1. 24 Dec, 2016 1 commit
  2. 08 Oct, 2016 1 commit
    • Alexey Dobriyan's avatar
      cred: simpler, 1D supplementary groups · 81243eac
      Alexey Dobriyan authored
      Current supplementary groups code can massively overallocate memory and
      is implemented in a way so that access to individual gid is done via 2D
      array.
      
      If number of gids is <= 32, memory allocation is more or less tolerable
      (140/148 bytes).  But if it is not, code allocates full page (!)
      regardless and, what's even more fun, doesn't reuse small 32-entry
      array.
      
      2D array means dependent shifts, loads and LEAs without possibility to
      optimize them (gid is never known at compile time).
      
      All of the above is unnecessary.  Switch to the usual
      trailing-zero-len-array scheme.  Memory is allocated with
      kmalloc/vmalloc() and only as much as needed.  Accesses become simpler
      (LEA 8(gi,idx,4) or even without displacement).
      
      Maximum number of gids is 65536 which translates to 256KB+8 bytes.  I
      think kernel can handle such allocation.
      
      On my usual desktop system with whole 9 (nine) aux groups, struct
      group_info shrinks from 148 bytes to 44 bytes, yay!
      
      Nice side effects:
      
       - "gi->gid[i]" is shorter than "GROUP_AT(gi, i)", less typing,
      
       - fix little mess in net/ipv4/ping.c
         should have been using GROUP_AT macro but this point becomes moot,
      
       - aux group allocation is persistent and should be accounted as such.
      
      Link: http://lkml.kernel.org/r/20160817201927.GA2096@p183.telecom.bySigned-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
      Cc: Vasily Kulikov <segoon@openwall.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      81243eac
  3. 15 Apr, 2015 1 commit
    • Iulia Manda's avatar
      kernel: conditionally support non-root users, groups and capabilities · 2813893f
      Iulia Manda authored
      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: default avatarIulia Manda <iulia.manda21@gmail.com>
      Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
      Acked-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
      Tested-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      Reviewed-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2813893f
  4. 09 Dec, 2014 1 commit
  5. 05 Dec, 2014 1 commit
    • Eric W. Biederman's avatar
      groups: Consolidate the setgroups permission checks · 7ff4d90b
      Eric W. Biederman authored
      Today there are 3 instances of setgroups and due to an oversight their
      permission checking has diverged.  Add a common function so that
      they may all share the same permission checking code.
      
      This corrects the current oversight in the current permission checks
      and adds a helper to avoid this in the future.
      
      A user namespace security fix will update this new helper, shortly.
      
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
      7ff4d90b
  6. 03 Apr, 2014 1 commit
  7. 31 Aug, 2013 1 commit
  8. 03 May, 2012 2 commits
  9. 31 Oct, 2011 1 commit
    • Paul Gortmaker's avatar
      kernel: Map most files to use export.h instead of module.h · 9984de1a
      Paul Gortmaker authored
      The changed files were only including linux/module.h for the
      EXPORT_SYMBOL infrastructure, and nothing else.  Revector them
      onto the isolated export header for faster compile times.
      
      Nothing to see here but a whole lot of instances of:
      
        -#include <linux/module.h>
        +#include <linux/export.h>
      
      This commit is only changing the kernel dir; next targets
      will probably be mm, fs, the arch dirs, etc.
      Signed-off-by: default avatarPaul Gortmaker <paul.gortmaker@windriver.com>
      9984de1a
  10. 24 Mar, 2011 1 commit
  11. 10 Sep, 2010 1 commit
  12. 12 Apr, 2010 1 commit
  13. 17 Jun, 2009 1 commit