shm: add memfd_create() syscall

[pandora-kernel.git] / mm / shmem.c

diff --git a/mm/shmem.c b/mm/shmem.c
index c4cb595..cc956cf 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -63,7 +63,9 @@ static struct vfsmount *shm_mnt;
 #include <linux/highmem.h>
 #include <linux/seq_file.h>
 #include <linux/magic.h>
 #include <linux/highmem.h>
 #include <linux/seq_file.h>
 #include <linux/magic.h>

+#include <linux/syscalls.h>

 #include <linux/fcntl.h>
 #include <linux/fcntl.h>

+#include <uapi/linux/memfd.h>

 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>


@@ -2425,6 +2427,77 @@ static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs)
        shmem_show_mpol(seq, sbinfo->mpol);
        return 0;
 }
        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)
 #endif /* CONFIG_TMPFS */
 
 static void shmem_put_super(struct super_block *sb)