| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <20250624180742.5795-4-sashal@kernel.org>
Date: Tue, 24 Jun 2025 14:07:23 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: linux-doc@...r.kernel.org,
linux-api@...r.kernel.org,
workflows@...r.kernel.org,
tools@...nel.org,
Sasha Levin <sashal@...nel.org>
Subject: [RFC v2 03/22] eventpoll: add API specification for epoll_create
Add kernel API specification for the epoll_create() system call.
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
fs/eventpoll.c | 122 +++++++++++++++++++++++++++++++-
include/linux/kernel_api_spec.h | 13 ++++
2 files changed, 132 insertions(+), 3 deletions(-)
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 620de3ccc7708..c3c16f8e6ac7d 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -2300,8 +2300,8 @@ DEFINE_KERNEL_API_SPEC(sys_epoll_create1)
KAPI_ERROR(4, -EINTR, "EINTR", "Interrupted by signal",
"The system call was interrupted by a signal before the epoll instance could be created.")
- .error_count = 5,
- .param_count = 1,
+ KAPI_ERROR_COUNT(5)
+ KAPI_PARAM_COUNT(1)
.since_version = "2.6.27",
KAPI_EXAMPLES("int epfd = epoll_create1(EPOLL_CLOEXEC);")
KAPI_NOTES("EPOLL_CLOEXEC sets the close-on-exec (FD_CLOEXEC) flag on the new file descriptor. "
@@ -2366,7 +2366,7 @@ DEFINE_KERNEL_API_SPEC(sys_epoll_create1)
KAPI_SIGNAL_QUEUE("uncatchable")
KAPI_SIGNAL_END
- .signal_count = 3,
+ KAPI_SIGNAL_COUNT(3)
/* Additional constraints */
KAPI_CONSTRAINT(0, "User Watch Limit",
@@ -2394,6 +2394,122 @@ SYSCALL_DEFINE1(epoll_create1, int, flags)
return do_epoll_create(flags);
}
+
+DEFINE_KERNEL_API_SPEC(sys_epoll_create)
+ KAPI_DESCRIPTION("Create an epoll instance (obsolete)")
+ KAPI_LONG_DESC("Creates a new epoll instance and returns a file descriptor "
+ "referring to that instance. This is the obsolete interface; "
+ "new applications should use epoll_create1() instead.")
+ KAPI_CONTEXT(KAPI_CTX_PROCESS | KAPI_CTX_SLEEPABLE)
+
+ KAPI_PARAM(0, "size", "int", "Ignored hint about expected number of file descriptors")
+ KAPI_PARAM_FLAGS(KAPI_PARAM_IN)
+ KAPI_PARAM_RANGE(1, INT_MAX)
+ KAPI_PARAM_CONSTRAINT_TYPE(KAPI_CONSTRAINT_RANGE)
+ KAPI_PARAM_CONSTRAINT("Must be greater than zero (ignored since Linux 2.6.8)")
+ KAPI_PARAM_END
+
+ KAPI_RETURN("long", "File descriptor on success, negative error code on failure")
+ KAPI_RETURN_TYPE(KAPI_TYPE_INT)
+ KAPI_RETURN_CHECK_TYPE(KAPI_RETURN_FD)
+ KAPI_RETURN_END
+
+ KAPI_ERROR(0, -EINVAL, "EINVAL", "size <= 0",
+ "The size parameter must be greater than zero.")
+ KAPI_ERROR(1, -EMFILE, "EMFILE", "Per-process file descriptor limit reached",
+ "The per-process limit on the number of open file descriptors has been reached.")
+ KAPI_ERROR(2, -ENFILE, "ENFILE", "System file table overflow",
+ "The system-wide limit on the total number of open files has been reached.")
+ KAPI_ERROR(3, -ENOMEM, "ENOMEM", "Insufficient kernel memory",
+ "There was insufficient kernel memory to create the epoll instance.")
+ KAPI_ERROR(4, -EINTR, "EINTR", "Interrupted by signal",
+ "The system call was interrupted by a signal before the epoll instance could be created.")
+
+ KAPI_ERROR_COUNT(5)
+ KAPI_PARAM_COUNT(1)
+ KAPI_SINCE_VERSION("2.6")
+ KAPI_DEPRECATED
+ KAPI_REPLACEMENT("epoll_create1")
+ KAPI_EXAMPLES("int epfd = epoll_create(1024); // size is ignored since Linux 2.6.8")
+ KAPI_NOTES("Since Linux 2.6.8, the size argument is ignored but must be greater than zero. "
+ "The kernel dynamically sizes the data structures as needed. "
+ "For new applications, epoll_create1() should be preferred as it allows "
+ "setting close-on-exec flag atomically. "
+ "Memory consumption: Each registered fd uses approximately 90 bytes on 32-bit kernels "
+ "and 160 bytes on 64-bit kernels. The total number of file descriptors registered "
+ "across all epoll instances is limited by /proc/sys/fs/epoll/max_user_watches. "
+ "When using dup() or fork(), multiple file descriptors may refer to the same epoll "
+ "instance and all will receive events.")
+
+ /* Side effects */
+ KAPI_SIDE_EFFECT(0, KAPI_EFFECT_RESOURCE_CREATE | KAPI_EFFECT_ALLOC_MEMORY,
+ "epoll instance",
+ "Creates a new epoll instance and allocates kernel memory for it")
+ KAPI_EFFECT_CONDITION("Always when successful")
+ KAPI_EFFECT_REVERSIBLE
+ KAPI_SIDE_EFFECT_END
+
+ KAPI_SIDE_EFFECT(1, KAPI_EFFECT_RESOURCE_CREATE,
+ "file descriptor",
+ "Allocates a new file descriptor in the process's file descriptor table")
+ KAPI_EFFECT_CONDITION("Always when successful")
+ KAPI_EFFECT_REVERSIBLE
+ KAPI_SIDE_EFFECT_END
+
+ KAPI_SIDE_EFFECT(2, KAPI_EFFECT_MODIFY_STATE,
+ "kernel file table",
+ "Adds new file structure to system-wide file table")
+ KAPI_EFFECT_CONDITION("Always when successful")
+ KAPI_EFFECT_REVERSIBLE
+ KAPI_SIDE_EFFECT_END
+
+ KAPI_SIDE_EFFECT_COUNT(3)
+
+ /* State transitions */
+ KAPI_STATE_TRANS(0, "epoll instance", "non-existent", "created and empty",
+ "A new epoll instance is created with no monitored file descriptors")
+ KAPI_STATE_TRANS_COND("On successful creation")
+ KAPI_STATE_TRANS_END
+
+ KAPI_STATE_TRANS(1, "file descriptor", "unallocated", "allocated and open",
+ "A new file descriptor is allocated in the process's fd table")
+ KAPI_STATE_TRANS_COND("On successful creation")
+ KAPI_STATE_TRANS_END
+
+ KAPI_STATE_TRANS_COUNT(2)
+
+ /* Signal specifications */
+ KAPI_SIGNAL(0, SIGINT, "SIGINT", KAPI_SIGNAL_RECEIVE, KAPI_SIGNAL_ACTION_RETURN)
+ KAPI_SIGNAL_CONDITION("During kernel memory allocation")
+ KAPI_SIGNAL_DESC("If interrupted during memory allocation or fd allocation, returns -EINTR")
+ KAPI_SIGNAL_RESTARTABLE
+ KAPI_SIGNAL_END
+
+ KAPI_SIGNAL(1, SIGTERM, "SIGTERM", KAPI_SIGNAL_RECEIVE, KAPI_SIGNAL_ACTION_RETURN)
+ KAPI_SIGNAL_CONDITION("During kernel memory allocation")
+ KAPI_SIGNAL_DESC("If interrupted during memory allocation or fd allocation, returns -EINTR")
+ KAPI_SIGNAL_RESTARTABLE
+ KAPI_SIGNAL_END
+
+ KAPI_SIGNAL(2, SIGKILL, "SIGKILL", KAPI_SIGNAL_RECEIVE, KAPI_SIGNAL_ACTION_TERMINATE)
+ KAPI_SIGNAL_CONDITION("At any point during the syscall")
+ KAPI_SIGNAL_DESC("Process is terminated immediately, epoll instance creation may be incomplete")
+ KAPI_SIGNAL_END
+
+ KAPI_SIGNAL(3, SIGHUP, "SIGHUP", KAPI_SIGNAL_RECEIVE, KAPI_SIGNAL_ACTION_RETURN)
+ KAPI_SIGNAL_CONDITION("During kernel operations")
+ KAPI_SIGNAL_DESC("If process is being terminated due to terminal hangup, may return -EINTR")
+ KAPI_SIGNAL_RESTARTABLE
+ KAPI_SIGNAL_END
+
+ KAPI_SIGNAL(4, SIGPIPE, "SIGPIPE", KAPI_SIGNAL_IGNORE, KAPI_SIGNAL_ACTION_DEFAULT)
+ KAPI_SIGNAL_CONDITION("Never generated by epoll_create")
+ KAPI_SIGNAL_DESC("This signal is not relevant to epoll_create as it doesn't involve pipes")
+ KAPI_SIGNAL_END
+
+ KAPI_SIGNAL_COUNT(5)
+KAPI_END_SPEC;
+
SYSCALL_DEFINE1(epoll_create, int, size)
{
if (size <= 0)
diff --git a/include/linux/kernel_api_spec.h b/include/linux/kernel_api_spec.h
index d8439d411f41e..1ee76a5f3ee1f 100644
--- a/include/linux/kernel_api_spec.h
+++ b/include/linux/kernel_api_spec.h
@@ -963,6 +963,19 @@ struct kernel_api_spec {
#define KAPI_NOTES(n) \
.notes = n,
+/**
+ * KAPI_DEPRECATED - Mark API as deprecated
+ */
+#define KAPI_DEPRECATED \
+ .deprecated = true,
+
+/**
+ * KAPI_REPLACEMENT - Set replacement API for deprecated function
+ * @repl: Replacement API name
+ */
+#define KAPI_REPLACEMENT(repl) \
+ .replacement = repl,
+
/**
* KAPI_SIGNAL - Define a signal specification
* @idx: Signal index
--
2.39.5
Powered by blists - more mailing lists