From 30f3e4f1c361b03034951265d2bf6796c4fdc7f4 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Mon, 29 Nov 2021 22:15:31 +0200 Subject: [PATCH] fanotify: use macros to get the offset to fanotify_info buffer [ Upstream commit 2d9374f095136206a02eb0b6cd9ef94632c1e9f7 ] The fanotify_info buffer contains up to two file handles and a name. Use macros to simplify the code that access the different items within the buffer. Add assertions to verify that stored fh len and name len do not overflow the u8 stored value in fanotify_info header. Remove the unused fanotify_info_len() helper. Link: https://lore.kernel.org/r/20211129201537.1932819-6-amir73il@gmail.com Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- fs/notify/fanotify/fanotify.c | 2 +- fs/notify/fanotify/fanotify.h | 41 +++++++++++++++++++++++++---------- 2 files changed, 31 insertions(+), 12 deletions(-) diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c index 85e542b16..ffad224be 100755 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -411,7 +411,7 @@ static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode, * be zero in that case if encoding fh len failed. */ err = -ENOENT; - if (fh_len < 4 || WARN_ON_ONCE(fh_len % 4)) + if (fh_len < 4 || WARN_ON_ONCE(fh_len % 4) || fh_len > MAX_HANDLE_SZ) goto out_err; /* No external buffer in a variable size allocated fh */ diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h index d25f500bf..dd23ba659 100755 --- a/fs/notify/fanotify/fanotify.h +++ b/fs/notify/fanotify/fanotify.h @@ -49,6 +49,22 @@ struct fanotify_info { * (optional) file_fh starts at buf[dir_fh_totlen] * name starts at buf[dir_fh_totlen + file_fh_totlen] */ +#define FANOTIFY_DIR_FH_SIZE(info) ((info)->dir_fh_totlen) +#define FANOTIFY_FILE_FH_SIZE(info) ((info)->file_fh_totlen) +#define FANOTIFY_NAME_SIZE(info) ((info)->name_len + 1) + +#define FANOTIFY_DIR_FH_OFFSET(info) 0 +#define FANOTIFY_FILE_FH_OFFSET(info) \ + (FANOTIFY_DIR_FH_OFFSET(info) + FANOTIFY_DIR_FH_SIZE(info)) +#define FANOTIFY_NAME_OFFSET(info) \ + (FANOTIFY_FILE_FH_OFFSET(info) + FANOTIFY_FILE_FH_SIZE(info)) + +#define FANOTIFY_DIR_FH_BUF(info) \ + ((info)->buf + FANOTIFY_DIR_FH_OFFSET(info)) +#define FANOTIFY_FILE_FH_BUF(info) \ + ((info)->buf + FANOTIFY_FILE_FH_OFFSET(info)) +#define FANOTIFY_NAME_BUF(info) \ + ((info)->buf + FANOTIFY_NAME_OFFSET(info)) } __aligned(4); static inline bool fanotify_fh_has_ext_buf(struct fanotify_fh *fh) @@ -87,7 +103,7 @@ static inline struct fanotify_fh *fanotify_info_dir_fh(struct fanotify_info *inf { BUILD_BUG_ON(offsetof(struct fanotify_info, buf) % 4); - return (struct fanotify_fh *)info->buf; + return (struct fanotify_fh *)FANOTIFY_DIR_FH_BUF(info); } static inline int fanotify_info_file_fh_len(struct fanotify_info *info) @@ -101,32 +117,35 @@ static inline int fanotify_info_file_fh_len(struct fanotify_info *info) static inline struct fanotify_fh *fanotify_info_file_fh(struct fanotify_info *info) { - return (struct fanotify_fh *)(info->buf + info->dir_fh_totlen); + return (struct fanotify_fh *)FANOTIFY_FILE_FH_BUF(info); } -static inline const char *fanotify_info_name(struct fanotify_info *info) +static inline char *fanotify_info_name(struct fanotify_info *info) { - return info->buf + info->dir_fh_totlen + info->file_fh_totlen; + if (!info->name_len) + return NULL; + + return FANOTIFY_NAME_BUF(info); } static inline void fanotify_info_init(struct fanotify_info *info) { + BUILD_BUG_ON(FANOTIFY_FH_HDR_LEN + MAX_HANDLE_SZ > U8_MAX); + BUILD_BUG_ON(NAME_MAX > U8_MAX); + info->dir_fh_totlen = 0; info->file_fh_totlen = 0; info->name_len = 0; } -static inline unsigned int fanotify_info_len(struct fanotify_info *info) -{ - return info->dir_fh_totlen + info->file_fh_totlen + info->name_len; -} - static inline void fanotify_info_copy_name(struct fanotify_info *info, const struct qstr *name) { + if (WARN_ON_ONCE(name->len > NAME_MAX)) + return; + info->name_len = name->len; - strcpy(info->buf + info->dir_fh_totlen + info->file_fh_totlen, - name->name); + strcpy(fanotify_info_name(info), name->name); } /*