ixgbe: Do not parse past IP header on fragments beyond the first
[linux-2.6/cjktty.git] / lib / strnlen_user.c
bloba28df5206d95c24d6f3b4116753747f1fb2a67e3
1 #include <linux/kernel.h>
2 #include <linux/export.h>
3 #include <linux/uaccess.h>
5 #include <asm/word-at-a-time.h>
7 /* Set bits in the first 'n' bytes when loaded from memory */
8 #ifdef __LITTLE_ENDIAN
9 # define aligned_byte_mask(n) ((1ul << 8*(n))-1)
10 #else
11 # define aligned_byte_mask(n) (~0xfful << (BITS_PER_LONG - 8 - 8*(n)))
12 #endif
15 * Do a strnlen, return length of string *with* final '\0'.
16 * 'count' is the user-supplied count, while 'max' is the
17 * address space maximum.
19 * Return 0 for exceptions (which includes hitting the address
20 * space maximum), or 'count+1' if hitting the user-supplied
21 * maximum count.
23 * NOTE! We can sometimes overshoot the user-supplied maximum
24 * if it fits in a aligned 'long'. The caller needs to check
25 * the return value against "> max".
27 static inline long do_strnlen_user(const char __user *src, unsigned long count, unsigned long max)
29 const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
30 long align, res = 0;
31 unsigned long c;
34 * Truncate 'max' to the user-specified limit, so that
35 * we only have one limit we need to check in the loop
37 if (max > count)
38 max = count;
41 * Do everything aligned. But that means that we
42 * need to also expand the maximum..
44 align = (sizeof(long) - 1) & (unsigned long)src;
45 src -= align;
46 max += align;
48 if (unlikely(__get_user(c,(unsigned long __user *)src)))
49 return 0;
50 c |= aligned_byte_mask(align);
52 for (;;) {
53 unsigned long data;
54 if (has_zero(c, &data, &constants)) {
55 data = prep_zero_mask(c, data, &constants);
56 data = create_zero_mask(data);
57 return res + find_zero(data) + 1 - align;
59 res += sizeof(unsigned long);
60 if (unlikely(max < sizeof(unsigned long)))
61 break;
62 max -= sizeof(unsigned long);
63 if (unlikely(__get_user(c,(unsigned long __user *)(src+res))))
64 return 0;
66 res -= align;
69 * Uhhuh. We hit 'max'. But was that the user-specified maximum
70 * too? If so, return the marker for "too long".
72 if (res >= count)
73 return count+1;
76 * Nope: we hit the address space limit, and we still had more
77 * characters the caller would have wanted. That's 0.
79 return 0;
82 /**
83 * strnlen_user: - Get the size of a user string INCLUDING final NUL.
84 * @str: The string to measure.
85 * @count: Maximum count (including NUL character)
87 * Context: User context only. This function may sleep.
89 * Get the size of a NUL-terminated string in user space.
91 * Returns the size of the string INCLUDING the terminating NUL.
92 * If the string is too long, returns 'count+1'.
93 * On exception (or invalid count), returns 0.
95 long strnlen_user(const char __user *str, long count)
97 unsigned long max_addr, src_addr;
99 if (unlikely(count <= 0))
100 return 0;
102 max_addr = user_addr_max();
103 src_addr = (unsigned long)str;
104 if (likely(src_addr < max_addr)) {
105 unsigned long max = max_addr - src_addr;
106 return do_strnlen_user(str, count, max);
108 return 0;
110 EXPORT_SYMBOL(strnlen_user);
113 * strlen_user: - Get the size of a user string INCLUDING final NUL.
114 * @str: The string to measure.
116 * Context: User context only. This function may sleep.
118 * Get the size of a NUL-terminated string in user space.
120 * Returns the size of the string INCLUDING the terminating NUL.
121 * On exception, returns 0.
123 * If there is a limit on the length of a valid string, you may wish to
124 * consider using strnlen_user() instead.
126 long strlen_user(const char __user *str)
128 unsigned long max_addr, src_addr;
130 max_addr = user_addr_max();
131 src_addr = (unsigned long)str;
132 if (likely(src_addr < max_addr)) {
133 unsigned long max = max_addr - src_addr;
134 return do_strnlen_user(str, ~0ul, max);
136 return 0;
138 EXPORT_SYMBOL(strlen_user);