Re: /tmp/perf-PID.map ownership

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Thu, Nov 12, 2015 at 10:27:26AM -0800, Brendan Gregg escreveu:
> G'Day,
> 
> # perf record -F 99 -a -g -- sleep 30
> [...]
> # perf report -n --stdio
> File /tmp/perf-25958.map not owned by current user or root, ignoring it.
> 
> Can root bypass this test? I'm root, and profiling apps from different

In other places such tests are overridable via '-f' (force), this one
should too, I think.

# perf report
File perf.data not owned by current user or root (use -f to override)
[root@zoo linux]# ls -la perf.data
-rw-------. 1 acme acme 20032 Nov 12 15:50 perf.data

- Arnaldo

> user-IDs, and the current workaround is to "chown root
> /tmp/perf*.map". Shouldn't root be able to read these map files? Could
> we:
> 
> --- linux-perf/tools/perf/util/symbol.c    2015-11-03 20:08:40.829320940 +0000
> +++ linux-perf-edited/tools/perf/util/symbol.c    2015-11-12
> 18:21:35.487077872 +0000
> @@ -1433,14 +1433,17 @@
>      dso->adjust_symbols = 0;
> 
>      if (strncmp(dso->name, "/tmp/perf-", 10) == 0) {
> +        uint_t euid;
>          struct stat st;
> 
>          if (lstat(dso->name, &st) < 0)
>              goto out;
> 
> -        if (st.st_uid && (st.st_uid != geteuid())) {
> -            pr_warning("File %s not owned by current user or root, "
> -                "ignoring it.\n", dso->name);
> +        euid = geteuid();
> +        if (euid && st.st_uid && (st.st_uid != euid)) {
> +            pr_warning("File %s not owned by current user, and "
> +                "current user is not root. Ignoring it.\n",
> +                dso->name);
>              goto out;
>          }
> 
> Brendan
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