[PATCH 1/1] fs: Allows for xattr support to be compiled out
From: Brian Ashworth
Date: Tue Apr 11 2017 - 18:48:55 EST
Allows for xattr syscalls and related functions to be compiled out.
These are not needed on machines that do not utilize filesystems that
support xattrs or userspaces that require extended attributes. This will
aid in the tinification efforts.
The xattr_full_name function was moved from fs/xattr.c to
include/linux/xattr.h and made static inline. This function only deals
with interaction of the xattr_handler struct and does not require any
of the xattr functions to be implemented.
The rest of the functions in fs/xattr.c have had stubs created in
include/linux/xattr.h to return the appropriate value to indicate that
it is not supported or that there is no data.
add/remove: 0/39 grow/shrink: 0/5 up/down: 0/-4020 (-4020)
function old new delta
xattr_getsecurity 6 - -6
simple_xattr_list_add 13 - -13
fdget 56 42 -14
sys_lremovexattr 15 - -15
sys_removexattr 18 - -18
cap_inode_killpriv 22 3 -19
xattr_full_name 25 - -25
sys_llistxattr 25 - -25
sys_listxattr 25 - -25
cap_inode_need_killpriv 28 3 -25
sys_lgetxattr 33 - -33
sys_getxattr 33 - -33
vfs_listxattr 34 - -34
sys_setxattr 43 - -43
sys_lsetxattr 43 - -43
removexattr 56 - -56
simple_xattr_alloc 59 - -59
sys_flistxattr 61 - -61
sys_fgetxattr 66 - -66
vfs_getxattr 69 - -69
__vfs_removexattr 70 - -70
__vfs_getxattr 71 - -71
sys_fremovexattr 75 - -75
simple_xattr_get 75 - -75
vfs_removexattr 79 - -79
simple_xattr_list 79 - -79
sys_fsetxattr 89 - -89
__vfs_setxattr 91 - -91
path_listxattr 98 - -98
path_getxattr 103 - -103
__vfs_setxattr_noperm 105 - -105
vfs_setxattr 113 - -113
path_removexattr 114 - -114
path_setxattr 132 - -132
listxattr 149 - -149
xattr_resolve_name 155 - -155
get_vfs_caps_from_disk 184 19 -165
generic_listxattr 194 - -194
xattr_permission 208 - -208
vfs_getxattr_alloc 216 - -216
simple_xattr_set 231 - -231
setxattr 239 - -239
getxattr 240 - -240
cap_bprm_set_creds 613 366 -247
Total: Before=1900297, After=1896277, chg -0.21%
Signed-off-by: Brian Ashworth <bosrsf04@xxxxxxxxx>
---
fs/Kconfig | 1 +
fs/Makefile | 3 +-
fs/cifs/Kconfig | 1 +
fs/ext2/Kconfig | 1 +
fs/f2fs/Kconfig | 1 +
fs/jffs2/Kconfig | 1 +
fs/reiserfs/Kconfig | 1 +
fs/squashfs/Kconfig | 1 +
fs/xattr.c | 24 --------
include/linux/xattr.h | 126 ++++++++++++++++++++++++++++++++++++++++-
init/Kconfig | 11 ++++
kernel/sys_ni.c | 12 ++++
security/integrity/evm/Kconfig | 1 +
13 files changed, 157 insertions(+), 27 deletions(-)
diff --git a/fs/Kconfig b/fs/Kconfig
index 83eab52fb3f6..18ce4032e177 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -173,6 +173,7 @@ config TMPFS_POSIX_ACL
config TMPFS_XATTR
bool "Tmpfs extended attributes"
depends on TMPFS
+ depends on XATTR_SYSCALLS
default n
help
Extended attributes are name:value pairs associated with inodes by
diff --git a/fs/Makefile b/fs/Makefile
index 7bbaca9c67b1..1645965883bc 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -9,7 +9,7 @@ obj-y := open.o read_write.o file_table.o super.o \
char_dev.o stat.o exec.o pipe.o namei.o fcntl.o \
ioctl.o readdir.o select.o dcache.o inode.o \
attr.o bad_inode.o file.o filesystems.o namespace.o \
- seq_file.o xattr.o libfs.o fs-writeback.o \
+ seq_file.o libfs.o fs-writeback.o \
pnode.o splice.o sync.o utimes.o \
stack.o fs_struct.o statfs.o fs_pin.o nsfs.o
@@ -32,6 +32,7 @@ obj-$(CONFIG_AIO) += aio.o
obj-$(CONFIG_FS_DAX) += dax.o
obj-$(CONFIG_FS_ENCRYPTION) += crypto/
obj-$(CONFIG_FILE_LOCKING) += locks.o
+obj-$(CONFIG_XATTR_SYSCALLS) += xattr.o
obj-$(CONFIG_COMPAT) += compat.o compat_ioctl.o
obj-$(CONFIG_BINFMT_AOUT) += binfmt_aout.o
obj-$(CONFIG_BINFMT_EM86) += binfmt_em86.o
diff --git a/fs/cifs/Kconfig b/fs/cifs/Kconfig
index 034f00f21390..3352f6b3efed 100644
--- a/fs/cifs/Kconfig
+++ b/fs/cifs/Kconfig
@@ -94,6 +94,7 @@ config CIFS_UPCALL
config CIFS_XATTR
bool "CIFS extended attributes"
depends on CIFS
+ depends on XATTR_SYSCALLS
help
Extended attributes are name:value pairs associated with inodes by
the kernel or by users (see the attr(5) manual page, or visit
diff --git a/fs/ext2/Kconfig b/fs/ext2/Kconfig
index c634874e12d9..9b16a31785a1 100644
--- a/fs/ext2/Kconfig
+++ b/fs/ext2/Kconfig
@@ -11,6 +11,7 @@ config EXT2_FS
config EXT2_FS_XATTR
bool "Ext2 extended attributes"
depends on EXT2_FS
+ depends on XATTR_SYSCALLS
help
Extended attributes are name:value pairs associated with inodes by
the kernel or by users (see the attr(5) manual page, or visit
diff --git a/fs/f2fs/Kconfig b/fs/f2fs/Kconfig
index 378c221d68a9..3594db075cce 100644
--- a/fs/f2fs/Kconfig
+++ b/fs/f2fs/Kconfig
@@ -32,6 +32,7 @@ config F2FS_STAT_FS
config F2FS_FS_XATTR
bool "F2FS extended attributes"
depends on F2FS_FS
+ depends on XATTR_SYSCALLS
default y
help
Extended attributes are name:value pairs associated with inodes by
diff --git a/fs/jffs2/Kconfig b/fs/jffs2/Kconfig
index d8bb6c411e96..c1646416c94f 100644
--- a/fs/jffs2/Kconfig
+++ b/fs/jffs2/Kconfig
@@ -65,6 +65,7 @@ config JFFS2_SUMMARY
config JFFS2_FS_XATTR
bool "JFFS2 XATTR support"
depends on JFFS2_FS
+ depends on XATTR_SYSCALLS
default n
help
Extended attributes are name:value pairs associated with inodes by
diff --git a/fs/reiserfs/Kconfig b/fs/reiserfs/Kconfig
index 7cd46666ba2c..98adeaa2b312 100644
--- a/fs/reiserfs/Kconfig
+++ b/fs/reiserfs/Kconfig
@@ -55,6 +55,7 @@ config REISERFS_PROC_INFO
config REISERFS_FS_XATTR
bool "ReiserFS extended attributes"
depends on REISERFS_FS
+ depends on XATTR_SYSCALLS
help
Extended attributes are name:value pairs associated with inodes by
the kernel or by users (see the attr(5) manual page, or visit
diff --git a/fs/squashfs/Kconfig b/fs/squashfs/Kconfig
index ffb093e72b6c..083de02a2ab5 100644
--- a/fs/squashfs/Kconfig
+++ b/fs/squashfs/Kconfig
@@ -100,6 +100,7 @@ endchoice
config SQUASHFS_XATTR
bool "Squashfs XATTR support"
depends on SQUASHFS
+ depends on XATTR_SYSCALLS
help
Saying Y here includes support for extended attributes (xattrs).
Xattrs are name:value pairs associated with inodes by
diff --git a/fs/xattr.c b/fs/xattr.c
index 7e3317cf4045..c97ae8365775 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -784,30 +784,6 @@ generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
}
EXPORT_SYMBOL(generic_listxattr);
-/**
- * xattr_full_name - Compute full attribute name from suffix
- *
- * @handler: handler of the xattr_handler operation
- * @name: name passed to the xattr_handler operation
- *
- * The get and set xattr handler operations are called with the remainder of
- * the attribute name after skipping the handler's prefix: for example, "foo"
- * is passed to the get operation of a handler with prefix "user." to get
- * attribute "user.foo". The full name is still "there" in the name though.
- *
- * Note: the list xattr handler operation when called from the vfs is passed a
- * NULL name; some file systems use this operation internally, with varying
- * semantics.
- */
-const char *xattr_full_name(const struct xattr_handler *handler,
- const char *name)
-{
- size_t prefix_len = strlen(xattr_prefix(handler));
-
- return name - prefix_len;
-}
-EXPORT_SYMBOL(xattr_full_name);
-
/*
* Allocate new xattr and copy in the value; but leave the name to callers.
*/
diff --git a/include/linux/xattr.h b/include/linux/xattr.h
index e77605a0c8da..b1d8ec5b2003 100644
--- a/include/linux/xattr.h
+++ b/include/linux/xattr.h
@@ -37,8 +37,6 @@ struct xattr_handler {
size_t size, int flags);
};
-const char *xattr_full_name(const struct xattr_handler *, const char *);
-
struct xattr {
const char *name;
void *value;
@@ -46,6 +44,9 @@ struct xattr {
};
ssize_t xattr_getsecurity(struct inode *, const char *, void *, size_t);
+
+#ifdef CONFIG_XATTR_SYSCALLS
+
ssize_t __vfs_getxattr(struct dentry *, struct inode *, const char *, void *, size_t);
ssize_t vfs_getxattr(struct dentry *, const char *, void *, size_t);
ssize_t vfs_listxattr(struct dentry *d, char *list, size_t size);
@@ -59,11 +60,97 @@ ssize_t generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_siz
ssize_t vfs_getxattr_alloc(struct dentry *dentry, const char *name,
char **xattr_value, size_t size, gfp_t flags);
+#else
+
+static inline ssize_t __vfs_getxattr(struct dentry *dentry, struct inode *inode,
+ const char *name, void *value, size_t size)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline ssize_t vfs_getxattr(struct dentry *dentry, const char *name,
+ void *value, size_t size)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline ssize_t vfs_listxattr(struct dentry *dentry, char *list, size_t size)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int __vfs_setxattr(struct dentry *dentry, struct inode *inode,
+ const char *name, const void *value, size_t size, int flags)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int __vfs_setxattr_noperm(struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline ssize_t vfs_setxattr(struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int __vfs_removexattr(struct dentry *dentry, const char *name)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int vfs_removexattr(struct dentry *dentry, const char *name)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline ssize_t generic_listxattr(struct dentry *dentry, char *buffer,
+ size_t buffer_size)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline ssize_t vfs_getxattr_alloc(struct dentry *dentry,
+ const char *name, char **xattr_value, size_t xattr_size,
+ gfp_t flags)
+{
+ return -EOPNOTSUPP;
+}
+
+#endif /* CONFIG_XATTR_SYSCALLS */
+
+
static inline const char *xattr_prefix(const struct xattr_handler *handler)
{
return handler->prefix ?: handler->name;
}
+/**
+ * xattr_full_name - Compute full attribute name from suffix
+ *
+ * @handler: handler of the xattr_handler operation
+ * @name: name passed to the xattr_handler operation
+ *
+ * The get and set xattr handler operations are called with the remainder of
+ * the attribute name after skipping the handler's prefix: for example, "foo"
+ * is passed to the get operation of a handler with prefix "user." to get
+ * attribute "user.foo". The full name is still "there" in the name though.
+ *
+ * Note: the list xattr handler operation when called from the vfs is passed a
+ * NULL name; some file systems use this operation internally, with varying
+ * semantics.
+ */
+static inline const char *xattr_full_name(const struct xattr_handler *handler,
+ const char *name)
+{
+ size_t prefix_len = strlen(xattr_prefix(handler));
+
+ return name - prefix_len;
+}
+
struct simple_xattrs {
struct list_head head;
spinlock_t lock;
@@ -98,6 +185,8 @@ static inline void simple_xattrs_free(struct simple_xattrs *xattrs)
}
}
+#ifdef CONFIG_XATTR_SYSCALLS
+
struct simple_xattr *simple_xattr_alloc(const void *value, size_t size);
int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
void *buffer, size_t size);
@@ -108,4 +197,37 @@ ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs, cha
void simple_xattr_list_add(struct simple_xattrs *xattrs,
struct simple_xattr *new_xattr);
+#else
+
+static inline struct simple_xattr *simple_xattr_alloc(const void *value,
+ size_t size)
+{
+ return NULL;
+}
+
+static inline int simple_xattr_get(struct simple_xattrs *xattrs,
+ const char *name, void *buffer, size_t size)
+{
+ return -ENODATA;
+}
+
+static inline int simple_xattr_set(struct simple_xattrs *xattrs,
+ const char *name, const void *value, size_t size, int flags)
+{
+ return -ENODATA;
+}
+
+static inline ssize_t simple_xattr_list(struct inode *inode,
+ struct simple_xattrs *xattrs, char *buffer, size_t size)
+{
+ return -ERANGE;
+}
+
+static inline void simple_xattr_list_add(struct simple_xattrs *xattrs,
+ struct simple_xattr *new_xattr)
+{
+}
+
+#endif /* CONFIG_XATTR_SYSCALLS */
+
#endif /* _LINUX_XATTR_H */
diff --git a/init/Kconfig b/init/Kconfig
index a92f27da4a27..bfb954adc1e6 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1460,6 +1460,17 @@ config SYSCTL_SYSCALL
If unsure say N here.
+config XATTR_SYSCALLS
+ bool "Support for the xattr family of syscalls" if EXPERT
+ default y
+ help
+ The xattr family of syscalls are used to access extended file
+ attributes from userspace. If you are using a filesystem or
+ userspace that does not use or require the system calls, they
+ can be compiled out.
+
+ If unsure say Y here.
+
config POSIX_TIMERS
bool "Posix Clocks & timers" if EXPERT
default y
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 8acef8576ce9..6f6b8105545d 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -178,6 +178,18 @@ cond_syscall(sys_setfsgid);
cond_syscall(sys_capget);
cond_syscall(sys_capset);
cond_syscall(sys_copy_file_range);
+cond_syscall(sys_setxattr);
+cond_syscall(sys_lsetxattr);
+cond_syscall(sys_fsetxattr);
+cond_syscall(sys_getxattr);
+cond_syscall(sys_lgetxattr);
+cond_syscall(sys_fgetxattr);
+cond_syscall(sys_listxattr);
+cond_syscall(sys_llistxattr);
+cond_syscall(sys_flistxattr);
+cond_syscall(sys_removexattr);
+cond_syscall(sys_lremovexattr);
+cond_syscall(sys_fremovexattr);
/* arch-specific weak syscall entries */
cond_syscall(sys_pciconfig_read);
diff --git a/security/integrity/evm/Kconfig b/security/integrity/evm/Kconfig
index e825e0ae78e7..56f76bfd5cfb 100644
--- a/security/integrity/evm/Kconfig
+++ b/security/integrity/evm/Kconfig
@@ -28,6 +28,7 @@ config EVM_ATTR_FSUUID
config EVM_EXTRA_SMACK_XATTRS
bool "Additional SMACK xattrs"
depends on EVM && SECURITY_SMACK
+ depends on XATTR_SYSCALLS
default n
help
Include additional SMACK xattrs for HMAC calculation.
--
2.12.2