From 5a0baf5123236362fda4e9772cc63b7faa16a0df Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Mon, 7 Oct 2019 10:02:21 +0300 Subject: [PATCH] perf tools: Fix mode setting in copyfile_mode_ns() 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 Acked-by: Jiri Olsa Tested-by: Arnaldo Carvalho de Melo Link: http://lore.kernel.org/lkml/20191007070221.11158-1-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo --- 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);