diff options
| author | Matteo Croce | 2019-07-18 15:58:50 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2019-07-18 17:08:07 -0700 |
| commit | eec4844fae7c033a0c1fc1eb3b8517aeb8b6cc49 (patch) | |
| tree | a7da379423835a85c020e116a43bea6acf3c9ace /fs | |
| parent | 371096949f0ad3950b06729989bd27de51b8c5f5 (diff) | |
proc/sysctl: add shared variables for range check
In the sysctl code the proc_dointvec_minmax() function is often used to
validate the user supplied value between an allowed range. This
function uses the extra1 and extra2 members from struct ctl_table as
minimum and maximum allowed value.
On sysctl handler declaration, in every source file there are some
readonly variables containing just an integer which address is assigned
to the extra1 and extra2 members, so the sysctl range is enforced.
The special values 0, 1 and INT_MAX are very often used as range
boundary, leading duplication of variables like zero=0, one=1,
int_max=INT_MAX in different source files:
$ git grep -E '\.extra[12].*&(zero|one|int_max)' |wc -l
248
Add a const int array containing the most commonly used values, some
macros to refer more easily to the correct array member, and use them
instead of creating a local one for every object file.
This is the bloat-o-meter output comparing the old and new binary
compiled with the default Fedora config:
# scripts/bloat-o-meter -d vmlinux.o.old vmlinux.o
add/remove: 2/2 grow/shrink: 0/2 up/down: 24/-188 (-164)
Data old new delta
sysctl_vals - 12 +12
__kstrtab_sysctl_vals - 12 +12
max 14 10 -4
int_max 16 - -16
one 68 - -68
zero 128 28 -100
Total: Before=20583249, After=20583085, chg -0.00%
[mcroce@redhat.com: tipc: remove two unused variables]
Link: http://lkml.kernel.org/r/20190530091952.4108-1-mcroce@redhat.com
[akpm@linux-foundation.org: fix net/ipv6/sysctl_net_ipv6.c]
[arnd@arndb.de: proc/sysctl: make firmware loader table conditional]
Link: http://lkml.kernel.org/r/20190617130014.1713870-1-arnd@arndb.de
[akpm@linux-foundation.org: fix fs/eventpoll.c]
Link: http://lkml.kernel.org/r/20190430180111.10688-1-mcroce@redhat.com
Signed-off-by: Matteo Croce <mcroce@redhat.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Aaron Tomlin <atomlin@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/eventpoll.c | 4 | ||||
| -rw-r--r-- | fs/notify/inotify/inotify_user.c | 8 | ||||
| -rw-r--r-- | fs/proc/proc_sysctl.c | 4 |
3 files changed, 9 insertions, 7 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 0f9c073d78d5..d7f1f5011fac 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -291,7 +291,7 @@ static LIST_HEAD(tfile_check_list); #include <linux/sysctl.h> -static long zero; +static long long_zero; static long long_max = LONG_MAX; struct ctl_table epoll_table[] = { @@ -301,7 +301,7 @@ struct ctl_table epoll_table[] = { .maxlen = sizeof(max_user_watches), .mode = 0644, .proc_handler = proc_doulongvec_minmax, - .extra1 = &zero, + .extra1 = &long_zero, .extra2 = &long_max, }, { } diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c index cce8de32779f..0b815178126e 100644 --- a/fs/notify/inotify/inotify_user.c +++ b/fs/notify/inotify/inotify_user.c @@ -45,8 +45,6 @@ struct kmem_cache *inotify_inode_mark_cachep __read_mostly; #include <linux/sysctl.h> -static int zero; - struct ctl_table inotify_table[] = { { .procname = "max_user_instances", @@ -54,7 +52,7 @@ struct ctl_table inotify_table[] = { .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, - .extra1 = &zero, + .extra1 = SYSCTL_ZERO, }, { .procname = "max_user_watches", @@ -62,7 +60,7 @@ struct ctl_table inotify_table[] = { .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, - .extra1 = &zero, + .extra1 = SYSCTL_ZERO, }, { .procname = "max_queued_events", @@ -70,7 +68,7 @@ struct ctl_table inotify_table[] = { .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, - .extra1 = &zero + .extra1 = SYSCTL_ZERO }, { } }; diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c index 36ad1b0d6259..d80989b6c344 100644 --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -22,6 +22,10 @@ static const struct inode_operations proc_sys_inode_operations; static const struct file_operations proc_sys_dir_file_operations; static const struct inode_operations proc_sys_dir_operations; +/* shared constants to be used in various sysctls */ +const int sysctl_vals[] = { 0, 1, INT_MAX }; +EXPORT_SYMBOL(sysctl_vals); + /* Support for permanently empty directories */ struct ctl_table sysctl_mount_point[] = { |