From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- drivers/tty/tty_audit.c | 251 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 251 insertions(+) create mode 100644 drivers/tty/tty_audit.c (limited to 'drivers/tty/tty_audit.c') diff --git a/drivers/tty/tty_audit.c b/drivers/tty/tty_audit.c new file mode 100644 index 000000000..d014af6ab --- /dev/null +++ b/drivers/tty/tty_audit.c @@ -0,0 +1,251 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Creating audit events from TTY input. + * + * Copyright (C) 2007 Red Hat, Inc. All rights reserved. + * + * Authors: Miloslav Trmac + */ + +#include +#include +#include +#include "tty.h" + +#define TTY_AUDIT_BUF_SIZE 4096 + +struct tty_audit_buf { + struct mutex mutex; /* Protects all data below */ + dev_t dev; /* The TTY which the data is from */ + bool icanon; + size_t valid; + u8 *data; /* Allocated size TTY_AUDIT_BUF_SIZE */ +}; + +static struct tty_audit_buf *tty_audit_buf_ref(void) +{ + struct tty_audit_buf *buf; + + buf = current->signal->tty_audit_buf; + WARN_ON(buf == ERR_PTR(-ESRCH)); + return buf; +} + +static struct tty_audit_buf *tty_audit_buf_alloc(void) +{ + struct tty_audit_buf *buf; + + buf = kzalloc_obj(*buf); + if (!buf) + goto err; + + buf->data = kmalloc(TTY_AUDIT_BUF_SIZE, GFP_KERNEL); + if (!buf->data) + goto err_buf; + + mutex_init(&buf->mutex); + + return buf; + +err_buf: + kfree(buf); +err: + return NULL; +} + +static void tty_audit_buf_free(struct tty_audit_buf *buf) +{ + WARN_ON(buf->valid != 0); + kfree(buf->data); + kfree(buf); +} + +static void tty_audit_log(const char *description, dev_t dev, + const u8 *data, size_t size) +{ + struct audit_buffer *ab; + pid_t pid = task_pid_nr(current); + uid_t uid = from_kuid(&init_user_ns, task_uid(current)); + uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(current)); + unsigned int sessionid = audit_get_sessionid(current); + char name[TASK_COMM_LEN]; + + ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_TTY); + if (!ab) + return; + + audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u major=%d minor=%d comm=", + description, pid, uid, loginuid, sessionid, + MAJOR(dev), MINOR(dev)); + get_task_comm(name, current); + audit_log_untrustedstring(ab, name); + audit_log_format(ab, " data="); + audit_log_n_hex(ab, data, size); + audit_log_end(ab); +} + +/* + * tty_audit_buf_push - Push buffered data out + * + * Generate an audit message from the contents of @buf, which is owned by + * the current task. @buf->mutex must be locked. + */ +static void tty_audit_buf_push(struct tty_audit_buf *buf) +{ + if (buf->valid == 0) + return; + if (audit_enabled == AUDIT_OFF) { + buf->valid = 0; + return; + } + tty_audit_log("tty", buf->dev, buf->data, buf->valid); + buf->valid = 0; +} + +/** + * tty_audit_exit - Handle a task exit + * + * Make sure all buffered data is written out and deallocate the buffer. + * Only needs to be called if current->signal->tty_audit_buf != %NULL. + * + * The process is single-threaded at this point; no other threads share + * current->signal. + */ +void tty_audit_exit(void) +{ + struct tty_audit_buf *buf; + + buf = xchg(¤t->signal->tty_audit_buf, ERR_PTR(-ESRCH)); + if (!buf) + return; + + tty_audit_buf_push(buf); + tty_audit_buf_free(buf); +} + +/* + * tty_audit_fork - Copy TTY audit state for a new task + * + * Set up TTY audit state in @sig from current. @sig needs no locking. + */ +void tty_audit_fork(struct signal_struct *sig) +{ + sig->audit_tty = current->signal->audit_tty; +} + +/* + * tty_audit_tiocsti - Log TIOCSTI + */ +void tty_audit_tiocsti(const struct tty_struct *tty, u8 ch) +{ + dev_t dev; + + dev = MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index; + if (tty_audit_push()) + return; + + if (audit_enabled) + tty_audit_log("ioctl=TIOCSTI", dev, &ch, 1); +} + +/* + * tty_audit_push - Flush current's pending audit data + * + * Returns 0 if success, -EPERM if tty audit is disabled + */ +int tty_audit_push(void) +{ + struct tty_audit_buf *buf; + + if (~current->signal->audit_tty & AUDIT_TTY_ENABLE) + return -EPERM; + + buf = tty_audit_buf_ref(); + if (!IS_ERR_OR_NULL(buf)) { + mutex_lock(&buf->mutex); + tty_audit_buf_push(buf); + mutex_unlock(&buf->mutex); + } + return 0; +} + +/* + * tty_audit_buf_get - Get an audit buffer. + * + * Get an audit buffer, allocate it if necessary. Return %NULL + * if out of memory or ERR_PTR(-ESRCH) if tty_audit_exit() has already + * occurred. Otherwise, return a new reference to the buffer. + */ +static struct tty_audit_buf *tty_audit_buf_get(void) +{ + struct tty_audit_buf *buf; + + buf = tty_audit_buf_ref(); + if (buf) + return buf; + + buf = tty_audit_buf_alloc(); + if (buf == NULL) { + audit_log_lost("out of memory in TTY auditing"); + return NULL; + } + + /* Race to use this buffer, free it if another wins */ + if (cmpxchg(¤t->signal->tty_audit_buf, NULL, buf) != NULL) + tty_audit_buf_free(buf); + return tty_audit_buf_ref(); +} + +/* + * tty_audit_add_data - Add data for TTY auditing. + * + * Audit @data of @size from @tty, if necessary. + */ +void tty_audit_add_data(const struct tty_struct *tty, const void *data, + size_t size) +{ + struct tty_audit_buf *buf; + unsigned int audit_tty; + bool icanon = L_ICANON(tty); + dev_t dev; + + audit_tty = READ_ONCE(current->signal->audit_tty); + if (~audit_tty & AUDIT_TTY_ENABLE) + return; + + if (unlikely(size == 0)) + return; + + if (tty->driver->type == TTY_DRIVER_TYPE_PTY + && tty->driver->subtype == PTY_TYPE_MASTER) + return; + + if ((~audit_tty & AUDIT_TTY_LOG_PASSWD) && icanon && !L_ECHO(tty)) + return; + + buf = tty_audit_buf_get(); + if (IS_ERR_OR_NULL(buf)) + return; + + mutex_lock(&buf->mutex); + dev = MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index; + if (buf->dev != dev || buf->icanon != icanon) { + tty_audit_buf_push(buf); + buf->dev = dev; + buf->icanon = icanon; + } + do { + size_t run; + + run = TTY_AUDIT_BUF_SIZE - buf->valid; + if (run > size) + run = size; + memcpy(buf->data + buf->valid, data, run); + buf->valid += run; + data += run; + size -= run; + if (buf->valid == TTY_AUDIT_BUF_SIZE) + tty_audit_buf_push(buf); + } while (size != 0); + mutex_unlock(&buf->mutex); +} -- cgit v1.3.1