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    Subject[PATCH 5.19 161/192] Smack: Provide read control for io_uring_cmd
    Date
    From: Casey Schaufler <casey@schaufler-ca.com>

    commit dd9373402280cf4715fdc8fd5070f7d039e43511 upstream.

    Limit io_uring "cmd" options to files for which the caller has
    Smack read access. There may be cases where the cmd option may
    be closer to a write access than a read, but there is no way
    to make that determination.

    Cc: stable@vger.kernel.org
    Fixes: ee692a21e9bf ("fs,io_uring: add infrastructure for uring-cmd")
    Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
    Signed-off-by: Paul Moore <paul@paul-moore.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    security/smack/smack_lsm.c | 32 ++++++++++++++++++++++++++++++++
    1 file changed, 32 insertions(+)

    --- a/security/smack/smack_lsm.c
    +++ b/security/smack/smack_lsm.c
    @@ -42,6 +42,7 @@
    #include <linux/fs_context.h>
    #include <linux/fs_parser.h>
    #include <linux/watch_queue.h>
    +#include <linux/io_uring.h>
    #include "smack.h"

    #define TRANS_TRUE "TRUE"
    @@ -4739,6 +4740,36 @@ static int smack_uring_sqpoll(void)
    return -EPERM;
    }

    +/**
    + * smack_uring_cmd - check on file operations for io_uring
    + * @ioucmd: the command in question
    + *
    + * Make a best guess about whether a io_uring "command" should
    + * be allowed. Use the same logic used for determining if the
    + * file could be opened for read in the absence of better criteria.
    + */
    +static int smack_uring_cmd(struct io_uring_cmd *ioucmd)
    +{
    + struct file *file = ioucmd->file;
    + struct smk_audit_info ad;
    + struct task_smack *tsp;
    + struct inode *inode;
    + int rc;
    +
    + if (!file)
    + return -EINVAL;
    +
    + tsp = smack_cred(file->f_cred);
    + inode = file_inode(file);
    +
    + smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_PATH);
    + smk_ad_setfield_u_fs_path(&ad, file->f_path);
    + rc = smk_tskacc(tsp, smk_of_inode(inode), MAY_READ, &ad);
    + rc = smk_bu_credfile(file->f_cred, file, MAY_READ, rc);
    +
    + return rc;
    +}
    +
    #endif /* CONFIG_IO_URING */

    struct lsm_blob_sizes smack_blob_sizes __lsm_ro_after_init = {
    @@ -4896,6 +4927,7 @@ static struct security_hook_list smack_h
    #ifdef CONFIG_IO_URING
    LSM_HOOK_INIT(uring_override_creds, smack_uring_override_creds),
    LSM_HOOK_INIT(uring_sqpoll, smack_uring_sqpoll),
    + LSM_HOOK_INIT(uring_cmd, smack_uring_cmd),
    #endif
    };


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