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21cb47be6f
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>
236 lines
5.8 KiB
C
236 lines
5.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* linux/fs/sysv/ialloc.c
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*
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* minix/bitmap.c
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* ext/freelists.c
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* Copyright (C) 1992 Remy Card (card@masi.ibp.fr)
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*
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* xenix/alloc.c
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* Copyright (C) 1992 Doug Evans
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*
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* coh/alloc.c
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* Copyright (C) 1993 Pascal Haible, Bruno Haible
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*
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* sysv/ialloc.c
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* Copyright (C) 1993 Bruno Haible
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*
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* This file contains code for allocating/freeing inodes.
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*/
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#include <linux/kernel.h>
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#include <linux/stddef.h>
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#include <linux/sched.h>
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#include <linux/stat.h>
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#include <linux/string.h>
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#include <linux/buffer_head.h>
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#include <linux/writeback.h>
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#include "sysv.h"
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/* We don't trust the value of
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sb->sv_sbd2->s_tinode = *sb->sv_sb_total_free_inodes
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but we nevertheless keep it up to date. */
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/* An inode on disk is considered free if both i_mode == 0 and i_nlink == 0. */
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/* return &sb->sv_sb_fic_inodes[i] = &sbd->s_inode[i]; */
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static inline sysv_ino_t *
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sv_sb_fic_inode(struct super_block * sb, unsigned int i)
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{
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struct sysv_sb_info *sbi = SYSV_SB(sb);
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if (sbi->s_bh1 == sbi->s_bh2)
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return &sbi->s_sb_fic_inodes[i];
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else {
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/* 512 byte Xenix FS */
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unsigned int offset = offsetof(struct xenix_super_block, s_inode[i]);
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if (offset < 512)
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return (sysv_ino_t*)(sbi->s_sbd1 + offset);
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else
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return (sysv_ino_t*)(sbi->s_sbd2 + offset);
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}
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}
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struct sysv_inode *
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sysv_raw_inode(struct super_block *sb, unsigned ino, struct buffer_head **bh)
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{
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struct sysv_sb_info *sbi = SYSV_SB(sb);
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struct sysv_inode *res;
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int block = sbi->s_firstinodezone + sbi->s_block_base;
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block += (ino-1) >> sbi->s_inodes_per_block_bits;
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*bh = sb_bread(sb, block);
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if (!*bh)
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return NULL;
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res = (struct sysv_inode *)(*bh)->b_data;
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return res + ((ino-1) & sbi->s_inodes_per_block_1);
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}
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static int refill_free_cache(struct super_block *sb)
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{
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struct sysv_sb_info *sbi = SYSV_SB(sb);
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struct buffer_head * bh;
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struct sysv_inode * raw_inode;
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int i = 0, ino;
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ino = SYSV_ROOT_INO+1;
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raw_inode = sysv_raw_inode(sb, ino, &bh);
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if (!raw_inode)
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goto out;
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while (ino <= sbi->s_ninodes) {
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if (raw_inode->i_mode == 0 && raw_inode->i_nlink == 0) {
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*sv_sb_fic_inode(sb,i++) = cpu_to_fs16(SYSV_SB(sb), ino);
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if (i == sbi->s_fic_size)
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break;
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}
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if ((ino++ & sbi->s_inodes_per_block_1) == 0) {
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brelse(bh);
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raw_inode = sysv_raw_inode(sb, ino, &bh);
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if (!raw_inode)
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goto out;
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} else
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raw_inode++;
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}
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brelse(bh);
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out:
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return i;
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}
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void sysv_free_inode(struct inode * inode)
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{
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struct super_block *sb = inode->i_sb;
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struct sysv_sb_info *sbi = SYSV_SB(sb);
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unsigned int ino;
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struct buffer_head * bh;
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struct sysv_inode * raw_inode;
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unsigned count;
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sb = inode->i_sb;
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ino = inode->i_ino;
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if (ino <= SYSV_ROOT_INO || ino > sbi->s_ninodes) {
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printk("sysv_free_inode: inode 0,1,2 or nonexistent inode\n");
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return;
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}
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raw_inode = sysv_raw_inode(sb, ino, &bh);
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if (!raw_inode) {
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printk("sysv_free_inode: unable to read inode block on device "
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"%s\n", inode->i_sb->s_id);
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return;
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}
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mutex_lock(&sbi->s_lock);
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count = fs16_to_cpu(sbi, *sbi->s_sb_fic_count);
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if (count < sbi->s_fic_size) {
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*sv_sb_fic_inode(sb,count++) = cpu_to_fs16(sbi, ino);
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*sbi->s_sb_fic_count = cpu_to_fs16(sbi, count);
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}
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fs16_add(sbi, sbi->s_sb_total_free_inodes, 1);
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dirty_sb(sb);
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memset(raw_inode, 0, sizeof(struct sysv_inode));
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mark_buffer_dirty(bh);
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mutex_unlock(&sbi->s_lock);
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brelse(bh);
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}
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struct inode * sysv_new_inode(const struct inode * dir, umode_t mode)
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{
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struct super_block *sb = dir->i_sb;
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struct sysv_sb_info *sbi = SYSV_SB(sb);
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struct inode *inode;
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sysv_ino_t ino;
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unsigned count;
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struct writeback_control wbc = {
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.sync_mode = WB_SYNC_NONE
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};
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inode = new_inode(sb);
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if (!inode)
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return ERR_PTR(-ENOMEM);
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mutex_lock(&sbi->s_lock);
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count = fs16_to_cpu(sbi, *sbi->s_sb_fic_count);
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if (count == 0 || (*sv_sb_fic_inode(sb,count-1) == 0)) {
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count = refill_free_cache(sb);
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if (count == 0) {
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iput(inode);
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mutex_unlock(&sbi->s_lock);
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return ERR_PTR(-ENOSPC);
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}
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}
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/* Now count > 0. */
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ino = *sv_sb_fic_inode(sb,--count);
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*sbi->s_sb_fic_count = cpu_to_fs16(sbi, count);
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fs16_add(sbi, sbi->s_sb_total_free_inodes, -1);
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dirty_sb(sb);
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inode_init_owner(&init_user_ns, inode, dir, mode);
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inode->i_ino = fs16_to_cpu(sbi, ino);
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inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
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inode->i_blocks = 0;
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memset(SYSV_I(inode)->i_data, 0, sizeof(SYSV_I(inode)->i_data));
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SYSV_I(inode)->i_dir_start_lookup = 0;
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insert_inode_hash(inode);
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mark_inode_dirty(inode);
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sysv_write_inode(inode, &wbc); /* ensure inode not allocated again */
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mark_inode_dirty(inode); /* cleared by sysv_write_inode() */
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/* That's it. */
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mutex_unlock(&sbi->s_lock);
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return inode;
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}
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unsigned long sysv_count_free_inodes(struct super_block * sb)
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{
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struct sysv_sb_info *sbi = SYSV_SB(sb);
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struct buffer_head * bh;
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struct sysv_inode * raw_inode;
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int ino, count, sb_count;
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mutex_lock(&sbi->s_lock);
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sb_count = fs16_to_cpu(sbi, *sbi->s_sb_total_free_inodes);
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if (0)
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goto trust_sb;
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/* this causes a lot of disk traffic ... */
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count = 0;
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ino = SYSV_ROOT_INO+1;
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raw_inode = sysv_raw_inode(sb, ino, &bh);
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if (!raw_inode)
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goto Eio;
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while (ino <= sbi->s_ninodes) {
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if (raw_inode->i_mode == 0 && raw_inode->i_nlink == 0)
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count++;
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if ((ino++ & sbi->s_inodes_per_block_1) == 0) {
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brelse(bh);
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raw_inode = sysv_raw_inode(sb, ino, &bh);
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if (!raw_inode)
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goto Eio;
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} else
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raw_inode++;
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}
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brelse(bh);
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if (count != sb_count)
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goto Einval;
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out:
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mutex_unlock(&sbi->s_lock);
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return count;
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Einval:
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printk("sysv_count_free_inodes: "
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"free inode count was %d, correcting to %d\n",
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sb_count, count);
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if (!sb_rdonly(sb)) {
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*sbi->s_sb_total_free_inodes = cpu_to_fs16(SYSV_SB(sb), count);
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dirty_sb(sb);
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}
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goto out;
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Eio:
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printk("sysv_count_free_inodes: unable to read inode table\n");
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trust_sb:
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count = sb_count;
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goto out;
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}
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