80 lines
2.8 KiB
Diff
80 lines
2.8 KiB
Diff
From: Jeff Mahoney <jeffm@suse.com>
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Subject: [PATCH] reiserfs: Fix permissions on .reiserfs_priv
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References: bnc#593906 CVE-2010-1146
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Patch-mainline: Submitted 8 Apr 2010
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Commit 677c9b2e393a0cd203bd54e9c18b012b2c73305a removed the magic
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from the lookup code to hide the .reiserfs_priv directory since it
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was getting loaded at mount-time instead. The intent was that the
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entry would be hidden from the user via a poisoned d_compare, but
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this was faulty.
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This introduced a security issue where unpriviledged users could
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access and modify extended attributes or ACLs belonging to other
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users, including root.
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This patch resolves the issue by properly hiding .reiserfs_priv. This
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was the intent of the xattr poisoning code, but it appears to have
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never worked as expected. This is fixed by using d_revalidate instead
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of d_compare.
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This patch makes -oexpose_privroot a no-op. I'm fine leaving it this
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way. The effort involved in working out the corner cases wrt permissions
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and caching outweigh the benefit of the feature.
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Signed-off-by: Jeff Mahoney <jeffm@suse.com>
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---
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fs/reiserfs/dir.c | 2 --
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fs/reiserfs/xattr.c | 17 ++++-------------
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2 files changed, 4 insertions(+), 15 deletions(-)
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--- a/fs/reiserfs/dir.c
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+++ b/fs/reiserfs/dir.c
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@@ -45,8 +45,6 @@ static inline bool is_privroot_deh(struc
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struct reiserfs_de_head *deh)
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{
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struct dentry *privroot = REISERFS_SB(dir->d_sb)->priv_root;
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- if (reiserfs_expose_privroot(dir->d_sb))
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- return 0;
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return (dir == dir->d_parent && privroot->d_inode &&
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deh->deh_objectid == INODE_PKEY(privroot->d_inode)->k_objectid);
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}
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--- a/fs/reiserfs/xattr.c
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+++ b/fs/reiserfs/xattr.c
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@@ -972,21 +972,13 @@ int reiserfs_permission(struct inode *in
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return generic_permission(inode, mask, NULL);
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}
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-/* This will catch lookups from the fs root to .reiserfs_priv */
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-static int
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-xattr_lookup_poison(struct dentry *dentry, struct qstr *q1, struct qstr *name)
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+static int xattr_hide_revalidate(struct dentry *dentry, struct nameidata *nd)
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{
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- struct dentry *priv_root = REISERFS_SB(dentry->d_sb)->priv_root;
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- if (container_of(q1, struct dentry, d_name) == priv_root)
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- return -ENOENT;
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- if (q1->len == name->len &&
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- !memcmp(q1->name, name->name, name->len))
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- return 0;
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- return 1;
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+ return -EPERM;
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}
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static const struct dentry_operations xattr_lookup_poison_ops = {
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- .d_compare = xattr_lookup_poison,
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+ .d_revalidate = xattr_hide_revalidate,
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};
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int reiserfs_lookup_privroot(struct super_block *s)
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@@ -1000,8 +992,7 @@ int reiserfs_lookup_privroot(struct supe
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strlen(PRIVROOT_NAME));
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if (!IS_ERR(dentry)) {
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REISERFS_SB(s)->priv_root = dentry;
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- if (!reiserfs_expose_privroot(s))
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- s->s_root->d_op = &xattr_lookup_poison_ops;
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+ dentry->d_op = &xattr_lookup_poison_ops;
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if (dentry->d_inode)
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dentry->d_inode->i_flags |= S_PRIVATE;
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} else
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