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perf tools: Fix mode setting in copyfile_mode_ns()

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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 <adrian.hunter@intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: http://lore.kernel.org/lkml/20191007070221.11158-1-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Adrian Hunter 2019-10-07 10:02:21 +03:00 committed by Arnaldo Carvalho de Melo
parent f948eb45e3
commit 5a0baf5123
1 changed files with 5 additions and 3 deletions
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8
tools/perf/util/copyfile.c
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@ -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);