[PATCH v4 3/3] fs: introduce getfsxattrat and setfsxattrat syscalls
From: Andrey Albershteyn <hidden>
Date: 2025-03-21 19:49:22
Also in:
linux-alpha, linux-api, linux-arch, linux-fsdevel, linux-m68k, linux-mips, linux-s390, linux-sh, linux-xfs, linuxppc-dev, lkml, sparclinux
Subsystem:
abi/api, alpha port, arm port, arm64 port (aarch64 architecture), filesystems (vfs and infrastructure), generic include/asm header files, linux for powerpc (32-bit and 64-bit), m68k architecture, microblaze architecture, mips, parisc architecture, s390 architecture, sparc + ultrasparc (sparc/sparc64), superh, tensilica xtensa port (xtensa), the rest, x86 architecture (32-bit and 64-bit), x86 entry code · Maintainers:
Richard Henderson, Matt Turner, Magnus Lindholm, Russell King, Catalin Marinas, Will Deacon, Alexander Viro, Christian Brauner, Arnd Bergmann, Madhavan Srinivasan, Michael Ellerman, Geert Uytterhoeven, Michal Simek, Thomas Bogendoerfer, "James E.J. Bottomley", Helge Deller, Heiko Carstens, Vasily Gorbik, Alexander Gordeev, "David S. Miller", Andreas Larsson, Yoshinori Sato, Rich Felker, John Paul Adrian Glaubitz, Chris Zankel, Max Filippov, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Andy Lutomirski
From: Andrey Albershteyn <redacted> Introduce getfsxattrat and setfsxattrat 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: linux-api@vger.kernel.org CC: linux-fsdevel@vger.kernel.org CC: linux-xfs@vger.kernel.org Signed-off-by: Andrey Albershteyn <redacted> Acked-by: Arnd Bergmann <arnd@arndb.de> --- 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/inode.c | 130 ++++++++++++++++++++++++++++ include/linux/syscalls.h | 6 ++ include/uapi/asm-generic/unistd.h | 8 +- include/uapi/linux/fs.h | 3 + 20 files changed, 178 insertions(+), 1 deletion(-)
diff --git a/arch/alpha/kernel/syscalls/syscall.tbl b/arch/alpha/kernel/syscalls/syscall.tbl
index c59d53d6d3f3490f976ca179ddfe02e69265ae4d..4b9e687494c16b60c6fd6ca1dc4d6564706a7e25 100644
--- a/arch/alpha/kernel/syscalls/syscall.tbl
+++ b/arch/alpha/kernel/syscalls/syscall.tbl@@ -506,3 +506,5 @@ 574 common getxattrat sys_getxattrat 575 common listxattrat sys_listxattrat 576 common removexattrat sys_removexattrat +577 common getfsxattrat sys_getfsxattrat +578 common setfsxattrat sys_setfsxattrat
diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl
index 49eeb2ad8dbd8e074c6240417693f23fb328afa8..66466257f3c2debb3e2299f0b608c6740c98cab2 100644
--- a/arch/arm/tools/syscall.tbl
+++ b/arch/arm/tools/syscall.tbl@@ -481,3 +481,5 @@ 464 common getxattrat sys_getxattrat 465 common listxattrat sys_listxattrat 466 common removexattrat sys_removexattrat +467 common getfsxattrat sys_getfsxattrat +468 common setfsxattrat sys_setfsxattrat
diff --git a/arch/arm64/tools/syscall_32.tbl b/arch/arm64/tools/syscall_32.tbl
index 69a829912a05eb8a3e21ed701d1030e31c0148bc..9c516118b154811d8d11d5696f32817430320dbf 100644
--- a/arch/arm64/tools/syscall_32.tbl
+++ b/arch/arm64/tools/syscall_32.tbl@@ -478,3 +478,5 @@ 464 common getxattrat sys_getxattrat 465 common listxattrat sys_listxattrat 466 common removexattrat sys_removexattrat +467 common getfsxattrat sys_getfsxattrat +468 common setfsxattrat sys_setfsxattrat
diff --git a/arch/m68k/kernel/syscalls/syscall.tbl b/arch/m68k/kernel/syscalls/syscall.tbl
index f5ed71f1910d09769c845c2d062d99ee0449437c..159476387f394a92ee5e29db89b118c630372db2 100644
--- a/arch/m68k/kernel/syscalls/syscall.tbl
+++ b/arch/m68k/kernel/syscalls/syscall.tbl@@ -466,3 +466,5 @@ 464 common getxattrat sys_getxattrat 465 common listxattrat sys_listxattrat 466 common removexattrat sys_removexattrat +467 common getfsxattrat sys_getfsxattrat +468 common setfsxattrat sys_setfsxattrat
diff --git a/arch/microblaze/kernel/syscalls/syscall.tbl b/arch/microblaze/kernel/syscalls/syscall.tbl
index 680f568b77f2cbefc3eacb2517f276041f229b1e..a6d59ee740b58cacf823702003cf9bad17c0d3b7 100644
--- a/arch/microblaze/kernel/syscalls/syscall.tbl
+++ b/arch/microblaze/kernel/syscalls/syscall.tbl@@ -472,3 +472,5 @@ 464 common getxattrat sys_getxattrat 465 common listxattrat sys_listxattrat 466 common removexattrat sys_removexattrat +467 common getfsxattrat sys_getfsxattrat +468 common setfsxattrat sys_setfsxattrat
diff --git a/arch/mips/kernel/syscalls/syscall_n32.tbl b/arch/mips/kernel/syscalls/syscall_n32.tbl
index 0b9b7e25b69ad592642f8533bee9ccfe95ce9626..cfe38fcebe1a0279e11751378d3e71c5ec6b6569 100644
--- a/arch/mips/kernel/syscalls/syscall_n32.tbl
+++ b/arch/mips/kernel/syscalls/syscall_n32.tbl@@ -405,3 +405,5 @@ 464 n32 getxattrat sys_getxattrat 465 n32 listxattrat sys_listxattrat 466 n32 removexattrat sys_removexattrat +467 n32 getfsxattrat sys_getfsxattrat +468 n32 setfsxattrat sys_setfsxattrat
diff --git a/arch/mips/kernel/syscalls/syscall_n64.tbl b/arch/mips/kernel/syscalls/syscall_n64.tbl
index c844cd5cda620b2809a397cdd6f4315ab6a1bfe2..29a0c5974d1aa2f01e33edc0252d75fb97abe230 100644
--- a/arch/mips/kernel/syscalls/syscall_n64.tbl
+++ b/arch/mips/kernel/syscalls/syscall_n64.tbl@@ -381,3 +381,5 @@ 464 n64 getxattrat sys_getxattrat 465 n64 listxattrat sys_listxattrat 466 n64 removexattrat sys_removexattrat +467 n64 getfsxattrat sys_getfsxattrat +468 n64 setfsxattrat sys_setfsxattrat
diff --git a/arch/mips/kernel/syscalls/syscall_o32.tbl b/arch/mips/kernel/syscalls/syscall_o32.tbl
index 349b8aad1159f404103bd2057a1e64e9bf309f18..6c00436807c57c492ba957fcd59af1202231cf80 100644
--- a/arch/mips/kernel/syscalls/syscall_o32.tbl
+++ b/arch/mips/kernel/syscalls/syscall_o32.tbl@@ -454,3 +454,5 @@ 464 o32 getxattrat sys_getxattrat 465 o32 listxattrat sys_listxattrat 466 o32 removexattrat sys_removexattrat +467 o32 getfsxattrat sys_getfsxattrat +468 o32 setfsxattrat sys_setfsxattrat
diff --git a/arch/parisc/kernel/syscalls/syscall.tbl b/arch/parisc/kernel/syscalls/syscall.tbl
index d9fc94c869657fcfbd7aca1d5f5abc9fae2fb9d8..b3578fac43d6b65167787fcc97d2d09f5a9828e7 100644
--- a/arch/parisc/kernel/syscalls/syscall.tbl
+++ b/arch/parisc/kernel/syscalls/syscall.tbl@@ -465,3 +465,5 @@ 464 common getxattrat sys_getxattrat 465 common listxattrat sys_listxattrat 466 common removexattrat sys_removexattrat +467 common getfsxattrat sys_getfsxattrat +468 common setfsxattrat sys_setfsxattrat
diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl
index d8b4ab78bef076bd50d49b87dea5060fd8c1686a..808045d82c9465c3bfa96b15947546efe5851e9a 100644
--- a/arch/powerpc/kernel/syscalls/syscall.tbl
+++ b/arch/powerpc/kernel/syscalls/syscall.tbl@@ -557,3 +557,5 @@ 464 common getxattrat sys_getxattrat 465 common listxattrat sys_listxattrat 466 common removexattrat sys_removexattrat +467 common getfsxattrat sys_getfsxattrat +468 common setfsxattrat sys_setfsxattrat
diff --git a/arch/s390/kernel/syscalls/syscall.tbl b/arch/s390/kernel/syscalls/syscall.tbl
index e9115b4d8b635b846e5c9ad6ce229605323723a5..78dfc2c184d4815baf8a9e61c546c9936d58a47c 100644
--- a/arch/s390/kernel/syscalls/syscall.tbl
+++ b/arch/s390/kernel/syscalls/syscall.tbl@@ -469,3 +469,5 @@ 464 common getxattrat sys_getxattrat sys_getxattrat 465 common listxattrat sys_listxattrat sys_listxattrat 466 common removexattrat sys_removexattrat sys_removexattrat +467 common getfsxattrat sys_getfsxattrat sys_getfsxattrat +468 common setfsxattrat sys_setfsxattrat sys_setfsxattrat
diff --git a/arch/sh/kernel/syscalls/syscall.tbl b/arch/sh/kernel/syscalls/syscall.tbl
index c8cad33bf250ea110de37bd1407f5a43ec5e38f2..d5a5c8339f0ed25ea07c4aba90351d352033c8a0 100644
--- a/arch/sh/kernel/syscalls/syscall.tbl
+++ b/arch/sh/kernel/syscalls/syscall.tbl@@ -470,3 +470,5 @@ 464 common getxattrat sys_getxattrat 465 common listxattrat sys_listxattrat 466 common removexattrat sys_removexattrat +467 common getfsxattrat sys_getfsxattrat +468 common setfsxattrat sys_setfsxattrat
diff --git a/arch/sparc/kernel/syscalls/syscall.tbl b/arch/sparc/kernel/syscalls/syscall.tbl
index 727f99d333b304b3db0711953a3d91ece18a28eb..817dcd8603bcbffc47f3f59aa3b74b16486453d0 100644
--- a/arch/sparc/kernel/syscalls/syscall.tbl
+++ b/arch/sparc/kernel/syscalls/syscall.tbl@@ -512,3 +512,5 @@ 464 common getxattrat sys_getxattrat 465 common listxattrat sys_listxattrat 466 common removexattrat sys_removexattrat +467 common getfsxattrat sys_getfsxattrat +468 common setfsxattrat sys_setfsxattrat
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 4d0fb2fba7e208ae9455459afe11e277321d9f74..b4842c027c5d00c0236b2ba89387c5e2267447bd 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl@@ -472,3 +472,5 @@ 464 i386 getxattrat sys_getxattrat 465 i386 listxattrat sys_listxattrat 466 i386 removexattrat sys_removexattrat +467 i386 getfsxattrat sys_getfsxattrat +468 i386 setfsxattrat sys_setfsxattrat
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 5eb708bff1c791debd6cfc5322583b2ae53f6437..b6f0a7236aaee624cf9b484239a1068085a8ffe1 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl@@ -390,6 +390,8 @@ 464 common getxattrat sys_getxattrat 465 common listxattrat sys_listxattrat 466 common removexattrat sys_removexattrat +467 common getfsxattrat sys_getfsxattrat +468 common setfsxattrat sys_setfsxattrat # # 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 37effc1b134eea061f2c350c1d68b4436b65a4dd..425d56be337d1de22f205ac503df61ff86224fee 100644
--- a/arch/xtensa/kernel/syscalls/syscall.tbl
+++ b/arch/xtensa/kernel/syscalls/syscall.tbl@@ -437,3 +437,5 @@ 464 common getxattrat sys_getxattrat 465 common listxattrat sys_listxattrat 466 common removexattrat sys_removexattrat +467 common getfsxattrat sys_getfsxattrat +468 common setfsxattrat sys_setfsxattrat
diff --git a/fs/inode.c b/fs/inode.c
index 6b4c77268fc0ecace4ac78a9ca777fbffc277f4a..811debf379ab299f287ed90863277cfda27db30c 100644
--- a/fs/inode.c
+++ b/fs/inode.c@@ -23,6 +23,9 @@ #include <linux/rw_hint.h> #include <linux/seq_file.h> #include <linux/debugfs.h> +#include <linux/syscalls.h> +#include <linux/fileattr.h> +#include <linux/namei.h> #include <trace/events/writeback.h> #define CREATE_TRACE_POINTS #include <trace/events/timestamp.h>
@@ -2953,3 +2956,130 @@ umode_t mode_strip_sgid(struct mnt_idmap *idmap, return mode & ~S_ISGID; } EXPORT_SYMBOL(mode_strip_sgid); + +SYSCALL_DEFINE5(getfsxattrat, int, dfd, const char __user *, filename, + struct fsxattr __user *, ufsx, size_t, usize, + unsigned int, at_flags) +{ + struct fileattr fa = {}; + struct path filepath; + 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 (at_flags & AT_EMPTY_PATH) + lookup_flags |= LOOKUP_EMPTY; + + if (usize > PAGE_SIZE) + return -E2BIG; + + if (usize < FSXATTR_SIZE_VER0) + return -EINVAL; + + name = getname_maybe_null(filename, at_flags); + if (!name) { + CLASS(fd, f)(dfd); + + if (fd_empty(f)) + return -EBADF; + error = vfs_fileattr_get(file_dentry(fd_file(f)), &fa); + } else { + error = filename_lookup(dfd, name, lookup_flags, &filepath, + NULL); + if (error) + goto out; + error = vfs_fileattr_get(filepath.dentry, &fa); + path_put(&filepath); + } + if (error == -ENOIOCTLCMD) + error = -EOPNOTSUPP; + if (!error) { + fileattr_to_fsxattr(&fa, &fsx); + error = copy_struct_to_user(ufsx, usize, &fsx, + sizeof(struct fsxattr), NULL); + } +out: + putname(name); + return error; +} + +SYSCALL_DEFINE5(setfsxattrat, int, dfd, const char __user *, filename, + struct fsxattr __user *, ufsx, size_t, usize, + unsigned int, at_flags) +{ + struct fileattr fa; + struct path filepath; + int error; + unsigned int lookup_flags = 0; + struct filename *name; + struct mnt_idmap *idmap; + struct dentry *dentry; + struct vfsmount *mnt; + 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 (at_flags & AT_EMPTY_PATH) + lookup_flags |= LOOKUP_EMPTY; + + 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; + + fsxattr_to_fileattr(&fsx, &fa); + + name = getname_maybe_null(filename, at_flags); + if (!name) { + CLASS(fd, f)(dfd); + + if (fd_empty(f)) + return -EBADF; + + idmap = file_mnt_idmap(fd_file(f)); + dentry = file_dentry(fd_file(f)); + mnt = fd_file(f)->f_path.mnt; + } else { + error = filename_lookup(dfd, name, lookup_flags, &filepath, + NULL); + if (error) + return error; + + idmap = mnt_idmap(filepath.mnt); + dentry = filepath.dentry; + mnt = filepath.mnt; + } + + error = mnt_want_write(mnt); + if (!error) { + error = vfs_fileattr_set(idmap, dentry, &fa); + if (error == -ENOIOCTLCMD) + error = -EOPNOTSUPP; + mnt_drop_write(mnt); + } + + path_put(&filepath); + return error; +}
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index c6333204d45130eb022f6db460eea34a1f6e91db..e242ea39b3e63a8008bc777764b616fd63bd40c4 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_getfsxattrat(int dfd, const char __user *filename, + struct fsxattr __user *ufsx, size_t usize, + unsigned int at_flags); +asmlinkage long sys_setfsxattrat(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 88dc393c2bca38c0fa1b3fae579f7cfe4931223c..50be2e1007bc2779120d05c6e9512a689f86779c 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h@@ -850,8 +850,14 @@ __SYSCALL(__NR_listxattrat, sys_listxattrat) #define __NR_removexattrat 466 __SYSCALL(__NR_removexattrat, sys_removexattrat) +/* fs/inode.c */ +#define __NR_getfsxattrat 467 +__SYSCALL(__NR_getfsxattrat, sys_getfsxattrat) +#define __NR_setfsxattrat 468 +__SYSCALL(__NR_setfsxattrat, sys_setfsxattrat) + #undef __NR_syscalls -#define __NR_syscalls 467 +#define __NR_syscalls 469 /* * 32 bit systems traditionally used different
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 7539717707337a8cb22396a869baba3bafa08371..aed753e5d50c97da9b895a187fdaecf0477db74b 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h@@ -139,6 +139,9 @@ 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