kata-containers/s390-tools
1
0
Fork 0
mirror of https://github.com/ibm-s390-linux/s390-tools.git synced 2026-08-05 02:14:52 +00:00
Code Issues Packages Projects Releases Wiki Activity

chreipl: correct read-only attributes handling

Browse Source 
chreipl could only be used as root (effective userid 0), which is
explicitly checked upon invocation.

"access" call is a wrong method to check super user read/write access
for sysfs files, because it is simply always returns 0 (success), despite
actual sysfs file permissions or underlying sysfs file callbacks setup.
The only guaranteed way of checking sysfs file super user access is an
actual open call with the corresponding access mode.

The problem is that chreipl always tries to update some sysfs attributes
even through they are not specified as command line arguments. Together
with a broken sysfs file access checks this leads to inability to use
the tool, when some sysfs attributes are read-only (which is the case
on older systems where diag308 set does not work).

$ chreipl ccw -d 0.0.ec5a
chreipl: Could not open "reipl/ccw/parm" (Permission denied)

The change fixes access checks, which are in place to handle "diag308
set does not work" case (presence of read-only sysfs attributes).

Also replaces R_OK with F_OK in "set_target_type_auto" to underline that
only file presence is checked, not an actual read access.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
This commit is contained in:
Vasily Gorbik
2018-04-05 16:55:32 +02:00
committed by Jan Höppner
parent 262a827ab4
commit edaad2a927
1 changed files with 34 additions and 39 deletions
Download Patch File Download Diff File Expand all files Collapse all files
ipl_tools/cmd_chreipl.c
+34 -39
View File
@@ -445,7 +445,7 @@ static void set_target_type_auto(const char *arg)
{
char busid[10];
if (access(arg, R_OK) == 0) {
if (access(arg, F_OK) == 0) {
set_target_type(TT_NODE, 1);
return;
}
@@ -539,12 +539,19 @@ static void parse_chreipl_options(int argc, char *argv[])
parse_pos_args(&argv[optind], argc - optind);
}
static void verify_write_access(const char *path, const char *attr)
static void check_exists(const char *path, const char *attr)
{
char fpath[PATH_MAX];
snprintf(fpath, sizeof(fpath), "/sys/firmware/%s", path);
if (access(fpath, W_OK) != 0)
if (access(fpath, F_OK) != 0)
ERR_EXIT("System does not allow to set %s", attr);
}
static void write_str_optional(char *string, char *file, int exit_on_fail,
const char *attr)
{
if (write_str_errno(string, file) && exit_on_fail)
ERR_EXIT("System does not allow to set %s", attr);
}
@@ -585,22 +592,18 @@ static void chreipl_ccw(void)
ERR_EXIT("Could not find DASD CCW device \"%s\"", l.busid);
}
if (l.bootparms_set && strlen(l.bootparms) > BOOTPARMS_CCW_MAX) {
ERR_EXIT("Maximum boot parameter length exceeded (%zu/%u)",
strlen(l.bootparms), BOOTPARMS_CCW_MAX);
}
/*
* On old systems that use CCW reipl loadparm cannot be set
*/
if (l.loadparm_set)
verify_write_access("reipl/ccw/loadparm", "loadparm");
if (l.bootparms_set) {
verify_write_access("reipl/ccw/parm", "boot parameters");
if (strlen(l.bootparms) > BOOTPARMS_CCW_MAX)
ERR_EXIT("Maximum boot parameter length exceeded "
"(%zu/%u)", strlen(l.bootparms),
BOOTPARMS_CCW_MAX);
}
if (access("/sys/firmware/reipl/ccw/parm", W_OK) == 0)
write_str(l.bootparms, "reipl/ccw/parm");
if (access("/sys/firmware/reipl/ccw/loadparm", W_OK) == 0)
write_str(l.loadparm, "reipl/ccw/loadparm");
write_str_optional(l.loadparm, "reipl/ccw/loadparm", l.loadparm_set,
"loadparm");
write_str_optional(l.bootparms, "reipl/ccw/parm", l.bootparms_set,
"boot parameters");
write_str(l.busid, "reipl/ccw/device");
write_str("ccw", "reipl/reipl_type");
@@ -616,23 +619,18 @@ static void chreipl_fcp(void)
ERR_EXIT("Device is on cio_ignore list, try \"cio_ignore -r %s\"?", l.busid);
ERR_EXIT("Could not find FCP device \"%s\"", l.busid);
}
verify_write_access("reipl/fcp/device", "\"fcp\" re-IPL target");
check_exists("reipl/fcp/device", "\"fcp\" re-IPL target");
if (l.bootparms_set && strlen(l.bootparms) > BOOTPARMS_FCP_MAX) {
ERR_EXIT("Maximum boot parameter length exceeded (%zu/%u)",
strlen(l.bootparms), BOOTPARMS_FCP_MAX);
}
/*
* On old systems the FCP reipl loadparm cannot be set
*/
if (l.loadparm_set)
verify_write_access("reipl/fcp/loadparm", "loadparm");
if (l.bootparms_set) {
verify_write_access("reipl/fcp/scp_data", "boot parameters");
if (strlen(l.bootparms) > BOOTPARMS_FCP_MAX)
ERR_EXIT("Maximum boot parameter length exceeded "
"(%zu/%u)", strlen(l.bootparms),
BOOTPARMS_FCP_MAX);
}
if (access("/sys/firmware/reipl/fcp/scp_data", W_OK) == 0)
write_str(l.bootparms, "reipl/fcp/scp_data");
if (access("/sys/firmware/reipl/fcp/loadparm", W_OK) == 0)
write_str(l.loadparm, "reipl/fcp/loadparm");
write_str_optional(l.loadparm, "reipl/fcp/loadparm", l.loadparm_set,
"loadparm");
write_str_optional(l.bootparms, "reipl/fcp/scp_data", l.bootparms_set,
"boot parameters");
write_str(l.busid, "reipl/fcp/device");
write_str(l.wwpn, "reipl/fcp/wwpn");
write_str(l.lun, "reipl/fcp/lun");
@@ -652,17 +650,14 @@ static void chreipl_fcp(void)
static void chreipl_nss(void)
{
check_nss_opts();
verify_write_access("reipl/nss/name", "\"nss\" re-IPL target");
if (l.bootparms_set) {
verify_write_access("reipl/nss/parm", "boot parameters");
if (strlen(l.bootparms) > BOOTPARMS_NSS_MAX)
ERR_EXIT("Maximum boot parameter length exceeded "
"(%zu/%u)", strlen(l.bootparms),
BOOTPARMS_NSS_MAX);
check_exists("reipl/nss/name", "\"nss\" re-IPL target");
if (l.bootparms_set && strlen(l.bootparms) > BOOTPARMS_NSS_MAX) {
ERR_EXIT("Maximum boot parameter length exceeded (%zu/%u)",
strlen(l.bootparms), BOOTPARMS_NSS_MAX);
}
write_str_optional(l.bootparms, "reipl/nss/parm", l.bootparms_set,
"boot parameters");
write_str(l.nss_name, "reipl/nss/name");
if (access("/sys/firmware/reipl/nss/parm", W_OK) == 0)
write_str(l.bootparms, "reipl/nss/parm");
write_str("nss", "reipl/reipl_type");
print_nss(0);
}