X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=net%2Fcore%2Ffilter.c;h=9540946a48f35f9cbb89a0d82eacddcd2c4de3a3;hb=097916ecafd3bbedbde3ba068522093bf72319b3;hp=079c2edff789e95ccc9fbcec96184c2eb2772e84;hpb=ddbf9ef385bfbef897210733abfb73cb9b94ecec;p=linux-2.6 diff --git a/net/core/filter.c b/net/core/filter.c index 079c2edff7..9540946a48 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 @@ -73,8 +74,7 @@ static inline void *load_pointer(struct sk_buff *skb, int k, * filtering, filter is the array of filter instructions, and * len is the number of filter blocks in the array. */ - -int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen) +unsigned int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen) { struct sock_filter *fentry; /* We walk down these */ void *ptr; @@ -116,8 +116,6 @@ int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen) A /= X; continue; case BPF_ALU|BPF_DIV|BPF_K: - if (fentry->k == 0) - return 0; A /= fentry->k; continue; case BPF_ALU|BPF_AND|BPF_X: @@ -176,7 +174,7 @@ int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen) continue; case BPF_LD|BPF_W|BPF_ABS: k = fentry->k; - load_w: +load_w: ptr = load_pointer(skb, k, 4, &tmp); if (ptr != NULL) { A = ntohl(*(u32 *)ptr); @@ -185,7 +183,7 @@ int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen) break; case BPF_LD|BPF_H|BPF_ABS: k = fentry->k; - load_h: +load_h: ptr = load_pointer(skb, k, 2, &tmp); if (ptr != NULL) { A = ntohs(*(u16 *)ptr); @@ -242,9 +240,9 @@ load_b: A = X; continue; case BPF_RET|BPF_K: - return ((unsigned int)fentry->k); + return fentry->k; case BPF_RET|BPF_A: - return ((unsigned int)A); + return A; case BPF_ST: mem[fentry->k] = A; continue; @@ -252,7 +250,7 @@ load_b: mem[fentry->k] = X; continue; default: - /* Invalid instruction counts as RET */ + WARN_ON(1); return 0; } @@ -285,60 +283,107 @@ 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. + * + * All jumps are forward as they are not signed. * - * Returns 0 if the rule set is legal or a negative errno code if not. + * Returns 0 if the rule set is legal or -EINVAL if not. */ int sk_chk_filter(struct sock_filter *filter, int flen) { struct sock_filter *ftest; int pc; - if (((unsigned int)flen >= (~0U / sizeof(struct sock_filter))) || flen == 0) + if (flen == 0 || flen > BPF_MAXINSNS) return -EINVAL; /* check the filter code now */ 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 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: + /* 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 */ + + 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; } } - /* - * The program must end with a return. We don't care where they - * jumped within the script (its always forwards) but in the end - * they _will_ hit this. - */ - return (BPF_CLASS(filter[flen - 1].code) == BPF_RET) ? 0 : -EINVAL; + return (BPF_CLASS(filter[flen - 1].code) == BPF_RET) ? 0 : -EINVAL; } /** @@ -358,8 +403,8 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) int err; /* Make sure new filter is there and in the right amounts. */ - if (fprog->filter == NULL || fprog->len > BPF_MAXINSNS) - return -EINVAL; + if (fprog->filter == NULL) + return -EINVAL; fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL); if (!fp)