Messages in this thread Patch in this message | | | From | Roberto Sassu <> | Subject | [PATCH v3 4/5] smack: Initialize the in-memory inode in smack_inode_init_security() | Date | Thu, 16 Nov 2023 10:01:24 +0100 |
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From: Roberto Sassu <roberto.sassu@huawei.com>
Currently, Smack initializes in-memory new inodes in three steps. It first sets the xattrs in smack_inode_init_security(), fetches them in smack_d_instantiate() and finally, in the same function, sets the in-memory inodes depending on xattr values, unless they are in specially-handled filesystems.
Other than being inefficient, this also prevents filesystems not supporting xattrs from working properly since, without xattrs, there is no way to pass the label determined in smack_inode_init_security() to smack_d_instantiate().
Since the LSM infrastructure allows setting and getting the security field without xattrs through the inode_setsecurity and inode_getsecurity hooks, make the inode creation work too, by initializing the in-memory inode earlier in smack_inode_init_security().
Also mark the inode as instantiated, to prevent smack_d_instantiate() from overwriting the security field. As mentioned above, this potentially has impact for inodes in specially-handled filesystems in smack_d_instantiate(), if they are not handled in the same way in smack_inode_init_security().
Filesystems other than tmpfs don't call security_inode_init_security(), so they would be always initialized in smack_d_instantiate(), as before. For tmpfs, the current behavior is to assign to inodes the label '*', but actually that label is overwritten with the one fetched from the SMACK64 xattr, set in smack_inode_init_security() (default: '_').
Initializing the in-memory inode is straightforward: if not transmuting, nothing more needs to be done; if transmuting, overwrite the current inode label with the one from the parent directory, and set SMK_INODE_TRANSMUTE. Finally, set SMK_INODE_INSTANT for all cases, to mark the inode as instantiated.
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> --- security/smack/smack_lsm.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 72f97492f5c3..43e9389cbdfa 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -993,6 +993,7 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir, struct xattr *xattrs, int *xattr_count) { struct task_smack *tsp = smack_cred(current_cred()); + struct inode_smack *issp = smack_inode(inode); struct smack_known *skp = smk_of_task(tsp); struct smack_known *isp = smk_of_inode(inode); struct smack_known *dsp = smk_of_inode(dir); @@ -1028,7 +1029,9 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir, * smack_inode_alloc_security(). */ if (tsp->smk_task != tsp->smk_transmuted) - isp = dsp; + isp = issp->smk_inode = dsp; + + issp->smk_flags |= SMK_INODE_TRANSMUTE; xattr_transmute = lsm_get_xattr_slot(xattrs, xattr_count); if (xattr_transmute) { @@ -1043,6 +1046,8 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir, } } + issp->smk_flags |= SMK_INODE_INSTANT; + if (xattr) { xattr->value = kstrdup(isp->smk_known, GFP_NOFS); if (!xattr->value) -- 2.34.1
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