181 lines
5.5 KiB
Diff
181 lines
5.5 KiB
Diff
From e8de2e75d712dd9a750bde130b4367546b46a0bd Mon Sep 17 00:00:00 2001
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From: Karel Zak <kzak@redhat.com>
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Date: Mon, 22 Jan 2024 13:04:44 +0100
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Subject: libmount: ignore unwanted kernel events in monitor
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If the mount operation requires multiple steps, it's optimal for the
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libmount monitor to ignore the steps until we get a complete mount
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(reported by the utab.event file).
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This commit adds a new API function, mnt_monitor_veil_kernel(), to
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ignore unwanted kernel mount events.
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Note that this only makes sense when the application monitors kernel
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and userspace events simultaneously.
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Addresses: https://issues.redhat.com/browse/RHEL-14612
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Upstream: http://github.com/util-linux/util-linux/commit/a2b5a4e0adf9543843bb0aef94d21e7105cf8159
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Signed-off-by: Karel Zak <kzak@redhat.com>
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---
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libmount/docs/libmount-sections.txt | 1 +
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libmount/src/libmount.h.in | 2 ++
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libmount/src/libmount.sym | 1 +
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libmount/src/monitor.c | 55 ++++++++++++++++++++++++++---
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4 files changed, 54 insertions(+), 5 deletions(-)
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diff --git a/libmount/docs/libmount-sections.txt b/libmount/docs/libmount-sections.txt
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index d9263b8ad..43bb80f1c 100644
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--- a/libmount/docs/libmount-sections.txt
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+++ b/libmount/docs/libmount-sections.txt
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@@ -449,5 +449,6 @@ mnt_monitor_get_fd
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mnt_monitor_close_fd
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mnt_monitor_next_change
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mnt_monitor_event_cleanup
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+mnt_monitor_veil_kernel
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mnt_monitor_wait
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</SECTION>
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diff --git a/libmount/src/libmount.h.in b/libmount/src/libmount.h.in
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index a51ac1ea5..b57b6bcd6 100644
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--- a/libmount/src/libmount.h.in
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+++ b/libmount/src/libmount.h.in
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@@ -671,6 +671,8 @@ extern int mnt_monitor_enable_kernel(struct libmnt_monitor *mn, int enable);
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extern int mnt_monitor_enable_userspace(struct libmnt_monitor *mn,
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int enable, const char *filename);
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+extern int mnt_monitor_veil_kernel(struct libmnt_monitor *mn, int enable);
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+
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extern int mnt_monitor_get_fd(struct libmnt_monitor *mn);
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extern int mnt_monitor_close_fd(struct libmnt_monitor *mn);
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extern int mnt_monitor_wait(struct libmnt_monitor *mn, int timeout);
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diff --git a/libmount/src/libmount.sym b/libmount/src/libmount.sym
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index 88bce5c4b..13071b9cd 100644
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--- a/libmount/src/libmount.sym
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+++ b/libmount/src/libmount.sym
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@@ -368,4 +368,5 @@ MOUNT_2_37 {
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MOUNT_2_40 {
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mnt_ref_lock;
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mnt_unref_lock;
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+ mnt_monitor_veil_kernel;
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} MOUNT_2_37;
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diff --git a/libmount/src/monitor.c b/libmount/src/monitor.c
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index 040a5ee11..b5cc7e768 100644
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--- a/libmount/src/monitor.c
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+++ b/libmount/src/monitor.c
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@@ -64,6 +64,8 @@ struct libmnt_monitor {
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int fd; /* public monitor file descriptor */
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struct list_head ents;
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+
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+ unsigned int kernel_veiled: 1;
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};
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struct monitor_opers {
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@@ -469,12 +471,28 @@ err:
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return rc;
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}
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+static int kernel_event_verify(struct libmnt_monitor *mn,
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+ struct monitor_entry *me)
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+{
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+ int status = 1;
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+
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+ if (!mn || !me || me->fd < 0)
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+ return 0;
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+
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+ if (mn->kernel_veiled && access(MNT_PATH_UTAB ".act", F_OK) == 0) {
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+ status = 0;
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+ DBG(MONITOR, ul_debugobj(mn, "kernel event veiled"));
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+ }
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+ return status;
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+}
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+
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/*
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* kernel monitor operations
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*/
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static const struct monitor_opers kernel_opers = {
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.op_get_fd = kernel_monitor_get_fd,
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.op_close_fd = kernel_monitor_close_fd,
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+ .op_event_verify = kernel_event_verify
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};
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/**
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@@ -543,6 +561,28 @@ err:
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return rc;
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}
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+/**
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+ * mnt_monitor_veil_kernel:
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+ * @mn: monitor instance
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+ * @enable: 1 or 0
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+ *
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+ * Force monitor to ignore kernel events if the same mount/umount operation
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+ * will generate an userspace event later. The kernel-only mount operation will
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+ * be not affected.
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+ *
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+ * Return: 0 on success and <0 on error.
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+ *
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+ * Since: 2.40
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+ */
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+int mnt_monitor_veil_kernel(struct libmnt_monitor *mn, int enable)
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+{
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+ if (!mn)
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+ return -EINVAL;
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+
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+ mn->kernel_veiled = enable ? 1 : 0;
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+ return 0;
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+}
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+
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/*
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* Add/Remove monitor entry to/from monitor epoll.
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*/
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@@ -850,6 +890,8 @@ static struct libmnt_monitor *create_test_monitor(int argc, char *argv[])
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warn("failed to initialize kernel monitor");
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goto err;
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}
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+ } else if (strcmp(argv[i], "veil") == 0) {
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+ mnt_monitor_veil_kernel(mn, 1);
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}
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}
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if (i == 1) {
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@@ -896,12 +938,14 @@ static int __test_epoll(struct libmnt_test *ts, int argc, char *argv[], int clea
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goto done;
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}
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- printf("waiting for changes...\n");
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do {
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const char *filename = NULL;
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struct epoll_event events[1];
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- int n = epoll_wait(efd, events, 1, -1);
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+ int n;
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+
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+ printf("waiting for changes...\n");
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+ n = epoll_wait(efd, events, 1, -1);
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if (n < 0) {
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rc = -errno;
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warn("polling error");
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@@ -958,6 +1002,7 @@ static int test_wait(struct libmnt_test *ts, int argc, char *argv[])
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while (mnt_monitor_next_change(mn, &filename, NULL) == 0)
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printf(" %s: change detected\n", filename);
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+ printf("waiting for changes...\n");
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}
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mnt_unref_monitor(mn);
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return 0;
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@@ -966,9 +1011,9 @@ static int test_wait(struct libmnt_test *ts, int argc, char *argv[])
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int main(int argc, char *argv[])
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{
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struct libmnt_test tss[] = {
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- { "--epoll", test_epoll, "<userspace kernel ...> monitor in epoll" },
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- { "--epoll-clean", test_epoll_cleanup, "<userspace kernel ...> monitor in epoll and clean events" },
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- { "--wait", test_wait, "<userspace kernel ...> monitor wait function" },
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+ { "--epoll", test_epoll, "<userspace kernel veil ...> monitor in epoll" },
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+ { "--epoll-clean", test_epoll_cleanup, "<userspace kernel veil ...> monitor in epoll and clean events" },
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+ { "--wait", test_wait, "<userspace kernel veil ...> monitor wait function" },
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{ NULL }
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};
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--
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2.43.0
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