fs: introduce file_getattr and file_setattr syscalls

Introduce file_getattr() and file_setattr() syscalls to manipulate inode extended attributes. The syscalls takes pair of file descriptor and pathname. Then it operates on inode opened accroding to openat() semantics. The struct file_attr is passed to obtain/change extended attributes. 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.

Andrey Albershteyn committed 1 year ago

Commit be7efb21 parent 276e13621 files · +218 −1Browse files

Unified · Split

21 files

arch/alpha/kernel/syscalls/syscall.tbl +2 −0
arch/arm/tools/syscall.tbl +2 −0
arch/arm64/tools/syscall_32.tbl +2 −0
arch/m68k/kernel/syscalls/syscall.tbl +2 −0
arch/microblaze/kernel/syscalls/syscall.tbl +2 −0
arch/mips/kernel/syscalls/syscall_n32.tbl +2 −0
arch/mips/kernel/syscalls/syscall_n64.tbl +2 −0
arch/mips/kernel/syscalls/syscall_o32.tbl +2 −0
arch/parisc/kernel/syscalls/syscall.tbl +2 −0
arch/powerpc/kernel/syscalls/syscall.tbl +2 −0
arch/s390/kernel/syscalls/syscall.tbl +2 −0
arch/sh/kernel/syscalls/syscall.tbl +2 −0
arch/sparc/kernel/syscalls/syscall.tbl +2 −0
arch/x86/entry/syscalls/syscall_32.tbl +2 −0
arch/x86/entry/syscalls/syscall_64.tbl +2 −0
arch/xtensa/kernel/syscalls/syscall.tbl +2 −0
fs/file_attr.c +152 −0
include/linux/syscalls.h +7 −0
include/uapi/asm-generic/unistd.h +7 −1
include/uapi/linux/fs.h +18 −0
scripts/syscall.tbl +2 −0

arch/alpha/kernel/syscalls/syscall.tbl+2−0

@@ -507,3 +507,5 @@ · 506 unmodified lines
507	507	575 common listxattrat sys_listxattrat
508	508	576 common removexattrat sys_removexattrat
509	509	577 common open_tree_attr sys_open_tree_attr
	510	+578 common file_getattr sys_file_getattr
	511	+579 common file_setattr sys_file_setattr

arch/arm/tools/syscall.tbl+2−0

@@ -482,3 +482,5 @@ · 481 unmodified lines
482	482	465 common listxattrat sys_listxattrat
483	483	466 common removexattrat sys_removexattrat
484	484	467 common open_tree_attr sys_open_tree_attr
	485	+468 common file_getattr sys_file_getattr
	486	+469 common file_setattr sys_file_setattr

arch/arm64/tools/syscall_32.tbl+2−0

@@ -479,3 +479,5 @@ · 478 unmodified lines
479	479	465 common listxattrat sys_listxattrat
480	480	466 common removexattrat sys_removexattrat
481	481	467 common open_tree_attr sys_open_tree_attr
	482	+468 common file_getattr sys_file_getattr
	483	+469 common file_setattr sys_file_setattr

arch/m68k/kernel/syscalls/syscall.tbl+2−0

@@ -467,3 +467,5 @@ · 466 unmodified lines
467	467	465 common listxattrat sys_listxattrat
468	468	466 common removexattrat sys_removexattrat
469	469	467 common open_tree_attr sys_open_tree_attr
	470	+468 common file_getattr sys_file_getattr
	471	+469 common file_setattr sys_file_setattr

arch/microblaze/kernel/syscalls/syscall.tbl+2−0

@@ -473,3 +473,5 @@ · 472 unmodified lines
473	473	465 common listxattrat sys_listxattrat
474	474	466 common removexattrat sys_removexattrat
475	475	467 common open_tree_attr sys_open_tree_attr
	476	+468 common file_getattr sys_file_getattr
	477	+469 common file_setattr sys_file_setattr

arch/mips/kernel/syscalls/syscall_n32.tbl+2−0

@@ -406,3 +406,5 @@ · 405 unmodified lines
406	406	465 n32 listxattrat sys_listxattrat
407	407	466 n32 removexattrat sys_removexattrat
408	408	467 n32 open_tree_attr sys_open_tree_attr
	409	+468 n32 file_getattr sys_file_getattr
	410	+469 n32 file_setattr sys_file_setattr

arch/mips/kernel/syscalls/syscall_n64.tbl+2−0

@@ -382,3 +382,5 @@ · 381 unmodified lines
382	382	465 n64 listxattrat sys_listxattrat
383	383	466 n64 removexattrat sys_removexattrat
384	384	467 n64 open_tree_attr sys_open_tree_attr
	385	+468 n64 file_getattr sys_file_getattr
	386	+469 n64 file_setattr sys_file_setattr

arch/mips/kernel/syscalls/syscall_o32.tbl+2−0

@@ -455,3 +455,5 @@ · 454 unmodified lines
455	455	465 o32 listxattrat sys_listxattrat
456	456	466 o32 removexattrat sys_removexattrat
457	457	467 o32 open_tree_attr sys_open_tree_attr
	458	+468 o32 file_getattr sys_file_getattr
	459	+469 o32 file_setattr sys_file_setattr

arch/parisc/kernel/syscalls/syscall.tbl+2−0

@@ -466,3 +466,5 @@ · 465 unmodified lines
466	466	465 common listxattrat sys_listxattrat
467	467	466 common removexattrat sys_removexattrat
468	468	467 common open_tree_attr sys_open_tree_attr
	469	+468 common file_getattr sys_file_getattr
	470	+469 common file_setattr sys_file_setattr

arch/powerpc/kernel/syscalls/syscall.tbl+2−0

@@ -558,3 +558,5 @@ · 557 unmodified lines
558	558	465 common listxattrat sys_listxattrat
559	559	466 common removexattrat sys_removexattrat
560	560	467 common open_tree_attr sys_open_tree_attr
	561	+468 common file_getattr sys_file_getattr
	562	+469 common file_setattr sys_file_setattr

arch/s390/kernel/syscalls/syscall.tbl+2−0

@@ -470,3 +470,5 @@ · 469 unmodified lines
470	470	465 common listxattrat sys_listxattrat sys_listxattrat
471	471	466 common removexattrat sys_removexattrat sys_removexattrat
472	472	467 common open_tree_attr sys_open_tree_attr sys_open_tree_attr
	473	+468 common file_getattr sys_file_getattr sys_file_getattr
	474	+469 common file_setattr sys_file_setattr sys_file_setattr

arch/sh/kernel/syscalls/syscall.tbl+2−0

@@ -471,3 +471,5 @@ · 470 unmodified lines
471	471	465 common listxattrat sys_listxattrat
472	472	466 common removexattrat sys_removexattrat
473	473	467 common open_tree_attr sys_open_tree_attr
	474	+468 common file_getattr sys_file_getattr
	475	+469 common file_setattr sys_file_setattr

arch/sparc/kernel/syscalls/syscall.tbl+2−0

@@ -513,3 +513,5 @@ · 512 unmodified lines
513	513	465 common listxattrat sys_listxattrat
514	514	466 common removexattrat sys_removexattrat
515	515	467 common open_tree_attr sys_open_tree_attr
	516	+468 common file_getattr sys_file_getattr
	517	+469 common file_setattr sys_file_setattr

arch/x86/entry/syscalls/syscall_32.tbl+2−0

@@ -473,3 +473,5 @@ · 472 unmodified lines
473	473	465 i386 listxattrat sys_listxattrat
474	474	466 i386 removexattrat sys_removexattrat
475	475	467 i386 open_tree_attr sys_open_tree_attr
	476	+468 i386 file_getattr sys_file_getattr
	477	+469 i386 file_setattr sys_file_setattr

arch/x86/entry/syscalls/syscall_64.tbl+2−0

@@ -391,6 +391,8 @@ · 390 unmodified lines
391	391	465 common listxattrat sys_listxattrat
392	392	466 common removexattrat sys_removexattrat
393	393	467 common open_tree_attr sys_open_tree_attr
	394	+468 common file_getattr sys_file_getattr
	395	+469 common file_setattr sys_file_setattr
394	396
395	397	#
396	398	# Due to a historical design error, certain syscalls are numbered differently

arch/xtensa/kernel/syscalls/syscall.tbl+2−0

@@ -438,3 +438,5 @@ · 437 unmodified lines
438	438	465 common listxattrat sys_listxattrat
439	439	466 common removexattrat sys_removexattrat
440	440	467 common open_tree_attr sys_open_tree_attr
	441	+468 common file_getattr sys_file_getattr
	442	+469 common file_setattr sys_file_setattr

fs/file_attr.c+152−0

@@ -4,6 +4,10 @@ · 3 unmodified lines
4	4	#include <linux/fscrypt.h>
5	5	#include <linux/fileattr.h>
6	6	#include <linux/export.h>
	7	+#include <linux/syscalls.h>
	8	+#include <linux/namei.h>
	9	+
	10	+#include "internal.h"
7	11
8	12	/**
9	13	* fileattr_fill_xflags - initialize fileattr with xflags
@@ -90,6 +94,19 @@ int vfs_fileattr_get(struct dentry dentry, struct fileattr fa) · 80 unmodified lines
90	94	}
91	95	EXPORT_SYMBOL(vfs_fileattr_get);
92	96
	97	+static void fileattr_to_file_attr(const struct fileattr *fa,
	98	+ struct file_attr *fattr)
	99	+{
	100	+ __u32 mask = FS_XFLAGS_MASK;
	101	+
	102	+ memset(fattr, 0, sizeof(struct file_attr));
	103	+ fattr->fa_xflags = fa->fsx_xflags & mask;
	104	+ fattr->fa_extsize = fa->fsx_extsize;
	105	+ fattr->fa_nextents = fa->fsx_nextents;
	106	+ fattr->fa_projid = fa->fsx_projid;
	107	+ fattr->fa_cowextsize = fa->fsx_cowextsize;
	108	+}
	109	+
93	110	/**
94	111	* copy_fsxattr_to_user - copy fsxattr to userspace.
95	112	* @fa: fileattr pointer
@@ -116,6 +133,23 @@ int copy_fsxattr_to_user(const struct fileattr fa, struct fsxattr __user ufa) · 20 unmodified lines
116	133	}
117	134	EXPORT_SYMBOL(copy_fsxattr_to_user);
118	135
	136	+static int file_attr_to_fileattr(const struct file_attr *fattr,
	137	+ struct fileattr *fa)
	138	+{
	139	+ __u32 mask = FS_XFLAGS_MASK;
	140	+
	141	+ if (fattr->fa_xflags & ~mask)
	142	+ return -EINVAL;
	143	+
	144	+ fileattr_fill_xflags(fa, fattr->fa_xflags);
	145	+ fa->fsx_xflags &= ~FS_XFLAG_RDONLY_MASK;
	146	+ fa->fsx_extsize = fattr->fa_extsize;
	147	+ fa->fsx_projid = fattr->fa_projid;
	148	+ fa->fsx_cowextsize = fattr->fa_cowextsize;
	149	+
	150	+ return 0;
	151	+}
	152	+
119	153	static int copy_fsxattr_from_user(struct fileattr *fa,
120	154	struct fsxattr __user *ufa)
121	155	{
@@ -344,3 +378,121 @@ int ioctl_fssetxattr(struct file file, void __user argp) · 222 unmodified lines
344	378	return err;
345	379	}
346	380	EXPORT_SYMBOL(ioctl_fssetxattr);
	381	+
	382	+SYSCALL_DEFINE5(file_getattr, int, dfd, const char __user *, filename,
	383	+ struct file_attr __user *, ufattr, size_t, usize,
	384	+ unsigned int, at_flags)
	385	+{
	386	+ struct path filepath __free(path_put) = {};
	387	+ struct filename *name __free(putname) = NULL;
	388	+ unsigned int lookup_flags = 0;
	389	+ struct file_attr fattr;
	390	+ struct fileattr fa;
	391	+ int error;
	392	+
	393	+ BUILD_BUG_ON(sizeof(struct file_attr) < FILE_ATTR_SIZE_VER0);
	394	+ BUILD_BUG_ON(sizeof(struct file_attr) != FILE_ATTR_SIZE_LATEST);
	395	+
	396	+ if ((at_flags & ~(AT_SYMLINK_NOFOLLOW \| AT_EMPTY_PATH)) != 0)
	397	+ return -EINVAL;
	398	+
	399	+ if (!(at_flags & AT_SYMLINK_NOFOLLOW))
	400	+ lookup_flags \|= LOOKUP_FOLLOW;
	401	+
	402	+ if (usize > PAGE_SIZE)
	403	+ return -E2BIG;
	404	+
	405	+ if (usize < FILE_ATTR_SIZE_VER0)
	406	+ return -EINVAL;
	407	+
	408	+ name = getname_maybe_null(filename, at_flags);
	409	+ if (IS_ERR(name))
	410	+ return PTR_ERR(name);
	411	+
	412	+ if (!name && dfd >= 0) {
	413	+ CLASS(fd, f)(dfd);
	414	+ if (fd_empty(f))
	415	+ return -EBADF;
	416	+
	417	+ filepath = fd_file(f)->f_path;
	418	+ path_get(&filepath);
	419	+ } else {
	420	+ error = filename_lookup(dfd, name, lookup_flags, &filepath,
	421	+ NULL);
	422	+ if (error)
	423	+ return error;
	424	+ }
	425	+
	426	+ error = vfs_fileattr_get(filepath.dentry, &fa);
	427	+ if (error)
	428	+ return error;
	429	+
	430	+ fileattr_to_file_attr(&fa, &fattr);
	431	+ error = copy_struct_to_user(ufattr, usize, &fattr,
	432	+ sizeof(struct file_attr), NULL);
	433	+
	434	+ return error;
	435	+}
	436	+
	437	+SYSCALL_DEFINE5(file_setattr, int, dfd, const char __user *, filename,
	438	+ struct file_attr __user *, ufattr, size_t, usize,
	439	+ unsigned int, at_flags)
	440	+{
	441	+ struct path filepath __free(path_put) = {};
	442	+ struct filename *name __free(putname) = NULL;
	443	+ unsigned int lookup_flags = 0;
	444	+ struct file_attr fattr;
	445	+ struct fileattr fa;
	446	+ int error;
	447	+
	448	+ BUILD_BUG_ON(sizeof(struct file_attr) < FILE_ATTR_SIZE_VER0);
	449	+ BUILD_BUG_ON(sizeof(struct file_attr) != FILE_ATTR_SIZE_LATEST);
	450	+
	451	+ if ((at_flags & ~(AT_SYMLINK_NOFOLLOW \| AT_EMPTY_PATH)) != 0)
	452	+ return -EINVAL;
	453	+
	454	+ if (!(at_flags & AT_SYMLINK_NOFOLLOW))
	455	+ lookup_flags \|= LOOKUP_FOLLOW;
	456	+
	457	+ if (usize > PAGE_SIZE)
	458	+ return -E2BIG;
	459	+
	460	+ if (usize < FILE_ATTR_SIZE_VER0)
	461	+ return -EINVAL;
	462	+
	463	+ error = copy_struct_from_user(&fattr, sizeof(struct file_attr), ufattr,
	464	+ usize);
	465	+ if (error)
	466	+ return error;
	467	+
	468	+ error = file_attr_to_fileattr(&fattr, &fa);
	469	+ if (error)
	470	+ return error;
	471	+
	472	+ name = getname_maybe_null(filename, at_flags);
	473	+ if (IS_ERR(name))
	474	+ return PTR_ERR(name);
	475	+
	476	+ if (!name && dfd >= 0) {
	477	+ CLASS(fd, f)(dfd);
	478	+ if (fd_empty(f))
	479	+ return -EBADF;
	480	+
	481	+ filepath = fd_file(f)->f_path;
	482	+ path_get(&filepath);
	483	+ } else {
	484	+ error = filename_lookup(dfd, name, lookup_flags, &filepath,
	485	+ NULL);
	486	+ if (error)
	487	+ return error;
	488	+ }
	489	+
	490	+ error = mnt_want_write(filepath.mnt);
	491	+ if (!error) {
	492	+ error = vfs_fileattr_set(mnt_idmap(filepath.mnt),
	493	+ filepath.dentry, &fa);
	494	+ mnt_drop_write(filepath.mnt);
	495	+ }
	496	+
	497	+ return error;
	498	+}

include/linux/syscalls.h+7−0

@@ -78,6 +78,7 @@ struct cachestat; · 77 unmodified lines
78	78	struct statmount;
79	79	struct mnt_id_req;
80	80	struct xattr_args;
	81	+struct file_attr;
81	82
82	83	#include <linux/types.h>
83	84	#include <linux/aio_abi.h>
@@ -371,6 +372,12 @@ asmlinkage long sys_removexattrat(int dfd, const char __user *path, · 287 unmodified lines
371	372	asmlinkage long sys_lremovexattr(const char __user *path,
372	373	const char __user *name);
373	374	asmlinkage long sys_fremovexattr(int fd, const char __user *name);
	375	+asmlinkage long sys_file_getattr(int dfd, const char __user *filename,
	376	+ struct file_attr __user *attr, size_t usize,
	377	+ unsigned int at_flags);
	378	+asmlinkage long sys_file_setattr(int dfd, const char __user *filename,
	379	+ struct file_attr __user *attr, size_t usize,
	380	+ unsigned int at_flags);
374	381	asmlinkage long sys_getcwd(char __user *buf, unsigned long size);
375	382	asmlinkage long sys_eventfd2(unsigned int count, int flags);
376	383	asmlinkage long sys_epoll_create1(int flags);

include/uapi/asm-generic/unistd.h+7−1

@@ -852,8 +852,14 @@ __SYSCALL(__NR_removexattrat, sys_removexattrat) · 851 unmodified lines
852	852	#define __NR_open_tree_attr 467
853	853	__SYSCALL(__NR_open_tree_attr, sys_open_tree_attr)
854	854
	855	+/* fs/inode.c */
	856	+#define __NR_file_getattr 468
	857	+__SYSCALL(__NR_file_getattr, sys_file_getattr)
	858	+#define __NR_file_setattr 469
	859	+__SYSCALL(__NR_file_setattr, sys_file_setattr)
	860	+
855	861	#undef __NR_syscalls
856		−#define __NR_syscalls 468
	862	+#define __NR_syscalls 470
857	863
858	864	/*
859	865	* 32 bit systems traditionally used different

include/uapi/linux/fs.h+18−0

@@ -148,6 +148,24 @@ struct fsxattr { · 147 unmodified lines
148	148	unsigned char fsx_pad[8];
149	149	};
150	150
	151	+/*
	152	+ * Variable size structure for file_[sg]et_attr().
	153	+ *
	154	+ * Note. This is alternative to the structure 'struct fileattr'/'struct fsxattr'.
	155	+ * As this structure is passed to/from userspace with its size, this can
	156	+ * be versioned based on the size.
	157	+ */
	158	+struct file_attr {
	159	+ __u64 fa_xflags; /* xflags field value (get/set) */
	160	+ __u32 fa_extsize; /* extsize field value (get/set)*/
	161	+ __u32 fa_nextents; /* nextents field value (get) */
	162	+ __u32 fa_projid; /* project identifier (get/set) */
	163	+ __u32 fa_cowextsize; /* CoW extsize field value (get/set) */
	164	+};
	165	+
	166	+#define FILE_ATTR_SIZE_VER0 24
	167	+#define FILE_ATTR_SIZE_LATEST FILE_ATTR_SIZE_VER0
	168	+
151	169	/*
152	170	* Flags for the fsx_xflags field
153	171	*/

scripts/syscall.tbl+2−0

@@ -408,3 +408,5 @@ · 407 unmodified lines
408	408	465 common listxattrat sys_listxattrat
409	409	466 common removexattrat sys_removexattrat
410	410	467 common open_tree_attr sys_open_tree_attr
	411	+468 common file_getattr sys_file_getattr
	412	+469 common file_setattr sys_file_setattr