From 393d1d1d76933886d5e1ce603214c9987589c6d5 Mon Sep 17 00:00:00 2001 From: "Dr. Tilmann Bubeck" Date: Mon, 8 Apr 2013 12:54:05 -0400 Subject: [PATCH] ext4: implementation of a new ioctl called EXT4_IOC_SWAP_BOOT Add a new ioctl, EXT4_IOC_SWAP_BOOT which swaps i_blocks and associated attributes (like i_blocks, i_size, i_flags, ...) from the specified inode with inode EXT4_BOOT_LOADER_INO (#5). This is typically used to store a boot loader in a secure part of the filesystem, where it can't be changed by a normal user by accident. The data blocks of the previous boot loader will be associated with the given inode. This usercode program is a simple example of the usage: int main(int argc, char *argv[]) { int fd; int err; if ( argc != 2 ) { printf("usage: ext4-swap-boot-inode FILE-TO-SWAP\n"); exit(1); } fd = open(argv[1], O_WRONLY); if ( fd < 0 ) { perror("open"); exit(1); } err = ioctl(fd, EXT4_IOC_SWAP_BOOT); if ( err < 0 ) { perror("ioctl"); exit(1); } close(fd); exit(0); } [ Modified by Theodore Ts'o to fix a number of bugs in the original code.] Signed-off-by: Dr. Tilmann Bubeck Signed-off-by: "Theodore Ts'o" --- Documentation/filesystems/ext4.txt | 10 ++ fs/ext4/ext4.h | 8 ++ fs/ext4/inode.c | 11 +- fs/ext4/ioctl.c | 197 +++++++++++++++++++++++++++++ fs/ext4/move_extent.c | 48 +++---- 5 files changed, 248 insertions(+), 26 deletions(-) diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt index 34ea4f1fa6ea..5dd957d8b25b 100644 --- a/Documentation/filesystems/ext4.txt +++ b/Documentation/filesystems/ext4.txt @@ -587,6 +587,16 @@ Table of Ext4 specific ioctls bitmaps and inode table, the userspace tool thus just passes the new number of blocks. +EXT4_IOC_SWAP_BOOT Swap i_blocks and associated attributes + (like i_blocks, i_size, i_flags, ...) from + the specified inode with inode + EXT4_BOOT_LOADER_INO (#5). This is typically + used to store a boot loader in a secure part of + the filesystem, where it can't be changed by a + normal user by accident. + The data blocks of the previous boot loader + will be associated with the given inode. + .............................................................................. References diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index a0637e5057ae..d91871570982 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -616,6 +616,7 @@ enum { #define EXT4_IOC_ALLOC_DA_BLKS _IO('f', 12) #define EXT4_IOC_MOVE_EXT _IOWR('f', 15, struct move_extent) #define EXT4_IOC_RESIZE_FS _IOW('f', 16, __u64) +#define EXT4_IOC_SWAP_BOOT _IO('f', 17) #if defined(__KERNEL__) && defined(CONFIG_COMPAT) /* @@ -1341,6 +1342,7 @@ static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino) return ino == EXT4_ROOT_INO || ino == EXT4_USR_QUOTA_INO || ino == EXT4_GRP_QUOTA_INO || + ino == EXT4_BOOT_LOADER_INO || ino == EXT4_JOURNAL_INO || ino == EXT4_RESIZE_INO || (ino >= EXT4_FIRST_INO(sb) && @@ -2624,6 +2626,12 @@ extern int ext4_ind_migrate(struct inode *inode); /* move_extent.c */ +extern void ext4_double_down_write_data_sem(struct inode *first, + struct inode *second); +extern void ext4_double_up_write_data_sem(struct inode *orig_inode, + struct inode *donor_inode); +void ext4_inode_double_lock(struct inode *inode1, struct inode *inode2); +void ext4_inode_double_unlock(struct inode *inode1, struct inode *inode2); extern int ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 start_orig, __u64 start_donor, __u64 len, __u64 *moved_len); diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 769c656ea3b1..a29bfc2142ef 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4191,8 +4191,9 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino) * NeilBrown 1999oct15 */ if (inode->i_nlink == 0) { - if (inode->i_mode == 0 || - !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) { + if ((inode->i_mode == 0 || + !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) && + ino != EXT4_BOOT_LOADER_INO) { /* this inode is deleted */ ret = -ESTALE; goto bad_inode; @@ -4200,7 +4201,9 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino) /* The only unlinked inodes we let through here have * valid i_mode and are being read by the orphan * recovery code: that's fine, we're about to complete - * the process of deleting those. */ + * the process of deleting those. + * OR it is the EXT4_BOOT_LOADER_INO which is + * not initialized on a new filesystem. */ } ei->i_flags = le32_to_cpu(raw_inode->i_flags); inode->i_blocks = ext4_inode_blocks(raw_inode, ei); @@ -4320,6 +4323,8 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino) else init_special_inode(inode, inode->i_mode, new_decode_dev(le32_to_cpu(raw_inode->i_block[1]))); + } else if (ino == EXT4_BOOT_LOADER_INO) { + make_bad_inode(inode); } else { ret = -EIO; EXT4_ERROR_INODE(inode, "bogus i_mode (%o)", inode->i_mode); diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c index a07b7bc0856a..cbc3acea6bcf 100644 --- a/fs/ext4/ioctl.c +++ b/fs/ext4/ioctl.c @@ -17,9 +17,201 @@ #include #include "ext4_jbd2.h" #include "ext4.h" +#include "ext4_extents.h" #define MAX_32_NUM ((((unsigned long long) 1) << 32) - 1) +/** + * Swap memory between @a and @b for @len bytes. + * + * @a: pointer to first memory area + * @b: pointer to second memory area + * @len: number of bytes to swap + * + */ +static void memswap(void *a, void *b, size_t len) +{ + unsigned char *ap, *bp; + unsigned char tmp; + + ap = (unsigned char *)a; + bp = (unsigned char *)b; + while (len-- > 0) { + tmp = *ap; + *ap = *bp; + *bp = tmp; + ap++; + bp++; + } +} + +/** + * Swap i_data and associated attributes between @inode1 and @inode2. + * This function is used for the primary swap between inode1 and inode2 + * and also to revert this primary swap in case of errors. + * + * Therefore you have to make sure, that calling this method twice + * will revert all changes. + * + * @inode1: pointer to first inode + * @inode2: pointer to second inode + */ +static void swap_inode_data(struct inode *inode1, struct inode *inode2) +{ + loff_t isize; + struct ext4_inode_info *ei1; + struct ext4_inode_info *ei2; + + ei1 = EXT4_I(inode1); + ei2 = EXT4_I(inode2); + + memswap(&inode1->i_flags, &inode2->i_flags, sizeof(inode1->i_flags)); + memswap(&inode1->i_version, &inode2->i_version, + sizeof(inode1->i_version)); + memswap(&inode1->i_blocks, &inode2->i_blocks, + sizeof(inode1->i_blocks)); + memswap(&inode1->i_bytes, &inode2->i_bytes, sizeof(inode1->i_bytes)); + memswap(&inode1->i_atime, &inode2->i_atime, sizeof(inode1->i_atime)); + memswap(&inode1->i_mtime, &inode2->i_mtime, sizeof(inode1->i_mtime)); + + memswap(ei1->i_data, ei2->i_data, sizeof(ei1->i_data)); + memswap(&ei1->i_flags, &ei2->i_flags, sizeof(ei1->i_flags)); + memswap(&ei1->i_disksize, &ei2->i_disksize, sizeof(ei1->i_disksize)); + memswap(&ei1->i_es_tree, &ei2->i_es_tree, sizeof(ei1->i_es_tree)); + memswap(&ei1->i_es_lru_nr, &ei2->i_es_lru_nr, sizeof(ei1->i_es_lru_nr)); + + isize = i_size_read(inode1); + i_size_write(inode1, i_size_read(inode2)); + i_size_write(inode2, isize); +} + +/** + * Swap the information from the given @inode and the inode + * EXT4_BOOT_LOADER_INO. It will basically swap i_data and all other + * important fields of the inodes. + * + * @sb: the super block of the filesystem + * @inode: the inode to swap with EXT4_BOOT_LOADER_INO + * + */ +static long swap_inode_boot_loader(struct super_block *sb, + struct inode *inode) +{ + handle_t *handle; + int err; + struct inode *inode_bl; + struct ext4_inode_info *ei; + struct ext4_inode_info *ei_bl; + struct ext4_sb_info *sbi; + + if (inode->i_nlink != 1 || !S_ISREG(inode->i_mode)) { + err = -EINVAL; + goto swap_boot_out; + } + + if (!inode_owner_or_capable(inode) || !capable(CAP_SYS_ADMIN)) { + err = -EPERM; + goto swap_boot_out; + } + + sbi = EXT4_SB(sb); + ei = EXT4_I(inode); + + inode_bl = ext4_iget(sb, EXT4_BOOT_LOADER_INO); + if (IS_ERR(inode_bl)) { + err = PTR_ERR(inode_bl); + goto swap_boot_out; + } + ei_bl = EXT4_I(inode_bl); + + filemap_flush(inode->i_mapping); + filemap_flush(inode_bl->i_mapping); + + /* Protect orig inodes against a truncate and make sure, + * that only 1 swap_inode_boot_loader is running. */ + ext4_inode_double_lock(inode, inode_bl); + + truncate_inode_pages(&inode->i_data, 0); + truncate_inode_pages(&inode_bl->i_data, 0); + + /* Wait for all existing dio workers */ + ext4_inode_block_unlocked_dio(inode); + ext4_inode_block_unlocked_dio(inode_bl); + inode_dio_wait(inode); + inode_dio_wait(inode_bl); + + handle = ext4_journal_start(inode_bl, EXT4_HT_MOVE_EXTENTS, 2); + if (IS_ERR(handle)) { + err = -EINVAL; + goto swap_boot_out; + } + + /* Protect extent tree against block allocations via delalloc */ + ext4_double_down_write_data_sem(inode, inode_bl); + + if (inode_bl->i_nlink == 0) { + /* this inode has never been used as a BOOT_LOADER */ + set_nlink(inode_bl, 1); + i_uid_write(inode_bl, 0); + i_gid_write(inode_bl, 0); + inode_bl->i_flags = 0; + ei_bl->i_flags = 0; + inode_bl->i_version = 1; + i_size_write(inode_bl, 0); + inode_bl->i_mode = S_IFREG; + if (EXT4_HAS_INCOMPAT_FEATURE(sb, + EXT4_FEATURE_INCOMPAT_EXTENTS)) { + ext4_set_inode_flag(inode_bl, EXT4_INODE_EXTENTS); + ext4_ext_tree_init(handle, inode_bl); + } else + memset(ei_bl->i_data, 0, sizeof(ei_bl->i_data)); + } + + swap_inode_data(inode, inode_bl); + + inode->i_ctime = inode_bl->i_ctime = ext4_current_time(inode); + + spin_lock(&sbi->s_next_gen_lock); + inode->i_generation = sbi->s_next_generation++; + inode_bl->i_generation = sbi->s_next_generation++; + spin_unlock(&sbi->s_next_gen_lock); + + ext4_discard_preallocations(inode); + + err = ext4_mark_inode_dirty(handle, inode); + if (err < 0) { + ext4_warning(inode->i_sb, + "couldn't mark inode #%lu dirty (err %d)", + inode->i_ino, err); + /* Revert all changes: */ + swap_inode_data(inode, inode_bl); + } else { + err = ext4_mark_inode_dirty(handle, inode_bl); + if (err < 0) { + ext4_warning(inode_bl->i_sb, + "couldn't mark inode #%lu dirty (err %d)", + inode_bl->i_ino, err); + /* Revert all changes: */ + swap_inode_data(inode, inode_bl); + ext4_mark_inode_dirty(handle, inode); + } + } + + ext4_journal_stop(handle); + + ext4_double_up_write_data_sem(inode, inode_bl); + + ext4_inode_resume_unlocked_dio(inode); + ext4_inode_resume_unlocked_dio(inode_bl); + + ext4_inode_double_unlock(inode, inode_bl); + + iput(inode_bl); + +swap_boot_out: + return err; +} + long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) { struct inode *inode = file_inode(filp); @@ -353,6 +545,11 @@ group_add_out: return err; } + case EXT4_IOC_SWAP_BOOT: + if (!(filp->f_mode & FMODE_WRITE)) + return -EBADF; + return swap_inode_boot_loader(sb, inode); + case EXT4_IOC_RESIZE_FS: { ext4_fsblk_t n_blocks_count; struct super_block *sb = inode->i_sb; diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c index 33e1c086858b..a2e696e16331 100644 --- a/fs/ext4/move_extent.c +++ b/fs/ext4/move_extent.c @@ -144,12 +144,13 @@ mext_next_extent(struct inode *inode, struct ext4_ext_path *path, } /** - * double_down_write_data_sem - Acquire two inodes' write lock of i_data_sem + * ext4_double_down_write_data_sem - Acquire two inodes' write lock + * of i_data_sem * * Acquire write lock of i_data_sem of the two inodes */ -static void -double_down_write_data_sem(struct inode *first, struct inode *second) +void +ext4_double_down_write_data_sem(struct inode *first, struct inode *second) { if (first < second) { down_write(&EXT4_I(first)->i_data_sem); @@ -162,14 +163,15 @@ double_down_write_data_sem(struct inode *first, struct inode *second) } /** - * double_up_write_data_sem - Release two inodes' write lock of i_data_sem + * ext4_double_up_write_data_sem - Release two inodes' write lock of i_data_sem * * @orig_inode: original inode structure to be released its lock first * @donor_inode: donor inode structure to be released its lock second * Release write lock of i_data_sem of two inodes (orig and donor). */ -static void -double_up_write_data_sem(struct inode *orig_inode, struct inode *donor_inode) +void +ext4_double_up_write_data_sem(struct inode *orig_inode, + struct inode *donor_inode) { up_write(&EXT4_I(orig_inode)->i_data_sem); up_write(&EXT4_I(donor_inode)->i_data_sem); @@ -976,7 +978,7 @@ again: * necessary, just swap data blocks between orig and donor. */ if (uninit) { - double_down_write_data_sem(orig_inode, donor_inode); + ext4_double_down_write_data_sem(orig_inode, donor_inode); /* If any of extents in range became initialized we have to * fallback to data copying */ uninit = mext_check_coverage(orig_inode, orig_blk_offset, @@ -990,7 +992,7 @@ again: goto drop_data_sem; if (!uninit) { - double_up_write_data_sem(orig_inode, donor_inode); + ext4_double_up_write_data_sem(orig_inode, donor_inode); goto data_copy; } if ((page_has_private(pagep[0]) && @@ -1004,7 +1006,7 @@ again: donor_inode, orig_blk_offset, block_len_in_page, err); drop_data_sem: - double_up_write_data_sem(orig_inode, donor_inode); + ext4_double_up_write_data_sem(orig_inode, donor_inode); goto unlock_pages; } data_copy: @@ -1065,11 +1067,11 @@ repair_branches: * Extents are swapped already, but we are not able to copy data. * Try to swap extents to it's original places */ - double_down_write_data_sem(orig_inode, donor_inode); + ext4_double_down_write_data_sem(orig_inode, donor_inode); replaced_count = mext_replace_branches(handle, donor_inode, orig_inode, orig_blk_offset, block_len_in_page, &err2); - double_up_write_data_sem(orig_inode, donor_inode); + ext4_double_up_write_data_sem(orig_inode, donor_inode); if (replaced_count != block_len_in_page) { EXT4_ERROR_INODE_BLOCK(orig_inode, (sector_t)(orig_blk_offset), "Unable to copy data block," @@ -1209,15 +1211,15 @@ mext_check_arguments(struct inode *orig_inode, } /** - * mext_inode_double_lock - Lock i_mutex on both @inode1 and @inode2 + * ext4_inode_double_lock - Lock i_mutex on both @inode1 and @inode2 * * @inode1: the inode structure * @inode2: the inode structure * * Lock two inodes' i_mutex */ -static void -mext_inode_double_lock(struct inode *inode1, struct inode *inode2) +void +ext4_inode_double_lock(struct inode *inode1, struct inode *inode2) { BUG_ON(inode1 == inode2); if (inode1 < inode2) { @@ -1230,15 +1232,15 @@ mext_inode_double_lock(struct inode *inode1, struct inode *inode2) } /** - * mext_inode_double_unlock - Release i_mutex on both @inode1 and @inode2 + * ext4_inode_double_unlock - Release i_mutex on both @inode1 and @inode2 * * @inode1: the inode that is released first * @inode2: the inode that is released second * */ -static void -mext_inode_double_unlock(struct inode *inode1, struct inode *inode2) +void +ext4_inode_double_unlock(struct inode *inode1, struct inode *inode2) { mutex_unlock(&inode1->i_mutex); mutex_unlock(&inode2->i_mutex); @@ -1333,7 +1335,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, return -EINVAL; } /* Protect orig and donor inodes against a truncate */ - mext_inode_double_lock(orig_inode, donor_inode); + ext4_inode_double_lock(orig_inode, donor_inode); /* Wait for all existing dio workers */ ext4_inode_block_unlocked_dio(orig_inode); @@ -1342,7 +1344,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, inode_dio_wait(donor_inode); /* Protect extent tree against block allocations via delalloc */ - double_down_write_data_sem(orig_inode, donor_inode); + ext4_double_down_write_data_sem(orig_inode, donor_inode); /* Check the filesystem environment whether move_extent can be done */ ret = mext_check_arguments(orig_inode, donor_inode, orig_start, donor_start, &len); @@ -1466,7 +1468,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, * b. racing with ->readpage, ->write_begin, and ext4_get_block * in move_extent_per_page */ - double_up_write_data_sem(orig_inode, donor_inode); + ext4_double_up_write_data_sem(orig_inode, donor_inode); while (orig_page_offset <= seq_end_page) { @@ -1500,7 +1502,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, block_len_in_page = rest_blocks; } - double_down_write_data_sem(orig_inode, donor_inode); + ext4_double_down_write_data_sem(orig_inode, donor_inode); if (ret < 0) break; @@ -1538,10 +1540,10 @@ out: ext4_ext_drop_refs(holecheck_path); kfree(holecheck_path); } - double_up_write_data_sem(orig_inode, donor_inode); + ext4_double_up_write_data_sem(orig_inode, donor_inode); ext4_inode_resume_unlocked_dio(orig_inode); ext4_inode_resume_unlocked_dio(donor_inode); - mext_inode_double_unlock(orig_inode, donor_inode); + ext4_inode_double_unlock(orig_inode, donor_inode); return ret; } -- 2.30.2