/*
* fs/isofs/export.c
*
* (C) 2004 Paul Serice - The new inode scheme requires switching
* from iget() to iget5_locked() which means
* the NFS export operations have to be hand
* coded because the default routines rely on
* iget().
*
* The following files are helpful:
*
* Documentation/filesystems/nfs/Exporting
* fs/exportfs/expfs.c.
*/
#include "isofs.h"
static struct dentry *
isofs_export_iget(struct super_block *sb,
unsigned long block,
unsigned long offset,
__u32 generation)
{
struct inode *inode;
if (block == 0)
return ERR_PTR(-ESTALE);
inode = isofs_iget(sb, block, offset);
if (IS_ERR(inode))
return ERR_CAST(inode);
if (generation && inode->i_generation != generation) {
iput(inode);
return ERR_PTR(-ESTALE);
}
return d_obtain_alias(inode);
}
/* This function is surprisingly simple. The trick is understanding
* that "child" is always a directory. So, to find its parent, you
* simply need to find its ".." entry, normalize its block and offset,
* and return the underlying inode. See the comments for
* isofs_normalize_block_and_offset(). */
static struct dentry *isofs_export_get_parent(struct dentry *child)
{
unsigned long parent_block = 0;
unsigned long parent_offset = 0;
struct inode *child_inode = d_inode(child);
struct iso_inode_info *e_child_inode = ISOFS_I(child_inode);
struct iso_directory_record *de = NULL;
struct buffer_head * bh = NULL;
struct dentry *rv = NULL;
/* "child" must always be a directory. */
if (!S_ISDIR(child_inode->i_mode)) {
printk(KERN_ERR "isofs: isofs_export_get_parent(): "
"child is not a directory!\n");
rv = ERR_PTR(-EACCES);
goto out;
}
/* It is an invariant that the directory offset is zero. If
* it is not zero, it means the directory failed to be
* normalized for some reason. */
if (e_child_inode->i_iget5_offset != 0) {
printk(KERN_ERR "isofs: isofs_export_get_parent(): "
"child directory not normalized!\n");
rv = ERR_PTR(-EACCES);
goto out;
}
/* The child inode has been normalized such that its
* i_iget5_block value points to the "." entry. Fortunately,
* the ".." entry is located in the same block. */
parent_block = e_child_inode->i_iget5_block;
/* Get the block in question. */
bh = sb_bread(child_inode->i_sb, parent_block);
if (bh == NULL) {
rv = ERR_PTR(-EACCES);
goto out;
}
/* This is the "." entry. */
de = (struct iso_directory_record*)bh->b_data;
/* The ".." entry is always the second entry. */
parent_offset = (unsigned long)isonum_711(de->length);
de = (struct iso_directory_record*)(bh->b_data + parent_offset);
/* Verify it is in fact the ".." entry. */
if ((isonum_711(de->name_len) != 1) || (de->name[0] != 1)) {
printk(KERN_ERR "isofs: Unable to find the \"..\" "
"directory for NFS.\n");
rv = ERR_PTR(-EACCES);
goto out;
}
/* Normalize */
isofs_normalize_block_and_offset(de, &parent_block, &parent_offset);
rv = d_obtain_alias(isofs_iget(child_inode->i_sb, parent_block,
parent_offset));
out:
if (bh)
brelse(bh);
return rv;
}
static int
isofs_export_encode_fh(struct inode *inode,
__u32 *fh32,
int *max_len,
struct inode *parent)
{
struct iso_inode_info * ei = ISOFS_I(inode);
int len = *max_len;
int type = 1;
__u16 *fh16 = (__u16*)fh32;
/*
* WARNING: max_len is 5 for NFSv2. Because of this
* limitation, we use the lower 16 bits of fh32[1] to hold the
* offset of the inode and the upper 16 bits of fh32[1] to
* hold the offset of the parent.
*/
if (parent && (len < 5)) {
*max_len = 5;
return FILEID_INVALID;
} else if (len < 3) {
*max_len = 3;
return FILEID_INVALID;
}
len = 3;
fh32[0] = ei->i_iget5_block;
fh16[2] = (__u16)ei->i_iget5_offset; /* fh16 [sic] */
fh16[3] = 0; /* avoid leaking uninitialized data */
fh32[2] = inode->i_generation;
if (parent) {
struct iso_inode_info *eparent;
eparent = ISOFS_I(parent);
fh32[3] = eparent->i_iget5_block;
fh16[3] = (__u16)eparent->i_iget5_offset; /* fh16 [sic] */
fh32[4] = parent->i_generation;
len = 5;
type = 2;
}
*max_len = len;
return type;
}
struct isofs_fid {
u32 block;
u16 offset;
u16 parent_offset;
u32 generation;
u32 parent_block;
u32 parent_generation;
};
static struct dentry *isofs_fh_to_dentry(struct super_block *sb,
struct fid *fid, int fh_len, int fh_type)
{
struct isofs_fid *ifid = (struct isofs_fid *)fid;
if (fh_len < 3 || fh_type > 2)
return NULL;
return isofs_export_iget(sb, ifid->block, ifid->offset,
ifid->generation);
}
static struct dentry *isofs_fh_to_parent(struct super_block *sb,
struct fid *fid, int fh_len, int fh_type)
{
struct isofs_fid *ifid = (struct isofs_fid *)fid;
if (fh_len < 2 || fh_type != 2)
return NULL;
return isofs_export_iget(sb,
fh_len > 2 ? ifid->parent_block : 0,
ifid->parent_offset,
fh_len > 4 ? ifid->parent_generation : 0);
}
const struct export_operations isofs_export_ops = {
.encode_fh = isofs_export_encode_fh,
.fh_to_dentry = isofs_fh_to_dentry,
.fh_to_parent = isofs_fh_to_parent,
.get_parent = isofs_export_get_parent,
};
bc746ed9b415c25e92'>d53fbdac9d0781e39a13b2ac6b2bd258cf3b4140 /net/ipv6/ip6_icmp.c
| parent | bf29bddf0417a4783da3b24e8c9e017ac649326f (diff) |
|---|
efi/fdt: Avoid FDT manipulation after ExitBootServices()
Some AArch64 UEFI implementations disable the MMU in ExitBootServices(),
after which unaligned accesses to RAM are no longer supported.
Commit:
abfb7b686a3e ("efi/libstub/arm*: Pass latest memory map to the kernel")
fixed an issue in the memory map handling of the stub FDT code, but
inadvertently created an issue with such firmware, by moving some
of the FDT manipulation to after the invocation of ExitBootServices().
Given that the stub's libfdt implementation uses the ordinary, accelerated
string functions, which rely on hardware handling of unaligned accesses,
manipulating the FDT with the MMU off may result in alignment faults.
So fix the situation by moving the update_fdt_memmap() call into the
callback function invoked by efi_exit_boot_services() right before it
calls the ExitBootServices() UEFI service (which is arguably a better
place for it anyway)
Note that disabling the MMU in ExitBootServices() is not compliant with
the UEFI spec, and carries great risk due to the fact that switching from
cached to uncached memory accesses halfway through compiler generated code
(i.e., involving a stack) can never be done in a way that is architecturally
safe.
Fixes: abfb7b686a3e ("efi/libstub/arm*: Pass latest memory map to the kernel")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Riku Voipio <riku.voipio@linaro.org>
Cc: <stable@vger.kernel.org>
Cc: mark.rutland@arm.com
Cc: linux-efi@vger.kernel.org
Cc: matt@codeblueprint.co.uk
Cc: leif.lindholm@linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1485971102-23330-2-git-send-email-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>