From serue@us.ibm.com Fri Oct 9 10:37:17 2009 From: "Serge E. Hallyn" Date: Wed, 16 Sep 2009 16:27:41 -0500 Subject: Staging: p9auth: a few fixes To: Ashwin Ganti , Greg Kroah-Hartman Cc: lkml Message-ID: <20090916212741.GA19295@us.ibm.com> Content-Disposition: inline 1. The memory into which we copy 'u1@u2' needs space for u1, @, u2, and a final \0 which strcat copies in. 2. Strsep changes the value of its first argument. So use a temporary variable to pass to it, so we pass the original value to kfree! 3. Allocate an extra char to user_buf, because we need a trailing \0 since we later kstrdup it. I am about to send out an LTP testcase for this driver, but in addition the correctness of the hashing can be verified as follows: #include #include #include int main(int argc, char *argv[]) { char in[41], out[20]; unsigned int v; int i, ret; ret = read(STDIN_FILENO, in, 40); if (ret != 40) exit(1); in[40] = '\0'; for (i = 0; i < 20; i++) { sscanf(&in[2*i], "%02x", &v); out[i] = v; } write(STDOUT_FILENO, out, 20); } as root, to test userid 501 switching to uid 0, choosing 'random' string 'ab': echo -n "501@0" > plain openssl sha1 -hmac 'ab' plain |awk '{ print $2 '} > dgst ./unhex < dgst > dgst.u mknod /dev/caphash 504 0 mknod /dev/capuse 504 1 chmod ugo+w /dev/capuse cat dgst.u > /dev/caphash as uid 501, echo "501@0@ab" > /dev/capuse id -u # should now show 0. Signed-off-by: Serge E. Hallyn Signed-off-by: Greg Kroah-Hartman --- drivers/staging/p9auth/p9auth.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) --- a/drivers/staging/p9auth/p9auth.c +++ b/drivers/staging/p9auth/p9auth.c @@ -183,7 +183,7 @@ static ssize_t cap_write(struct file *fi user_buf_running = NULL; hash_str = NULL; node_ptr = kmalloc(sizeof(struct cap_node), GFP_KERNEL); - user_buf = kzalloc(count, GFP_KERNEL); + user_buf = kzalloc(count+1, GFP_KERNEL); if (!node_ptr || !user_buf) goto out; @@ -207,6 +207,7 @@ static ssize_t cap_write(struct file *fi list_add(&(node_ptr->list), &(dev->head->list)); node_ptr = NULL; } else { + char *tmpu; if (!cap_devices[0].head || list_empty(&(cap_devices[0].head->list))) { retval = -EINVAL; @@ -218,10 +219,10 @@ static ssize_t cap_write(struct file *fi * need to split it and hash 'user1@user2' using 'randomstring' * as the key. */ - user_buf_running = kstrdup(user_buf, GFP_KERNEL); - source_user = strsep(&user_buf_running, "@"); - target_user = strsep(&user_buf_running, "@"); - rand_str = strsep(&user_buf_running, "@"); + tmpu = user_buf_running = kstrdup(user_buf, GFP_KERNEL); + source_user = strsep(&tmpu, "@"); + target_user = strsep(&tmpu, "@"); + rand_str = tmpu; if (!source_user || !target_user || !rand_str) { retval = -EINVAL; goto out; @@ -229,7 +230,8 @@ static ssize_t cap_write(struct file *fi /* hash the string user1@user2 with rand_str as the key */ len = strlen(source_user) + strlen(target_user) + 1; - hash_str = kzalloc(len, GFP_KERNEL); + /* src, @, len, \0 */ + hash_str = kzalloc(len+1, GFP_KERNEL); strcat(hash_str, source_user); strcat(hash_str, "@"); strcat(hash_str, target_user);