On February 11, 2025 9:22:47 AM PST, Andrey Albershteyn <aalbersh@xxxxxxxxxx> wrote: >From: Andrey Albershteyn <aalbersh@xxxxxxxxxx> > >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. > >Also, as vfs_fileattr_set() is now will be called on special files >too, let's forbid any other attributes except projid and nextents >(symlink can have an extent). > >CC: linux-api@xxxxxxxxxxxxxxx >CC: linux-fsdevel@xxxxxxxxxxxxxxx >CC: linux-xfs@xxxxxxxxxxxxxxx >Signed-off-by: Andrey Albershteyn <aalbersh@xxxxxxxxxx> >--- >v1: >https://lore.kernel.org/linuxppc-dev/20250109174540.893098-1-aalbersh@xxxxxxxxxx/ > >Previous discussion: >https://lore.kernel.org/linux-xfs/20240520164624.665269-2-aalbersh@xxxxxxxxxx/ > >XFS has project quotas which could be attached to a directory. All >new inodes in these directories inherit project ID set on parent >directory. > >The project is created from userspace by opening and calling >FS_IOC_FSSETXATTR on each inode. This is not possible for special >files such as FIFO, SOCK, BLK etc. Therefore, some inodes are left >with empty project ID. Those inodes then are not shown in the quota >accounting but still exist in the directory. Moreover, in the case >when special files are created in the directory with already >existing project quota, these inode inherit extended attributes. >This than leaves them with these attributes without the possibility >to clear them out. This, in turn, prevents userspace from >re-creating quota project on these existing files. >--- >Changes in v3: >- Remove unnecessary "dfd is dir" check as it checked in user_path_at() >- Remove unnecessary "same filesystem" check >- Use CLASS() instead of directly calling fdget/fdput >- Link to v2: https://lore.kernel.org/r/20250122-xattrat-syscall-v2-1-5b360d4fbcb2@xxxxxxxxxx >--- > 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 | 75 +++++++++++++++++++++++++++++ > fs/ioctl.c | 16 +++++- > include/linux/fileattr.h | 1 + > include/linux/syscalls.h | 4 ++ > include/uapi/asm-generic/unistd.h | 8 ++- > 21 files changed, 133 insertions(+), 3 deletions(-) > >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..b2dddd9db4fabaf67a6cbf541a86978b290411ec 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 +2956,75 @@ umode_t mode_strip_sgid(struct mnt_idmap *idmap, > return mode & ~S_ISGID; > } > EXPORT_SYMBOL(mode_strip_sgid); >+ >+SYSCALL_DEFINE4(getfsxattrat, int, dfd, const char __user *, filename, >+ struct fsxattr __user *, fsx, unsigned int, at_flags) >+{ >+ CLASS(fd, dir)(dfd); >+ struct fileattr fa; >+ struct path filepath; >+ int error; >+ unsigned int lookup_flags = 0; >+ >+ if ((at_flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0) >+ return -EINVAL; >+ >+ if (at_flags & AT_SYMLINK_FOLLOW) >+ lookup_flags |= LOOKUP_FOLLOW; >+ >+ if (at_flags & AT_EMPTY_PATH) >+ lookup_flags |= LOOKUP_EMPTY; >+ >+ if (fd_empty(dir)) >+ return -EBADF; >+ >+ error = user_path_at(dfd, filename, lookup_flags, &filepath); >+ if (error) >+ return error; >+ >+ error = vfs_fileattr_get(filepath.dentry, &fa); >+ if (!error) >+ error = copy_fsxattr_to_user(&fa, fsx); >+ >+ path_put(&filepath); >+ return error; >+} >+ >+SYSCALL_DEFINE4(setfsxattrat, int, dfd, const char __user *, filename, >+ struct fsxattr __user *, fsx, unsigned int, at_flags) >+{ >+ CLASS(fd, dir)(dfd); >+ struct fileattr fa; >+ struct path filepath; >+ int error; >+ unsigned int lookup_flags = 0; >+ >+ if ((at_flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) >+ return -EINVAL; >+ >+ if (at_flags & AT_SYMLINK_FOLLOW) >+ lookup_flags |= LOOKUP_FOLLOW; >+ >+ if (at_flags & AT_EMPTY_PATH) >+ lookup_flags |= LOOKUP_EMPTY; >+ >+ if (fd_empty(dir)) >+ return -EBADF; >+ >+ if (copy_fsxattr_from_user(&fa, fsx)) >+ return -EFAULT; >+ >+ error = user_path_at(dfd, filename, lookup_flags, &filepath); >+ if (error) >+ return error; >+ >+ error = mnt_want_write(filepath.mnt); >+ if (!error) { >+ error = vfs_fileattr_set(file_mnt_idmap(fd_file(dir)), >+ filepath.dentry, &fa); >+ mnt_drop_write(filepath.mnt); >+ } >+ >+ path_put(&filepath); >+ return error; >+} >diff --git a/fs/ioctl.c b/fs/ioctl.c >index 638a36be31c14afc66a7fd6eb237d9545e8ad997..dc160c2ef145e4931d625f1f93c2a8ae7f87abf3 100644 >--- a/fs/ioctl.c >+++ b/fs/ioctl.c >@@ -558,8 +558,7 @@ int copy_fsxattr_to_user(const struct fileattr *fa, struct fsxattr __user *ufa) > } > EXPORT_SYMBOL(copy_fsxattr_to_user); > >-static int copy_fsxattr_from_user(struct fileattr *fa, >- struct fsxattr __user *ufa) >+int copy_fsxattr_from_user(struct fileattr *fa, struct fsxattr __user *ufa) > { > struct fsxattr xfa; > >@@ -646,6 +645,19 @@ static int fileattr_set_prepare(struct inode *inode, > if (fa->fsx_cowextsize == 0) > fa->fsx_xflags &= ~FS_XFLAG_COWEXTSIZE; > >+ /* >+ * The only use case for special files is to set project ID, forbid any >+ * other attributes >+ */ >+ if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))) { >+ if (fa->fsx_xflags & ~FS_XFLAG_PROJINHERIT) >+ return -EINVAL; >+ if (!S_ISLNK(inode->i_mode) && fa->fsx_nextents) >+ return -EINVAL; >+ if (fa->fsx_extsize || fa->fsx_cowextsize) >+ return -EINVAL; >+ } >+ > return 0; > } > >diff --git a/include/linux/fileattr.h b/include/linux/fileattr.h >index 47c05a9851d0600964b644c9c7218faacfd865f8..8598e94b530b8b280a2697eaf918dd60f573d6ee 100644 >--- a/include/linux/fileattr.h >+++ b/include/linux/fileattr.h >@@ -34,6 +34,7 @@ struct fileattr { > }; > > int copy_fsxattr_to_user(const struct fileattr *fa, struct fsxattr __user *ufa); >+int copy_fsxattr_from_user(struct fileattr *fa, struct fsxattr __user *ufa); > > void fileattr_fill_xflags(struct fileattr *fa, u32 xflags); > void fileattr_fill_flags(struct fileattr *fa, u32 flags); >diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h >index c6333204d45130eb022f6db460eea34a1f6e91db..3134d463d9af64c6e78adb37bff4b91f77b5305f 100644 >--- a/include/linux/syscalls.h >+++ b/include/linux/syscalls.h >@@ -371,6 +371,10 @@ 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 *fsx, unsigned int at_flags); >+asmlinkage long sys_setfsxattrat(int dfd, const char __user *filename, >+ struct fsxattr *fsx, 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 > >--- >base-commit: ffd294d346d185b70e28b1a28abe367bbfe53c04 >change-id: 20250114-xattrat-syscall-6a1136d2db59 > >Best regards, Could you please give a quick description of the API – even just the prototype – and, for the future, include in the cover letter?
