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![Richard Guy Briggs](/assets/img/avatar_default.png)
This patch adds a flag, FAN_INFO and an extensible buffer to provide additional information about response decisions. The buffer contains one or more headers defining the information type and the length of the following information. The patch defines one additional information type, FAN_RESPONSE_INFO_AUDIT_RULE, to audit a rule number. This will allow for the creation of other information types in the future if other users of the API identify different needs. The kernel can be tested if it supports a given info type by supplying the complete info extension but setting fd to FAN_NOFD. It will return the expected size but not issue an audit record. Suggested-by: Steve Grubb <sgrubb@redhat.com> Link: https://lore.kernel.org/r/2745105.e9J7NaK4W3@x2 Suggested-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20201001101219.GE17860@quack2.suse.cz Tested-by: Steve Grubb <sgrubb@redhat.com> Acked-by: Steve Grubb <sgrubb@redhat.com> Signed-off-by: Richard Guy Briggs <rgb@redhat.com> Signed-off-by: Jan Kara <jack@suse.cz> Message-Id: <10177cfcae5480926b7176321a28d9da6835b667.1675373475.git.rgb@redhat.com>
504 lines
14 KiB
C
504 lines
14 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#include <linux/fsnotify_backend.h>
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#include <linux/path.h>
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#include <linux/slab.h>
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#include <linux/exportfs.h>
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#include <linux/hashtable.h>
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extern struct kmem_cache *fanotify_mark_cache;
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extern struct kmem_cache *fanotify_fid_event_cachep;
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extern struct kmem_cache *fanotify_path_event_cachep;
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extern struct kmem_cache *fanotify_perm_event_cachep;
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/* Possible states of the permission event */
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enum {
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FAN_EVENT_INIT,
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FAN_EVENT_REPORTED,
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FAN_EVENT_ANSWERED,
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FAN_EVENT_CANCELED,
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};
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/*
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* 3 dwords are sufficient for most local fs (64bit ino, 32bit generation).
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* fh buf should be dword aligned. On 64bit arch, the ext_buf pointer is
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* stored in either the first or last 2 dwords.
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*/
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#define FANOTIFY_INLINE_FH_LEN (3 << 2)
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#define FANOTIFY_FH_HDR_LEN offsetof(struct fanotify_fh, buf)
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/* Fixed size struct for file handle */
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struct fanotify_fh {
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u8 type;
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u8 len;
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#define FANOTIFY_FH_FLAG_EXT_BUF 1
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u8 flags;
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u8 pad;
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unsigned char buf[];
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} __aligned(4);
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/* Variable size struct for dir file handle + child file handle + name */
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struct fanotify_info {
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/* size of dir_fh/file_fh including fanotify_fh hdr size */
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u8 dir_fh_totlen;
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u8 dir2_fh_totlen;
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u8 file_fh_totlen;
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u8 name_len;
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u8 name2_len;
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u8 pad[3];
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unsigned char buf[];
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/*
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* (struct fanotify_fh) dir_fh starts at buf[0]
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* (optional) dir2_fh starts at buf[dir_fh_totlen]
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* (optional) file_fh starts at buf[dir_fh_totlen + dir2_fh_totlen]
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* name starts at buf[dir_fh_totlen + dir2_fh_totlen + file_fh_totlen]
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* ...
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*/
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#define FANOTIFY_DIR_FH_SIZE(info) ((info)->dir_fh_totlen)
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#define FANOTIFY_DIR2_FH_SIZE(info) ((info)->dir2_fh_totlen)
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#define FANOTIFY_FILE_FH_SIZE(info) ((info)->file_fh_totlen)
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#define FANOTIFY_NAME_SIZE(info) ((info)->name_len + 1)
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#define FANOTIFY_NAME2_SIZE(info) ((info)->name2_len + 1)
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#define FANOTIFY_DIR_FH_OFFSET(info) 0
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#define FANOTIFY_DIR2_FH_OFFSET(info) \
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(FANOTIFY_DIR_FH_OFFSET(info) + FANOTIFY_DIR_FH_SIZE(info))
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#define FANOTIFY_FILE_FH_OFFSET(info) \
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(FANOTIFY_DIR2_FH_OFFSET(info) + FANOTIFY_DIR2_FH_SIZE(info))
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#define FANOTIFY_NAME_OFFSET(info) \
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(FANOTIFY_FILE_FH_OFFSET(info) + FANOTIFY_FILE_FH_SIZE(info))
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#define FANOTIFY_NAME2_OFFSET(info) \
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(FANOTIFY_NAME_OFFSET(info) + FANOTIFY_NAME_SIZE(info))
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#define FANOTIFY_DIR_FH_BUF(info) \
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((info)->buf + FANOTIFY_DIR_FH_OFFSET(info))
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#define FANOTIFY_DIR2_FH_BUF(info) \
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((info)->buf + FANOTIFY_DIR2_FH_OFFSET(info))
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#define FANOTIFY_FILE_FH_BUF(info) \
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((info)->buf + FANOTIFY_FILE_FH_OFFSET(info))
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#define FANOTIFY_NAME_BUF(info) \
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((info)->buf + FANOTIFY_NAME_OFFSET(info))
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#define FANOTIFY_NAME2_BUF(info) \
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((info)->buf + FANOTIFY_NAME2_OFFSET(info))
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} __aligned(4);
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static inline bool fanotify_fh_has_ext_buf(struct fanotify_fh *fh)
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{
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return (fh->flags & FANOTIFY_FH_FLAG_EXT_BUF);
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}
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static inline char **fanotify_fh_ext_buf_ptr(struct fanotify_fh *fh)
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{
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BUILD_BUG_ON(FANOTIFY_FH_HDR_LEN % 4);
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BUILD_BUG_ON(__alignof__(char *) - 4 + sizeof(char *) >
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FANOTIFY_INLINE_FH_LEN);
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return (char **)ALIGN((unsigned long)(fh->buf), __alignof__(char *));
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}
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static inline void *fanotify_fh_ext_buf(struct fanotify_fh *fh)
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{
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return *fanotify_fh_ext_buf_ptr(fh);
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}
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static inline void *fanotify_fh_buf(struct fanotify_fh *fh)
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{
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return fanotify_fh_has_ext_buf(fh) ? fanotify_fh_ext_buf(fh) : fh->buf;
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}
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static inline int fanotify_info_dir_fh_len(struct fanotify_info *info)
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{
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if (!info->dir_fh_totlen ||
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WARN_ON_ONCE(info->dir_fh_totlen < FANOTIFY_FH_HDR_LEN))
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return 0;
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return info->dir_fh_totlen - FANOTIFY_FH_HDR_LEN;
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}
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static inline struct fanotify_fh *fanotify_info_dir_fh(struct fanotify_info *info)
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{
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BUILD_BUG_ON(offsetof(struct fanotify_info, buf) % 4);
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return (struct fanotify_fh *)FANOTIFY_DIR_FH_BUF(info);
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}
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static inline int fanotify_info_dir2_fh_len(struct fanotify_info *info)
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{
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if (!info->dir2_fh_totlen ||
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WARN_ON_ONCE(info->dir2_fh_totlen < FANOTIFY_FH_HDR_LEN))
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return 0;
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return info->dir2_fh_totlen - FANOTIFY_FH_HDR_LEN;
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}
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static inline struct fanotify_fh *fanotify_info_dir2_fh(struct fanotify_info *info)
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{
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return (struct fanotify_fh *)FANOTIFY_DIR2_FH_BUF(info);
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}
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static inline int fanotify_info_file_fh_len(struct fanotify_info *info)
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{
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if (!info->file_fh_totlen ||
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WARN_ON_ONCE(info->file_fh_totlen < FANOTIFY_FH_HDR_LEN))
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return 0;
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return info->file_fh_totlen - FANOTIFY_FH_HDR_LEN;
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}
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static inline struct fanotify_fh *fanotify_info_file_fh(struct fanotify_info *info)
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{
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return (struct fanotify_fh *)FANOTIFY_FILE_FH_BUF(info);
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}
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static inline char *fanotify_info_name(struct fanotify_info *info)
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{
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if (!info->name_len)
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return NULL;
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return FANOTIFY_NAME_BUF(info);
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}
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static inline char *fanotify_info_name2(struct fanotify_info *info)
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{
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if (!info->name2_len)
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return NULL;
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return FANOTIFY_NAME2_BUF(info);
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}
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static inline void fanotify_info_init(struct fanotify_info *info)
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{
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BUILD_BUG_ON(FANOTIFY_FH_HDR_LEN + MAX_HANDLE_SZ > U8_MAX);
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BUILD_BUG_ON(NAME_MAX > U8_MAX);
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info->dir_fh_totlen = 0;
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info->dir2_fh_totlen = 0;
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info->file_fh_totlen = 0;
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info->name_len = 0;
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info->name2_len = 0;
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}
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/* These set/copy helpers MUST be called by order */
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static inline void fanotify_info_set_dir_fh(struct fanotify_info *info,
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unsigned int totlen)
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{
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if (WARN_ON_ONCE(info->dir2_fh_totlen > 0) ||
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WARN_ON_ONCE(info->file_fh_totlen > 0) ||
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WARN_ON_ONCE(info->name_len > 0) ||
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WARN_ON_ONCE(info->name2_len > 0))
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return;
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info->dir_fh_totlen = totlen;
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}
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static inline void fanotify_info_set_dir2_fh(struct fanotify_info *info,
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unsigned int totlen)
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{
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if (WARN_ON_ONCE(info->file_fh_totlen > 0) ||
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WARN_ON_ONCE(info->name_len > 0) ||
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WARN_ON_ONCE(info->name2_len > 0))
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return;
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info->dir2_fh_totlen = totlen;
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}
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static inline void fanotify_info_set_file_fh(struct fanotify_info *info,
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unsigned int totlen)
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{
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if (WARN_ON_ONCE(info->name_len > 0) ||
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WARN_ON_ONCE(info->name2_len > 0))
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return;
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info->file_fh_totlen = totlen;
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}
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static inline void fanotify_info_copy_name(struct fanotify_info *info,
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const struct qstr *name)
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{
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if (WARN_ON_ONCE(name->len > NAME_MAX) ||
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WARN_ON_ONCE(info->name2_len > 0))
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return;
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info->name_len = name->len;
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strcpy(fanotify_info_name(info), name->name);
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}
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static inline void fanotify_info_copy_name2(struct fanotify_info *info,
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const struct qstr *name)
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{
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if (WARN_ON_ONCE(name->len > NAME_MAX))
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return;
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info->name2_len = name->len;
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strcpy(fanotify_info_name2(info), name->name);
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}
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/*
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* Common structure for fanotify events. Concrete structs are allocated in
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* fanotify_handle_event() and freed when the information is retrieved by
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* userspace. The type of event determines how it was allocated, how it will
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* be freed and which concrete struct it may be cast to.
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*/
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enum fanotify_event_type {
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FANOTIFY_EVENT_TYPE_FID, /* fixed length */
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FANOTIFY_EVENT_TYPE_FID_NAME, /* variable length */
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FANOTIFY_EVENT_TYPE_PATH,
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FANOTIFY_EVENT_TYPE_PATH_PERM,
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FANOTIFY_EVENT_TYPE_OVERFLOW, /* struct fanotify_event */
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FANOTIFY_EVENT_TYPE_FS_ERROR, /* struct fanotify_error_event */
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__FANOTIFY_EVENT_TYPE_NUM
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};
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#define FANOTIFY_EVENT_TYPE_BITS \
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(ilog2(__FANOTIFY_EVENT_TYPE_NUM - 1) + 1)
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#define FANOTIFY_EVENT_HASH_BITS \
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(32 - FANOTIFY_EVENT_TYPE_BITS)
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struct fanotify_event {
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struct fsnotify_event fse;
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struct hlist_node merge_list; /* List for hashed merge */
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u32 mask;
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struct {
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unsigned int type : FANOTIFY_EVENT_TYPE_BITS;
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unsigned int hash : FANOTIFY_EVENT_HASH_BITS;
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};
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struct pid *pid;
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};
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static inline void fanotify_init_event(struct fanotify_event *event,
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unsigned int hash, u32 mask)
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{
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fsnotify_init_event(&event->fse);
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INIT_HLIST_NODE(&event->merge_list);
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event->hash = hash;
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event->mask = mask;
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event->pid = NULL;
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}
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#define FANOTIFY_INLINE_FH(name, size) \
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struct { \
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struct fanotify_fh (name); \
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/* Space for object_fh.buf[] - access with fanotify_fh_buf() */ \
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unsigned char _inline_fh_buf[(size)]; \
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}
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struct fanotify_fid_event {
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struct fanotify_event fae;
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__kernel_fsid_t fsid;
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FANOTIFY_INLINE_FH(object_fh, FANOTIFY_INLINE_FH_LEN);
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};
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static inline struct fanotify_fid_event *
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FANOTIFY_FE(struct fanotify_event *event)
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{
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return container_of(event, struct fanotify_fid_event, fae);
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}
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struct fanotify_name_event {
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struct fanotify_event fae;
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__kernel_fsid_t fsid;
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struct fanotify_info info;
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};
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static inline struct fanotify_name_event *
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FANOTIFY_NE(struct fanotify_event *event)
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{
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return container_of(event, struct fanotify_name_event, fae);
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}
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struct fanotify_error_event {
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struct fanotify_event fae;
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s32 error; /* Error reported by the Filesystem. */
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u32 err_count; /* Suppressed errors count */
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__kernel_fsid_t fsid; /* FSID this error refers to. */
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FANOTIFY_INLINE_FH(object_fh, MAX_HANDLE_SZ);
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};
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static inline struct fanotify_error_event *
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FANOTIFY_EE(struct fanotify_event *event)
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{
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return container_of(event, struct fanotify_error_event, fae);
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}
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static inline __kernel_fsid_t *fanotify_event_fsid(struct fanotify_event *event)
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{
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if (event->type == FANOTIFY_EVENT_TYPE_FID)
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return &FANOTIFY_FE(event)->fsid;
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else if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
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return &FANOTIFY_NE(event)->fsid;
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else if (event->type == FANOTIFY_EVENT_TYPE_FS_ERROR)
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return &FANOTIFY_EE(event)->fsid;
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else
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return NULL;
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}
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static inline struct fanotify_fh *fanotify_event_object_fh(
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struct fanotify_event *event)
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{
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if (event->type == FANOTIFY_EVENT_TYPE_FID)
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return &FANOTIFY_FE(event)->object_fh;
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else if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
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return fanotify_info_file_fh(&FANOTIFY_NE(event)->info);
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else if (event->type == FANOTIFY_EVENT_TYPE_FS_ERROR)
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return &FANOTIFY_EE(event)->object_fh;
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else
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return NULL;
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}
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static inline struct fanotify_info *fanotify_event_info(
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struct fanotify_event *event)
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{
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if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
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return &FANOTIFY_NE(event)->info;
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else
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return NULL;
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}
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static inline int fanotify_event_object_fh_len(struct fanotify_event *event)
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{
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struct fanotify_info *info = fanotify_event_info(event);
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struct fanotify_fh *fh = fanotify_event_object_fh(event);
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if (info)
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return info->file_fh_totlen ? fh->len : 0;
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else
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return fh ? fh->len : 0;
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}
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static inline int fanotify_event_dir_fh_len(struct fanotify_event *event)
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{
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struct fanotify_info *info = fanotify_event_info(event);
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return info ? fanotify_info_dir_fh_len(info) : 0;
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}
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static inline int fanotify_event_dir2_fh_len(struct fanotify_event *event)
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{
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struct fanotify_info *info = fanotify_event_info(event);
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return info ? fanotify_info_dir2_fh_len(info) : 0;
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}
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static inline bool fanotify_event_has_object_fh(struct fanotify_event *event)
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{
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/* For error events, even zeroed fh are reported. */
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if (event->type == FANOTIFY_EVENT_TYPE_FS_ERROR)
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return true;
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return fanotify_event_object_fh_len(event) > 0;
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}
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static inline bool fanotify_event_has_dir_fh(struct fanotify_event *event)
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{
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return fanotify_event_dir_fh_len(event) > 0;
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}
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static inline bool fanotify_event_has_dir2_fh(struct fanotify_event *event)
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{
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return fanotify_event_dir2_fh_len(event) > 0;
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}
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static inline bool fanotify_event_has_any_dir_fh(struct fanotify_event *event)
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{
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return fanotify_event_has_dir_fh(event) ||
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fanotify_event_has_dir2_fh(event);
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}
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struct fanotify_path_event {
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struct fanotify_event fae;
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struct path path;
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};
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static inline struct fanotify_path_event *
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FANOTIFY_PE(struct fanotify_event *event)
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{
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return container_of(event, struct fanotify_path_event, fae);
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}
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/*
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* Structure for permission fanotify events. It gets allocated and freed in
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* fanotify_handle_event() since we wait there for user response. When the
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* information is retrieved by userspace the structure is moved from
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* group->notification_list to group->fanotify_data.access_list to wait for
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* user response.
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*/
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struct fanotify_perm_event {
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struct fanotify_event fae;
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struct path path;
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u32 response; /* userspace answer to the event */
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unsigned short state; /* state of the event */
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int fd; /* fd we passed to userspace for this event */
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union {
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struct fanotify_response_info_header hdr;
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struct fanotify_response_info_audit_rule audit_rule;
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};
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};
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static inline struct fanotify_perm_event *
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FANOTIFY_PERM(struct fanotify_event *event)
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{
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return container_of(event, struct fanotify_perm_event, fae);
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}
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static inline bool fanotify_is_perm_event(u32 mask)
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{
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return IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS) &&
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mask & FANOTIFY_PERM_EVENTS;
|
|
}
|
|
|
|
static inline struct fanotify_event *FANOTIFY_E(struct fsnotify_event *fse)
|
|
{
|
|
return container_of(fse, struct fanotify_event, fse);
|
|
}
|
|
|
|
static inline bool fanotify_is_error_event(u32 mask)
|
|
{
|
|
return mask & FAN_FS_ERROR;
|
|
}
|
|
|
|
static inline const struct path *fanotify_event_path(struct fanotify_event *event)
|
|
{
|
|
if (event->type == FANOTIFY_EVENT_TYPE_PATH)
|
|
return &FANOTIFY_PE(event)->path;
|
|
else if (event->type == FANOTIFY_EVENT_TYPE_PATH_PERM)
|
|
return &FANOTIFY_PERM(event)->path;
|
|
else
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Use 128 size hash table to speed up events merge.
|
|
*/
|
|
#define FANOTIFY_HTABLE_BITS (7)
|
|
#define FANOTIFY_HTABLE_SIZE (1 << FANOTIFY_HTABLE_BITS)
|
|
#define FANOTIFY_HTABLE_MASK (FANOTIFY_HTABLE_SIZE - 1)
|
|
|
|
/*
|
|
* Permission events and overflow event do not get merged - don't hash them.
|
|
*/
|
|
static inline bool fanotify_is_hashed_event(u32 mask)
|
|
{
|
|
return !(fanotify_is_perm_event(mask) ||
|
|
fsnotify_is_overflow_event(mask));
|
|
}
|
|
|
|
static inline unsigned int fanotify_event_hash_bucket(
|
|
struct fsnotify_group *group,
|
|
struct fanotify_event *event)
|
|
{
|
|
return event->hash & FANOTIFY_HTABLE_MASK;
|
|
}
|
|
|
|
static inline unsigned int fanotify_mark_user_flags(struct fsnotify_mark *mark)
|
|
{
|
|
unsigned int mflags = 0;
|
|
|
|
if (mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)
|
|
mflags |= FAN_MARK_IGNORED_SURV_MODIFY;
|
|
if (mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF)
|
|
mflags |= FAN_MARK_EVICTABLE;
|
|
if (mark->flags & FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS)
|
|
mflags |= FAN_MARK_IGNORE;
|
|
|
|
return mflags;
|
|
}
|