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tools/power turbostat: relax dependency on root permission

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For turbostat to run as non-root, it needs to permissions:

1. read access to /dev/cpu/*/msr
	via standard user/group/world file permissions

2. CAP_SYS_RAWIO
	eg.  # setcap cap_sys_rawio=ep turbostat

Yes, running as root still works.

Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Len Brown 2014-08-15 00:36:50 -04:00
parent bfa76d4957
commit 98481e79b6
1 changed files with 41 additions and 12 deletions
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53
tools/power/x86/turbostat/turbostat.c
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@ -38,6 +38,8 @@
#include <ctype.h>
#include <sched.h>
#include <cpuid.h>
#include <linux/capability.h>
#include <errno.h>
char *proc_stat = "/proc/stat";
unsigned int interval_sec = 5; /* set with -i interval_sec */
@ -251,15 +253,13 @@ int get_msr(int cpu, off_t offset, unsigned long long *msr)
sprintf(pathname, "/dev/cpu/%d/msr", cpu);
fd = open(pathname, O_RDONLY);
if (fd < 0)
return -1;
err(-1, "%s open failed, try chown or chmod +r /dev/cpu/*/msr, or run as root", pathname);
retval = pread(fd, msr, sizeof *msr, offset);
close(fd);
if (retval != sizeof *msr) {
fprintf(stderr, "%s offset 0x%llx read failed\n", pathname, (unsigned long long)offset);
return -1;
}
if (retval != sizeof *msr)
err(-1, "%s offset 0x%llx read failed", pathname, (unsigned long long)offset);
return 0;
}
@ -1462,10 +1462,40 @@ void check_dev_msr()
"Try \"# modprobe msr\"");
}
void check_super_user()
void check_permissions()
{
if (getuid() != 0)
errx(-6, "must be root");
struct __user_cap_header_struct cap_header_data;
cap_user_header_t cap_header = &cap_header_data;
struct __user_cap_data_struct cap_data_data;
cap_user_data_t cap_data = &cap_data_data;
extern int capget(cap_user_header_t hdrp, cap_user_data_t datap);
int do_exit = 0;
/* check for CAP_SYS_RAWIO */
cap_header->pid = getpid();
cap_header->version = _LINUX_CAPABILITY_VERSION;
if (capget(cap_header, cap_data) < 0)
err(-6, "capget(2) failed");
if ((cap_data->effective & (1 << CAP_SYS_RAWIO)) == 0) {
do_exit++;
warnx("capget(CAP_SYS_RAWIO) failed,"
" try \"# setcap cap_sys_rawio=ep %s\"", progname);
}
/* test file permissions */
if (euidaccess("/dev/cpu/0/msr", R_OK)) {
do_exit++;
warn("/dev/cpu/0/msr open failed, try chown or chmod +r /dev/cpu/*/msr");
}
/* if all else fails, thell them to be root */
if (do_exit)
if (getuid() != 0)
warnx("Or simply run as root");
if (do_exit)
exit(-6);
}
int has_nehalem_turbo_ratio_limit(unsigned int family, unsigned int model)
@ -2299,10 +2329,9 @@ void setup_all_buffers(void)
void turbostat_init()
{
check_cpuid();
check_dev_msr();
check_super_user();
check_permissions();
check_cpuid();
setup_all_buffers();
@ -2441,7 +2470,7 @@ int main(int argc, char **argv)
cmdline(argc, argv);
if (verbose)
fprintf(stderr, "turbostat v3.7 Feb 6, 2014"
fprintf(stderr, "turbostat v3.8 14-Aug 2014"
" - Len Brown <lenb@kernel.org>\n");
turbostat_init();