Commit 36c8bb56 authored Jun 19, 2015 by Li Zhang Committed by Arnaldo Carvalho de Melo Jun 26, 2015

perf symbols: Check access permission when reading symbol files



There 2 problems when reading symbols files:

*  It doesn't report any errors even if when users specify symbol
   files which don't exist with --kallsyms or --vmlinux. The result
   just shows the address without symbols, which is not what is expected.
   So it's better to report errors and exit the program.

*  When using command perf report --kallsyms=/proc/kallsyms with a
   non-root user, symbols are resolved. Then select one symbol and
   annotate it, it reports the error as the following:
   Can't annotate __clear_user: No vmlinux file with build id xxx was
   found.

   The problem is caused by reading /proc/kcore without access permission.
   /proc/kcore requires CAP_SYS_RAWIO capability to access, so it needs to
   change access permission to allow a specific user to read /proc/kcore or
   use root to execute the perf command.

This patch is to report errors when symbol files specified by users
don't exist. And check access permission of /proc/kcore when reading it.

Signed-off-by: Li Zhang <zhlcindy@linux.vnet.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1434704253-2632-1-git-send-email-zhlcindy@linux.vnet.ibm.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent 32b8af82

tools/perf/builtin-report.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -742,6 +742,17 @@ int cmd_report(int argc, const char *argv, const char prefix __maybe_unused)

		argc = parse_options(argc, argv, options, report_usage, 0);

		if (symbol_conf.vmlinux_name &&
		access(symbol_conf.vmlinux_name, R_OK)) {
		pr_err("Invalid file: %s\n", symbol_conf.vmlinux_name);
		return -EINVAL;
		}
		if (symbol_conf.kallsyms_name &&
		access(symbol_conf.kallsyms_name, R_OK)) {
		pr_err("Invalid file: %s\n", symbol_conf.kallsyms_name);
		return -EINVAL;
		}

		if (report.use_stdio)
		use_browser = 0;
		else if (report.use_tui)

tools/perf/util/symbol.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -1132,8 +1132,11 @@ static int dso__load_kcore(struct dso dso, struct map map,
		INIT_LIST_HEAD(&md.maps);

		fd = open(kcore_filename, O_RDONLY);
		if (fd < 0)
		if (fd < 0) {
		pr_err("%s requires CAP_SYS_RAWIO capability to access.\n",
		kcore_filename);
		return -EINVAL;
		}

		/* Read new maps into temporary lists */
		err = file__read_maps(fd, md.type == MAP__FUNCTION, kcore_mapfn, &md,

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