diff options
| -rw-r--r-- | fs/notify/fanotify/fanotify_user.c | 85 | ||||
| -rw-r--r-- | include/linux/fanotify.h | 3 | ||||
| -rw-r--r-- | include/uapi/linux/fanotify.h | 13 |
3 files changed, 96 insertions, 5 deletions
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index 99d145eaab49..084a83b1214d 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -1,6 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 #include <linux/fanotify.h> #include <linux/fcntl.h> +#include <linux/fdtable.h> #include <linux/file.h> #include <linux/fs.h> #include <linux/anon_inodes.h> @@ -106,6 +107,8 @@ struct kmem_cache *fanotify_perm_event_cachep __read_mostly; #define FANOTIFY_EVENT_ALIGN 4 #define FANOTIFY_FID_INFO_HDR_LEN \ (sizeof(struct fanotify_event_info_fid) + sizeof(struct file_handle)) +#define FANOTIFY_PIDFD_INFO_HDR_LEN \ + sizeof(struct fanotify_event_info_pidfd) static int fanotify_fid_info_len(int fh_len, int name_len) { @@ -138,6 +141,9 @@ static int fanotify_event_info_len(unsigned int info_mode, dot_len = 1; } + if (info_mode & FAN_REPORT_PIDFD) + info_len += FANOTIFY_PIDFD_INFO_HDR_LEN; + if (fh_len) info_len += fanotify_fid_info_len(fh_len, dot_len); @@ -401,13 +407,34 @@ static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh, return info_len; } +static int copy_pidfd_info_to_user(int pidfd, + char __user *buf, + size_t count) +{ + struct fanotify_event_info_pidfd info = { }; + size_t info_len = FANOTIFY_PIDFD_INFO_HDR_LEN; + + if (WARN_ON_ONCE(info_len > count)) + return -EFAULT; + + info.hdr.info_type = FAN_EVENT_INFO_TYPE_PIDFD; + info.hdr.len = info_len; + info.pidfd = pidfd; + + if (copy_to_user(buf, &info, info_len)) + return -EFAULT; + + return info_len; +} + static int copy_info_records_to_user(struct fanotify_event *event, struct fanotify_info *info, - unsigned int info_mode, + unsigned int info_mode, int pidfd, char __user *buf, size_t count) { int ret, total_bytes = 0, info_type = 0; unsigned int fid_mode = info_mode & FANOTIFY_FID_BITS; + unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD; /* * Event info records order is as follows: dir fid + name, child fid. @@ -478,6 +505,16 @@ static int copy_info_records_to_user(struct fanotify_event *event, total_bytes += ret; } + if (pidfd_mode) { + ret = copy_pidfd_info_to_user(pidfd, buf, count); + if (ret < 0) + return ret; + + buf += ret; + count -= ret; + total_bytes += ret; + } + return total_bytes; } @@ -489,8 +526,9 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group, struct path *path = fanotify_event_path(event); struct fanotify_info *info = fanotify_event_info(event); unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES); + unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD; struct file *f = NULL; - int ret, fd = FAN_NOFD; + int ret, pidfd = FAN_NOPIDFD, fd = FAN_NOFD; pr_debug("%s: group=%p event=%p\n", __func__, group, event); @@ -524,6 +562,33 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group, } metadata.fd = fd; + if (pidfd_mode) { + /* + * Complain if the FAN_REPORT_PIDFD and FAN_REPORT_TID mutual + * exclusion is ever lifted. At the time of incoporating pidfd + * support within fanotify, the pidfd API only supported the + * creation of pidfds for thread-group leaders. + */ + WARN_ON_ONCE(FAN_GROUP_FLAG(group, FAN_REPORT_TID)); + + /* + * The PIDTYPE_TGID check for an event->pid is performed + * preemptively in an attempt to catch out cases where the event + * listener reads events after the event generating process has + * already terminated. Report FAN_NOPIDFD to the event listener + * in those cases, with all other pidfd creation errors being + * reported as FAN_EPIDFD. + */ + if (metadata.pid == 0 || + !pid_has_task(event->pid, PIDTYPE_TGID)) { + pidfd = FAN_NOPIDFD; + } else { + pidfd = pidfd_create(event->pid, 0); + if (pidfd < 0) + pidfd = FAN_EPIDFD; + } + } + ret = -EFAULT; /* * Sanity check copy size in case get_one_event() and @@ -545,7 +610,7 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group, fd_install(fd, f); if (info_mode) { - ret = copy_info_records_to_user(event, info, info_mode, + ret = copy_info_records_to_user(event, info, info_mode, pidfd, buf, count); if (ret < 0) goto out_close_fd; @@ -558,6 +623,10 @@ out_close_fd: put_unused_fd(fd); fput(f); } + + if (pidfd >= 0) + close_fd(pidfd); + return ret; } @@ -1103,6 +1172,14 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) #endif return -EINVAL; + /* + * A pidfd can only be returned for a thread-group leader; thus + * FAN_REPORT_PIDFD and FAN_REPORT_TID need to remain mutually + * exclusive. + */ + if ((flags & FAN_REPORT_PIDFD) && (flags & FAN_REPORT_TID)) + return -EINVAL; + if (event_f_flags & ~FANOTIFY_INIT_ALL_EVENT_F_BITS) return -EINVAL; @@ -1504,7 +1581,7 @@ static int __init fanotify_user_setup(void) FANOTIFY_DEFAULT_MAX_USER_MARKS); BUILD_BUG_ON(FANOTIFY_INIT_FLAGS & FANOTIFY_INTERNAL_GROUP_FLAGS); - BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 10); + BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 11); BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 9); fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h index 10a7e26ddba6..eec3b7c40811 100644 --- a/include/linux/fanotify.h +++ b/include/linux/fanotify.h @@ -27,7 +27,7 @@ extern struct ctl_table fanotify_table[]; /* for sysctl */ #define FANOTIFY_FID_BITS (FAN_REPORT_FID | FAN_REPORT_DFID_NAME) -#define FANOTIFY_INFO_MODES (FANOTIFY_FID_BITS) +#define FANOTIFY_INFO_MODES (FANOTIFY_FID_BITS | FAN_REPORT_PIDFD) /* * fanotify_init() flags that require CAP_SYS_ADMIN. @@ -37,6 +37,7 @@ extern struct ctl_table fanotify_table[]; /* for sysctl */ */ #define FANOTIFY_ADMIN_INIT_FLAGS (FANOTIFY_PERM_CLASSES | \ FAN_REPORT_TID | \ + FAN_REPORT_PIDFD | \ FAN_UNLIMITED_QUEUE | \ FAN_UNLIMITED_MARKS) diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h index fbf9c5c7dd59..64553df9d735 100644 --- a/include/uapi/linux/fanotify.h +++ b/include/uapi/linux/fanotify.h @@ -51,6 +51,7 @@ #define FAN_ENABLE_AUDIT 0x00000040 /* Flags to determine fanotify event format */ +#define FAN_REPORT_PIDFD 0x00000080 /* Report pidfd for event->pid */ #define FAN_REPORT_TID 0x00000100 /* event->pid is thread id */ #define FAN_REPORT_FID 0x00000200 /* Report unique file id */ #define FAN_REPORT_DIR_FID 0x00000400 /* Report unique directory id */ @@ -123,6 +124,7 @@ struct fanotify_event_metadata { #define FAN_EVENT_INFO_TYPE_FID 1 #define FAN_EVENT_INFO_TYPE_DFID_NAME 2 #define FAN_EVENT_INFO_TYPE_DFID 3 +#define FAN_EVENT_INFO_TYPE_PIDFD 4 /* Variable length info record following event metadata */ struct fanotify_event_info_header { @@ -148,6 +150,15 @@ struct fanotify_event_info_fid { unsigned char handle[0]; }; +/* + * This structure is used for info records of type FAN_EVENT_INFO_TYPE_PIDFD. + * It holds a pidfd for the pid that was responsible for generating an event. + */ +struct fanotify_event_info_pidfd { + struct fanotify_event_info_header hdr; + __s32 pidfd; +}; + struct fanotify_response { __s32 fd; __u32 response; @@ -160,6 +171,8 @@ struct fanotify_response { /* No fd set in event */ #define FAN_NOFD -1 +#define FAN_NOPIDFD FAN_NOFD +#define FAN_EPIDFD -2 /* Helper functions to deal with fanotify_event_metadata buffers */ #define FAN_EVENT_METADATA_LEN (sizeof(struct fanotify_event_metadata)) |