From: Masami Hiramatsu <mhiramat@kernel.org> To: Christoph Hellwig <hch@lst.de> Cc: x86@kernel.org, Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, Linus Torvalds <torvalds@linux-foundation.org>, Andrew Morton <akpm@linux-foundation.org>, linux-parisc@vger.kernel.org, linux-um@lists.infradead.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 14/23] tracing/kprobes: handle mixed kernel/userspace probes better Date: Fri, 22 May 2020 09:04:50 +0900 [thread overview] Message-ID: <20200522090450.a6ef7a53878c61d10340949a@kernel.org> (raw) In-Reply-To: <20200521152301.2587579-15-hch@lst.de> On Thu, 21 May 2020 17:22:52 +0200 Christoph Hellwig <hch@lst.de> wrote: > Instead of using the dangerous probe_kernel_read and strncpy_from_unsafe > helpers, rework probes to try a user probe based on the address if the > architecture has a common address space for kernel and userspace. > This looks good to me. Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Thank you! > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > kernel/trace/trace_kprobe.c | 72 ++++++++++++++++++++++--------------- > 1 file changed, 43 insertions(+), 29 deletions(-) > > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > index 4325f9e7fadaa..4aeaef53ba970 100644 > --- a/kernel/trace/trace_kprobe.c > +++ b/kernel/trace/trace_kprobe.c > @@ -1200,6 +1200,15 @@ static const struct file_operations kprobe_profile_ops = { > > /* Kprobe specific fetch functions */ > > +/* Return the length of string -- including null terminal byte */ > +static nokprobe_inline int > +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 > fetch_store_strlen(unsigned long addr) > @@ -1207,30 +1216,27 @@ 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 fetch_store_strlen_user(addr); > +#endif > + > do { > - ret = probe_kernel_read(&c, (u8 *)addr + len, 1); > + ret = probe_kernel_read_strict(&c, (u8 *)addr + len, 1); > len++; > } while (c && ret == 0 && len < MAX_STRING_SIZE); > > return (ret < 0) ? ret : len; > } > > -/* Return the length of string -- including null terminal byte */ > -static nokprobe_inline int > -fetch_store_strlen_user(unsigned long addr) > -{ > - const void __user *uaddr = (__force const void __user *)addr; > - > - return strnlen_user_nofault(uaddr, MAX_STRING_SIZE); > -} > - > /* > - * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max > - * length and relative data location. > + * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf > + * with max length and relative data location. > */ > static nokprobe_inline int > -fetch_store_string(unsigned long addr, void *dest, void *base) > +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; > @@ -1240,11 +1246,7 @@ fetch_store_string(unsigned long addr, void *dest, void *base) > > __dest = get_loc_data(dest, base); > > - /* > - * Try to get string again, since the string can be changed while > - * probing. > - */ > - ret = strncpy_from_unsafe(__dest, (void *)addr, maxlen); > + ret = strncpy_from_user_nofault(__dest, uaddr, maxlen); > if (ret >= 0) > *(u32 *)dest = make_data_loc(ret, __dest - base); > > @@ -1252,35 +1254,37 @@ fetch_store_string(unsigned long addr, void *dest, void *base) > } > > /* > - * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf > - * with max length and relative data location. > + * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max > + * length and relative data location. > */ > static nokprobe_inline int > -fetch_store_string_user(unsigned long addr, void *dest, void *base) > +fetch_store_string(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; > > +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE > + if ((unsigned long)addr < TASK_SIZE) > + return fetch_store_string_user(addr, dest, base); > +#endif > + > if (unlikely(!maxlen)) > return -ENOMEM; > > __dest = get_loc_data(dest, base); > > - ret = strncpy_from_user_nofault(__dest, uaddr, maxlen); > + /* > + * Try to get string again, since the string can be changed while > + * probing. > + */ > + ret = strncpy_from_user_nofault(__dest, (void *)addr, maxlen); > if (ret >= 0) > *(u32 *)dest = make_data_loc(ret, __dest - base); > > return ret; > } > > -static nokprobe_inline int > -probe_mem_read(void *dest, void *src, size_t size) > -{ > - return probe_kernel_read(dest, src, size); > -} > - > static nokprobe_inline int > probe_mem_read_user(void *dest, void *src, size_t size) > { > @@ -1289,6 +1293,16 @@ probe_mem_read_user(void *dest, void *src, size_t size) > return probe_user_read(dest, uaddr, size); > } > > +static nokprobe_inline int > +probe_mem_read(void *dest, void *src, size_t size) > +{ > +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE > + if ((unsigned long)src < TASK_SIZE) > + return probe_mem_read_user(dest, src, size); > +#endif > + return probe_kernel_read_strict(dest, src, size); > +} > + > /* Note that we don't verify it, since the code does not come from user space */ > static int > process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest, > -- > 2.26.2 > -- Masami Hiramatsu <mhiramat@kernel.org>
WARNING: multiple messages have this Message-ID (diff)
From: Masami Hiramatsu <mhiramat@kernel.org> To: Christoph Hellwig <hch@lst.de> Cc: linux-parisc@vger.kernel.org, Daniel Borkmann <daniel@iogearbox.net>, netdev@vger.kernel.org, x86@kernel.org, linux-um@lists.infradead.org, Alexei Starovoitov <ast@kernel.org>, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>, Linus Torvalds <torvalds@linux-foundation.org>, bpf@vger.kernel.org Subject: Re: [PATCH 14/23] tracing/kprobes: handle mixed kernel/userspace probes better Date: Fri, 22 May 2020 09:04:50 +0900 [thread overview] Message-ID: <20200522090450.a6ef7a53878c61d10340949a@kernel.org> (raw) In-Reply-To: <20200521152301.2587579-15-hch@lst.de> On Thu, 21 May 2020 17:22:52 +0200 Christoph Hellwig <hch@lst.de> wrote: > Instead of using the dangerous probe_kernel_read and strncpy_from_unsafe > helpers, rework probes to try a user probe based on the address if the > architecture has a common address space for kernel and userspace. > This looks good to me. Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Thank you! > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > kernel/trace/trace_kprobe.c | 72 ++++++++++++++++++++++--------------- > 1 file changed, 43 insertions(+), 29 deletions(-) > > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > index 4325f9e7fadaa..4aeaef53ba970 100644 > --- a/kernel/trace/trace_kprobe.c > +++ b/kernel/trace/trace_kprobe.c > @@ -1200,6 +1200,15 @@ static const struct file_operations kprobe_profile_ops = { > > /* Kprobe specific fetch functions */ > > +/* Return the length of string -- including null terminal byte */ > +static nokprobe_inline int > +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 > fetch_store_strlen(unsigned long addr) > @@ -1207,30 +1216,27 @@ 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 fetch_store_strlen_user(addr); > +#endif > + > do { > - ret = probe_kernel_read(&c, (u8 *)addr + len, 1); > + ret = probe_kernel_read_strict(&c, (u8 *)addr + len, 1); > len++; > } while (c && ret == 0 && len < MAX_STRING_SIZE); > > return (ret < 0) ? ret : len; > } > > -/* Return the length of string -- including null terminal byte */ > -static nokprobe_inline int > -fetch_store_strlen_user(unsigned long addr) > -{ > - const void __user *uaddr = (__force const void __user *)addr; > - > - return strnlen_user_nofault(uaddr, MAX_STRING_SIZE); > -} > - > /* > - * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max > - * length and relative data location. > + * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf > + * with max length and relative data location. > */ > static nokprobe_inline int > -fetch_store_string(unsigned long addr, void *dest, void *base) > +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; > @@ -1240,11 +1246,7 @@ fetch_store_string(unsigned long addr, void *dest, void *base) > > __dest = get_loc_data(dest, base); > > - /* > - * Try to get string again, since the string can be changed while > - * probing. > - */ > - ret = strncpy_from_unsafe(__dest, (void *)addr, maxlen); > + ret = strncpy_from_user_nofault(__dest, uaddr, maxlen); > if (ret >= 0) > *(u32 *)dest = make_data_loc(ret, __dest - base); > > @@ -1252,35 +1254,37 @@ fetch_store_string(unsigned long addr, void *dest, void *base) > } > > /* > - * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf > - * with max length and relative data location. > + * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max > + * length and relative data location. > */ > static nokprobe_inline int > -fetch_store_string_user(unsigned long addr, void *dest, void *base) > +fetch_store_string(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; > > +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE > + if ((unsigned long)addr < TASK_SIZE) > + return fetch_store_string_user(addr, dest, base); > +#endif > + > if (unlikely(!maxlen)) > return -ENOMEM; > > __dest = get_loc_data(dest, base); > > - ret = strncpy_from_user_nofault(__dest, uaddr, maxlen); > + /* > + * Try to get string again, since the string can be changed while > + * probing. > + */ > + ret = strncpy_from_user_nofault(__dest, (void *)addr, maxlen); > if (ret >= 0) > *(u32 *)dest = make_data_loc(ret, __dest - base); > > return ret; > } > > -static nokprobe_inline int > -probe_mem_read(void *dest, void *src, size_t size) > -{ > - return probe_kernel_read(dest, src, size); > -} > - > static nokprobe_inline int > probe_mem_read_user(void *dest, void *src, size_t size) > { > @@ -1289,6 +1293,16 @@ probe_mem_read_user(void *dest, void *src, size_t size) > return probe_user_read(dest, uaddr, size); > } > > +static nokprobe_inline int > +probe_mem_read(void *dest, void *src, size_t size) > +{ > +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE > + if ((unsigned long)src < TASK_SIZE) > + return probe_mem_read_user(dest, src, size); > +#endif > + return probe_kernel_read_strict(dest, src, size); > +} > + > /* Note that we don't verify it, since the code does not come from user space */ > static int > process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest, > -- > 2.26.2 > -- Masami Hiramatsu <mhiramat@kernel.org> _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um
next prev parent reply other threads:[~2020-05-22 0:04 UTC|newest] Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-05-21 15:22 clean up and streamline probe_kernel_* and friends v4 Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-21 15:22 ` [PATCH 01/23] maccess: unexport probe_kernel_write and probe_user_write Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-21 15:22 ` [PATCH 02/23] maccess: remove various unused weak aliases Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-21 15:22 ` [PATCH 03/23] maccess: remove duplicate kerneldoc comments Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-21 15:22 ` [PATCH 04/23] maccess: clarify " Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-21 15:22 ` [PATCH 05/23] maccess: update the top of file comment Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-21 15:22 ` [PATCH 06/23] maccess: rename strncpy_from_unsafe_user to strncpy_from_user_nofault Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-21 15:22 ` [PATCH 07/23] maccess: rename strncpy_from_unsafe_strict to strncpy_from_kernel_nofault Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-21 15:22 ` [PATCH 08/23] maccess: rename strnlen_unsafe_user to strnlen_user_nofault Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-21 15:22 ` [PATCH 09/23] maccess: remove probe_read_common and probe_write_common Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-21 15:22 ` [PATCH 10/23] maccess: unify the probe kernel arch hooks Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-28 0:55 ` Andrew Morton 2020-05-28 0:55 ` Andrew Morton 2020-05-21 15:22 ` [PATCH 11/23] bpf: factor out a bpf_trace_copy_string helper Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-21 22:10 ` Andrii Nakryiko 2020-05-21 22:10 ` Andrii Nakryiko 2020-05-21 22:10 ` Andrii Nakryiko 2020-05-21 15:22 ` [PATCH 12/23] bpf: handle the compat string in bpf_trace_copy_string better Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-21 22:10 ` Andrii Nakryiko 2020-05-21 22:10 ` Andrii Nakryiko 2020-05-21 22:10 ` Andrii Nakryiko 2020-05-28 2:04 ` Andrew Morton 2020-05-28 2:04 ` Andrew Morton 2020-05-28 2:26 ` Yonghong Song 2020-05-28 2:26 ` Yonghong Song 2020-05-28 4:39 ` Christoph Hellwig 2020-05-28 4:39 ` Christoph Hellwig 2020-05-28 17:06 ` Yonghong Song 2020-05-28 17:06 ` Yonghong Song 2020-05-21 15:22 ` [PATCH 13/23] bpf: rework the compat kernel probe handling Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-21 22:10 ` Andrii Nakryiko 2020-05-21 22:10 ` Andrii Nakryiko 2020-05-21 22:10 ` Andrii Nakryiko 2020-05-21 15:22 ` [PATCH 14/23] tracing/kprobes: handle mixed kernel/userspace probes better Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-22 0:04 ` Masami Hiramatsu [this message] 2020-05-22 0:04 ` Masami Hiramatsu 2020-05-21 15:22 ` [PATCH 15/23] maccess: remove strncpy_from_unsafe Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-21 15:22 ` [PATCH 16/23] maccess: always use strict semantics for probe_kernel_read Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-21 15:22 ` [PATCH 17/23] maccess: move user access routines together Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-21 15:22 ` [PATCH 18/23] maccess: allow architectures to provide kernel probing directly Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-21 15:22 ` [PATCH 19/23] x86: use non-set_fs based maccess routines Christoph Hellwig 2020-05-21 15:22 ` Christoph Hellwig 2020-05-21 15:22 ` [PATCH 20/23] maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault Christoph Hellwig 2020-05-21 15:22 ` [PATCH 20/23] maccess: rename probe_kernel_{read, write} to copy_{from, to}_kernel_nofault Christoph Hellwig 2020-05-21 15:22 ` [PATCH 21/23] maccess: rename probe_user_{read,write} to copy_{from,to}_user_nofault Christoph Hellwig 2020-05-21 15:22 ` [PATCH 21/23] maccess: rename probe_user_{read, write} to copy_{from, to}_user_nofault Christoph Hellwig 2020-05-21 15:23 ` [PATCH 22/23] maccess: rename probe_kernel_address to get_kernel_nofault Christoph Hellwig 2020-05-21 15:23 ` Christoph Hellwig 2020-05-21 15:23 ` [PATCH 23/23] maccess: return -ERANGE when copy_from_kernel_nofault_allowed fails Christoph Hellwig 2020-05-21 15:23 ` Christoph Hellwig 2020-05-21 18:03 ` clean up and streamline probe_kernel_* and friends v4 Linus Torvalds 2020-05-21 18:03 ` Linus Torvalds 2020-05-21 18:03 ` Linus Torvalds 2020-05-22 0:22 ` Masami Hiramatsu 2020-05-22 0:22 ` Masami Hiramatsu 2020-05-25 22:19 ` Andrew Morton 2020-05-25 22:19 ` Andrew Morton 2020-05-26 6:13 ` Christoph Hellwig 2020-05-26 6:13 ` Christoph Hellwig 2020-05-28 0:36 ` Andrew Morton 2020-05-28 0:36 ` Andrew Morton
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