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2813893f8b
There are a lot of embedded systems that run most or all of their functionality in init, running as root:root. For these systems, supporting multiple users is not necessary. This patch adds a new symbol, CONFIG_MULTIUSER, that makes support for non-root users, non-root groups, and capabilities optional. It is enabled under CONFIG_EXPERT menu. When this symbol is not defined, UID and GID are zero in any possible case and processes always have all capabilities. The following syscalls are compiled out: setuid, setregid, setgid, setreuid, setresuid, getresuid, setresgid, getresgid, setgroups, getgroups, setfsuid, setfsgid, capget, capset. Also, groups.c is compiled out completely. In kernel/capability.c, capable function was moved in order to avoid adding two ifdef blocks. This change saves about 25 KB on a defconfig build. The most minimal kernels have total text sizes in the high hundreds of kB rather than low MB. (The 25k goes down a bit with allnoconfig, but not that much. The kernel was booted in Qemu. All the common functionalities work. Adding users/groups is not possible, failing with -ENOSYS. Bloat-o-meter output: add/remove: 7/87 grow/shrink: 19/397 up/down: 1675/-26325 (-24650) [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Iulia Manda <iulia.manda21@gmail.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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| android | ||
| board | ||
| clocking-wizard | ||
| comedi | ||
| dgap | ||
| dgnc | ||
| emxx_udc | ||
| fbtft | ||
| fsl-mc | ||
| ft1000 | ||
| fwserial | ||
| gdm72xx | ||
| gdm724x | ||
| goldfish | ||
| gs_fpgaboot | ||
| i2o | ||
| iio | ||
| lustre | ||
| media | ||
| mt29f_spinand | ||
| netlogic | ||
| nvec | ||
| octeon | ||
| octeon-usb | ||
| olpc_dcon | ||
| ozwpan | ||
| panel | ||
| rtl8188eu | ||
| rtl8192e | ||
| rtl8192u | ||
| rtl8712 | ||
| rtl8723au | ||
| rts5208 | ||
| skein | ||
| slicoss | ||
| sm7xxfb | ||
| sm750fb | ||
| speakup | ||
| ste_rmi4 | ||
| unisys | ||
| vme | ||
| vt6655 | ||
| vt6656 | ||
| wlan-ng | ||
| xgifb | ||
| Kconfig | ||
| Makefile | ||
| staging.c | ||