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-rw-r--r--mm/shmem.c73
1 files changed, 73 insertions, 0 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index 8b43bb7..4a54987 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -66,7 +66,9 @@ static struct vfsmount *shm_mnt;
#include <linux/highmem.h>
#include <linux/seq_file.h>
#include <linux/magic.h>
+#include <linux/syscalls.h>
#include <linux/fcntl.h>
+#include <uapi/linux/memfd.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
@@ -2732,6 +2734,77 @@ static int shmem_show_options(struct seq_file *seq, struct dentry *root)
shmem_show_mpol(seq, sbinfo->mpol);
return 0;
}
+
+#define MFD_NAME_PREFIX "memfd:"
+#define MFD_NAME_PREFIX_LEN (sizeof(MFD_NAME_PREFIX) - 1)
+#define MFD_NAME_MAX_LEN (NAME_MAX - MFD_NAME_PREFIX_LEN)
+
+#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING)
+
+SYSCALL_DEFINE2(memfd_create,
+ const char __user *, uname,
+ unsigned int, flags)
+{
+ struct shmem_inode_info *info;
+ struct file *file;
+ int fd, error;
+ char *name;
+ long len;
+
+ if (flags & ~(unsigned int)MFD_ALL_FLAGS)
+ return -EINVAL;
+
+ /* length includes terminating zero */
+ len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1);
+ if (len <= 0)
+ return -EFAULT;
+ if (len > MFD_NAME_MAX_LEN + 1)
+ return -EINVAL;
+
+ name = kmalloc(len + MFD_NAME_PREFIX_LEN, GFP_TEMPORARY);
+ if (!name)
+ return -ENOMEM;
+
+ strcpy(name, MFD_NAME_PREFIX);
+ if (copy_from_user(&name[MFD_NAME_PREFIX_LEN], uname, len)) {
+ error = -EFAULT;
+ goto err_name;
+ }
+
+ /* terminating-zero may have changed after strnlen_user() returned */
+ if (name[len + MFD_NAME_PREFIX_LEN - 1]) {
+ error = -EFAULT;
+ goto err_name;
+ }
+
+ fd = get_unused_fd_flags((flags & MFD_CLOEXEC) ? O_CLOEXEC : 0);
+ if (fd < 0) {
+ error = fd;
+ goto err_name;
+ }
+
+ file = shmem_file_setup(name, 0, VM_NORESERVE);
+ if (IS_ERR(file)) {
+ error = PTR_ERR(file);
+ goto err_fd;
+ }
+ info = SHMEM_I(file_inode(file));
+ file->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
+ file->f_flags |= O_RDWR | O_LARGEFILE;
+ if (flags & MFD_ALLOW_SEALING)
+ info->seals &= ~F_SEAL_SEAL;
+
+ fd_install(fd, file);
+ kfree(name);
+ return fd;
+
+err_fd:
+ put_unused_fd(fd);
+err_name:
+ kfree(name);
+ return error;
+}
+
#endif /* CONFIG_TMPFS */
static void shmem_put_super(struct super_block *sb)
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