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-rw-r--r--fs/notify/fanotify/fanotify_user.c251
-rw-r--r--fs/notify/fsnotify.c6
-rw-r--r--fs/notify/fsnotify.h15
-rw-r--r--fs/notify/mark.c52
-rw-r--r--include/linux/fanotify.h3
-rw-r--r--include/linux/fs.h7
-rw-r--r--include/linux/fsnotify.h9
-rw-r--r--include/linux/pid.h1
-rw-r--r--include/uapi/linux/fanotify.h13
-rw-r--r--kernel/pid.c15
10 files changed, 276 insertions, 96 deletions
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 28b67cb9458d..6facdf476255 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>
@@ -109,8 +110,10 @@ struct kmem_cache *fanotify_path_event_cachep __read_mostly;
struct kmem_cache *fanotify_perm_event_cachep __read_mostly;
#define FANOTIFY_EVENT_ALIGN 4
-#define FANOTIFY_INFO_HDR_LEN \
+#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)
{
@@ -119,10 +122,11 @@ static int fanotify_fid_info_len(int fh_len, int name_len)
if (name_len)
info_len += name_len + 1;
- return roundup(FANOTIFY_INFO_HDR_LEN + info_len, FANOTIFY_EVENT_ALIGN);
+ return roundup(FANOTIFY_FID_INFO_HDR_LEN + info_len,
+ FANOTIFY_EVENT_ALIGN);
}
-static int fanotify_event_info_len(unsigned int fid_mode,
+static int fanotify_event_info_len(unsigned int info_mode,
struct fanotify_event *event)
{
struct fanotify_info *info = fanotify_event_info(event);
@@ -133,7 +137,8 @@ static int fanotify_event_info_len(unsigned int fid_mode,
if (dir_fh_len) {
info_len += fanotify_fid_info_len(dir_fh_len, info->name_len);
- } else if ((fid_mode & FAN_REPORT_NAME) && (event->mask & FAN_ONDIR)) {
+ } else if ((info_mode & FAN_REPORT_NAME) &&
+ (event->mask & FAN_ONDIR)) {
/*
* With group flag FAN_REPORT_NAME, if name was not recorded in
* event on a directory, we will report the name ".".
@@ -141,6 +146,9 @@ static int fanotify_event_info_len(unsigned int fid_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);
@@ -176,7 +184,7 @@ static struct fanotify_event *get_one_event(struct fsnotify_group *group,
size_t event_size = FAN_EVENT_METADATA_LEN;
struct fanotify_event *event = NULL;
struct fsnotify_event *fsn_event;
- unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
+ unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES);
pr_debug("%s: group=%p count=%zd\n", __func__, group, count);
@@ -186,8 +194,8 @@ static struct fanotify_event *get_one_event(struct fsnotify_group *group,
goto out;
event = FANOTIFY_E(fsn_event);
- if (fid_mode)
- event_size += fanotify_event_info_len(fid_mode, event);
+ if (info_mode)
+ event_size += fanotify_event_info_len(info_mode, event);
if (event_size > count) {
event = ERR_PTR(-EINVAL);
@@ -308,9 +316,10 @@ static int process_access_response(struct fsnotify_group *group,
return -ENOENT;
}
-static int copy_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
- int info_type, const char *name, size_t name_len,
- char __user *buf, size_t count)
+static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
+ int info_type, const char *name,
+ size_t name_len,
+ char __user *buf, size_t count)
{
struct fanotify_event_info_fid info = { };
struct file_handle handle = { };
@@ -403,6 +412,117 @@ static int copy_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, 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.
+ */
+ if (fanotify_event_dir_fh_len(event)) {
+ info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME :
+ FAN_EVENT_INFO_TYPE_DFID;
+ ret = copy_fid_info_to_user(fanotify_event_fsid(event),
+ fanotify_info_dir_fh(info),
+ info_type,
+ fanotify_info_name(info),
+ info->name_len, buf, count);
+ if (ret < 0)
+ return ret;
+
+ buf += ret;
+ count -= ret;
+ total_bytes += ret;
+ }
+
+ if (fanotify_event_object_fh_len(event)) {
+ const char *dot = NULL;
+ int dot_len = 0;
+
+ if (fid_mode == FAN_REPORT_FID || info_type) {
+ /*
+ * With only group flag FAN_REPORT_FID only type FID is
+ * reported. Second info record type is always FID.
+ */
+ info_type = FAN_EVENT_INFO_TYPE_FID;
+ } else if ((fid_mode & FAN_REPORT_NAME) &&
+ (event->mask & FAN_ONDIR)) {
+ /*
+ * With group flag FAN_REPORT_NAME, if name was not
+ * recorded in an event on a directory, report the name
+ * "." with info type DFID_NAME.
+ */
+ info_type = FAN_EVENT_INFO_TYPE_DFID_NAME;
+ dot = ".";
+ dot_len = 1;
+ } else if ((event->mask & ALL_FSNOTIFY_DIRENT_EVENTS) ||
+ (event->mask & FAN_ONDIR)) {
+ /*
+ * With group flag FAN_REPORT_DIR_FID, a single info
+ * record has type DFID for directory entry modification
+ * event and for event on a directory.
+ */
+ info_type = FAN_EVENT_INFO_TYPE_DFID;
+ } else {
+ /*
+ * With group flags FAN_REPORT_DIR_FID|FAN_REPORT_FID,
+ * a single info record has type FID for event on a
+ * non-directory, when there is no directory to report.
+ * For example, on FAN_DELETE_SELF event.
+ */
+ info_type = FAN_EVENT_INFO_TYPE_FID;
+ }
+
+ ret = copy_fid_info_to_user(fanotify_event_fsid(event),
+ fanotify_event_object_fh(event),
+ info_type, dot, dot_len,
+ buf, count);
+ if (ret < 0)
+ return ret;
+
+ buf += ret;
+ count -= ret;
+ 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;
+}
+
static ssize_t copy_event_to_user(struct fsnotify_group *group,
struct fanotify_event *event,
char __user *buf, size_t count)
@@ -410,15 +530,15 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
struct fanotify_event_metadata metadata;
struct path *path = fanotify_event_path(event);
struct fanotify_info *info = fanotify_event_info(event);
- unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
+ 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 info_type = 0;
+ int ret, pidfd = FAN_NOPIDFD, fd = FAN_NOFD;
pr_debug("%s: group=%p event=%p\n", __func__, group, event);
metadata.event_len = FAN_EVENT_METADATA_LEN +
- fanotify_event_info_len(fid_mode, event);
+ fanotify_event_info_len(info_mode, event);
metadata.metadata_len = FAN_EVENT_METADATA_LEN;
metadata.vers = FANOTIFY_METADATA_VERSION;
metadata.reserved = 0;
@@ -447,6 +567,33 @@ 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
@@ -467,67 +614,11 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
if (f)
fd_install(fd, f);
- /* Event info records order is: dir fid + name, child fid */
- if (fanotify_event_dir_fh_len(event)) {
- info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME :
- FAN_EVENT_INFO_TYPE_DFID;
- ret = copy_info_to_user(fanotify_event_fsid(event),
- fanotify_info_dir_fh(info),
- info_type, fanotify_info_name(info),
- info->name_len, buf, count);
+ if (info_mode) {
+ ret = copy_info_records_to_user(event, info, info_mode, pidfd,
+ buf, count);
if (ret < 0)
goto out_close_fd;
-
- buf += ret;
- count -= ret;
- }
-
- if (fanotify_event_object_fh_len(event)) {
- const char *dot = NULL;
- int dot_len = 0;
-
- if (fid_mode == FAN_REPORT_FID || info_type) {
- /*
- * With only group flag FAN_REPORT_FID only type FID is
- * reported. Second info record type is always FID.
- */
- info_type = FAN_EVENT_INFO_TYPE_FID;
- } else if ((fid_mode & FAN_REPORT_NAME) &&
- (event->mask & FAN_ONDIR)) {
- /*
- * With group flag FAN_REPORT_NAME, if name was not
- * recorded in an event on a directory, report the
- * name "." with info type DFID_NAME.
- */
- info_type = FAN_EVENT_INFO_TYPE_DFID_NAME;
- dot = ".";
- dot_len = 1;
- } else if ((event->mask & ALL_FSNOTIFY_DIRENT_EVENTS) ||
- (event->mask & FAN_ONDIR)) {
- /*
- * With group flag FAN_REPORT_DIR_FID, a single info
- * record has type DFID for directory entry modification
- * event and for event on a directory.
- */
- info_type = FAN_EVENT_INFO_TYPE_DFID;
- } else {
- /*
- * With group flags FAN_REPORT_DIR_FID|FAN_REPORT_FID,
- * a single info record has type FID for event on a
- * non-directory, when there is no directory to report.
- * For example, on FAN_DELETE_SELF event.
- */
- info_type = FAN_EVENT_INFO_TYPE_FID;
- }
-
- ret = copy_info_to_user(fanotify_event_fsid(event),
- fanotify_event_object_fh(event),
- info_type, dot, dot_len, buf, count);
- if (ret < 0)
- goto out_close_fd;
-
- buf += ret;
- count -= ret;
}
return metadata.event_len;
@@ -537,6 +628,10 @@ out_close_fd:
put_unused_fd(fd);
fput(f);
}
+
+ if (pidfd >= 0)
+ close_fd(pidfd);
+
return ret;
}
@@ -1082,6 +1177,14 @@ 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;
@@ -1483,7 +1586,7 @@ 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/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 30d422b8c0fc..963e6ce75b96 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -87,15 +87,15 @@ static void fsnotify_unmount_inodes(struct super_block *sb)
if (iput_inode)
iput(iput_inode);
- /* Wait for outstanding inode references from connectors */
- wait_var_event(&sb->s_fsnotify_inode_refs,
- !atomic_long_read(&sb->s_fsnotify_inode_refs));
}
void fsnotify_sb_delete(struct super_block *sb)
{
fsnotify_unmount_inodes(sb);
fsnotify_clear_marks_by_sb(sb);
+ /* Wait for outstanding object references from connectors */
+ wait_var_event(&sb->s_fsnotify_connectors,
+ !atomic_long_read(&sb->s_fsnotify_connectors));
}
/*
diff --git a/fs/notify/fsnotify.h b/fs/notify/fsnotify.h
index ff2063ec6b0f..87d8a50ee803 100644
--- a/fs/notify/fsnotify.h
+++ b/fs/notify/fsnotify.h
@@ -27,6 +27,21 @@ static inline struct super_block *fsnotify_conn_sb(
return container_of(conn->obj, struct super_block, s_fsnotify_marks);
}
+static inline struct super_block *fsnotify_connector_sb(
+ struct fsnotify_mark_connector *conn)
+{
+ switch (conn->type) {
+ case FSNOTIFY_OBJ_TYPE_INODE:
+ return fsnotify_conn_inode(conn)->i_sb;
+ case FSNOTIFY_OBJ_TYPE_VFSMOUNT:
+ return fsnotify_conn_mount(conn)->mnt.mnt_sb;
+ case FSNOTIFY_OBJ_TYPE_SB:
+ return fsnotify_conn_sb(conn);
+ default:
+ return NULL;
+ }
+}
+
/* destroy all events sitting in this groups notification queue */
extern void fsnotify_flush_notify(struct fsnotify_group *group);
diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index d32ab349db74..95006d1d29ab 100644
--- a/fs/notify/mark.c
+++ b/fs/notify/mark.c
@@ -169,6 +169,37 @@ static void fsnotify_connector_destroy_workfn(struct work_struct *work)
}
}
+static void fsnotify_get_inode_ref(struct inode *inode)
+{
+ ihold(inode);
+ atomic_long_inc(&inode->i_sb->s_fsnotify_connectors);
+}
+
+static void fsnotify_put_inode_ref(struct inode *inode)
+{
+ struct super_block *sb = inode->i_sb;
+
+ iput(inode);
+ if (atomic_long_dec_and_test(&sb->s_fsnotify_connectors))
+ wake_up_var(&sb->s_fsnotify_connectors);
+}
+
+static void fsnotify_get_sb_connectors(struct fsnotify_mark_connector *conn)
+{
+ struct super_block *sb = fsnotify_connector_sb(conn);
+
+ if (sb)
+ atomic_long_inc(&sb->s_fsnotify_connectors);
+}
+
+static void fsnotify_put_sb_connectors(struct fsnotify_mark_connector *conn)
+{
+ struct super_block *sb = fsnotify_connector_sb(conn);
+
+ if (sb && atomic_long_dec_and_test(&sb->s_fsnotify_connectors))
+ wake_up_var(&sb->s_fsnotify_connectors);
+}
+
static void *fsnotify_detach_connector_from_object(
struct fsnotify_mark_connector *conn,
unsigned int *type)
@@ -182,13 +213,13 @@ static void *fsnotify_detach_connector_from_object(
if (conn->type == FSNOTIFY_OBJ_TYPE_INODE) {
inode = fsnotify_conn_inode(conn);
inode->i_fsnotify_mask = 0;
- atomic_long_inc(&inode->i_sb->s_fsnotify_inode_refs);
} else if (conn->type == FSNOTIFY_OBJ_TYPE_VFSMOUNT) {
fsnotify_conn_mount(conn)->mnt_fsnotify_mask = 0;
} else if (conn->type == FSNOTIFY_OBJ_TYPE_SB) {
fsnotify_conn_sb(conn)->s_fsnotify_mask = 0;
}
+ fsnotify_put_sb_connectors(conn);
rcu_assign_pointer(*(conn->obj), NULL);
conn->obj = NULL;
conn->type = FSNOTIFY_OBJ_TYPE_DETACHED;
@@ -209,19 +240,12 @@ static void fsnotify_final_mark_destroy(struct fsnotify_mark *mark)
/* Drop object reference originally held by a connector */
static void fsnotify_drop_object(unsigned int type, void *objp)
{
- struct inode *inode;
- struct super_block *sb;
-
if (!objp)
return;
/* Currently only inode references are passed to be dropped */
if (WARN_ON_ONCE(type != FSNOTIFY_OBJ_TYPE_INODE))
return;
- inode = objp;
- sb = inode->i_sb;
- iput(inode);
- if (atomic_long_dec_and_test(&sb->s_fsnotify_inode_refs))
- wake_up_var(&sb->s_fsnotify_inode_refs);
+ fsnotify_put_inode_ref(objp);
}
void fsnotify_put_mark(struct fsnotify_mark *mark)
@@ -493,8 +517,12 @@ static int fsnotify_attach_connector_to_object(fsnotify_connp_t *connp,
conn->fsid.val[0] = conn->fsid.val[1] = 0;
conn->flags = 0;
}
- if (conn->type == FSNOTIFY_OBJ_TYPE_INODE)
- inode = igrab(fsnotify_conn_inode(conn));
+ if (conn->type == FSNOTIFY_OBJ_TYPE_INODE) {
+ inode = fsnotify_conn_inode(conn);
+ fsnotify_get_inode_ref(inode);
+ }
+ fsnotify_get_sb_connectors(conn);
+
/*
* cmpxchg() provides the barrier so that readers of *connp can see
* only initialized structure
@@ -502,7 +530,7 @@ static int fsnotify_attach_connector_to_object(fsnotify_connp_t *connp,
if (cmpxchg(connp, NULL, conn)) {
/* Someone else created list structure for us */
if (inode)
- iput(inode);
+ fsnotify_put_inode_ref(inode);
kmem_cache_free(fsnotify_mark_connector_cachep, conn);
}
diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
index a16dbeced152..eec3b7c40811 100644
--- a/include/linux/fanotify.h
+++ b/include/linux/fanotify.h
@@ -27,6 +27,8 @@ 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 | FAN_REPORT_PIDFD)
+
/*
* fanotify_init() flags that require CAP_SYS_ADMIN.
* We do not allow unprivileged groups to request permission events.
@@ -35,6 +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/linux/fs.h b/include/linux/fs.h
index 640574294216..bea8ec5c726c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1507,8 +1507,11 @@ struct super_block {
/* Number of inodes with nlink == 0 but still referenced */
atomic_long_t s_remove_count;
- /* Pending fsnotify inode refs */
- atomic_long_t s_fsnotify_inode_refs;
+ /*
+ * Number of inode/mount/sb objects that are being watched, note that
+ * inodes objects are currently double-accounted.
+ */
+ atomic_long_t s_fsnotify_connectors;
/* Being remounted read-only */
int s_readonly_remount;
diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index f8acddcf54fb..12d3a7d308ab 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -30,6 +30,9 @@ static inline void fsnotify_name(struct inode *dir, __u32 mask,
struct inode *child,
const struct qstr *name, u32 cookie)
{
+ if (atomic_long_read(&dir->i_sb->s_fsnotify_connectors) == 0)
+ return;
+
fsnotify(mask, child, FSNOTIFY_EVENT_INODE, dir, name, NULL, cookie);
}
@@ -41,6 +44,9 @@ static inline void fsnotify_dirent(struct inode *dir, struct dentry *dentry,
static inline void fsnotify_inode(struct inode *inode, __u32 mask)
{
+ if (atomic_long_read(&inode->i_sb->s_fsnotify_connectors) == 0)
+ return;
+
if (S_ISDIR(inode->i_mode))
mask |= FS_ISDIR;
@@ -53,6 +59,9 @@ static inline int fsnotify_parent(struct dentry *dentry, __u32 mask,
{
struct inode *inode = d_inode(dentry);
+ if (atomic_long_read(&inode->i_sb->s_fsnotify_connectors) == 0)
+ return 0;
+
if (S_ISDIR(inode->i_mode)) {
mask |= FS_ISDIR;
diff --git a/include/linux/pid.h b/include/linux/pid.h
index fa10acb8d6a4..af308e15f174 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -78,6 +78,7 @@ struct file;
extern struct pid *pidfd_pid(const struct file *file);
struct pid *pidfd_get_pid(unsigned int fd, unsigned int *flags);
+int pidfd_create(struct pid *pid, unsigned int flags);
static inline struct pid *get_pid(struct pid *pid)
{
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))
diff --git a/kernel/pid.c b/kernel/pid.c
index ebdf9c60cd0b..efe87db44683 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -550,13 +550,21 @@ struct pid *pidfd_get_pid(unsigned int fd, unsigned int *flags)
* Note, that this function can only be called after the fd table has
* been unshared to avoid leaking the pidfd to the new process.
*
+ * This symbol should not be explicitly exported to loadable modules.
+ *
* Return: On success, a cloexec pidfd is returned.
* On error, a negative errno number will be returned.
*/
-static int pidfd_create(struct pid *pid, unsigned int flags)
+int pidfd_create(struct pid *pid, unsigned int flags)
{
int fd;
+ if (!pid || !pid_has_task(pid, PIDTYPE_TGID))
+ return -EINVAL;
+
+ if (flags & ~(O_NONBLOCK | O_RDWR | O_CLOEXEC))
+ return -EINVAL;
+
fd = anon_inode_getfd("[pidfd]", &pidfd_fops, get_pid(pid),
flags | O_RDWR | O_CLOEXEC);
if (fd < 0)
@@ -596,10 +604,7 @@ SYSCALL_DEFINE2(pidfd_open, pid_t, pid, unsigned int, flags)
if (!p)
return -ESRCH;
- if (pid_has_task(p, PIDTYPE_TGID))
- fd = pidfd_create(p, flags);
- else
- fd = -EINVAL;
+ fd = pidfd_create(p, flags);
put_pid(p);
return fd;