170 lines
5.2 KiB
Diff
170 lines
5.2 KiB
Diff
From e6525eb45b8c8eafc18fb08cfa13df29435f984a Mon Sep 17 00:00:00 2001
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From: Adrian Chelaru <che.adrian@yahoo.com>
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Date: Wed, 8 Feb 2023 16:33:36 +0000
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Subject: [PATCH 3/5] Backport shm add memfd create syscall
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---
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arch/x86/syscalls/syscall_32.tbl | 1 +
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arch/x86/syscalls/syscall_64.tbl | 1 +
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include/linux/syscalls.h | 1 +
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include/uapi/linux/memfd.h | 8 ++++
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kernel/sys_ni.c | 1 +
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mm/shmem.c | 74 ++++++++++++++++++++++++++++++++
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6 files changed, 86 insertions(+)
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create mode 100644 include/uapi/linux/memfd.h
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diff --git a/arch/x86/syscalls/syscall_32.tbl b/arch/x86/syscalls/syscall_32.tbl
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index 29f9f055..199c47e8 100644
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--- a/arch/x86/syscalls/syscall_32.tbl
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+++ b/arch/x86/syscalls/syscall_32.tbl
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@@ -355,3 +355,4 @@
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346 i386 setns sys_setns
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347 i386 process_vm_readv sys_process_vm_readv compat_sys_process_vm_readv
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348 i386 process_vm_writev sys_process_vm_writev compat_sys_process_vm_writev
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+356 i386 memfd_create sys_memfd_create
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diff --git a/arch/x86/syscalls/syscall_64.tbl b/arch/x86/syscalls/syscall_64.tbl
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index dd29a9ea..6b52cf60 100644
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--- a/arch/x86/syscalls/syscall_64.tbl
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+++ b/arch/x86/syscalls/syscall_64.tbl
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@@ -318,6 +318,7 @@
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309 common getcpu sys_getcpu
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310 64 process_vm_readv sys_process_vm_readv
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311 64 process_vm_writev sys_process_vm_writev
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+319 common memfd_create sys_memfd_create
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#
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# x32-specific system call numbers start at 512 to avoid cache impact
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# for native 64-bit operation.
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diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
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index 3de3acb8..d97575d9 100644
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--- a/include/linux/syscalls.h
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+++ b/include/linux/syscalls.h
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@@ -813,6 +813,7 @@ asmlinkage long sys_timerfd_settime(int ufd, int flags,
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asmlinkage long sys_timerfd_gettime(int ufd, struct itimerspec __user *otmr);
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asmlinkage long sys_eventfd(unsigned int count);
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asmlinkage long sys_eventfd2(unsigned int count, int flags);
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+asmlinkage long sys_memfd_create(const char __user *uname_ptr, unsigned int flags);
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asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len);
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asmlinkage long sys_old_readdir(unsigned int, struct old_linux_dirent __user *, unsigned int);
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asmlinkage long sys_pselect6(int, fd_set __user *, fd_set __user *,
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diff --git a/include/uapi/linux/memfd.h b/include/uapi/linux/memfd.h
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new file mode 100644
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index 00000000..9a772654
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--- /dev/null
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+++ b/include/uapi/linux/memfd.h
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@@ -0,0 +1,8 @@
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+#ifndef _UAPI_LINUX_MEMFD_H
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+#define _UAPI_LINUX_MEMFD_H
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+
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+/* flags for memfd_create(2) (unsigned int) */
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+#define MFD_CLOEXEC 0x0001U
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+#define MFD_ALLOW_SEALING 0x0002U
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+
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+#endif /* _UAPI_LINUX_MEMFD_H */
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diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
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index 47bfa164..f2d7d96f 100644
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--- a/kernel/sys_ni.c
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+++ b/kernel/sys_ni.c
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@@ -191,6 +191,7 @@ cond_syscall(compat_sys_timerfd_settime);
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cond_syscall(compat_sys_timerfd_gettime);
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cond_syscall(sys_eventfd);
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cond_syscall(sys_eventfd2);
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+cond_syscall(sys_memfd_create);
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/* performance counters: */
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cond_syscall(sys_perf_event_open);
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diff --git a/mm/shmem.c b/mm/shmem.c
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index fbb6b2fc..625fbf09 100644
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--- a/mm/shmem.c
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+++ b/mm/shmem.c
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@@ -63,7 +63,9 @@ static struct vfsmount *shm_mnt;
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#include <linux/highmem.h>
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#include <linux/seq_file.h>
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#include <linux/magic.h>
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+#include <linux/syscalls.h>
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#include <linux/fcntl.h>
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+#include <uapi/linux/memfd.h>
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#include <asm/uaccess.h>
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#include <asm/pgtable.h>
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@@ -2349,6 +2351,78 @@ static int shmem_show_options(struct seq_file *seq, struct dentry *root)
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shmem_show_mpol(seq, sbinfo->mpol);
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return 0;
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}
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+
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+
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+#define MFD_NAME_PREFIX "memfd:"
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+#define MFD_NAME_PREFIX_LEN (sizeof(MFD_NAME_PREFIX) - 1)
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+#define MFD_NAME_MAX_LEN (NAME_MAX - MFD_NAME_PREFIX_LEN)
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+
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+#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING)
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+
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+SYSCALL_DEFINE2(memfd_create,
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+ const char __user *, uname,
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+ unsigned int, flags)
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+{
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+ struct shmem_inode_info *info;
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+ struct file *file;
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+ int fd, error;
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+ char *name;
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+ long len;
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+
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+ if (flags & ~(unsigned int)MFD_ALL_FLAGS)
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+ return -EINVAL;
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+
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+ /* length includes terminating zero */
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+ len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1);
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+ if (len <= 0)
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+ return -EFAULT;
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+ if (len > MFD_NAME_MAX_LEN + 1)
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+ return -EINVAL;
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+
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+ name = kmalloc(len + MFD_NAME_PREFIX_LEN, GFP_TEMPORARY);
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+ if (!name)
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+ return -ENOMEM;
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+
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+ strcpy(name, MFD_NAME_PREFIX);
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+ if (copy_from_user(&name[MFD_NAME_PREFIX_LEN], uname, len)) {
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+ error = -EFAULT;
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+ goto err_name;
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+ }
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+
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+ /* terminating-zero may have changed after strnlen_user() returned */
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+ if (name[len + MFD_NAME_PREFIX_LEN - 1]) {
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+ error = -EFAULT;
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+ goto err_name;
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+ }
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+
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+ fd = get_unused_fd_flags((flags & MFD_CLOEXEC) ? O_CLOEXEC : 0);
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+ if (fd < 0) {
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+ error = fd;
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+ goto err_name;
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+ }
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+
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+ file = shmem_file_setup(name, 0, VM_NORESERVE);
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+ if (IS_ERR(file)) {
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+ error = PTR_ERR(file);
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+ goto err_fd;
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+ }
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+ info = SHMEM_I(file_inode(file));
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+ file->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
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+ file->f_flags |= O_RDWR | O_LARGEFILE;
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+ if (flags & MFD_ALLOW_SEALING)
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+ info->seals &= ~F_SEAL_SEAL;
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+
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+ fd_install(fd, file);
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+ kfree(name);
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+ return fd;
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+
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+err_fd:
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+ put_unused_fd(fd);
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+err_name:
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+ kfree(name);
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+ return error;
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+}
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+
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#endif /* CONFIG_TMPFS */
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static void shmem_put_super(struct super_block *sb)
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--
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2.38.3
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