diff options
author | Christoph Hellwig <hch@lst.de> | 2020-06-09 07:34:27 +0300 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-06-09 19:39:15 +0300 |
commit | eab0c6089b68974ebc6a9a7eab68456eeb6a99c7 (patch) | |
tree | 6b03656fac37fc4c4e43c74e33a5fd5b9f3d2b68 /mm | |
parent | cd0309058f849257f08d1a3dd0c384d1fd20c1e8 (diff) |
maccess: unify the probe kernel arch hooks
Currently architectures have to override every routine that probes
kernel memory, which includes a pure read and strcpy, both in strict
and not strict variants. Just provide a single arch hooks instead to
make sure all architectures cover all the cases.
[akpm@linux-foundation.org: fix !CONFIG_X86_64 build]
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/20200521152301.2587579-11-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/maccess.c | 50 |
1 files changed, 37 insertions, 13 deletions
diff --git a/mm/maccess.c b/mm/maccess.c index 2526d30739ad..f784da7ed2ad 100644 --- a/mm/maccess.c +++ b/mm/maccess.c @@ -6,6 +6,17 @@ #include <linux/mm.h> #include <linux/uaccess.h> +static long __probe_kernel_read(void *dst, const void *src, size_t size, + bool strict); +static long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, + long count, bool strict); + +bool __weak probe_kernel_read_allowed(const void *unsafe_src, size_t size, + bool strict) +{ + return true; +} + /** * probe_kernel_read(): safely attempt to read from any location * @dst: pointer to the buffer that shall take the data @@ -19,8 +30,11 @@ * 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 probe_kernel_read(void *dst, const void *src, size_t size) - __attribute__((alias("__probe_kernel_read"))); +long probe_kernel_read(void *dst, const void *src, size_t size) +{ + return __probe_kernel_read(dst, src, size, false); +} +EXPORT_SYMBOL_GPL(probe_kernel_read); /** * probe_kernel_read_strict(): safely attempt to read from kernel-space @@ -36,15 +50,20 @@ long __weak probe_kernel_read(void *dst, const void *src, size_t size) * probe_kernel_read() suitable for use within regions where the caller * already holds mmap_lock, or other locks which nest inside mmap_lock. */ +long probe_kernel_read_strict(void *dst, const void *src, size_t size) +{ + return __probe_kernel_read(dst, src, size, true); +} -long __weak probe_kernel_read_strict(void *dst, const void *src, size_t size) - __attribute__((alias("__probe_kernel_read"))); - -long __probe_kernel_read(void *dst, const void *src, size_t size) +static long __probe_kernel_read(void *dst, const void *src, size_t size, + bool strict) { long ret; mm_segment_t old_fs = get_fs(); + if (!probe_kernel_read_allowed(src, size, strict)) + return -EFAULT; + set_fs(KERNEL_DS); pagefault_disable(); ret = __copy_from_user_inatomic(dst, (__force const void __user *)src, @@ -56,7 +75,6 @@ long __probe_kernel_read(void *dst, const void *src, size_t size) return -EFAULT; return 0; } -EXPORT_SYMBOL_GPL(probe_kernel_read); /** * probe_user_read(): safely attempt to read from a user-space location @@ -163,8 +181,10 @@ EXPORT_SYMBOL_GPL(probe_user_write); * 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 strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count) +{ + return __strncpy_from_unsafe(dst, unsafe_addr, count, false); +} /** * strncpy_from_kernel_nofault: - Copy a NUL terminated string from unsafe @@ -184,11 +204,13 @@ long __weak strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count) * 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"))); +long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count) +{ + return __strncpy_from_unsafe(dst, unsafe_addr, count, true); +} -long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count) +static long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, + long count, bool strict) { mm_segment_t old_fs = get_fs(); const void *src = unsafe_addr; @@ -196,6 +218,8 @@ long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count) if (unlikely(count <= 0)) return 0; + if (!probe_kernel_read_allowed(unsafe_addr, count, strict)) + return -EFAULT; set_fs(KERNEL_DS); pagefault_disable(); |