[RFC PATCH] CAP_FS_MASK: add some long-missing capabilities to cap_fs_mask
From: Serge E. Hallyn <hidden>
Date: 2009-03-18 20:51:55
Also in:
linux-nfs, lkml
Subsystem:
capabilities, the rest · Maintainers:
Serge Hallyn, Linus Torvalds
When POSIX capabilities were introduced during the 2.1 Linux cycle, the fs mask, which represents the capabilities which having fsuid==0 is supposed to grant, did not include CAP_MKNOD and CAP_LINUX_IMMUTABLE. However, before capabilities the privilege to call these did in fact depend upon fsuid==0. This patch introduces those capabilities into the fsmask, restoring the old behavior. See the thread starting at http://lkml.org/lkml/2009/3/11/157 for reference. Note that if this fix is deemed valid, then earlier kernel versions (2.4 and 2.2) ought to be fixed too. Reported-by: Igor Zhbanov <redacted> Signed-off-by: Serge E. Hallyn <redacted> --- include/linux/capability.h | 18 +++++++++++++++++- 1 files changed, 17 insertions(+), 1 deletions(-)
diff --git a/include/linux/capability.h b/include/linux/capability.h
index 1b98725..eae98b1 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h@@ -377,7 +377,21 @@ struct cpu_vfs_cap_data { #define CAP_FOR_EACH_U32(__capi) \ for (__capi = 0; __capi < _KERNEL_CAPABILITY_U32S; ++__capi) +/* + * CAP_FS_MASK and CAP_NFSD_MASKS: + * + * The fs mask is all the privileges that fsuid==0 historically meant. + * At one time in the past, that included CAP_MKNOD and CAP_LINUX_IMMUTABLE. + * + * It has never meant setting security.* and trusted.* xattrs. + * + * We could also define fsmask as follows: + * 1. CAP_FS_MASK is the privilege to bypass all fs-related DAC permissions + * 2. The security.* and trusted.* xattrs are fs-related MAC permissions + */ + # define CAP_FS_MASK_B0 (CAP_TO_MASK(CAP_CHOWN) \ + | CAP_TO_MASK(CAP_MKNOD) \ | CAP_TO_MASK(CAP_DAC_OVERRIDE) \ | CAP_TO_MASK(CAP_DAC_READ_SEARCH) \ | CAP_TO_MASK(CAP_FOWNER) \
@@ -392,7 +406,9 @@ struct cpu_vfs_cap_data { # define CAP_EMPTY_SET ((kernel_cap_t){{ 0, 0 }}) # define CAP_FULL_SET ((kernel_cap_t){{ ~0, ~0 }}) # define CAP_INIT_EFF_SET ((kernel_cap_t){{ ~CAP_TO_MASK(CAP_SETPCAP), ~0 }}) -# define CAP_FS_SET ((kernel_cap_t){{ CAP_FS_MASK_B0, CAP_FS_MASK_B1 } }) +# define CAP_FS_SET ((kernel_cap_t){{ CAP_FS_MASK_B0 \ + | CAP_TO_MASK(CAP_LINUX_IMMUTABLE), \ + CAP_FS_MASK_B1 } }) # define CAP_NFSD_SET ((kernel_cap_t){{ CAP_FS_MASK_B0|CAP_TO_MASK(CAP_SYS_RESOURCE), \ CAP_FS_MASK_B1 } })
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1.5.4.3