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xfs: Change how listxattr generates synthetic attributes
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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>
Cc: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Andreas Gruenbacher authored and Al Viro committed Dec 7, 2015
1 parent 786534b commit 5d92b75
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Showing 3 changed files with 59 additions and 105 deletions.
23 changes: 0 additions & 23 deletions fs/xfs/xfs_acl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -252,29 +252,6 @@ xfs_set_mode(struct inode *inode, umode_t mode)
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)
{
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4 changes: 0 additions & 4 deletions fs/xfs/xfs_acl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -24,16 +24,12 @@ 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 */

extern void xfs_forget_acl(struct inode *inode, const char *name, int xflags);
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137 changes: 59 additions & 78 deletions fs/xfs/xfs_xattr.c
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Original file line number Diff line number Diff line change
Expand Up @@ -129,90 +129,95 @@ 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) {
context->count = -1; /* insufficient space */
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,
int namelen,
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
Expand All @@ -221,7 +226,6 @@ 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.
Expand All @@ -230,37 +234,14 @@ 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(XATTR_NAME_POSIX_ACL_ACCESS,
strlen(XATTR_NAME_POSIX_ACL_ACCESS) + 1,
data, size, &context.count);
if (error)
return error;
}

if (posix_acl_default_exists(inode)) {
error = list_one_attr(XATTR_NAME_POSIX_ACL_DEFAULT,
strlen(XATTR_NAME_POSIX_ACL_DEFAULT) + 1,
data, size, &context.count);
if (error)
return error;
}

return context.count;
}

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