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%
[[email protected]: tipc: remove two unused variables]
Link: http://lkml.kernel.org/r/[email protected]
[[email protected]: fix net/ipv6/sysctl_net_ipv6.c]
[[email protected]: proc/sysctl: make firmware loader table conditional]
Link: http://lkml.kernel.org/r/[email protected]
[[email protected]: fix fs/eventpoll.c]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Matteo Croce <[email protected]>
Signed-off-by: Arnd Bergmann <[email protected]>
Acked-by: Kees Cook <[email protected]>
Reviewed-by: Aaron Tomlin <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
33 files changed
