diff options
author | Mark Brown <broonie@linaro.org> | 2013-12-05 10:15:16 +0000 |
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committer | Mark Brown <broonie@linaro.org> | 2013-12-05 10:15:16 +0000 |
commit | dffe2a3eed105c631500778dfaba0998d7bf8512 (patch) | |
tree | 4c2492d710e0b101f57a7f399b3e891129b1c8b4 /Documentation | |
parent | 3b21b35761de8348dd2f7cff9752449281d7a17b (diff) | |
parent | 538069756ce13f9d0e0ccb7a17b6935a0bfb7cad (diff) |
Merge tag 'v3.10.22' into linux-linaro-lsk
This is the 3.10.22 stable release
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/sysctl/kernel.txt | 25 |
1 files changed, 18 insertions, 7 deletions
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt index ccd42589e124..9b34b1685078 100644 --- a/Documentation/sysctl/kernel.txt +++ b/Documentation/sysctl/kernel.txt @@ -289,13 +289,24 @@ Default value is "/sbin/hotplug". kptr_restrict: This toggle indicates whether restrictions are placed on -exposing kernel addresses via /proc and other interfaces. When -kptr_restrict is set to (0), there are no restrictions. When -kptr_restrict is set to (1), the default, kernel pointers -printed using the %pK format specifier will be replaced with 0's -unless the user has CAP_SYSLOG. When kptr_restrict is set to -(2), kernel pointers printed using %pK will be replaced with 0's -regardless of privileges. +exposing kernel addresses via /proc and other interfaces. + +When kptr_restrict is set to (0), the default, there are no restrictions. + +When kptr_restrict is set to (1), kernel pointers printed using the %pK +format specifier will be replaced with 0's unless the user has CAP_SYSLOG +and effective user and group ids are equal to the real ids. This is +because %pK checks are done at read() time rather than open() time, so +if permissions are elevated between the open() and the read() (e.g via +a setuid binary) then %pK will not leak kernel pointers to unprivileged +users. Note, this is a temporary solution only. The correct long-term +solution is to do the permission checks at open() time. Consider removing +world read permissions from files that use %pK, and using dmesg_restrict +to protect against uses of %pK in dmesg(8) if leaking kernel pointer +values to unprivileged users is a concern. + +When kptr_restrict is set to (2), kernel pointers printed using +%pK will be replaced with 0's regardless of privileges. ============================================================== |