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80 lines
2.5 KiB
80 lines
2.5 KiB
From: Andreas Gruenbacher <agruen@suse.de>
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Date: Fri, 11 Jun 2010 16:12:50 +0530
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Subject: [PATCH 11/16] richacl: Check if an acl is equivalent to a file mode
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Patch-mainline: not yet
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This function is used to avoid storing richacls on disk if the acl can
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be computed from the file permission bits.
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Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
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Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
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---
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fs/richacl_base.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
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include/linux/richacl.h | 1 +
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2 files changed, 49 insertions(+)
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--- a/fs/richacl_base.c
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+++ b/fs/richacl_base.c
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@@ -544,3 +544,51 @@ mask:
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return acl;
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}
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EXPORT_SYMBOL_GPL(richacl_inherit);
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+
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+/**
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+ * richacl_equiv_mode - check if @acl is equivalent to file permission bits
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+ * @mode_p: the file mode (including the file type)
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+ *
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+ * If @acl can be fully represented by file permission bits, this function
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+ * returns 0, and the file permission bits in @mode_p are set to the equivalent
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+ * of @acl.
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+ *
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+ * This function is used to avoid storing richacls on disk if the acl can be
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+ * computed from the file permission bits. It allows user-space to make sure
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+ * that a file has no explicit richacl set.
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+ */
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+int
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+richacl_equiv_mode(const struct richacl *acl, mode_t *mode_p)
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+{
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+ const struct richace *ace = acl->a_entries;
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+ unsigned int x;
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+ mode_t mode;
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+
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+ if (acl->a_count != 1 ||
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+ acl->a_flags ||
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+ !richace_is_everyone(ace) ||
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+ !richace_is_allow(ace) ||
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+ ace->e_flags & ~ACE4_SPECIAL_WHO)
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+ return -1;
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+
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+ /*
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+ * Figure out the permissions we care about: ACE4_DELETE_CHILD is
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+ * meaningless for non-directories, so we ignore it.
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+ */
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+ x = ~ACE4_POSIX_ALWAYS_ALLOWED;
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+ if (!S_ISDIR(*mode_p))
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+ x &= ~ACE4_DELETE_CHILD;
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+
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+ if ((ace->e_mask & x) != (ACE4_POSIX_MODE_ALL & x))
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+ return -1;
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+
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+ mode = richacl_masks_to_mode(acl);
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+ if ((acl->a_owner_mask & x) != (richacl_mode_to_mask(mode >> 6) & x) ||
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+ (acl->a_group_mask & x) != (richacl_mode_to_mask(mode >> 3) & x) ||
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+ (acl->a_other_mask & x) != (richacl_mode_to_mask(mode) & x))
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+ return -1;
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+
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+ *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
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+ return 0;
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+}
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+EXPORT_SYMBOL_GPL(richacl_equiv_mode);
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--- a/include/linux/richacl.h
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+++ b/include/linux/richacl.h
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@@ -273,6 +273,7 @@ extern struct richacl *richacl_chmod(str
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extern int richacl_permission(struct inode *, const struct richacl *,
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unsigned int);
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extern struct richacl *richacl_inherit(const struct richacl *, struct inode *);
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+extern int richacl_equiv_mode(const struct richacl *, mode_t *);
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/* richacl_inode.c */
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