diff options
| -rw-r--r-- | net/core/filter.c | 112 |
1 files changed, 80 insertions, 32 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index 3a10e0bc90e..8964d344558 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -13,6 +13,7 @@ * 2 of the License, or (at your option) any later version. * * Andi Kleen - Fix a few bad bugs and races. + * Kris Katterjohn - Added many additional checks in sk_chk_filter() */ #include <linux/module.h> @@ -250,7 +251,7 @@ load_b: mem[fentry->k] = X; continue; default: - /* Invalid instruction counts as RET */ + WARN_ON(1); return 0; } @@ -283,8 +284,8 @@ load_b: * * Check the user's filter code. If we let some ugly * filter code slip through kaboom! The filter must contain - * no references or jumps that are out of range, no illegal instructions - * and no backward jumps. It must end with a RET instruction + * no references or jumps that are out of range, no illegal + * instructions, and must end with a RET instruction. * * Returns 0 if the rule set is legal or a negative errno code if not. */ @@ -300,38 +301,85 @@ int sk_chk_filter(struct sock_filter *filter, int flen) for (pc = 0; pc < flen; pc++) { /* all jumps are forward as they are not signed */ ftest = &filter[pc]; - if (BPF_CLASS(ftest->code) == BPF_JMP) { - /* but they mustn't jump off the end */ - if (BPF_OP(ftest->code) == BPF_JA) { - /* - * Note, the large ftest->k might cause loops. - * Compare this with conditional jumps below, - * where offsets are limited. --ANK (981016) - */ - if (ftest->k >= (unsigned)(flen-pc-1)) - return -EINVAL; - } else { - /* for conditionals both must be safe */ - if (pc + ftest->jt +1 >= flen || - pc + ftest->jf +1 >= flen) - return -EINVAL; - } - } - /* check for division by zero -Kris Katterjohn 2005-10-30 */ - if (ftest->code == (BPF_ALU|BPF_DIV|BPF_K) && ftest->k == 0) - return -EINVAL; + /* Only allow valid instructions */ + switch (ftest->code) { + case BPF_ALU|BPF_ADD|BPF_K: + case BPF_ALU|BPF_ADD|BPF_X: + case BPF_ALU|BPF_SUB|BPF_K: + case BPF_ALU|BPF_SUB|BPF_X: + case BPF_ALU|BPF_MUL|BPF_K: + case BPF_ALU|BPF_MUL|BPF_X: + case BPF_ALU|BPF_DIV|BPF_X: + case BPF_ALU|BPF_AND|BPF_K: + case BPF_ALU|BPF_AND|BPF_X: + case BPF_ALU|BPF_OR|BPF_K: + case BPF_ALU|BPF_OR|BPF_X: + case BPF_ALU|BPF_LSH|BPF_K: + case BPF_ALU|BPF_LSH|BPF_X: + case BPF_ALU|BPF_RSH|BPF_K: + case BPF_ALU|BPF_RSH|BPF_X: + case BPF_ALU|BPF_NEG: + case BPF_LD|BPF_W|BPF_ABS: + case BPF_LD|BPF_H|BPF_ABS: + case BPF_LD|BPF_B|BPF_ABS: + case BPF_LD|BPF_W|BPF_LEN: + case BPF_LD|BPF_W|BPF_IND: + case BPF_LD|BPF_H|BPF_IND: + case BPF_LD|BPF_B|BPF_IND: + case BPF_LD|BPF_IMM: + case BPF_LDX|BPF_W|BPF_LEN: + case BPF_LDX|BPF_B|BPF_MSH: + case BPF_LDX|BPF_IMM: + case BPF_MISC|BPF_TAX: + case BPF_MISC|BPF_TXA: + case BPF_RET|BPF_K: + case BPF_RET|BPF_A: + break; + + /* Some instructions need special checks */ - /* check that memory operations use valid addresses. */ - if (ftest->k >= BPF_MEMWORDS) { - /* but it might not be a memory operation... */ - switch (ftest->code) { - case BPF_ST: - case BPF_STX: - case BPF_LD|BPF_MEM: - case BPF_LDX|BPF_MEM: + case BPF_ALU|BPF_DIV|BPF_K: + /* check for division by zero */ + if (ftest->k == 0) return -EINVAL; - } + break; + + case BPF_LD|BPF_MEM: + case BPF_LDX|BPF_MEM: + case BPF_ST: + case BPF_STX: + /* check for invalid memory addresses */ + if (ftest->k >= BPF_MEMWORDS) + return -EINVAL; + break; + + case BPF_JMP|BPF_JA: + /* + * Note, the large ftest->k might cause loops. + * Compare this with conditional jumps below, + * where offsets are limited. --ANK (981016) + */ + if (ftest->k >= (unsigned)(flen-pc-1)) + return -EINVAL; + break; + + case BPF_JMP|BPF_JEQ|BPF_K: + case BPF_JMP|BPF_JEQ|BPF_X: + case BPF_JMP|BPF_JGE|BPF_K: + case BPF_JMP|BPF_JGE|BPF_X: + case BPF_JMP|BPF_JGT|BPF_K: + case BPF_JMP|BPF_JGT|BPF_X: + case BPF_JMP|BPF_JSET|BPF_K: + case BPF_JMP|BPF_JSET|BPF_X: + /* for conditionals both must be safe */ + if (pc + ftest->jt + 1 >= flen || + pc + ftest->jf + 1 >= flen) + return -EINVAL; + break; + + default: + return -EINVAL; } } |