Commit 3c7b2045 authored by Bernd Schmidt's avatar Bernd Schmidt Committed by Linus Torvalds

nommu: allow private mappings of read-only devices

Slightly rearrange the logic that determines capabilities and vm_flags.
Disable BDI_CAP_MAP_DIRECT in all cases if the device can't support the
protections.  Allow private readonly mappings of readonly backing devices.
Signed-off-by: default avatarBernd Schmidt <bernds_cb1@t-online.de>
Signed-off-by: default avatarMike Frysinger <vapier@gentoo.org>
Acked-by: default avatarDavid McCullough <davidm@snapgear.com>
Acked-by: default avatarGreg Ungerer <gerg@uclinux.org>
Acked-by: default avatarPaul Mundt <lethal@linux-sh.org>
Acked-by: default avatarDavid Howells <dhowells@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0cae3457
...@@ -918,14 +918,6 @@ static int validate_mmap_request(struct file *file, ...@@ -918,14 +918,6 @@ static int validate_mmap_request(struct file *file,
if (!(capabilities & BDI_CAP_MAP_DIRECT)) if (!(capabilities & BDI_CAP_MAP_DIRECT))
return -ENODEV; return -ENODEV;
if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) ||
((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP))
) {
printk("MAP_SHARED not completely supported on !MMU\n");
return -EINVAL;
}
/* we mustn't privatise shared mappings */ /* we mustn't privatise shared mappings */
capabilities &= ~BDI_CAP_MAP_COPY; capabilities &= ~BDI_CAP_MAP_COPY;
} }
...@@ -941,6 +933,20 @@ static int validate_mmap_request(struct file *file, ...@@ -941,6 +933,20 @@ static int validate_mmap_request(struct file *file,
capabilities &= ~BDI_CAP_MAP_DIRECT; capabilities &= ~BDI_CAP_MAP_DIRECT;
} }
if (capabilities & BDI_CAP_MAP_DIRECT) {
if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) ||
((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP))
) {
capabilities &= ~BDI_CAP_MAP_DIRECT;
if (flags & MAP_SHARED) {
printk(KERN_WARNING
"MAP_SHARED not completely supported on !MMU\n");
return -EINVAL;
}
}
}
/* handle executable mappings and implied executable /* handle executable mappings and implied executable
* mappings */ * mappings */
if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
...@@ -996,22 +1002,20 @@ static unsigned long determine_vm_flags(struct file *file, ...@@ -996,22 +1002,20 @@ static unsigned long determine_vm_flags(struct file *file,
unsigned long vm_flags; unsigned long vm_flags;
vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags); vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
/* vm_flags |= mm->def_flags; */ /* vm_flags |= mm->def_flags; */
if (!(capabilities & BDI_CAP_MAP_DIRECT)) { if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
/* attempt to share read-only copies of mapped file chunks */ /* attempt to share read-only copies of mapped file chunks */
vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
if (file && !(prot & PROT_WRITE)) if (file && !(prot & PROT_WRITE))
vm_flags |= VM_MAYSHARE; vm_flags |= VM_MAYSHARE;
} } else {
else {
/* overlay a shareable mapping on the backing device or inode /* overlay a shareable mapping on the backing device or inode
* if possible - used for chardevs, ramfs/tmpfs/shmfs and * if possible - used for chardevs, ramfs/tmpfs/shmfs and
* romfs/cramfs */ * romfs/cramfs */
vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS);
if (flags & MAP_SHARED) if (flags & MAP_SHARED)
vm_flags |= VM_MAYSHARE | VM_SHARED; vm_flags |= VM_SHARED;
else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
vm_flags |= VM_MAYSHARE;
} }
/* refuse to let anyone share private mappings with this process if /* refuse to let anyone share private mappings with this process if
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment