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Fix portability bugs in use of credentials control messages for peer auth.

Browse Source 
Even though our existing code for handling credentials control messages has
been basically unchanged since 2001, it was fundamentally wrong: it did not
ensure proper alignment of the supplied buffer, and it was calculating
buffer sizes and message sizes incorrectly.  This led to failures on
platforms where alignment padding is relevant, for instance FreeBSD on
64-bit platforms, as seen in a recent Debian bug report passed on by
Martin Pitt (http://bugs.debian.org//cgi-bin/bugreport.cgi?bug=612888).

Rewrite to do the message-whacking using the macros specified in RFC 2292,
following a suggestion from Theo de Raadt in that thread.  Tested by me
on Debian/kFreeBSD-amd64; since OpenBSD and NetBSD document the identical
CMSG API, it should work there too.

Back-patch to all supported branches.
This commit is contained in:
Tom Lane
2011-05-30 19:16:22 -04:00
parent f064a4f263
commit 1d6dd87c4b
2 changed files with 46 additions and 34 deletions
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22
src/interfaces/libpq/fe-auth.c
View File

@ -709,11 +709,12 @@ pg_local_sendauth(PGconn *conn)
struct msghdr msg;
#ifdef HAVE_STRUCT_CMSGCRED
/* Prevent padding */
char cmsgmem[sizeof(struct cmsghdr) + sizeof(struct cmsgcred)];
/* Point to start of first structure */
struct cmsghdr *cmsg = (struct cmsghdr *) cmsgmem;
struct cmsghdr *cmsg;
union
{
struct cmsghdr hdr;
unsigned char buf[CMSG_SPACE(sizeof(struct cmsgcred))];
} cmsgbuf;
#endif
/*
@ -729,11 +730,12 @@ pg_local_sendauth(PGconn *conn)
msg.msg_iovlen = 1;
#ifdef HAVE_STRUCT_CMSGCRED
/* Create control header, FreeBSD */
msg.msg_control = cmsg;
msg.msg_controllen = sizeof(cmsgmem);
memset(cmsg, 0, sizeof(cmsgmem));
cmsg->cmsg_len = sizeof(cmsgmem);
/* FreeBSD needs us to set up a message that will be filled in by kernel */
memset(&cmsgbuf, 0, sizeof(cmsgbuf));
msg.msg_control = &cmsgbuf.buf;
msg.msg_controllen = sizeof(cmsgbuf.buf);
cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_len = CMSG_LEN(sizeof(struct cmsgcred));
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_CREDS;
#endif