From 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 Mon Sep 17 00:00:00 2001 From: Yunhong Jiang Date: Tue, 4 Aug 2015 12:17:53 -0700 Subject: Add the rt linux 4.1.3-rt3 as base Import the rt linux 4.1.3-rt3 as OPNFV kvm base. It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and the base is: commit 0917f823c59692d751951bf5ea699a2d1e2f26a2 Author: Sebastian Andrzej Siewior Date: Sat Jul 25 12:13:34 2015 +0200 Prepare v4.1.3-rt3 Signed-off-by: Sebastian Andrzej Siewior We lose all the git history this way and it's not good. We should apply another opnfv project repo in future. Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423 Signed-off-by: Yunhong Jiang --- kernel/lib/strnlen_user.c | 148 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 148 insertions(+) create mode 100644 kernel/lib/strnlen_user.c (limited to 'kernel/lib/strnlen_user.c') diff --git a/kernel/lib/strnlen_user.c b/kernel/lib/strnlen_user.c new file mode 100644 index 000000000..3a5f2b366 --- /dev/null +++ b/kernel/lib/strnlen_user.c @@ -0,0 +1,148 @@ +#include +#include +#include + +#include + +/* Set bits in the first 'n' bytes when loaded from memory */ +#ifdef __LITTLE_ENDIAN +# define aligned_byte_mask(n) ((1ul << 8*(n))-1) +#else +# define aligned_byte_mask(n) (~0xfful << (BITS_PER_LONG - 8 - 8*(n))) +#endif + +/* + * Do a strnlen, return length of string *with* final '\0'. + * 'count' is the user-supplied count, while 'max' is the + * address space maximum. + * + * Return 0 for exceptions (which includes hitting the address + * space maximum), or 'count+1' if hitting the user-supplied + * maximum count. + * + * NOTE! We can sometimes overshoot the user-supplied maximum + * if it fits in a aligned 'long'. The caller needs to check + * the return value against "> max". + */ +static inline long do_strnlen_user(const char __user *src, unsigned long count, unsigned long max) +{ + const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; + long align, res = 0; + unsigned long c; + + /* + * Truncate 'max' to the user-specified limit, so that + * we only have one limit we need to check in the loop + */ + if (max > count) + max = count; + + /* + * Do everything aligned. But that means that we + * need to also expand the maximum.. + */ + align = (sizeof(long) - 1) & (unsigned long)src; + src -= align; + max += align; + + if (unlikely(__get_user(c,(unsigned long __user *)src))) + return 0; + c |= aligned_byte_mask(align); + + for (;;) { + unsigned long data; + if (has_zero(c, &data, &constants)) { + data = prep_zero_mask(c, data, &constants); + data = create_zero_mask(data); + return res + find_zero(data) + 1 - align; + } + res += sizeof(unsigned long); + /* We already handled 'unsigned long' bytes. Did we do it all ? */ + if (unlikely(max <= sizeof(unsigned long))) + break; + max -= sizeof(unsigned long); + if (unlikely(__get_user(c,(unsigned long __user *)(src+res)))) + return 0; + } + res -= align; + + /* + * Uhhuh. We hit 'max'. But was that the user-specified maximum + * too? If so, return the marker for "too long". + */ + if (res >= count) + return count+1; + + /* + * Nope: we hit the address space limit, and we still had more + * characters the caller would have wanted. That's 0. + */ + return 0; +} + +/** + * strnlen_user: - Get the size of a user string INCLUDING final NUL. + * @str: The string to measure. + * @count: Maximum count (including NUL character) + * + * Context: User context only. This function may sleep if pagefaults are + * enabled. + * + * Get the size of a NUL-terminated string in user space. + * + * Returns the size of the string INCLUDING the terminating NUL. + * If the string is too long, returns a number larger than @count. User + * has to check the return value against "> count". + * On exception (or invalid count), returns 0. + * + * NOTE! You should basically never use this function. There is + * almost never any valid case for using the length of a user space + * string, since the string can be changed at any time by other + * threads. Use "strncpy_from_user()" instead to get a stable copy + * of the string. + */ +long strnlen_user(const char __user *str, long count) +{ + unsigned long max_addr, src_addr; + + if (unlikely(count <= 0)) + return 0; + + max_addr = user_addr_max(); + src_addr = (unsigned long)str; + if (likely(src_addr < max_addr)) { + unsigned long max = max_addr - src_addr; + return do_strnlen_user(str, count, max); + } + return 0; +} +EXPORT_SYMBOL(strnlen_user); + +/** + * strlen_user: - Get the size of a user string INCLUDING final NUL. + * @str: The string to measure. + * + * Context: User context only. This function may sleep if pagefaults are + * enabled. + * + * Get the size of a NUL-terminated string in user space. + * + * Returns the size of the string INCLUDING the terminating NUL. + * On exception, returns 0. + * + * If there is a limit on the length of a valid string, you may wish to + * consider using strnlen_user() instead. + */ +long strlen_user(const char __user *str) +{ + unsigned long max_addr, src_addr; + + max_addr = user_addr_max(); + src_addr = (unsigned long)str; + if (likely(src_addr < max_addr)) { + unsigned long max = max_addr - src_addr; + return do_strnlen_user(str, ~0ul, max); + } + return 0; +} +EXPORT_SYMBOL(strlen_user); -- cgit 1.2.3-korg