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linux/fs/ext2/ialloc.c
Eric Paris 2a7dba391e fs/vfs/security: pass last path component to LSM on inode creation 
SELinux would like to implement a new labeling behavior of newly created
inodes.  We currently label new inodes based on the parent and the creating
process.  This new behavior would also take into account the name of the
new object when deciding the new label.  This is not the (supposed) full path,
just the last component of the path.

This is very useful because creating /etc/shadow is different than creating
/etc/passwd but the kernel hooks are unable to differentiate these
operations.  We currently require that userspace realize it is doing some
difficult operation like that and than userspace jumps through SELinux hoops
to get things set up correctly.  This patch does not implement new
behavior, that is obviously contained in a seperate SELinux patch, but it
does pass the needed name down to the correct LSM hook.  If no such name
exists it is fine to pass NULL.

Signed-off-by: Eric Paris <eparis@redhat.com>
2011-02-01 11:12:29 -05:00

675 lines
18 KiB
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/*
* linux/fs/ext2/ialloc.c
*
* Copyright (C) 1992, 1993, 1994, 1995
* Remy Card (card@masi.ibp.fr)
* Laboratoire MASI - Institut Blaise Pascal
* Universite Pierre et Marie Curie (Paris VI)
*
* BSD ufs-inspired inode and directory allocation by
* Stephen Tweedie (sct@dcs.ed.ac.uk), 1993
* Big-endian to little-endian byte-swapping/bitmaps by
* David S. Miller (davem@caip.rutgers.edu), 1995
*/
#include <linux/quotaops.h>
#include <linux/sched.h>
#include <linux/backing-dev.h>
#include <linux/buffer_head.h>
#include <linux/random.h>
#include "ext2.h"
#include "xattr.h"
#include "acl.h"
/*
* ialloc.c contains the inodes allocation and deallocation routines
*/
/*
* The free inodes are managed by bitmaps. A file system contains several
* blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
* block for inodes, N blocks for the inode table and data blocks.
*
* The file system contains group descriptors which are located after the
* super block. Each descriptor contains the number of the bitmap block and
* the free blocks count in the block.
*/
/*
* Read the inode allocation bitmap for a given block_group, reading
* into the specified slot in the superblock's bitmap cache.
*
* Return buffer_head of bitmap on success or NULL.
*/
static struct buffer_head *
read_inode_bitmap(struct super_block * sb, unsigned long block_group)
{
struct ext2_group_desc *desc;
struct buffer_head *bh = NULL;
desc = ext2_get_group_desc(sb, block_group, NULL);
if (!desc)
goto error_out;
bh = sb_bread(sb, le32_to_cpu(desc->bg_inode_bitmap));
if (!bh)
ext2_error(sb, "read_inode_bitmap",
"Cannot read inode bitmap - "
"block_group = %lu, inode_bitmap = %u",
block_group, le32_to_cpu(desc->bg_inode_bitmap));
error_out:
return bh;
}
static void ext2_release_inode(struct super_block *sb, int group, int dir)
{
struct ext2_group_desc * desc;
struct buffer_head *bh;
desc = ext2_get_group_desc(sb, group, &bh);
if (!desc) {
ext2_error(sb, "ext2_release_inode",
"can't get descriptor for group %d", group);
return;
}
spin_lock(sb_bgl_lock(EXT2_SB(sb), group));
le16_add_cpu(&desc->bg_free_inodes_count, 1);
if (dir)
le16_add_cpu(&desc->bg_used_dirs_count, -1);
spin_unlock(sb_bgl_lock(EXT2_SB(sb), group));
if (dir)
percpu_counter_dec(&EXT2_SB(sb)->s_dirs_counter);
sb->s_dirt = 1;
mark_buffer_dirty(bh);
}
/*
* NOTE! When we get the inode, we're the only people
* that have access to it, and as such there are no
* race conditions we have to worry about. The inode
* is not on the hash-lists, and it cannot be reached
* through the filesystem because the directory entry
* has been deleted earlier.
*
* HOWEVER: we must make sure that we get no aliases,
* which means that we have to call "clear_inode()"
* _before_ we mark the inode not in use in the inode
* bitmaps. Otherwise a newly created file might use
* the same inode number (not actually the same pointer
* though), and then we'd have two inodes sharing the
* same inode number and space on the harddisk.
*/
void ext2_free_inode (struct inode * inode)
{
struct super_block * sb = inode->i_sb;
int is_directory;
unsigned long ino;
struct buffer_head *bitmap_bh;
unsigned long block_group;
unsigned long bit;
struct ext2_super_block * es;
ino = inode->i_ino;
ext2_debug ("freeing inode %lu\n", ino);
/*
* Note: we must free any quota before locking the superblock,
* as writing the quota to disk may need the lock as well.
*/
/* Quota is already initialized in iput() */
ext2_xattr_delete_inode(inode);
dquot_free_inode(inode);
dquot_drop(inode);
es = EXT2_SB(sb)->s_es;
is_directory = S_ISDIR(inode->i_mode);
if (ino < EXT2_FIRST_INO(sb) ||
ino > le32_to_cpu(es->s_inodes_count)) {
ext2_error (sb, "ext2_free_inode",
"reserved or nonexistent inode %lu", ino);
return;
}
block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb);
bit = (ino - 1) % EXT2_INODES_PER_GROUP(sb);
bitmap_bh = read_inode_bitmap(sb, block_group);
if (!bitmap_bh)
return;
/* Ok, now we can actually update the inode bitmaps.. */
if (!ext2_clear_bit_atomic(sb_bgl_lock(EXT2_SB(sb), block_group),
bit, (void *) bitmap_bh->b_data))
ext2_error (sb, "ext2_free_inode",
"bit already cleared for inode %lu", ino);
else
ext2_release_inode(sb, block_group, is_directory);
mark_buffer_dirty(bitmap_bh);
if (sb->s_flags & MS_SYNCHRONOUS)
sync_dirty_buffer(bitmap_bh);
brelse(bitmap_bh);
}
/*
* We perform asynchronous prereading of the new inode's inode block when
* we create the inode, in the expectation that the inode will be written
* back soon. There are two reasons:
*
* - When creating a large number of files, the async prereads will be
* nicely merged into large reads
* - When writing out a large number of inodes, we don't need to keep on
* stalling the writes while we read the inode block.
*
* FIXME: ext2_get_group_desc() needs to be simplified.
*/
static void ext2_preread_inode(struct inode *inode)
{
unsigned long block_group;
unsigned long offset;
unsigned long block;
struct ext2_group_desc * gdp;
struct backing_dev_info *bdi;
bdi = inode->i_mapping->backing_dev_info;
if (bdi_read_congested(bdi))
return;
if (bdi_write_congested(bdi))
return;
block_group = (inode->i_ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);
gdp = ext2_get_group_desc(inode->i_sb, block_group, NULL);
if (gdp == NULL)
return;
/*
* Figure out the offset within the block group inode table
*/
offset = ((inode->i_ino - 1) % EXT2_INODES_PER_GROUP(inode->i_sb)) *
EXT2_INODE_SIZE(inode->i_sb);
block = le32_to_cpu(gdp->bg_inode_table) +
(offset >> EXT2_BLOCK_SIZE_BITS(inode->i_sb));
sb_breadahead(inode->i_sb, block);
}
/*
* There are two policies for allocating an inode. If the new inode is
* a directory, then a forward search is made for a block group with both
* free space and a low directory-to-inode ratio; if that fails, then of
* the groups with above-average free space, that group with the fewest
* directories already is chosen.
*
* For other inodes, search forward from the parent directory\'s block
* group to find a free inode.
*/
static int find_group_dir(struct super_block *sb, struct inode *parent)
{
int ngroups = EXT2_SB(sb)->s_groups_count;
int avefreei = ext2_count_free_inodes(sb) / ngroups;
struct ext2_group_desc *desc, *best_desc = NULL;
int group, best_group = -1;
for (group = 0; group < ngroups; group++) {
desc = ext2_get_group_desc (sb, group, NULL);
if (!desc || !desc->bg_free_inodes_count)
continue;
if (le16_to_cpu(desc->bg_free_inodes_count) < avefreei)
continue;
if (!best_desc ||
(le16_to_cpu(desc->bg_free_blocks_count) >
le16_to_cpu(best_desc->bg_free_blocks_count))) {
best_group = group;
best_desc = desc;
}
}
if (!best_desc)
return -1;
return best_group;
}
/*
* Orlov's allocator for directories.
*
* We always try to spread first-level directories.
*
* If there are blockgroups with both free inodes and free blocks counts
* not worse than average we return one with smallest directory count.
* Otherwise we simply return a random group.
*
* For the rest rules look so:
*
* It's OK to put directory into a group unless
* it has too many directories already (max_dirs) or
* it has too few free inodes left (min_inodes) or
* it has too few free blocks left (min_blocks) or
* it's already running too large debt (max_debt).
* Parent's group is preferred, if it doesn't satisfy these
* conditions we search cyclically through the rest. If none
* of the groups look good we just look for a group with more
* free inodes than average (starting at parent's group).
*
* Debt is incremented each time we allocate a directory and decremented
* when we allocate an inode, within 0--255.
*/
#define INODE_COST 64
#define BLOCK_COST 256
static int find_group_orlov(struct super_block *sb, struct inode *parent)
{
int parent_group = EXT2_I(parent)->i_block_group;
struct ext2_sb_info *sbi = EXT2_SB(sb);
struct ext2_super_block *es = sbi->s_es;
int ngroups = sbi->s_groups_count;
int inodes_per_group = EXT2_INODES_PER_GROUP(sb);
int freei;
int avefreei;
int free_blocks;
int avefreeb;
int blocks_per_dir;
int ndirs;
int max_debt, max_dirs, min_blocks, min_inodes;
int group = -1, i;
struct ext2_group_desc *desc;
freei = percpu_counter_read_positive(&sbi->s_freeinodes_counter);
avefreei = freei / ngroups;
free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
avefreeb = free_blocks / ngroups;
ndirs = percpu_counter_read_positive(&sbi->s_dirs_counter);
if ((parent == sb->s_root->d_inode) ||
(EXT2_I(parent)->i_flags & EXT2_TOPDIR_FL)) {
struct ext2_group_desc *best_desc = NULL;
int best_ndir = inodes_per_group;
int best_group = -1;
get_random_bytes(&group, sizeof(group));
parent_group = (unsigned)group % ngroups;
for (i = 0; i < ngroups; i++) {
group = (parent_group + i) % ngroups;
desc = ext2_get_group_desc (sb, group, NULL);
if (!desc || !desc->bg_free_inodes_count)
continue;
if (le16_to_cpu(desc->bg_used_dirs_count) >= best_ndir)
continue;
if (le16_to_cpu(desc->bg_free_inodes_count) < avefreei)
continue;
if (le16_to_cpu(desc->bg_free_blocks_count) < avefreeb)
continue;
best_group = group;
best_ndir = le16_to_cpu(desc->bg_used_dirs_count);
best_desc = desc;
}
if (best_group >= 0) {
desc = best_desc;
group = best_group;
goto found;
}
goto fallback;
}
if (ndirs == 0)
ndirs = 1; /* percpu_counters are approximate... */
blocks_per_dir = (le32_to_cpu(es->s_blocks_count)-free_blocks) / ndirs;
max_dirs = ndirs / ngroups + inodes_per_group / 16;
min_inodes = avefreei - inodes_per_group / 4;
min_blocks = avefreeb - EXT2_BLOCKS_PER_GROUP(sb) / 4;
max_debt = EXT2_BLOCKS_PER_GROUP(sb) / max(blocks_per_dir, BLOCK_COST);
if (max_debt * INODE_COST > inodes_per_group)
max_debt = inodes_per_group / INODE_COST;
if (max_debt > 255)
max_debt = 255;
if (max_debt == 0)
max_debt = 1;
for (i = 0; i < ngroups; i++) {
group = (parent_group + i) % ngroups;
desc = ext2_get_group_desc (sb, group, NULL);
if (!desc || !desc->bg_free_inodes_count)
continue;
if (sbi->s_debts[group] >= max_debt)
continue;
if (le16_to_cpu(desc->bg_used_dirs_count) >= max_dirs)
continue;
if (le16_to_cpu(desc->bg_free_inodes_count) < min_inodes)
continue;
if (le16_to_cpu(desc->bg_free_blocks_count) < min_blocks)
continue;
goto found;
}
fallback:
for (i = 0; i < ngroups; i++) {
group = (parent_group + i) % ngroups;
desc = ext2_get_group_desc (sb, group, NULL);
if (!desc || !desc->bg_free_inodes_count)
continue;
if (le16_to_cpu(desc->bg_free_inodes_count) >= avefreei)
goto found;
}
if (avefreei) {
/*
* The free-inodes counter is approximate, and for really small
* filesystems the above test can fail to find any blockgroups
*/
avefreei = 0;
goto fallback;
}
return -1;
found:
return group;
}
static int find_group_other(struct super_block *sb, struct inode *parent)
{
int parent_group = EXT2_I(parent)->i_block_group;
int ngroups = EXT2_SB(sb)->s_groups_count;
struct ext2_group_desc *desc;
int group, i;
/*
* Try to place the inode in its parent directory
*/
group = parent_group;
desc = ext2_get_group_desc (sb, group, NULL);
if (desc && le16_to_cpu(desc->bg_free_inodes_count) &&
le16_to_cpu(desc->bg_free_blocks_count))
goto found;
/*
* We're going to place this inode in a different blockgroup from its
* parent. We want to cause files in a common directory to all land in
* the same blockgroup. But we want files which are in a different
* directory which shares a blockgroup with our parent to land in a
* different blockgroup.
*
* So add our directory's i_ino into the starting point for the hash.
*/
group = (group + parent->i_ino) % ngroups;
/*
* Use a quadratic hash to find a group with a free inode and some
* free blocks.
*/
for (i = 1; i < ngroups; i <<= 1) {
group += i;
if (group >= ngroups)
group -= ngroups;
desc = ext2_get_group_desc (sb, group, NULL);
if (desc && le16_to_cpu(desc->bg_free_inodes_count) &&
le16_to_cpu(desc->bg_free_blocks_count))
goto found;
}
/*
* That failed: try linear search for a free inode, even if that group
* has no free blocks.
*/
group = parent_group;
for (i = 0; i < ngroups; i++) {
if (++group >= ngroups)
group = 0;
desc = ext2_get_group_desc (sb, group, NULL);
if (desc && le16_to_cpu(desc->bg_free_inodes_count))
goto found;
}
return -1;
found:
return group;
}
struct inode *ext2_new_inode(struct inode *dir, int mode,
const struct qstr *qstr)
{
struct super_block *sb;
struct buffer_head *bitmap_bh = NULL;
struct buffer_head *bh2;
int group, i;
ino_t ino = 0;
struct inode * inode;
struct ext2_group_desc *gdp;
struct ext2_super_block *es;
struct ext2_inode_info *ei;
struct ext2_sb_info *sbi;
int err;
sb = dir->i_sb;
inode = new_inode(sb);
if (!inode)
return ERR_PTR(-ENOMEM);
ei = EXT2_I(inode);
sbi = EXT2_SB(sb);
es = sbi->s_es;
if (S_ISDIR(mode)) {
if (test_opt(sb, OLDALLOC))
group = find_group_dir(sb, dir);
else
group = find_group_orlov(sb, dir);
} else
group = find_group_other(sb, dir);
if (group == -1) {
err = -ENOSPC;
goto fail;
}
for (i = 0; i < sbi->s_groups_count; i++) {
gdp = ext2_get_group_desc(sb, group, &bh2);
brelse(bitmap_bh);
bitmap_bh = read_inode_bitmap(sb, group);
if (!bitmap_bh) {
err = -EIO;
goto fail;
}
ino = 0;
repeat_in_this_group:
ino = ext2_find_next_zero_bit((unsigned long *)bitmap_bh->b_data,
EXT2_INODES_PER_GROUP(sb), ino);
if (ino >= EXT2_INODES_PER_GROUP(sb)) {
/*
* Rare race: find_group_xx() decided that there were
* free inodes in this group, but by the time we tried
* to allocate one, they're all gone. This can also
* occur because the counters which find_group_orlov()
* uses are approximate. So just go and search the
* next block group.
*/
if (++group == sbi->s_groups_count)
group = 0;
continue;
}
if (ext2_set_bit_atomic(sb_bgl_lock(sbi, group),
ino, bitmap_bh->b_data)) {
/* we lost this inode */
if (++ino >= EXT2_INODES_PER_GROUP(sb)) {
/* this group is exhausted, try next group */
if (++group == sbi->s_groups_count)
group = 0;
continue;
}
/* try to find free inode in the same group */
goto repeat_in_this_group;
}
goto got;
}
/*
* Scanned all blockgroups.
*/
err = -ENOSPC;
goto fail;
got:
mark_buffer_dirty(bitmap_bh);
if (sb->s_flags & MS_SYNCHRONOUS)
sync_dirty_buffer(bitmap_bh);
brelse(bitmap_bh);
ino += group * EXT2_INODES_PER_GROUP(sb) + 1;
if (ino < EXT2_FIRST_INO(sb) || ino > le32_to_cpu(es->s_inodes_count)) {
ext2_error (sb, "ext2_new_inode",
"reserved inode or inode > inodes count - "
"block_group = %d,inode=%lu", group,
(unsigned long) ino);
err = -EIO;
goto fail;
}
percpu_counter_add(&sbi->s_freeinodes_counter, -1);
if (S_ISDIR(mode))
percpu_counter_inc(&sbi->s_dirs_counter);
spin_lock(sb_bgl_lock(sbi, group));
le16_add_cpu(&gdp->bg_free_inodes_count, -1);
if (S_ISDIR(mode)) {
if (sbi->s_debts[group] < 255)
sbi->s_debts[group]++;
le16_add_cpu(&gdp->bg_used_dirs_count, 1);
} else {
if (sbi->s_debts[group])
sbi->s_debts[group]--;
}
spin_unlock(sb_bgl_lock(sbi, group));
sb->s_dirt = 1;
mark_buffer_dirty(bh2);
if (test_opt(sb, GRPID)) {
inode->i_mode = mode;
inode->i_uid = current_fsuid();
inode->i_gid = dir->i_gid;
} else
inode_init_owner(inode, dir, mode);
inode->i_ino = ino;
inode->i_blocks = 0;
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
memset(ei->i_data, 0, sizeof(ei->i_data));
ei->i_flags =
ext2_mask_flags(mode, EXT2_I(dir)->i_flags & EXT2_FL_INHERITED);
ei->i_faddr = 0;
ei->i_frag_no = 0;
ei->i_frag_size = 0;
ei->i_file_acl = 0;
ei->i_dir_acl = 0;
ei->i_dtime = 0;
ei->i_block_alloc_info = NULL;
ei->i_block_group = group;
ei->i_dir_start_lookup = 0;
ei->i_state = EXT2_STATE_NEW;
ext2_set_inode_flags(inode);
spin_lock(&sbi->s_next_gen_lock);
inode->i_generation = sbi->s_next_generation++;
spin_unlock(&sbi->s_next_gen_lock);
if (insert_inode_locked(inode) < 0) {
err = -EINVAL;
goto fail_drop;
}
dquot_initialize(inode);
err = dquot_alloc_inode(inode);
if (err)
goto fail_drop;
err = ext2_init_acl(inode, dir);
if (err)
goto fail_free_drop;
err = ext2_init_security(inode, dir, qstr);
if (err)
goto fail_free_drop;
mark_inode_dirty(inode);
ext2_debug("allocating inode %lu\n", inode->i_ino);
ext2_preread_inode(inode);
return inode;
fail_free_drop:
dquot_free_inode(inode);
fail_drop:
dquot_drop(inode);
inode->i_flags |= S_NOQUOTA;
inode->i_nlink = 0;
unlock_new_inode(inode);
iput(inode);
return ERR_PTR(err);
fail:
make_bad_inode(inode);
iput(inode);
return ERR_PTR(err);
}
unsigned long ext2_count_free_inodes (struct super_block * sb)
{
struct ext2_group_desc *desc;
unsigned long desc_count = 0;
int i;
#ifdef EXT2FS_DEBUG
struct ext2_super_block *es;
unsigned long bitmap_count = 0;
struct buffer_head *bitmap_bh = NULL;
es = EXT2_SB(sb)->s_es;
for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
unsigned x;
desc = ext2_get_group_desc (sb, i, NULL);
if (!desc)
continue;
desc_count += le16_to_cpu(desc->bg_free_inodes_count);
brelse(bitmap_bh);
bitmap_bh = read_inode_bitmap(sb, i);
if (!bitmap_bh)
continue;
x = ext2_count_free(bitmap_bh, EXT2_INODES_PER_GROUP(sb) / 8);
printk("group %d: stored = %d, counted = %u\n",
i, le16_to_cpu(desc->bg_free_inodes_count), x);
bitmap_count += x;
}
brelse(bitmap_bh);
printk("ext2_count_free_inodes: stored = %lu, computed = %lu, %lu\n",
percpu_counter_read(&EXT2_SB(sb)->s_freeinodes_counter),
desc_count, bitmap_count);
return desc_count;
#else
for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
desc = ext2_get_group_desc (sb, i, NULL);
if (!desc)
continue;
desc_count += le16_to_cpu(desc->bg_free_inodes_count);
}
return desc_count;
#endif
}
/* Called at mount-time, super-block is locked */
unsigned long ext2_count_dirs (struct super_block * sb)
{
unsigned long count = 0;
int i;
for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
struct ext2_group_desc *gdp = ext2_get_group_desc (sb, i, NULL);
if (!gdp)
continue;
count += le16_to_cpu(gdp->bg_used_dirs_count);
}
return count;
}
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