commit c4cb164426aebd635baa53685b0ebf1a127e9803 upstream
This matches the naming of strncpy_from_user_nofault, and also makes it more clear what the function is supposed to do.
conflict resolution: comments in mm/maccess.c
Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: Andrew Morton akpm@linux-foundation.org Cc: Alexei Starovoitov ast@kernel.org Cc: Daniel Borkmann daniel@iogearbox.net Cc: "H. Peter Anvin" hpa@zytor.com Cc: Ingo Molnar mingo@elte.hu Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Thomas Gleixner tglx@linutronix.de Link: http://lkml.kernel.org/r/20200521152301.2587579-8-hch@lst.de Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Cc: stable@vger.kernel.org # 5.4 Signed-off-by: Tsahi Zidenberg tsahee@amazon.com --- arch/x86/mm/maccess.c | 2 +- include/linux/uaccess.h | 4 ++-- kernel/trace/bpf_trace.c | 4 ++-- mm/maccess.c | 31 +++++++++++++++++++++++++------ 4 files changed, 30 insertions(+), 11 deletions(-)
diff --git a/arch/x86/mm/maccess.c b/arch/x86/mm/maccess.c index f5b85bdc0535..62c4017a2473 100644 --- a/arch/x86/mm/maccess.c +++ b/arch/x86/mm/maccess.c @@ -34,7 +34,7 @@ long probe_kernel_read_strict(void *dst, const void *src, size_t size) return __probe_kernel_read(dst, src, size); } -long strncpy_from_unsafe_strict(char *dst, const void *unsafe_addr, long count) +long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count) { if (unlikely(invalid_probe_range((unsigned long)unsafe_addr))) return -EFAULT; diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index 23e655549be2..7c61d3ddae57 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -351,8 +351,8 @@ extern long notrace probe_user_write(void __user *dst, const void *src, size_t s extern long notrace __probe_user_write(void __user *dst, const void *src, size_t size); extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count); -extern long strncpy_from_unsafe_strict(char *dst, const void *unsafe_addr, - long count); +long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, + long count); extern long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count); long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr, long count); diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 720d78c62d05..7b905aa800b2 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -242,7 +242,7 @@ bpf_probe_read_kernel_str_common(void *dst, u32 size, const void *unsafe_ptr, * is returned that can be used for bpf_perf_event_output() et al. */ ret = compat ? strncpy_from_unsafe(dst, unsafe_ptr, size) : - strncpy_from_unsafe_strict(dst, unsafe_ptr, size); + strncpy_from_kernel_nofault(dst, unsafe_ptr, size); if (unlikely(ret < 0)) out: memset(dst, 0, size); @@ -414,7 +414,7 @@ BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1, break; #endif case 'k': - strncpy_from_unsafe_strict(buf, unsafe_ptr, + strncpy_from_kernel_nofault(buf, unsafe_ptr, sizeof(buf)); break; case 'u': diff --git a/mm/maccess.c b/mm/maccess.c index 84c598673aa9..82863bc6b550 100644 --- a/mm/maccess.c +++ b/mm/maccess.c @@ -167,17 +167,36 @@ EXPORT_SYMBOL_GPL(probe_user_write); * If @count is smaller than the length of the string, copies @count-1 bytes, * sets the last byte of @dst buffer to NUL and returns @count. * - * strncpy_from_unsafe_strict() is the same as strncpy_from_unsafe() except - * for the case where architectures have non-overlapping user and kernel address - * ranges: strncpy_from_unsafe_strict() will additionally return -EFAULT for - * probing memory on a user address range where strncpy_from_unsafe_user() is - * supposed to be used instead. + * Same as strncpy_from_kernel_nofault() except that for architectures with + * not fully separated user and kernel address spaces this function also works + * for user address tanges. + * + * DO NOT USE THIS FUNCTION - it is broken on architectures with entirely + * separate kernel and user address spaces, and also a bad idea otherwise. */ long __weak strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count) __attribute__((alias("__strncpy_from_unsafe"))); -long __weak strncpy_from_unsafe_strict(char *dst, const void *unsafe_addr, +/** + * strncpy_from_kernel_nofault: - Copy a NUL terminated string from unsafe + * address. + * @dst: Destination address, in kernel space. This buffer must be at + * least @count bytes long. + * @unsafe_addr: Unsafe address. + * @count: Maximum number of bytes to copy, including the trailing NUL. + * + * Copies a NUL-terminated string from unsafe address to kernel buffer. + * + * On success, returns the length of the string INCLUDING the trailing NUL. + * + * If access fails, returns -EFAULT (some data may have been copied + * and the trailing NUL added). + * + * If @count is smaller than the length of the string, copies @count-1 bytes, + * sets the last byte of @dst buffer to NUL and returns @count. + */ +long __weak strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count) __attribute__((alias("__strncpy_from_unsafe")));