[PATCH v13 24/51] xfs: Change how listxattr generates synthetic attributes

Andreas Gruenbacher
2015-11-03T15:20:26Z

Instead of adding the synthesized POSIX ACL attribute names after listing all
non-synthesized attributes, generate them immediately when listing the
non-synthesized attributes.

In addition, merge xfs_xattr_put_listent and xfs_xattr_put_listent_sizes to
ensure that the list size is computed correctly; the split version was
overestimating the list size for non-root users.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
fs/xfs/xfs_acl.c | 23 ---------
fs/xfs/xfs_acl.h | 4 --
fs/xfs/xfs_xattr.c | 137 +++++++++++++++++++++++------------------------------
3 files changed, 59 insertions(+), 105 deletions(-)

diff --git a/fs/xfs/xfs_acl.c b/fs/xfs/xfs_acl.c
index 7b03383..778a464 100644
--- a/fs/xfs/xfs_acl.c
+++ b/fs/xfs/xfs_acl.c
@@ -231,29 +231,6 @@ __xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
return error;
}

-static int
-xfs_acl_exists(struct inode *inode, unsigned char *name)
-{
- int len = XFS_ACL_MAX_SIZE(XFS_M(inode->i_sb));
-
- return (xfs_attr_get(XFS_I(inode), name, NULL, &len,
- ATTR_ROOT|ATTR_KERNOVAL) == 0);
-}
-
-int
-posix_acl_access_exists(struct inode *inode)
-{
- return xfs_acl_exists(inode, SGI_ACL_FILE);
-}
-
-int
-posix_acl_default_exists(struct inode *inode)
-{
- if (!S_ISDIR(inode->i_mode))
- return 0;
- return xfs_acl_exists(inode, SGI_ACL_DEFAULT);
-}
-
int
xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
{
diff --git a/fs/xfs/xfs_acl.h b/fs/xfs/xfs_acl.h
index 9ee0a0d..cf973f5 100644
--- a/fs/xfs/xfs_acl.h
+++ b/fs/xfs/xfs_acl.h
@@ -24,15 +24,11 @@ struct posix_acl;
#ifdef CONFIG_XFS_POSIX_ACL
extern struct posix_acl *xfs_get_acl(struct inode *inode, int type);
extern int xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type);
-extern int posix_acl_access_exists(struct inode *inode);
-extern int posix_acl_default_exists(struct inode *inode);
#else
static inline struct posix_acl *xfs_get_acl(struct inode *inode, int type)
{
return NULL;
}
# define xfs_set_acl NULL
-# define posix_acl_access_exists(inode) 0
-# define posix_acl_default_exists(inode) 0
#endif /* CONFIG_XFS_POSIX_ACL */
#endif /* __XFS_ACL_H__ */
diff --git a/fs/xfs/xfs_xattr.c b/fs/xfs/xfs_xattr.c
index c0368151..8428aed 100644
--- a/fs/xfs/xfs_xattr.c
+++ b/fs/xfs/xfs_xattr.c
@@ -106,47 +106,19 @@ const struct xattr_handler *xfs_xattr_handlers[] = {
NULL
};

-static unsigned int xfs_xattr_prefix_len(int flags)
-{
- if (flags & XFS_ATTR_SECURE)
- return sizeof("security");
- else if (flags & XFS_ATTR_ROOT)
- return sizeof("trusted");
- else
- return sizeof("user");
-}
-
-static const char *xfs_xattr_prefix(int flags)
-{
- if (flags & XFS_ATTR_SECURE)
- return xfs_xattr_security_handler.prefix;
- else if (flags & XFS_ATTR_ROOT)
- return xfs_xattr_trusted_handler.prefix;
- else
- return xfs_xattr_user_handler.prefix;
-}
-
static int
-xfs_xattr_put_listent(
+__xfs_xattr_put_listent(
struct xfs_attr_list_context *context,
- int flags,
- unsigned char *name,
- int namelen,
- int valuelen,
- unsigned char *value)
+ char *prefix,
+ int prefix_len,
+ unsigned char *name,
+ int namelen)
{
- unsigned int prefix_len = xfs_xattr_prefix_len(flags);
char *offset;
int arraytop;

- ASSERT(context->count >= 0);
-
- /*
- * Only show root namespace entries if we are actually allowed to
- * see them.
- */
- if ((flags & XFS_ATTR_ROOT) && !capable(CAP_SYS_ADMIN))
- return 0;
+ if (!context->alist)
+ goto compute_size;

arraytop = context->count + prefix_len + namelen + 1;
if (arraytop > context->firstu) {
@@ -154,17 +126,19 @@ xfs_xattr_put_listent(
return 1;
}
offset = (char *)context->alist + context->count;
- strncpy(offset, xfs_xattr_prefix(flags), prefix_len);
+ strncpy(offset, prefix, prefix_len);
offset += prefix_len;
strncpy(offset, (char *)name, namelen); /* real name */
offset += namelen;
*offset = '\0';
+
+compute_size:
context->count += prefix_len + namelen + 1;
return 0;
}

static int
-xfs_xattr_put_listent_sizes(
+xfs_xattr_put_listent(
struct xfs_attr_list_context *context,
int flags,
unsigned char *name,
@@ -172,24 +146,55 @@ xfs_xattr_put_listent_sizes(
int valuelen,
unsigned char *value)
{
- context->count += xfs_xattr_prefix_len(flags) + namelen + 1;
- return 0;
-}
+ char *prefix;
+ int prefix_len;

-static int
-list_one_attr(const char *name, const size_t len, void *data,
- size_t size, ssize_t *result)
-{
- char *p = data + *result;
+ ASSERT(context->count >= 0);

- *result += len;
- if (!size)
- return 0;
- if (*result > size)
- return -ERANGE;
+ if (flags & XFS_ATTR_ROOT) {
+#ifdef CONFIG_XFS_POSIX_ACL
+ if (namelen == SGI_ACL_FILE_SIZE &&
+ strncmp(name, SGI_ACL_FILE,
+ SGI_ACL_FILE_SIZE) == 0) {
+ int ret = __xfs_xattr_put_listent(
+ context, XATTR_SYSTEM_PREFIX,
+ XATTR_SYSTEM_PREFIX_LEN,
+ XATTR_POSIX_ACL_ACCESS,
+ strlen(XATTR_POSIX_ACL_ACCESS));
+ if (ret)
+ return ret;
+ } else if (namelen == SGI_ACL_DEFAULT_SIZE &&
+ strncmp(name, SGI_ACL_DEFAULT,
+ SGI_ACL_DEFAULT_SIZE) == 0) {
+ int ret = __xfs_xattr_put_listent(
+ context, XATTR_SYSTEM_PREFIX,
+ XATTR_SYSTEM_PREFIX_LEN,
+ XATTR_POSIX_ACL_DEFAULT,
+ strlen(XATTR_POSIX_ACL_DEFAULT));
+ if (ret)
+ return ret;
+ }
+#endif

- strcpy(p, name);
- return 0;
+ /*
+ * Only show root namespace entries if we are actually allowed to
+ * see them.
+ */
+ if (!capable(CAP_SYS_ADMIN))
+ return 0;
+
+ prefix = XATTR_TRUSTED_PREFIX;
+ prefix_len = XATTR_TRUSTED_PREFIX_LEN;
+ } else if (flags & XFS_ATTR_SECURE) {
+ prefix = XATTR_SECURITY_PREFIX;
+ prefix_len = XATTR_SECURITY_PREFIX_LEN;
+ } else {
+ prefix = XATTR_USER_PREFIX;
+ prefix_len = XATTR_USER_PREFIX_LEN;
+ }
+
+ return __xfs_xattr_put_listent(context, prefix, prefix_len, name,
+ namelen);
}

ssize_t
@@ -198,7 +203,6 @@ xfs_vn_listxattr(struct dentry *dentry, char *data, size_t size)
struct xfs_attr_list_context context;
struct attrlist_cursor_kern cursor = { 0 };
struct inode *inode = d_inode(dentry);
- int error;

/*
* First read the regular on-disk attributes.
@@ -207,37 +211,14 @@ xfs_vn_listxattr(struct dentry *dentry, char *data, size_t size)
context.dp = XFS_I(inode);
context.cursor = &cursor;
context.resynch = 1;
- context.alist = data;
+ context.alist = size ? data : NULL;
context.bufsize = size;
context.firstu = context.bufsize;
-
- if (size)
- context.put_listent = xfs_xattr_put_listent;
- else
- context.put_listent = xfs_xattr_put_listent_sizes;
+ context.put_listent = xfs_xattr_put_listent;

xfs_attr_list_int(&context);
if (context.count < 0)
return -ERANGE;

- /*
- * Then add the two synthetic ACL attributes.
- */
- if (posix_acl_access_exists(inode)) {
- error = list_one_attr(POSIX_ACL_XATTR_ACCESS,
- strlen(POSIX_ACL_XATTR_ACCESS) + 1,
- data, size, &context.count);
- if (error)
- return error;
- }
-
- if (posix_acl_default_exists(inode)) {
- error = list_one_attr(POSIX_ACL_XATTR_DEFAULT,
- strlen(POSIX_ACL_XATTR_DEFAULT) + 1,
- data, size, &context.count);
- if (error)
- return error;
- }
-
return context.count;