[PATCH v5 7/7] fs: introduce file_getattr and file_setattr syscalls

From: Andrey Albershteyn <[email protected]>

Introduce file_getattr and file_setattr syscalls to manipulate inode
extended attributes/flags. The syscalls take parent directory fd and
path to the child together with struct fsxattr.

This is an alternative to FS_IOC_FSSETXATTR ioctl with a difference
that file don't need to be open as we can reference it with a path
instead of fd. By having this we can manipulated inode extended
attributes not only on regular files but also on special ones. This
is not possible with FS_IOC_FSSETXATTR ioctl as with special files
we can not call ioctl() directly on the filesystem inode using fd.

This patch adds two new syscalls which allows userspace to get/set
extended inode attributes on special files by using parent directory
and a path - *at() like syscall.

CC: [email protected]
CC: [email protected]
CC: [email protected]
Signed-off-by: Andrey Albershteyn <[email protected]>
Acked-by: Arnd Bergmann <[email protected]>
---
 arch/alpha/kernel/syscalls/syscall.tbl      |   2 +
 arch/arm/tools/syscall.tbl                  |   2 +
 arch/arm64/tools/syscall_32.tbl             |   2 +
 arch/m68k/kernel/syscalls/syscall.tbl       |   2 +
 arch/microblaze/kernel/syscalls/syscall.tbl |   2 +
 arch/mips/kernel/syscalls/syscall_n32.tbl   |   2 +
 arch/mips/kernel/syscalls/syscall_n64.tbl   |   2 +
 arch/mips/kernel/syscalls/syscall_o32.tbl   |   2 +
 arch/parisc/kernel/syscalls/syscall.tbl     |   2 +
 arch/powerpc/kernel/syscalls/syscall.tbl    |   2 +
 arch/s390/kernel/syscalls/syscall.tbl       |   2 +
 arch/sh/kernel/syscalls/syscall.tbl         |   2 +
 arch/sparc/kernel/syscalls/syscall.tbl      |   2 +
 arch/x86/entry/syscalls/syscall_32.tbl      |   2 +
 arch/x86/entry/syscalls/syscall_64.tbl      |   2 +
 arch/xtensa/kernel/syscalls/syscall.tbl     |   2 +
 fs/file_attr.c                              | 119 ++++++++++++++++++++++++++++
 include/linux/syscalls.h                    |   6 ++
 include/uapi/asm-generic/unistd.h           |   8 +-
 include/uapi/linux/fs.h                     |   3 +
 20 files changed, 167 insertions(+), 1 deletion(-)

diff --git a/arch/alpha/kernel/syscalls/syscall.tbl b/arch/alpha/kernel/syscalls/syscall.tbl
index 2dd6340de6b4efddc406f0c235701c15cf02f650..16dca28ebf17e5df2230f640f3686835dc5a1f76 100644
--- a/arch/alpha/kernel/syscalls/syscall.tbl
+++ b/arch/alpha/kernel/syscalls/syscall.tbl
@@ -507,3 +507,5 @@
 575	common	listxattrat			sys_listxattrat
 576	common	removexattrat			sys_removexattrat
 577	common	open_tree_attr			sys_open_tree_attr
+578	common	file_getattr			sys_file_getattr
+579	common	file_setattr			sys_file_setattr
diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl
index 27c1d5ebcd91c8c296dc6676307f66bfdf4ab78d..b07e699aaa3c2840452109c0004529fc68e153ac 100644
--- a/arch/arm/tools/syscall.tbl
+++ b/arch/arm/tools/syscall.tbl
@@ -482,3 +482,5 @@
 465	common	listxattrat			sys_listxattrat
 466	common	removexattrat			sys_removexattrat
 467	common	open_tree_attr			sys_open_tree_attr
+468	common	file_getattr			sys_file_getattr
+469	common	file_setattr			sys_file_setattr
diff --git a/arch/arm64/tools/syscall_32.tbl b/arch/arm64/tools/syscall_32.tbl
index 0765b3a8d6d600d7b9f83182d401d9f80c03476c..8d9088bc577df0c6dba6d5d0c227585283789a3f 100644
--- a/arch/arm64/tools/syscall_32.tbl
+++ b/arch/arm64/tools/syscall_32.tbl
@@ -479,3 +479,5 @@
 465	common	listxattrat			sys_listxattrat
 466	common	removexattrat			sys_removexattrat
 467	common	open_tree_attr			sys_open_tree_attr
+468	common	file_getattr			sys_file_getattr
+469	common	file_setattr			sys_file_setattr
diff --git a/arch/m68k/kernel/syscalls/syscall.tbl b/arch/m68k/kernel/syscalls/syscall.tbl
index 9fe47112c586f152662af38a9a7f90957cb96cf8..f41d38dfbf1382339316f4e3e6e79c75dc2804ec 100644
--- a/arch/m68k/kernel/syscalls/syscall.tbl
+++ b/arch/m68k/kernel/syscalls/syscall.tbl
@@ -467,3 +467,5 @@
 465	common	listxattrat			sys_listxattrat
 466	common	removexattrat			sys_removexattrat
 467	common	open_tree_attr			sys_open_tree_attr
+468	common	file_getattr			sys_file_getattr
+469	common	file_setattr			sys_file_setattr
diff --git a/arch/microblaze/kernel/syscalls/syscall.tbl b/arch/microblaze/kernel/syscalls/syscall.tbl
index 7b6e97828e552d4da90046ddfcd4a55723e522bb..580af574fe733af29ea69f40ae6e902ad2166ab2 100644
--- a/arch/microblaze/kernel/syscalls/syscall.tbl
+++ b/arch/microblaze/kernel/syscalls/syscall.tbl
@@ -473,3 +473,5 @@
 465	common	listxattrat			sys_listxattrat
 466	common	removexattrat			sys_removexattrat
 467	common	open_tree_attr			sys_open_tree_attr
+468	common	file_getattr			sys_file_getattr
+469	common	file_setattr			sys_file_setattr
diff --git a/arch/mips/kernel/syscalls/syscall_n32.tbl b/arch/mips/kernel/syscalls/syscall_n32.tbl
index aa70e371bb54ab5d9c8dd8923b6ecf9693ee914d..d824ffe9a01496a13194710d5278dcc443e40894 100644
--- a/arch/mips/kernel/syscalls/syscall_n32.tbl
+++ b/arch/mips/kernel/syscalls/syscall_n32.tbl
@@ -406,3 +406,5 @@
 465	n32	listxattrat			sys_listxattrat
 466	n32	removexattrat			sys_removexattrat
 467	n32	open_tree_attr			sys_open_tree_attr
+468	n32	file_getattr			sys_file_getattr
+469	n32	file_setattr			sys_file_setattr
diff --git a/arch/mips/kernel/syscalls/syscall_n64.tbl b/arch/mips/kernel/syscalls/syscall_n64.tbl
index 1e8c44c7b61492eabf00c777831e457a7a6e579c..7a7049c2c307885fe8be33aedb503cfe8afbfb24 100644
--- a/arch/mips/kernel/syscalls/syscall_n64.tbl
+++ b/arch/mips/kernel/syscalls/syscall_n64.tbl
@@ -382,3 +382,5 @@
 465	n64	listxattrat			sys_listxattrat
 466	n64	removexattrat			sys_removexattrat
 467	n64	open_tree_attr			sys_open_tree_attr
+468	n64	file_getattr			sys_file_getattr
+469	n64	file_setattr			sys_file_setattr
diff --git a/arch/mips/kernel/syscalls/syscall_o32.tbl b/arch/mips/kernel/syscalls/syscall_o32.tbl
index 114a5a1a62302e32dd74d1679ff423a2d57c3c6b..d330274f06010c9f9bf80d55898d0bd38994ef58 100644
--- a/arch/mips/kernel/syscalls/syscall_o32.tbl
+++ b/arch/mips/kernel/syscalls/syscall_o32.tbl
@@ -455,3 +455,5 @@
 465	o32	listxattrat			sys_listxattrat
 466	o32	removexattrat			sys_removexattrat
 467	o32	open_tree_attr			sys_open_tree_attr
+468	o32	file_getattr			sys_file_getattr
+469	o32	file_setattr			sys_file_setattr
diff --git a/arch/parisc/kernel/syscalls/syscall.tbl b/arch/parisc/kernel/syscalls/syscall.tbl
index 94df3cb957e9d547d192e8732c0cf23ef2b5ce5d..88a788a7b18d17967019098b33d2be48a430aed3 100644
--- a/arch/parisc/kernel/syscalls/syscall.tbl
+++ b/arch/parisc/kernel/syscalls/syscall.tbl
@@ -466,3 +466,5 @@
 465	common	listxattrat			sys_listxattrat
 466	common	removexattrat			sys_removexattrat
 467	common	open_tree_attr			sys_open_tree_attr
+468	common	file_getattr			sys_file_getattr
+469	common	file_setattr			sys_file_setattr
diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl
index 9a084bdb892694bc562f514b55212d167cbac12f..b453e80dfc003796a08f022f6bd44cf76a5f82ab 100644
--- a/arch/powerpc/kernel/syscalls/syscall.tbl
+++ b/arch/powerpc/kernel/syscalls/syscall.tbl
@@ -558,3 +558,5 @@
 465	common	listxattrat			sys_listxattrat
 466	common	removexattrat			sys_removexattrat
 467	common	open_tree_attr			sys_open_tree_attr
+468	common	file_getattr			sys_file_getattr
+469	common	file_setattr			sys_file_setattr
diff --git a/arch/s390/kernel/syscalls/syscall.tbl b/arch/s390/kernel/syscalls/syscall.tbl
index a4569b96ef06c54ce7aa795d039541c90a38284f..8a6744d658db3986f0ac0fd3c90592cdbd27249c 100644
--- a/arch/s390/kernel/syscalls/syscall.tbl
+++ b/arch/s390/kernel/syscalls/syscall.tbl
@@ -470,3 +470,5 @@
 465  common	listxattrat		sys_listxattrat			sys_listxattrat
 466  common	removexattrat		sys_removexattrat		sys_removexattrat
 467  common	open_tree_attr		sys_open_tree_attr		sys_open_tree_attr
+468  common	file_getattr		sys_file_getattr		sys_file_getattr
+469  common	file_setattr		sys_file_setattr		sys_file_setattr
diff --git a/arch/sh/kernel/syscalls/syscall.tbl b/arch/sh/kernel/syscalls/syscall.tbl
index 52a7652fcff6394b96ace1f3b0ed72250ee5e669..5e9c9eff5539e24113bb757f1e5b51bd7c32864e 100644
--- a/arch/sh/kernel/syscalls/syscall.tbl
+++ b/arch/sh/kernel/syscalls/syscall.tbl
@@ -471,3 +471,5 @@
 465	common	listxattrat			sys_listxattrat
 466	common	removexattrat			sys_removexattrat
 467	common	open_tree_attr			sys_open_tree_attr
+468	common	file_getattr			sys_file_getattr
+469	common	file_setattr			sys_file_setattr
diff --git a/arch/sparc/kernel/syscalls/syscall.tbl b/arch/sparc/kernel/syscalls/syscall.tbl
index 83e45eb6c095a36baaf749927628e6052fe900e6..ebb7d06d1044fa9b113b0a3fe0316c77f48fc3d0 100644
--- a/arch/sparc/kernel/syscalls/syscall.tbl
+++ b/arch/sparc/kernel/syscalls/syscall.tbl
@@ -513,3 +513,5 @@
 465	common	listxattrat			sys_listxattrat
 466	common	removexattrat			sys_removexattrat
 467	common	open_tree_attr			sys_open_tree_attr
+468	common	file_getattr			sys_file_getattr
+469	common	file_setattr			sys_file_setattr
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index ac007ea00979dc28b0ef7c002a0615ce86dd3101..4877e16da69a50f2225088e556661051dbe3c7a3 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -473,3 +473,5 @@
 465	i386	listxattrat		sys_listxattrat
 466	i386	removexattrat		sys_removexattrat
 467	i386	open_tree_attr		sys_open_tree_attr
+468	i386	file_getattr		sys_file_getattr
+469	i386	file_setattr		sys_file_setattr
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index cfb5ca41e30de1a4e073750096f5b51a2ec137d2..92cf0fe2291eb99b536e4de4201aec16b3472094 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -391,6 +391,8 @@
 465	common	listxattrat		sys_listxattrat
 466	common	removexattrat		sys_removexattrat
 467	common	open_tree_attr		sys_open_tree_attr
+468	common	file_getattr		sys_file_getattr
+469	common	file_setattr		sys_file_setattr
 
 #
 # Due to a historical design error, certain syscalls are numbered differently
diff --git a/arch/xtensa/kernel/syscalls/syscall.tbl b/arch/xtensa/kernel/syscalls/syscall.tbl
index f657a77314f8667fa019a01e10c84ea270024adc..374e4cb788d8a6d4e1f3358b949ea8b600013e1c 100644
--- a/arch/xtensa/kernel/syscalls/syscall.tbl
+++ b/arch/xtensa/kernel/syscalls/syscall.tbl
@@ -438,3 +438,5 @@
 465	common	listxattrat			sys_listxattrat
 466	common	removexattrat			sys_removexattrat
 467	common	open_tree_attr			sys_open_tree_attr
+468	common	file_getattr			sys_file_getattr
+469	common	file_setattr			sys_file_setattr
diff --git a/fs/file_attr.c b/fs/file_attr.c
index 6cd1e820f7b108c12c06654df843104f460b94cf..791a97bb2b612b2a0f2c06b7cfb41bac469ea5d1 100644
--- a/fs/file_attr.c
+++ b/fs/file_attr.c
@@ -3,6 +3,10 @@
 #include <linux/security.h>
 #include <linux/fscrypt.h>
 #include <linux/fileattr.h>
+#include <linux/syscalls.h>
+#include <linux/namei.h>
+
+#include "internal.h"
 
 /**
  * fileattr_fill_xflags - initialize fileattr with xflags
@@ -354,3 +358,118 @@ int ioctl_fssetxattr(struct file *file, void __user *argp)
 	return err;
 }
 EXPORT_SYMBOL(ioctl_fssetxattr);
+
+SYSCALL_DEFINE5(file_getattr, int, dfd, const char __user *, filename,
+		struct fsxattr __user *, ufsx, size_t, usize,
+		unsigned int, at_flags)
+{
+	struct fileattr fa = {};
+	struct path filepath __free(path_put) = {};
+	int error;
+	unsigned int lookup_flags = 0;
+	struct filename *name;
+	struct fsxattr fsx = {};
+
+	BUILD_BUG_ON(sizeof(struct fsxattr) < FSXATTR_SIZE_VER0);
+	BUILD_BUG_ON(sizeof(struct fsxattr) != FSXATTR_SIZE_LATEST);
+
+	if ((at_flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
+		return -EINVAL;
+
+	if (!(at_flags & AT_SYMLINK_NOFOLLOW))
+		lookup_flags |= LOOKUP_FOLLOW;
+
+	if (usize > PAGE_SIZE)
+		return -E2BIG;
+
+	if (usize < FSXATTR_SIZE_VER0)
+		return -EINVAL;
+
+	name = getname_maybe_null(filename, at_flags);
+	if (IS_ERR(name))
+		return PTR_ERR(name);
+
+	if (!name && dfd >= 0) {
+		CLASS(fd, f)(dfd);
+
+		filepath = fd_file(f)->f_path;
+		path_get(&filepath);
+	} else {
+		error = filename_lookup(dfd, name, lookup_flags, &filepath,
+					NULL);
+		putname(name);
+		if (error)
+			return error;
+	}
+
+	error = vfs_fileattr_get(filepath.dentry, &fa);
+	if (error)
+		return error;
+
+	fileattr_to_fsxattr(&fa, &fsx);
+	error = copy_struct_to_user(ufsx, usize, &fsx, sizeof(struct fsxattr),
+				    NULL);
+
+	return error;
+}
+
+SYSCALL_DEFINE5(file_setattr, int, dfd, const char __user *, filename,
+		struct fsxattr __user *, ufsx, size_t, usize,
+		unsigned int, at_flags)
+{
+	struct fileattr fa;
+	struct path filepath __free(path_put) = {};
+	int error;
+	unsigned int lookup_flags = 0;
+	struct filename *name;
+	struct fsxattr fsx = {};
+
+	BUILD_BUG_ON(sizeof(struct fsxattr) < FSXATTR_SIZE_VER0);
+	BUILD_BUG_ON(sizeof(struct fsxattr) != FSXATTR_SIZE_LATEST);
+
+	if ((at_flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
+		return -EINVAL;
+
+	if (!(at_flags & AT_SYMLINK_NOFOLLOW))
+		lookup_flags |= LOOKUP_FOLLOW;
+
+	if (usize > PAGE_SIZE)
+		return -E2BIG;
+
+	if (usize < FSXATTR_SIZE_VER0)
+		return -EINVAL;
+
+	error = copy_struct_from_user(&fsx, sizeof(struct fsxattr), ufsx, usize);
+	if (error)
+		return error;
+
+	error = fsxattr_to_fileattr(&fsx, &fa);
+	if (error)
+		return error;
+
+	name = getname_maybe_null(filename, at_flags);
+	if (IS_ERR(name))
+		return PTR_ERR(name);
+
+	if (!name && dfd >= 0) {
+		CLASS(fd, f)(dfd);
+
+		filepath = fd_file(f)->f_path;
+		path_get(&filepath);
+	} else {
+		error = filename_lookup(dfd, name, lookup_flags, &filepath,
+					NULL);
+		putname(name);
+		if (error)
+			return error;
+	}
+
+	error = mnt_want_write(filepath.mnt);
+	if (!error) {
+		error = vfs_fileattr_set(mnt_idmap(filepath.mnt),
+					 filepath.dentry, &fa);
+		mnt_drop_write(filepath.mnt);
+	}
+
+	return error;
+}
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index e5603cc91963dabb79324d6e9e2274f327311245..f2a747479718f9c93f6a448cdab2e60f7ee87709 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -371,6 +371,12 @@ asmlinkage long sys_removexattrat(int dfd, const char __user *path,
 asmlinkage long sys_lremovexattr(const char __user *path,
 				 const char __user *name);
 asmlinkage long sys_fremovexattr(int fd, const char __user *name);
+asmlinkage long sys_file_getattr(int dfd, const char __user *filename,
+				 struct fsxattr __user *ufsx, size_t usize,
+				 unsigned int at_flags);
+asmlinkage long sys_file_setattr(int dfd, const char __user *filename,
+				 struct fsxattr __user *ufsx, size_t usize,
+				 unsigned int at_flags);
 asmlinkage long sys_getcwd(char __user *buf, unsigned long size);
 asmlinkage long sys_eventfd2(unsigned int count, int flags);
 asmlinkage long sys_epoll_create1(int flags);
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index 2892a45023af6d3eb941623d4fed04841ab07e02..04e0077fb4c97a4d565da86d3d0d1d243f32336e 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -852,8 +852,14 @@ __SYSCALL(__NR_removexattrat, sys_removexattrat)
 #define __NR_open_tree_attr 467
 __SYSCALL(__NR_open_tree_attr, sys_open_tree_attr)
 
+/* fs/inode.c */
+#define __NR_file_getattr 468
+__SYSCALL(__NR_file_getattr, sys_file_getattr)
+#define __NR_file_setattr 469
+__SYSCALL(__NR_file_setattr, sys_file_setattr)
+
 #undef __NR_syscalls
-#define __NR_syscalls 468
+#define __NR_syscalls 470
 
 /*
  * 32 bit systems traditionally used different
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index e762e1af650c4bf08766ba7a8ab7a2288e987039..bc1467b44b80e1db3527dd1b70f1a3a3ca7e4484 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -148,6 +148,9 @@ struct fsxattr {
 	unsigned char	fsx_pad[8];
 };
 
+#define FSXATTR_SIZE_VER0 28
+#define FSXATTR_SIZE_LATEST FSXATTR_SIZE_VER0
+
 /*
  * Flags for the fsx_xflags field
  */

-- 
2.47.2