[Kernel] [PATCH OpenHarmony-4.19 25/49] pstore: Add locking around superblock changes

From: Kees Cook <keescook(a)chromium.org> stable inclusion from stable-5.10 category: feature commit:27e5041a87e8af2d0b6452dffe053d0253e914cc issue: #I4919J -------------------------------- Nothing was protecting changes to the pstorefs superblock. Add locking and refactor away is_pstore_mounted(), instead using a helper to add a way to safely lock the pstorefs root inode during filesystem changes. Link: https://lore.kernel.org/lkml/20200506152114.50375-9-keescook@chromium.org/ Signed-off-by: Kees Cook <keescook(a)chromium.org> (cherry picked from commit 27e5041a87e8af2d0b6452dffe053d0253e914cc) Signed-off-by: roger <kongzhengrong(a)huawei.com> --- fs/pstore/inode.c | 65 +++++++++++++++++++++++++++++--------------- fs/pstore/internal.h | 1 - fs/pstore/platform.c | 5 ++-- 3 files changed, 45 insertions(+), 26 deletions(-) diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c index 7bec953e2dbc..c29e4d4a3359 100644 --- a/fs/pstore/inode.c +++ b/fs/pstore/inode.c @@ -43,6 +43,9 @@ static DEFINE_MUTEX(records_list_lock); static LIST_HEAD(records_list); +static DEFINE_MUTEX(pstore_sb_lock); +static struct super_block *pstore_sb; + struct pstore_private { struct list_head list; struct pstore_record *record; @@ -294,11 +297,25 @@ static const struct super_operations pstore_ops = { .show_options = pstore_show_options, }; -static struct super_block *pstore_sb; - -bool pstore_is_mounted(void) +static struct dentry *psinfo_lock_root(void) { - return pstore_sb != NULL; + struct dentry *root; + + mutex_lock(&pstore_sb_lock); + /* + * Having no backend is fine -- no records appear. + * Not being mounted is fine -- nothing to do. + */ + if (!psinfo || !pstore_sb) { + mutex_unlock(&pstore_sb_lock); + return NULL; + } + + root = pstore_sb->s_root; + inode_lock(d_inode(root)); + mutex_unlock(&pstore_sb_lock); + + return root; } /* @@ -315,20 +332,18 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record) struct pstore_private *private, *pos; size_t size = record->size + record->ecc_notice_size; - WARN_ON(!inode_is_locked(d_inode(root))); + if (WARN_ON(!inode_is_locked(d_inode(root)))) + return -EINVAL; + rc = -EEXIST; + /* Skip records that are already present in the filesystem. */ mutex_lock(&records_list_lock); list_for_each_entry(pos, &records_list, list) { if (pos->record->type == record->type && pos->record->id == record->id && - pos->record->psi == record->psi) { - rc = -EEXIST; - break; - } + pos->record->psi == record->psi) + goto fail; } - mutex_unlock(&records_list_lock); - if (rc) - return rc; rc = -ENOMEM; inode = pstore_get_inode(root->d_sb); @@ -359,7 +374,6 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record) d_add(dentry, inode); - mutex_lock(&records_list_lock); list_add(&private->list, &records_list); mutex_unlock(&records_list_lock); @@ -369,8 +383,8 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record) free_pstore_private(private); fail_inode: iput(inode); - fail: + mutex_unlock(&records_list_lock); return rc; } @@ -382,16 +396,13 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record) */ void pstore_get_records(int quiet) { - struct pstore_info *psi = psinfo; struct dentry *root; - if (!psi || !pstore_sb) + root = psinfo_lock_root(); + if (!root) return; - root = pstore_sb->s_root; - - inode_lock(d_inode(root)); - pstore_get_backend_records(psi, root, quiet); + pstore_get_backend_records(psinfo, root, quiet); inode_unlock(d_inode(root)); } @@ -399,8 +410,6 @@ static int pstore_fill_super(struct super_block *sb, void *data, int silent) { struct inode *inode; - pstore_sb = sb; - sb->s_maxbytes = MAX_LFS_FILESIZE; sb->s_blocksize = PAGE_SIZE; sb->s_blocksize_bits = PAGE_SHIFT; @@ -421,6 +430,10 @@ static int pstore_fill_super(struct super_block *sb, void *data, int silent) if (!sb->s_root) return -ENOMEM; + mutex_lock(&pstore_sb_lock); + pstore_sb = sb; + mutex_unlock(&pstore_sb_lock); + pstore_get_records(0); return 0; @@ -434,9 +447,17 @@ static struct dentry *pstore_mount(struct file_system_type *fs_type, static void pstore_kill_sb(struct super_block *sb) { + mutex_lock(&pstore_sb_lock); + WARN_ON(pstore_sb != sb); + kill_litter_super(sb); pstore_sb = NULL; + + mutex_lock(&records_list_lock); INIT_LIST_HEAD(&records_list); + mutex_unlock(&records_list_lock); + + mutex_unlock(&pstore_sb_lock); } static struct file_system_type pstore_fs_type = { diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h index 7062ea4bc57c..fe5f7ef7323f 100644 --- a/fs/pstore/internal.h +++ b/fs/pstore/internal.h @@ -33,7 +33,6 @@ extern void pstore_get_backend_records(struct pstore_info *psi, struct dentry *root, int quiet); extern int pstore_mkfile(struct dentry *root, struct pstore_record *record); -extern bool pstore_is_mounted(void); extern void pstore_record_init(struct pstore_record *record, struct pstore_info *psi); diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c index 2a561728443f..405f714b69d3 100644 --- a/fs/pstore/platform.c +++ b/fs/pstore/platform.c @@ -488,7 +488,7 @@ static void pstore_dump(struct kmsg_dumper *dumper, } ret = psinfo->write(&record); - if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted()) + if (ret == 0 && reason == KMSG_DUMP_OOPS) pstore_new_entry = 1; total += record.size; @@ -628,8 +628,7 @@ int pstore_register(struct pstore_info *psi) if (psi->flags & PSTORE_FLAGS_DMESG) allocate_buf_for_compression(); - if (pstore_is_mounted()) - pstore_get_records(0); + pstore_get_records(0); if (psi->flags & PSTORE_FLAGS_DMESG) pstore_register_kmsg(); -- 2.17.1