linux/fs/minix/bitmap.c
Christian Brauner 21cb47be6f
inode: make init and permission helpers idmapped mount aware
The inode_owner_or_capable() helper determines whether the caller is the
owner of the inode or is capable with respect to that inode. Allow it to
handle idmapped mounts. If the inode is accessed through an idmapped
mount it according to the mount's user namespace. Afterwards the checks
are identical to non-idmapped mounts. If the initial user namespace is
passed nothing changes so non-idmapped mounts will see identical
behavior as before.

Similarly, allow the inode_init_owner() helper to handle idmapped
mounts. It initializes a new inode on idmapped mounts by mapping the
fsuid and fsgid of the caller from the mount's user namespace. If the
initial user namespace is passed nothing changes so non-idmapped mounts
will see identical behavior as before.

Link: https://lore.kernel.org/r/20210121131959.646623-7-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2021-01-24 14:27:16 +01:00

274 lines
6.7 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/minix/bitmap.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
/*
* Modified for 680x0 by Hamish Macdonald
* Fixed for 680x0 by Andreas Schwab
*/
/* bitmap.c contains the code that handles the inode and block bitmaps */
#include "minix.h"
#include <linux/buffer_head.h>
#include <linux/bitops.h>
#include <linux/sched.h>
static DEFINE_SPINLOCK(bitmap_lock);
/*
* bitmap consists of blocks filled with 16bit words
* bit set == busy, bit clear == free
* endianness is a mess, but for counting zero bits it really doesn't matter...
*/
static __u32 count_free(struct buffer_head *map[], unsigned blocksize, __u32 numbits)
{
__u32 sum = 0;
unsigned blocks = DIV_ROUND_UP(numbits, blocksize * 8);
while (blocks--) {
unsigned words = blocksize / 2;
__u16 *p = (__u16 *)(*map++)->b_data;
while (words--)
sum += 16 - hweight16(*p++);
}
return sum;
}
void minix_free_block(struct inode *inode, unsigned long block)
{
struct super_block *sb = inode->i_sb;
struct minix_sb_info *sbi = minix_sb(sb);
struct buffer_head *bh;
int k = sb->s_blocksize_bits + 3;
unsigned long bit, zone;
if (block < sbi->s_firstdatazone || block >= sbi->s_nzones) {
printk("Trying to free block not in datazone\n");
return;
}
zone = block - sbi->s_firstdatazone + 1;
bit = zone & ((1<<k) - 1);
zone >>= k;
if (zone >= sbi->s_zmap_blocks) {
printk("minix_free_block: nonexistent bitmap buffer\n");
return;
}
bh = sbi->s_zmap[zone];
spin_lock(&bitmap_lock);
if (!minix_test_and_clear_bit(bit, bh->b_data))
printk("minix_free_block (%s:%lu): bit already cleared\n",
sb->s_id, block);
spin_unlock(&bitmap_lock);
mark_buffer_dirty(bh);
return;
}
int minix_new_block(struct inode * inode)
{
struct minix_sb_info *sbi = minix_sb(inode->i_sb);
int bits_per_zone = 8 * inode->i_sb->s_blocksize;
int i;
for (i = 0; i < sbi->s_zmap_blocks; i++) {
struct buffer_head *bh = sbi->s_zmap[i];
int j;
spin_lock(&bitmap_lock);
j = minix_find_first_zero_bit(bh->b_data, bits_per_zone);
if (j < bits_per_zone) {
minix_set_bit(j, bh->b_data);
spin_unlock(&bitmap_lock);
mark_buffer_dirty(bh);
j += i * bits_per_zone + sbi->s_firstdatazone-1;
if (j < sbi->s_firstdatazone || j >= sbi->s_nzones)
break;
return j;
}
spin_unlock(&bitmap_lock);
}
return 0;
}
unsigned long minix_count_free_blocks(struct super_block *sb)
{
struct minix_sb_info *sbi = minix_sb(sb);
u32 bits = sbi->s_nzones - sbi->s_firstdatazone + 1;
return (count_free(sbi->s_zmap, sb->s_blocksize, bits)
<< sbi->s_log_zone_size);
}
struct minix_inode *
minix_V1_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
{
int block;
struct minix_sb_info *sbi = minix_sb(sb);
struct minix_inode *p;
if (!ino || ino > sbi->s_ninodes) {
printk("Bad inode number on dev %s: %ld is out of range\n",
sb->s_id, (long)ino);
return NULL;
}
ino--;
block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
ino / MINIX_INODES_PER_BLOCK;
*bh = sb_bread(sb, block);
if (!*bh) {
printk("Unable to read inode block\n");
return NULL;
}
p = (void *)(*bh)->b_data;
return p + ino % MINIX_INODES_PER_BLOCK;
}
struct minix2_inode *
minix_V2_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
{
int block;
struct minix_sb_info *sbi = minix_sb(sb);
struct minix2_inode *p;
int minix2_inodes_per_block = sb->s_blocksize / sizeof(struct minix2_inode);
*bh = NULL;
if (!ino || ino > sbi->s_ninodes) {
printk("Bad inode number on dev %s: %ld is out of range\n",
sb->s_id, (long)ino);
return NULL;
}
ino--;
block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
ino / minix2_inodes_per_block;
*bh = sb_bread(sb, block);
if (!*bh) {
printk("Unable to read inode block\n");
return NULL;
}
p = (void *)(*bh)->b_data;
return p + ino % minix2_inodes_per_block;
}
/* Clear the link count and mode of a deleted inode on disk. */
static void minix_clear_inode(struct inode *inode)
{
struct buffer_head *bh = NULL;
if (INODE_VERSION(inode) == MINIX_V1) {
struct minix_inode *raw_inode;
raw_inode = minix_V1_raw_inode(inode->i_sb, inode->i_ino, &bh);
if (raw_inode) {
raw_inode->i_nlinks = 0;
raw_inode->i_mode = 0;
}
} else {
struct minix2_inode *raw_inode;
raw_inode = minix_V2_raw_inode(inode->i_sb, inode->i_ino, &bh);
if (raw_inode) {
raw_inode->i_nlinks = 0;
raw_inode->i_mode = 0;
}
}
if (bh) {
mark_buffer_dirty(bh);
brelse (bh);
}
}
void minix_free_inode(struct inode * inode)
{
struct super_block *sb = inode->i_sb;
struct minix_sb_info *sbi = minix_sb(inode->i_sb);
struct buffer_head *bh;
int k = sb->s_blocksize_bits + 3;
unsigned long ino, bit;
ino = inode->i_ino;
if (ino < 1 || ino > sbi->s_ninodes) {
printk("minix_free_inode: inode 0 or nonexistent inode\n");
return;
}
bit = ino & ((1<<k) - 1);
ino >>= k;
if (ino >= sbi->s_imap_blocks) {
printk("minix_free_inode: nonexistent imap in superblock\n");
return;
}
minix_clear_inode(inode); /* clear on-disk copy */
bh = sbi->s_imap[ino];
spin_lock(&bitmap_lock);
if (!minix_test_and_clear_bit(bit, bh->b_data))
printk("minix_free_inode: bit %lu already cleared\n", bit);
spin_unlock(&bitmap_lock);
mark_buffer_dirty(bh);
}
struct inode *minix_new_inode(const struct inode *dir, umode_t mode, int *error)
{
struct super_block *sb = dir->i_sb;
struct minix_sb_info *sbi = minix_sb(sb);
struct inode *inode = new_inode(sb);
struct buffer_head * bh;
int bits_per_zone = 8 * sb->s_blocksize;
unsigned long j;
int i;
if (!inode) {
*error = -ENOMEM;
return NULL;
}
j = bits_per_zone;
bh = NULL;
*error = -ENOSPC;
spin_lock(&bitmap_lock);
for (i = 0; i < sbi->s_imap_blocks; i++) {
bh = sbi->s_imap[i];
j = minix_find_first_zero_bit(bh->b_data, bits_per_zone);
if (j < bits_per_zone)
break;
}
if (!bh || j >= bits_per_zone) {
spin_unlock(&bitmap_lock);
iput(inode);
return NULL;
}
if (minix_test_and_set_bit(j, bh->b_data)) { /* shouldn't happen */
spin_unlock(&bitmap_lock);
printk("minix_new_inode: bit already set\n");
iput(inode);
return NULL;
}
spin_unlock(&bitmap_lock);
mark_buffer_dirty(bh);
j += i * bits_per_zone;
if (!j || j > sbi->s_ninodes) {
iput(inode);
return NULL;
}
inode_init_owner(&init_user_ns, inode, dir, mode);
inode->i_ino = j;
inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
inode->i_blocks = 0;
memset(&minix_i(inode)->u, 0, sizeof(minix_i(inode)->u));
insert_inode_hash(inode);
mark_inode_dirty(inode);
*error = 0;
return inode;
}
unsigned long minix_count_free_inodes(struct super_block *sb)
{
struct minix_sb_info *sbi = minix_sb(sb);
u32 bits = sbi->s_ninodes + 1;
return count_free(sbi->s_imap, sb->s_blocksize, bits);
}