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2e9906f84f
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 <akpm@linux-foundation.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Fixes: bd82631d7c ("tracing: Add support for dynamic strings to synthetic events")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
116 lines
2.9 KiB
C
116 lines
2.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __TRACE_PROBE_KERNEL_H_
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#define __TRACE_PROBE_KERNEL_H_
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#define FAULT_STRING "(fault)"
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/*
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* This depends on trace_probe.h, but can not include it due to
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* the way trace_probe_tmpl.h is used by trace_kprobe.c and trace_eprobe.c.
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* Which means that any other user must include trace_probe.h before including
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* this file.
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*/
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/* Return the length of string -- including null terminal byte */
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static nokprobe_inline int
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kern_fetch_store_strlen_user(unsigned long addr)
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{
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const void __user *uaddr = (__force const void __user *)addr;
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int ret;
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ret = strnlen_user_nofault(uaddr, MAX_STRING_SIZE);
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/*
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* strnlen_user_nofault returns zero on fault, insert the
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* FAULT_STRING when that occurs.
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*/
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if (ret <= 0)
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return strlen(FAULT_STRING) + 1;
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return ret;
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}
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/* Return the length of string -- including null terminal byte */
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static nokprobe_inline int
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kern_fetch_store_strlen(unsigned long addr)
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{
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int ret, len = 0;
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u8 c;
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#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
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if (addr < TASK_SIZE)
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return kern_fetch_store_strlen_user(addr);
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#endif
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do {
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ret = copy_from_kernel_nofault(&c, (u8 *)addr + len, 1);
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len++;
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} while (c && ret == 0 && len < MAX_STRING_SIZE);
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/* For faults, return enough to hold the FAULT_STRING */
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return (ret < 0) ? strlen(FAULT_STRING) + 1 : len;
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}
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static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void *base, int len)
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{
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if (ret >= 0) {
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*(u32 *)dest = make_data_loc(ret, __dest - base);
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} else {
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strscpy(__dest, FAULT_STRING, len);
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ret = strlen(__dest) + 1;
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}
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}
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/*
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* Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf
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* with max length and relative data location.
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*/
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static nokprobe_inline int
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kern_fetch_store_string_user(unsigned long addr, void *dest, void *base)
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{
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const void __user *uaddr = (__force const void __user *)addr;
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int maxlen = get_loc_len(*(u32 *)dest);
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void *__dest;
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long ret;
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if (unlikely(!maxlen))
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return -ENOMEM;
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__dest = get_loc_data(dest, base);
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ret = strncpy_from_user_nofault(__dest, uaddr, maxlen);
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set_data_loc(ret, dest, __dest, base, maxlen);
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return ret;
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}
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/*
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* Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max
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* length and relative data location.
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*/
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static nokprobe_inline int
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kern_fetch_store_string(unsigned long addr, void *dest, void *base)
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{
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int maxlen = get_loc_len(*(u32 *)dest);
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void *__dest;
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long ret;
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#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
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if ((unsigned long)addr < TASK_SIZE)
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return kern_fetch_store_string_user(addr, dest, base);
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#endif
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if (unlikely(!maxlen))
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return -ENOMEM;
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__dest = get_loc_data(dest, base);
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/*
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* Try to get string again, since the string can be changed while
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* probing.
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*/
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ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen);
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set_data_loc(ret, dest, __dest, base, maxlen);
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return ret;
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}
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#endif /* __TRACE_PROBE_KERNEL_H_ */
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