From f1d3cbfaafc10464550c6d3a125f4fc802bbaed5 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" Date: Wed, 12 Oct 2022 06:40:56 -0400 Subject: tracing: Move duplicate code of trace_kprobe/eprobe.c into header The functions: fetch_store_strlen_user() fetch_store_strlen() fetch_store_string_user() fetch_store_string() are identical in both trace_kprobe.c and trace_eprobe.c. Move them into a new header file trace_probe_kernel.h to share it. This code will later be used by the synthetic events as well. Marked for stable as a fix for a crash in synthetic events requires it. Link: https://lkml.kernel.org/r/20221012104534.467668078@goodmis.org Cc: stable@vger.kernel.org Cc: Andrew Morton Cc: Tom Zanussi Acked-by: Masami Hiramatsu (Google) Reviewed-by: Tom Zanussi Fixes: bd82631d7ccdc ("tracing: Add support for dynamic strings to synthetic events") Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_probe_kernel.h | 96 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 96 insertions(+) create mode 100644 kernel/trace/trace_probe_kernel.h (limited to 'kernel/trace/trace_probe_kernel.h') diff --git a/kernel/trace/trace_probe_kernel.h b/kernel/trace/trace_probe_kernel.h new file mode 100644 index 000000000000..1d43df29a1f8 --- /dev/null +++ b/kernel/trace/trace_probe_kernel.h @@ -0,0 +1,96 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __TRACE_PROBE_KERNEL_H_ +#define __TRACE_PROBE_KERNEL_H_ + +/* + * This depends on trace_probe.h, but can not include it due to + * the way trace_probe_tmpl.h is used by trace_kprobe.c and trace_eprobe.c. + * Which means that any other user must include trace_probe.h before including + * this file. + */ +/* Return the length of string -- including null terminal byte */ +static nokprobe_inline int +kern_fetch_store_strlen_user(unsigned long addr) +{ + const void __user *uaddr = (__force const void __user *)addr; + + return strnlen_user_nofault(uaddr, MAX_STRING_SIZE); +} + +/* Return the length of string -- including null terminal byte */ +static nokprobe_inline int +kern_fetch_store_strlen(unsigned long addr) +{ + int ret, len = 0; + u8 c; + +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE + if (addr < TASK_SIZE) + return kern_fetch_store_strlen_user(addr); +#endif + + do { + ret = copy_from_kernel_nofault(&c, (u8 *)addr + len, 1); + len++; + } while (c && ret == 0 && len < MAX_STRING_SIZE); + + return (ret < 0) ? ret : len; +} + +/* + * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf + * with max length and relative data location. + */ +static nokprobe_inline int +kern_fetch_store_string_user(unsigned long addr, void *dest, void *base) +{ + const void __user *uaddr = (__force const void __user *)addr; + int maxlen = get_loc_len(*(u32 *)dest); + void *__dest; + long ret; + + if (unlikely(!maxlen)) + return -ENOMEM; + + __dest = get_loc_data(dest, base); + + ret = strncpy_from_user_nofault(__dest, uaddr, maxlen); + if (ret >= 0) + *(u32 *)dest = make_data_loc(ret, __dest - base); + + return ret; +} + +/* + * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max + * length and relative data location. + */ +static nokprobe_inline int +kern_fetch_store_string(unsigned long addr, void *dest, void *base) +{ + int maxlen = get_loc_len(*(u32 *)dest); + void *__dest; + long ret; + +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE + if ((unsigned long)addr < TASK_SIZE) + return kern_fetch_store_string_user(addr, dest, base); +#endif + + if (unlikely(!maxlen)) + return -ENOMEM; + + __dest = get_loc_data(dest, base); + + /* + * Try to get string again, since the string can be changed while + * probing. + */ + ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen); + if (ret >= 0) + *(u32 *)dest = make_data_loc(ret, __dest - base); + + return ret; +} + +#endif /* __TRACE_PROBE_KERNEL_H_ */ -- cgit v1.2.3 From 2e9906f84fc7c99388bb7123ade167250d50f1c0 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" Date: Wed, 12 Oct 2022 06:40:57 -0400 Subject: tracing: Add "(fault)" name injection to kernel probes Have the specific functions for kernel probes that read strings to inject the "(fault)" name directly. trace_probes.c does this too (for uprobes) but as the code to read strings are going to be used by synthetic events (and perhaps other utilities), it simplifies the code by making sure those other uses do not need to implement the "(fault)" name injection as well. Link: https://lkml.kernel.org/r/20221012104534.644803645@goodmis.org Cc: stable@vger.kernel.org Cc: Andrew Morton Cc: Tom Zanussi Acked-by: Masami Hiramatsu (Google) Reviewed-by: Tom Zanussi Fixes: bd82631d7ccdc ("tracing: Add support for dynamic strings to synthetic events") Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_probe_kernel.h | 31 +++++++++++++++++++++++++------ 1 file changed, 25 insertions(+), 6 deletions(-) (limited to 'kernel/trace/trace_probe_kernel.h') diff --git a/kernel/trace/trace_probe_kernel.h b/kernel/trace/trace_probe_kernel.h index 1d43df29a1f8..77dbd9ff9782 100644 --- a/kernel/trace/trace_probe_kernel.h +++ b/kernel/trace/trace_probe_kernel.h @@ -2,6 +2,8 @@ #ifndef __TRACE_PROBE_KERNEL_H_ #define __TRACE_PROBE_KERNEL_H_ +#define FAULT_STRING "(fault)" + /* * This depends on trace_probe.h, but can not include it due to * the way trace_probe_tmpl.h is used by trace_kprobe.c and trace_eprobe.c. @@ -13,8 +15,16 @@ static nokprobe_inline int kern_fetch_store_strlen_user(unsigned long addr) { const void __user *uaddr = (__force const void __user *)addr; + int ret; - return strnlen_user_nofault(uaddr, MAX_STRING_SIZE); + ret = strnlen_user_nofault(uaddr, MAX_STRING_SIZE); + /* + * strnlen_user_nofault returns zero on fault, insert the + * FAULT_STRING when that occurs. + */ + if (ret <= 0) + return strlen(FAULT_STRING) + 1; + return ret; } /* Return the length of string -- including null terminal byte */ @@ -34,7 +44,18 @@ kern_fetch_store_strlen(unsigned long addr) len++; } while (c && ret == 0 && len < MAX_STRING_SIZE); - return (ret < 0) ? ret : len; + /* For faults, return enough to hold the FAULT_STRING */ + return (ret < 0) ? strlen(FAULT_STRING) + 1 : len; +} + +static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void *base, int len) +{ + if (ret >= 0) { + *(u32 *)dest = make_data_loc(ret, __dest - base); + } else { + strscpy(__dest, FAULT_STRING, len); + ret = strlen(__dest) + 1; + } } /* @@ -55,8 +76,7 @@ kern_fetch_store_string_user(unsigned long addr, void *dest, void *base) __dest = get_loc_data(dest, base); ret = strncpy_from_user_nofault(__dest, uaddr, maxlen); - if (ret >= 0) - *(u32 *)dest = make_data_loc(ret, __dest - base); + set_data_loc(ret, dest, __dest, base, maxlen); return ret; } @@ -87,8 +107,7 @@ kern_fetch_store_string(unsigned long addr, void *dest, void *base) * probing. */ ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen); - if (ret >= 0) - *(u32 *)dest = make_data_loc(ret, __dest - base); + set_data_loc(ret, dest, __dest, base, maxlen); return ret; } -- cgit v1.2.3