On Mon, Oct 07, 2019 at 10:02:21AM +0300, Adrian Hunter wrote: > slow_copyfile() opens the file by name, so "write" permissions must not > be removed in copyfile_mode_ns() before calling slow_copyfile(). > > Example: > > Before: > $ sudo chmod +r /proc/kcore > $ sudo setcap "cap_sys_admin,cap_sys_ptrace,cap_syslog,cap_sys_rawio=ep" > tools/perf/perf > $ tools/perf/perf buildid-cache -k /proc/kcore > Couldn't add /proc/kcore > > After: > $ sudo chmod +r /proc/kcore > $ sudo setcap "cap_sys_admin,cap_sys_ptrace,cap_syslog,cap_sys_rawio=ep" > tools/perf/perf > $ tools/perf/perf buildid-cache -v -k /proc/kcore > kcore added to build-id cache directory > /home/ahunter/.debug/[kernel.kcore]/37e340b1b5a7cf4f57ba8de2bc777359588a957f/2019100709562289 > > Signed-off-by: Adrian Hunter <[email protected]>
Acked-by: Jiri Olsa <[email protected]> thanks, jirka > --- > tools/perf/util/copyfile.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/tools/perf/util/copyfile.c b/tools/perf/util/copyfile.c > index 3fa0db136667..47e03de7c235 100644 > --- a/tools/perf/util/copyfile.c > +++ b/tools/perf/util/copyfile.c > @@ -101,14 +101,16 @@ static int copyfile_mode_ns(const char *from, const > char *to, mode_t mode, > if (tofd < 0) > goto out; > > - if (fchmod(tofd, mode)) > - goto out_close_to; > - > if (st.st_size == 0) { /* /proc? do it slowly... */ > err = slow_copyfile(from, tmp, nsi); > + if (!err && fchmod(tofd, mode)) > + err = -1; > goto out_close_to; > } > > + if (fchmod(tofd, mode)) > + goto out_close_to; > + > nsinfo__mountns_enter(nsi, &nsc); > fromfd = open(from, O_RDONLY); > nsinfo__mountns_exit(&nsc); > -- > 2.17.1 >
