3.2.97-rc1 review patch. If anyone has any objections, please let me know.
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From: Casey Schaufler casey@schaufler-ca.com
commit 57e7ba04d422c3d41c8426380303ec9b7533ded9 upstream.
security_inode_getsecurity() provides the text string value of a security attribute. It does not provide a "secctx". The code in xattr_getsecurity() that calls security_inode_getsecurity() and then calls security_release_secctx() happened to work because SElinux and Smack treat the attribute and the secctx the same way. It fails for cap_inode_getsecurity(), because that module has no secctx that ever needs releasing. It turns out that Smack is the one that's doing things wrong by not allocating memory when instructed to do so by the "alloc" parameter.
The fix is simple enough. Change the security_release_secctx() to kfree() because it isn't a secctx being returned by security_inode_getsecurity(). Change Smack to allocate the string when told to do so.
Note: this also fixes memory leaks for LSMs which implement inode_getsecurity but not release_secctx, such as capabilities.
Signed-off-by: Casey Schaufler casey@schaufler-ca.com Reported-by: Konstantin Khlebnikov khlebnikov@yandex-team.ru Signed-off-by: James Morris james.l.morris@oracle.com [bwh: Backported to 3.2: - s/isp->smk_known/isp/ - Adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- fs/xattr.c | 2 +- security/smack/smack_lsm.c | 55 +++++++++++++++++++++------------------------- 2 files changed, 26 insertions(+), 31 deletions(-)
--- a/fs/xattr.c +++ b/fs/xattr.c @@ -161,7 +161,7 @@ xattr_getsecurity(struct inode *inode, c } memcpy(value, buffer, len); out: - security_release_secctx(buffer, len); + kfree(buffer); out_noalloc: return len; } --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -940,7 +940,7 @@ static int smack_inode_removexattr(struc * @inode: the object * @name: attribute name * @buffer: where to put the result - * @alloc: unused + * @alloc: duplicate memory * * Returns the size of the attribute or an error code */ @@ -953,43 +953,38 @@ static int smack_inode_getsecurity(const struct super_block *sbp; struct inode *ip = (struct inode *)inode; char *isp; - int ilen; - int rc = 0;
- if (strcmp(name, XATTR_SMACK_SUFFIX) == 0) { + if (strcmp(name, XATTR_SMACK_SUFFIX) == 0) isp = smk_of_inode(inode); - ilen = strlen(isp); - *buffer = isp; - return ilen; + else { + /* + * The rest of the Smack xattrs are only on sockets. + */ + sbp = ip->i_sb; + if (sbp->s_magic != SOCKFS_MAGIC) + return -EOPNOTSUPP; + + sock = SOCKET_I(ip); + if (sock == NULL || sock->sk == NULL) + return -EOPNOTSUPP; + + ssp = sock->sk->sk_security; + + if (strcmp(name, XATTR_SMACK_IPIN) == 0) + isp = ssp->smk_in; + else if (strcmp(name, XATTR_SMACK_IPOUT) == 0) + isp = ssp->smk_out; + else + return -EOPNOTSUPP; }
- /* - * The rest of the Smack xattrs are only on sockets. - */ - sbp = ip->i_sb; - if (sbp->s_magic != SOCKFS_MAGIC) - return -EOPNOTSUPP; - - sock = SOCKET_I(ip); - if (sock == NULL || sock->sk == NULL) - return -EOPNOTSUPP; - - ssp = sock->sk->sk_security; - - if (strcmp(name, XATTR_SMACK_IPIN) == 0) - isp = ssp->smk_in; - else if (strcmp(name, XATTR_SMACK_IPOUT) == 0) - isp = ssp->smk_out; - else - return -EOPNOTSUPP; - - ilen = strlen(isp); - if (rc == 0) { - *buffer = isp; - rc = ilen; + if (alloc) { + *buffer = kstrdup(isp, GFP_KERNEL); + if (*buffer == NULL) + return -ENOMEM; }
- return rc; + return strlen(isp); }