From 0a076036b631f086a6bce93a45eaa216f234f121 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Fri, 15 Nov 2024 10:30:19 -0500 Subject: fanotify: reserve event bit of deprecated FAN_DIR_MODIFY Avoid reusing it, because we would like to reserve it for future FAN_PATH_MODIFY pre-content event. Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara Link: https://patch.msgid.link/632d9f80428e2e7a6b6a8ccc2925d87c92bbb518.1731684329.git.josef@toxicpanda.com --- include/uapi/linux/fanotify.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h index 34f221d3a1b9..79072b6894f2 100644 --- a/include/uapi/linux/fanotify.h +++ b/include/uapi/linux/fanotify.h @@ -25,6 +25,7 @@ #define FAN_OPEN_PERM 0x00010000 /* File open in perm check */ #define FAN_ACCESS_PERM 0x00020000 /* File accessed in perm check */ #define FAN_OPEN_EXEC_PERM 0x00040000 /* File open/exec in perm check */ +/* #define FAN_DIR_MODIFY 0x00080000 */ /* Deprecated (reserved) */ #define FAN_EVENT_ON_CHILD 0x08000000 /* Interested in child events */ -- cgit v1.2.3 From 4f8afa33817a6420398d1c177c6e220a05081f51 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Fri, 15 Nov 2024 10:30:23 -0500 Subject: fanotify: introduce FAN_PRE_ACCESS permission event Similar to FAN_ACCESS_PERM permission event, but it is only allowed with class FAN_CLASS_PRE_CONTENT and only allowed on regular files and dirs. Unlike FAN_ACCESS_PERM, it is safe to write to the file being accessed in the context of the event handler. This pre-content event is meant to be used by hierarchical storage managers that want to fill the content of files on first read access. Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara Link: https://patch.msgid.link/b80986f8d5b860acea2c9a73c0acd93587be5fe4.1731684329.git.josef@toxicpanda.com --- include/uapi/linux/fanotify.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h index 79072b6894f2..7596168c80eb 100644 --- a/include/uapi/linux/fanotify.h +++ b/include/uapi/linux/fanotify.h @@ -27,6 +27,8 @@ #define FAN_OPEN_EXEC_PERM 0x00040000 /* File open/exec in perm check */ /* #define FAN_DIR_MODIFY 0x00080000 */ /* Deprecated (reserved) */ +#define FAN_PRE_ACCESS 0x00100000 /* Pre-content access hook */ + #define FAN_EVENT_ON_CHILD 0x08000000 /* Interested in child events */ #define FAN_RENAME 0x10000000 /* File was renamed */ -- cgit v1.2.3 From 870499bc1d4dc04cba1f63dd5e7bc02b983e2458 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Fri, 15 Nov 2024 10:30:24 -0500 Subject: fanotify: report file range info with pre-content events With group class FAN_CLASS_PRE_CONTENT, report offset and length info along with FAN_PRE_ACCESS pre-content events. This information is meant to be used by hierarchical storage managers that want to fill partial content of files on first access to range. Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara Link: https://patch.msgid.link/b90a9e6c809dd3cad5684da90f23ea93ec6ce8c8.1731684329.git.josef@toxicpanda.com --- include/uapi/linux/fanotify.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h index 7596168c80eb..0636a9c85dd0 100644 --- a/include/uapi/linux/fanotify.h +++ b/include/uapi/linux/fanotify.h @@ -146,6 +146,7 @@ struct fanotify_event_metadata { #define FAN_EVENT_INFO_TYPE_DFID 3 #define FAN_EVENT_INFO_TYPE_PIDFD 4 #define FAN_EVENT_INFO_TYPE_ERROR 5 +#define FAN_EVENT_INFO_TYPE_RANGE 6 /* Special info types for FAN_RENAME */ #define FAN_EVENT_INFO_TYPE_OLD_DFID_NAME 10 @@ -192,6 +193,13 @@ struct fanotify_event_info_error { __u32 error_count; }; +struct fanotify_event_info_range { + struct fanotify_event_info_header hdr; + __u32 pad; + __u64 offset; + __u64 count; +}; + /* * User space may need to record additional information about its decision. * The extra information type records what kind of information is included. -- cgit v1.2.3 From b4b2ff4f61ded819bfa22e50fdec7693f51cbbee Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Fri, 15 Nov 2024 10:30:25 -0500 Subject: fanotify: allow to set errno in FAN_DENY permission response With FAN_DENY response, user trying to perform the filesystem operation gets an error with errno set to EPERM. It is useful for hierarchical storage management (HSM) service to be able to deny access for reasons more diverse than EPERM, for example EAGAIN, if HSM could retry the operation later. Allow fanotify groups with priority FAN_CLASSS_PRE_CONTENT to responsd to permission events with the response value FAN_DENY_ERRNO(errno), instead of FAN_DENY to return a custom error. Limit custom error values to errors expected on read(2)/write(2) and open(2) of regular files. This list could be extended in the future. Userspace can test for legitimate values of FAN_DENY_ERRNO(errno) by writing a response to an fanotify group fd with a value of FAN_NOFD in the fd field of the response. The change in fanotify_response is backward compatible, because errno is written in the high 8 bits of the 32bit response field and old kernels reject respose value with high bits set. Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara Link: https://patch.msgid.link/1e5fb6af84b69ca96b5c849fa5f10bdf4d1dc414.1731684329.git.josef@toxicpanda.com --- include/uapi/linux/fanotify.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h index 0636a9c85dd0..bd8167979707 100644 --- a/include/uapi/linux/fanotify.h +++ b/include/uapi/linux/fanotify.h @@ -235,6 +235,13 @@ struct fanotify_response_info_audit_rule { /* Legit userspace responses to a _PERM event */ #define FAN_ALLOW 0x01 #define FAN_DENY 0x02 +/* errno other than EPERM can specified in upper byte of deny response */ +#define FAN_ERRNO_BITS 8 +#define FAN_ERRNO_SHIFT (32 - FAN_ERRNO_BITS) +#define FAN_ERRNO_MASK ((1 << FAN_ERRNO_BITS) - 1) +#define FAN_DENY_ERRNO(err) \ + (FAN_DENY | ((((__u32)(err)) & FAN_ERRNO_MASK) << FAN_ERRNO_SHIFT)) + #define FAN_AUDIT 0x10 /* Bitmask to create audit record for result */ #define FAN_INFO 0x20 /* Bitmask to indicate additional information */ -- cgit v1.2.3