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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH 18/27] ASN.1: Fix handling of CHOICE in ASN.1 compiler From: David Howells To: mcgrof@gmail.com Cc: mjg59@srcf.ucam.org, keyrings@linux-nfs.org, gregkh@linuxfoundation.org, kyle@kernel.org, linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, seth.forshee@canonical.com, linux-security-module@vger.kernel.org, zohar@linux.vnet.ibm.com, dwmw2@infradead.org Date: Fri, 17 Jul 2015 17:18:29 +0100 Message-ID: <20150717161829.2578.86456.stgit@warthog.procyon.org.uk> In-Reply-To: <20150717161456.2578.95678.stgit@warthog.procyon.org.uk> References: <20150717161456.2578.95678.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Fix the handling of CHOICE types in the ASN.1 compiler to make SEQUENCE and SET elements in a CHOICE be correctly rendered as skippable and conditional as appropriate. For example, in the following ASN.1: Foo ::= SEQUENCE { w1 INTEGER, w2 Bar, w3 OBJECT IDENTIFIER } Bar ::= CHOICE { x1 Seq1, x2 [0] IMPLICIT OCTET STRING, x3 Seq2, x4 SET OF INTEGER } Seq1 ::= SEQUENCE { y1 INTEGER, y2 INTEGER, y3 INTEGER } Seq2 ::= SEQUENCE { z1 BOOLEAN, z2 BOOLEAN, z3 BOOLEAN } the output in foo.c generated by: ./scripts/asn1_compiler foo.asn1 foo.c foo.h included: // Bar // Seq1 [ 4] = ASN1_OP_MATCH, [ 5] = _tag(UNIV, CONS, SEQ), ... [ 13] = ASN1_OP_COND_MATCH_OR_SKIP, // x2 [ 14] = _tagn(CONT, PRIM, 0), // Seq2 [ 15] = ASN1_OP_MATCH, [ 16] = _tag(UNIV, CONS, SEQ), ... [ 24] = ASN1_OP_COND_MATCH_JUMP_OR_SKIP, // x4 [ 25] = _tag(UNIV, CONS, SET), ... [ 27] = ASN1_OP_COND_FAIL, as a result of the CHOICE - but this is wrong on lines 4 and 15 because both of these should be skippable (one and only one of the four can be picked) and the one on line 15 should also be conditional so that it is ignored if anything before it matches. After the patch, it looks like: // Bar // Seq1 [ 4] = ASN1_OP_MATCH_JUMP_OR_SKIP, // x1 [ 5] = _tag(UNIV, CONS, SEQ), ... [ 7] = ASN1_OP_COND_MATCH_OR_SKIP, // x2 [ 8] = _tagn(CONT, PRIM, 0), // Seq2 [ 9] = ASN1_OP_COND_MATCH_JUMP_OR_SKIP, // x3 [ 10] = _tag(UNIV, CONS, SEQ), ... [ 12] = ASN1_OP_COND_MATCH_JUMP_OR_SKIP, // x4 [ 13] = _tag(UNIV, CONS, SET), ... [ 15] = ASN1_OP_COND_FAIL, where all four options are skippable and the second, third and fourth are all conditional, as is the backstop at the end. This hasn't been a problem so far because in the ASN.1 specs we have are either using primitives or are using SET OF and SEQUENCE OF which are handled correctly. Whilst we're at it, also make sure that element labels get included in comments in the output for elements that have complex types. Signed-off-by: David Howells Reviewed-By: David Woodhouse --- scripts/asn1_compiler.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/scripts/asn1_compiler.c b/scripts/asn1_compiler.c index 866f85e5fdd2..ac9706d45c6b 100644 --- a/scripts/asn1_compiler.c +++ b/scripts/asn1_compiler.c @@ -682,7 +682,7 @@ struct element { unsigned flags; #define ELEMENT_IMPLICIT 0x0001 #define ELEMENT_EXPLICIT 0x0002 -#define ELEMENT_MARKED 0x0004 +#define ELEMENT_TAG_SPECIFIED 0x0004 #define ELEMENT_RENDERED 0x0008 #define ELEMENT_SKIPPABLE 0x0010 #define ELEMENT_CONDITIONAL 0x0020 @@ -895,6 +895,7 @@ static struct element *parse_type(struct token **_cursor, struct token *end, element->tag &= ~0x1f; element->tag |= strtoul(cursor->value, &p, 10); + element->flags |= ELEMENT_TAG_SPECIFIED; if (p - cursor->value != cursor->size) abort(); cursor++; @@ -1230,9 +1231,10 @@ static void dump_element(const struct element *e, int level) asn1_methods[e->method], e->tag); - printf("%c%c%c%c %c %*s[*] \e[33m%s\e[m %*.*s %*.*s\n", + printf("%c%c%c%c%c %c %*s[*] \e[33m%s\e[m %*.*s %*.*s\n", e->flags & ELEMENT_IMPLICIT ? 'I' : '-', e->flags & ELEMENT_EXPLICIT ? 'E' : '-', + e->flags & ELEMENT_TAG_SPECIFIED ? 'T' : '-', e->flags & ELEMENT_SKIPPABLE ? 'S' : '-', e->flags & ELEMENT_CONDITIONAL ? 'C' : '-', "-tTqQcato"[e->compound], @@ -1438,7 +1440,7 @@ static void render_out_of_line_list(FILE *out) */ static void render_element(FILE *out, struct element *e, struct element *tag) { - struct element *ec; + struct element *ec, *x; const char *cond, *act; int entry, skippable = 0, outofline = 0; @@ -1497,15 +1499,17 @@ static void render_element(FILE *out, struct element *e, struct element *tag) break; } - if (e->name) + x = tag ?: e; + if (x->name) render_more(out, "\t\t// %*.*s", - (int)e->name->size, (int)e->name->size, - e->name->value); + (int)x->name->size, (int)x->name->size, + x->name->value); render_more(out, "\n"); /* Render the tag */ - if (!tag) + if (!tag || !(tag->flags & ELEMENT_TAG_SPECIFIED)) tag = e; + if (tag->class == ASN1_UNIV && tag->tag != 14 && tag->tag != 15 && @@ -1601,7 +1605,7 @@ dont_render_tag: case CHOICE: for (ec = e->children; ec; ec = ec->next) - render_element(out, ec, NULL); + render_element(out, ec, ec); if (!skippable) render_opcode(out, "ASN1_OP_COND_FAIL,\n"); if (e->action)