handlers;
sb->s_xattr = ovl_xattr_handlers(ofs);
sb->s_fs_info = ofs;
#ifdef CONFIG_FS_POSIX_ACL
sb->s_flags |= SB_POSIXACL;
Expand Down
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