summaryrefslogtreecommitdiff
path: root/lib
diff options
context:
space:
mode:
authorKees Cook <keescook@chromium.org>2014-12-12 06:06:49 +0300
committerRusty Russell <rusty@rustcorp.com.au>2014-12-18 05:08:51 +0300
commitb0a65b0cccd477b2fd8b7adad0ac39433df54829 (patch)
treecd34e0b1dfae25117f114becd0b5153133193098 /lib
parent18eb74fa94161380c1acc9cf562cb835c4e54a25 (diff)
downloadlinux-b0a65b0cccd477b2fd8b7adad0ac39433df54829.tar.xz
param: do not set store func without write perm
When a module_param is defined without DAC write permissions, it can still be changed at runtime and updated. Drivers using a 0444 permission may be surprised that these values can still be changed. For drivers that want to allow updates, any S_IW* flag will set the "store" function as before. Drivers without S_IW* flags will have the "store" function unset, unforcing a read-only value. Drivers that wish neither "store" nor "get" can continue to use "0" for perms to stay out of sysfs entirely. Old behavior: # cd /sys/module/snd/parameters # ls -l total 0 -r--r--r-- 1 root root 4096 Dec 11 13:55 cards_limit -r--r--r-- 1 root root 4096 Dec 11 13:55 major -r--r--r-- 1 root root 4096 Dec 11 13:55 slots # cat major 116 # echo -1 > major -bash: major: Permission denied # chmod u+w major # echo -1 > major # cat major -1 New behavior: ... # chmod u+w major # echo -1 > major -bash: echo: write error: Input/output error Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'lib')
0 files changed, 0 insertions, 0 deletions