On Thu, Mar 08, 2018 at 02:20:17PM -0500, Mimi Zohar wrote: > On Thu, 2018-03-08 at 12:04 -0700, Tycho Andersen wrote: > > On Thu, Mar 08, 2018 at 01:50:30PM -0500, Mimi Zohar wrote: > > > On Thu, 2018-03-08 at 11:37 -0700, Tycho Andersen wrote: > > > > On Thu, Mar 08, 2018 at 07:47:37PM +0200, Andy Shevchenko wrote: > > > > > On Thu, Mar 8, 2018 at 7:14 PM, Tycho Andersen <tycho@xxxxxxxx> wrote: > > > > > > In keeping with the directive to get rid of VLAs [1], let's drop the VLA > > > > > > from ima_audit_measurement(). We need to adjust the return type of > > > > > > ima_audit_measurement, because now this function can fail if an allocation > > > > > > fails. > > > > > > > > > > > > > > > > > > > > > + algo_hash_len = hash_len + strlen(algo_name) + 2; > > > > > > + algo_hash = kzalloc(algo_hash_len, GFP_KERNEL); > > > > > > > > > > > - snprintf(algo_hash, sizeof(algo_hash), "%s:%s", algo_name, hash); > > > > > > + snprintf(algo_hash, algo_hash_len, "%s:%s", algo_name, hash); > > > > > > > > > > kasprintf() ? > > > > > > > > Sure, in fact I think we could just do: > > > > > > > > - snprintf(algo_hash, algo_hash_len, "%s:%s", algo_name, hash); > > > > - audit_log_untrustedstring(ab, algo_hash); > > > > + audit_log_untrustedstring(ab, algo_name); > > > > + audit_log_format(ab, ":"); > > > > + audit_log_untrustedstring(ab, hash); > > > > > > > > and get rid of the allocation entirely. I'll test and make sure it > > > > works and then re-send. > > > > > > The hash algorithm name is an enumeration that comes from the kernel. > > > It's defined in crypto/hash_info.c: hash_algo_name. Why do we need > > > to use audit_log_untrustedstring()? > > > > Yes, I suppose we don't need it for the hash either, since we're > > generating that and we know it's just hex digits and not any audit > > control characters or "s or anything. > > > > It looks like we could get rid of the other allocation too by just > > using audit_log_n_hex, but that uses hex_byte_pack_upper, vs. the > > hex_byte_pack that's currently in use in this function. Is that too > > much of a breakage? > > Based on the discussion with Richard Briggs, we need to differentiate > between the ima_audit_measurement() and the ima_parse_rule() usage of > AUDIT_INTEGRITY_RULE. The ima_parse_rule() will continue to use > AUDIT_INTEGRITY_RULE. ima_audit_measurement() will need to define and > use a new number. Auidt name suggestions would be appreciated. > > When we make that sort of change, any other changes are insignificant. > How different are the two formats? It's just uppercase and lowercase in the hash value, so: Mar 8 16:56:46 ima kernel: [ 104.922927] audit: type=1805 audit(1520528206.082:53): file="/bin/cat" hash="sha1:79e52322102f073684e2dd0ab7653c7c6fcc49b4" ppid=2049 pid=2123 auid=1000 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts0 ses=1 comm="bash" exe="/bin/bash" vs. Mar 8 19:45:12 ima kernel: [ 207.124383] audit: type=1805 audit(1520538312.740:239): file="/root/.viminfo" hash="sha1:3322BE0C00190AB0D20C47574575842EC3020BF5" ppid=2045 pid=2195 auid=1000 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts0 ses=1 comm="vi" exe="/usr/bin/vim.basic" I'm happy to do either way. Tycho
