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fs: add open_tree_attr()
Add open_tree_attr() which allow to atomically create a detached mount tree and set mount options on it. If OPEN_TREE_CLONE is used this will allow the creation of a detached mount with a new set of mount options without it ever being exposed to userspace without that set of mount options applied. Link: https://lore.kernel.org/r/[email protected] Reviewed-by: "Seth Forshee (DigitalOcean)" <[email protected]> Signed-off-by: Christian Brauner <[email protected]>
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‎arch/alpha/kernel/syscalls/syscall.tbl

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@@ -506,3 +506,4 @@
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574 common getxattrat sys_getxattrat
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575 common listxattrat sys_listxattrat
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576 common removexattrat sys_removexattrat
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577 common open_tree_attr sys_open_tree_attr

‎arch/arm/tools/syscall.tbl

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@@ -481,3 +481,4 @@
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464 common getxattrat sys_getxattrat
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465 common listxattrat sys_listxattrat
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466 common removexattrat sys_removexattrat
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467 common open_tree_attr sys_open_tree_attr

‎arch/arm64/tools/syscall_32.tbl

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@@ -478,3 +478,4 @@
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464 common getxattrat sys_getxattrat
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465 common listxattrat sys_listxattrat
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466 common removexattrat sys_removexattrat
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467 common open_tree_attr sys_open_tree_attr

‎arch/m68k/kernel/syscalls/syscall.tbl

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@@ -466,3 +466,4 @@
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464 common getxattrat sys_getxattrat
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465 common listxattrat sys_listxattrat
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466 common removexattrat sys_removexattrat
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467 common open_tree_attr sys_open_tree_attr

‎arch/microblaze/kernel/syscalls/syscall.tbl

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@@ -472,3 +472,4 @@
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464 common getxattrat sys_getxattrat
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465 common listxattrat sys_listxattrat
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466 common removexattrat sys_removexattrat
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467 common open_tree_attr sys_open_tree_attr

‎arch/mips/kernel/syscalls/syscall_n32.tbl

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@@ -405,3 +405,4 @@
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464 n32 getxattrat sys_getxattrat
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465 n32 listxattrat sys_listxattrat
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466 n32 removexattrat sys_removexattrat
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467 n32 open_tree_attr sys_open_tree_attr

‎arch/mips/kernel/syscalls/syscall_n64.tbl

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@@ -381,3 +381,4 @@
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464 n64 getxattrat sys_getxattrat
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465 n64 listxattrat sys_listxattrat
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466 n64 removexattrat sys_removexattrat
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467 n64 open_tree_attr sys_open_tree_attr

‎arch/mips/kernel/syscalls/syscall_o32.tbl

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@@ -454,3 +454,4 @@
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464 o32 getxattrat sys_getxattrat
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465 o32 listxattrat sys_listxattrat
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466 o32 removexattrat sys_removexattrat
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467 o32 open_tree_attr sys_open_tree_attr

‎arch/parisc/kernel/syscalls/syscall.tbl

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@@ -465,3 +465,4 @@
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464 common getxattrat sys_getxattrat
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465 common listxattrat sys_listxattrat
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466 common removexattrat sys_removexattrat
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467 common open_tree_attr sys_open_tree_attr

‎arch/powerpc/kernel/syscalls/syscall.tbl

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@@ -557,3 +557,4 @@
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464 common getxattrat sys_getxattrat
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465 common listxattrat sys_listxattrat
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466 common removexattrat sys_removexattrat
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467 common open_tree_attr sys_open_tree_attr

‎arch/s390/kernel/syscalls/syscall.tbl

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@@ -469,3 +469,4 @@
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464 common getxattrat sys_getxattrat sys_getxattrat
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465 common listxattrat sys_listxattrat sys_listxattrat
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466 common removexattrat sys_removexattrat sys_removexattrat
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467 common open_tree_attr sys_open_tree_attr sys_open_tree_attr

‎arch/sh/kernel/syscalls/syscall.tbl

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@@ -470,3 +470,4 @@
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464 common getxattrat sys_getxattrat
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465 common listxattrat sys_listxattrat
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466 common removexattrat sys_removexattrat
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467 common open_tree_attr sys_open_tree_attr

‎arch/sparc/kernel/syscalls/syscall.tbl

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@@ -512,3 +512,4 @@
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464 common getxattrat sys_getxattrat
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465 common listxattrat sys_listxattrat
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466 common removexattrat sys_removexattrat
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467 common open_tree_attr sys_open_tree_attr

‎arch/x86/entry/syscalls/syscall_32.tbl

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@@ -472,3 +472,4 @@
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464 i386 getxattrat sys_getxattrat
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465 i386 listxattrat sys_listxattrat
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466 i386 removexattrat sys_removexattrat
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467 i386 open_tree_attr sys_open_tree_attr

‎arch/x86/entry/syscalls/syscall_64.tbl

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@@ -390,6 +390,7 @@
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464 common getxattrat sys_getxattrat
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465 common listxattrat sys_listxattrat
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466 common removexattrat sys_removexattrat
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467 common open_tree_attr sys_open_tree_attr
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#
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# Due to a historical design error, certain syscalls are numbered differently

‎arch/xtensa/kernel/syscalls/syscall.tbl

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@@ -437,3 +437,4 @@
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464 common getxattrat sys_getxattrat
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465 common listxattrat sys_listxattrat
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466 common removexattrat sys_removexattrat
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467 common open_tree_attr sys_open_tree_attr

‎fs/namespace.c

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@@ -4995,6 +4995,45 @@ SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path,
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return err;
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}
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SYSCALL_DEFINE5(open_tree_attr, int, dfd, const char __user *, filename,
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unsigned, flags, struct mount_attr __user *, uattr,
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size_t, usize)
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{
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struct file __free(fput) *file = NULL;
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int fd;
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if (!uattr && usize)
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return -EINVAL;
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file = vfs_open_tree(dfd, filename, flags);
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if (IS_ERR(file))
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return PTR_ERR(file);
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if (uattr) {
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int ret;
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struct mount_kattr kattr = {
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.recurse = !!(flags & AT_RECURSIVE),
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};
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ret = copy_mount_setattr(uattr, usize, &kattr);
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if (ret)
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return ret;
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ret = do_mount_setattr(&file->f_path, &kattr);
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if (ret)
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return ret;
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finish_mount_kattr(&kattr);
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}
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fd = get_unused_fd_flags(flags & O_CLOEXEC);
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if (fd < 0)
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return fd;
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fd_install(fd, no_free_ptr(file));
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return fd;
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}
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int show_path(struct seq_file *m, struct dentry *root)
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{
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if (root->d_sb->s_op->show_path)

‎include/linux/syscalls.h

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@@ -951,6 +951,10 @@ asmlinkage long sys_statx(int dfd, const char __user *path, unsigned flags,
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asmlinkage long sys_rseq(struct rseq __user *rseq, uint32_t rseq_len,
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int flags, uint32_t sig);
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asmlinkage long sys_open_tree(int dfd, const char __user *path, unsigned flags);
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asmlinkage long sys_open_tree_attr(int dfd, const char __user *path,
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unsigned flags,
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struct mount_attr __user *uattr,
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size_t usize);
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asmlinkage long sys_move_mount(int from_dfd, const char __user *from_path,
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int to_dfd, const char __user *to_path,
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unsigned int ms_flags);

‎include/uapi/asm-generic/unistd.h

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@@ -849,9 +849,11 @@ __SYSCALL(__NR_getxattrat, sys_getxattrat)
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__SYSCALL(__NR_listxattrat, sys_listxattrat)
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#define __NR_removexattrat 466
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__SYSCALL(__NR_removexattrat, sys_removexattrat)
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#define __NR_open_tree_attr 467
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__SYSCALL(__NR_open_tree_attr, sys_open_tree_attr)
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#undef __NR_syscalls
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#define __NR_syscalls 467
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#define __NR_syscalls 468
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/*
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* 32 bit systems traditionally used different

‎scripts/syscall.tbl

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464 common getxattrat sys_getxattrat
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465 common listxattrat sys_listxattrat
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466 common removexattrat sys_removexattrat
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467 common open_tree_attr sys_open_tree_attr

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