Build fix: retrieve unix socket peer PID on non-unix platforms

The previous attempt at extending the credential retrieval wrapper was
broken and didn't build on FreeBSD, macOS, and cygwin.

A platform-specific way of retrieving the PID of a unix peer is
implemented for FreeBSD (getsockopt using LOCAL_PEERCRED, note that the
cr_pid field is only available from FreeBSD 13 and up),
macOS (getsockopt using LOCAL_PEERPID, macOS 10.8+), and
Solaris (getpeerucreds).

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ifcf522c70ee4c2e0799293ae0961f41aebff5056

diff --git a/src/common/compat/socket.h b/src/common/compat/socket.h
index 464678292b95eed68afa5cc2d9e0311bd6843b41..fda00e536413ed22ab69302fcd4aa0fe8f8740dd 100644 (file)
--- a/src/common/compat/socket.h
+++ b/src/common/compat/socket.h
@@ -10,6 +10,7 @@
 
 #include <sys/socket.h>
 #include <sys/un.h>
+#include <unistd.h>
 
 #include <common/macros.h>
 
@@ -97,8 +98,58 @@ ssize_t lttng_recvmsg_nosigpipe(int sockfd, struct msghdr *msg)
 }
 #endif
 
+#ifdef __sun__
+
+# ifndef CMSG_ALIGN
+#  ifdef _CMSG_DATA_ALIGN
+#   define CMSG_ALIGN(len) _CMSG_DATA_ALIGN(len)
+#  else
+    /* aligning to sizeof (long) is assumed to be portable (fd.o#40235) */
+#   define CMSG_ALIGN(len) (((len) + sizeof (long) - 1) & ~(sizeof (long) - 1))
+#  endif
+#  ifndef CMSG_SPACE
+#    define CMSG_SPACE(len) (CMSG_ALIGN (sizeof (struct cmsghdr)) + CMSG_ALIGN (len))
+#  endif
+#  ifndef CMSG_LEN
+#    define CMSG_LEN(len) (CMSG_ALIGN (sizeof (struct cmsghdr)) + (len))
+#  endif
+# endif
+
+#include <ucred.h>
 
-#ifdef __linux__
+static inline
+int getpeereid(int s, uid_t *euid, gid_t *gid)
+{
+       int ret = 0;
+       ucred_t *ucred = NULL;
+
+       ret = getpeerucred(s, &ucred);
+       if (ret == -1) {
+               goto end;
+       }
+
+       ret = ucred_geteuid(ucred);
+       if (ret == -1) {
+               goto free;
+       }
+       *euid = ret;
+
+       ret = ucred_getrgid(ucred);
+       if (ret == -1) {
+               goto free;
+       }
+       *gid = ret;
+
+       ret = 0;
+free:
+       ucred_free(ucred);
+end:
+       return ret;
+}
+#endif /* __sun__ */
+
+
+#if defined(__linux__) || defined(__CYGWIN__)
 
 #define LTTNG_SOCK_CREDS SCM_CREDENTIALS
 
@@ -112,7 +163,7 @@ typedef struct ucred lttng_sock_cred;
 #define LTTNG_SOCK_GET_GID_CRED(c) LTTNG_REF(c)->gid
 #define LTTNG_SOCK_GET_PID_CRED(c) LTTNG_REF(c)->pid
 
-#elif (defined(__FreeBSD__) || defined(__CYGWIN__) || defined(__sun__) || defined(__APPLE__))
+#elif (defined(__FreeBSD__) || defined(__sun__) || defined(__APPLE__))
 
 struct lttng_sock_cred {
        uid_t uid;
@@ -124,39 +175,27 @@ typedef struct lttng_sock_cred lttng_sock_cred;
 
 #define LTTNG_SOCK_SET_UID_CRED(c, u) LTTNG_REF(c)->uid = u
 #define LTTNG_SOCK_SET_GID_CRED(c, g) LTTNG_REF(c)->gid = g
-#define LTTNG_SOCK_SET_PID_CRED(c, p)
+#define LTTNG_SOCK_SET_PID_CRED(c, p) LTTNG_REF(c)->pid = p
 
 #define LTTNG_SOCK_GET_UID_CRED(c) LTTNG_REF(c)->uid
 #define LTTNG_SOCK_GET_GID_CRED(c) LTTNG_REF(c)->gid
-#define LTTNG_SOCK_GET_PID_CRED(c) -1
-
-#else
-#error "Please add support for your OS."
-#endif /* __linux__ , __FreeBSD__ */
-
-
-#ifdef __sun__
+#define LTTNG_SOCK_GET_PID_CRED(c) LTTNG_REF(c)->pid
 
-# ifndef CMSG_ALIGN
-#  ifdef _CMSG_DATA_ALIGN
-#   define CMSG_ALIGN(len) _CMSG_DATA_ALIGN(len)
-#  else
-    /* aligning to sizeof (long) is assumed to be portable (fd.o#40235) */
-#   define CMSG_ALIGN(len) (((len) + sizeof (long) - 1) & ~(sizeof (long) - 1))
-#  endif
-#  ifndef CMSG_SPACE
-#    define CMSG_SPACE(len) (CMSG_ALIGN (sizeof (struct cmsghdr)) + CMSG_ALIGN (len))
-#  endif
-#  ifndef CMSG_LEN
-#    define CMSG_LEN(len) (CMSG_ALIGN (sizeof (struct cmsghdr)) + (len))
-#  endif
-# endif
+#ifdef __APPLE__
 
+static inline
+int lttng_get_unix_socket_peer_pid(int socket_fd, pid_t *pid)
+{
+       /* The getsockopt LOCAL_PEERPID option is available since macOS 10.8. */
+       return getsockopt(socket_fd, SOL_LOCAL, LOCAL_PEERPID, pid,
+                       &((socklen_t) {sizeof(*pid)}));
+}
 
-#include <ucred.h>
+#elif defined(__sun__)
 
+/* Use the getpeerucreds interface on Solaris. */
 static inline
-int getpeereid(int s, uid_t *euid, gid_t *gid, pid_t *pid)
+int lttng_get_unix_socket_peer_pid(int socket_fd, pid_t *pid)
 {
        int ret = 0;
        ucred_t *ucred = NULL;
@@ -166,24 +205,12 @@ int getpeereid(int s, uid_t *euid, gid_t *gid, pid_t *pid)
                goto end;
        }
 
-       ret = ucred_geteuid(ucred);
-       if (ret == -1) {
-               goto free;
-       }
-       *euid = ret;
-
-       ret = ucred_getrgid(ucred);
-       if (ret == -1) {
-               goto free;
-       }
-       *gid = ret;
-
        ret = ucred_getpid(ucred);
        if (ret == -1) {
                goto free;
        }
-       *pid = ret;
 
+       *pid = ret;
        ret = 0;
 free:
        ucred_free(ucred);
@@ -191,6 +218,53 @@ end:
        return ret;
 }
 
-#endif /* __sun__ */
+#elif defined(__FreeBSD__)
+
+#include <sys/ucred.h>
+
+static inline
+int lttng_get_unix_socket_peer_pid(int socket_fd, pid_t *pid)
+{
+       int ret;
+       struct xucred sock_creds = {};
+
+       /* Only available in FreeBSD 13.0 and up. */
+       ret = getsockopt(socket_fd, SOL_LOCAL, LOCAL_PEERCRED, &sock_creds,
+                       &((socklen_t) {sizeof(sock_creds)}));
+       if (ret) {
+               goto end;
+       }
+
+       *pid = sock_creds.cr_pid;
+end:
+       return ret;
+}
+
+#endif /* __APPLE__ */
+
+
+static inline
+int lttng_get_unix_socket_peer_creds(int socket_fd, struct lttng_sock_cred *creds)
+{
+       int ret;
+
+       /* This is a BSD extension that is supported by Cygwin. */
+       ret = getpeereid(socket_fd, &creds->uid, &creds->gid);
+       if (ret) {
+               goto end;
+       }
+
+       /*
+        * Getting a peer's PID is a bit more troublesome as it is platform
+        * specific.
+        */
+       ret = lttng_get_unix_socket_peer_pid(socket_fd, &creds->pid);
+end:
+       return ret;
+}
+
+#else
+#error "Please add support for your OS."
+#endif /* __linux__ , __FreeBSD__, __APPLE__ */
 
 #endif /* _COMPAT_SOCKET_H */

diff --git a/src/common/unix.c b/src/common/unix.c
index 12622e5dd03152a78ee492699539b7f86335f104..4c5c7acc61a260b10162d83089b7373c8c18d297 100644 (file)
--- a/src/common/unix.c
+++ b/src/common/unix.c
@@ -992,14 +992,14 @@ ssize_t lttcomm_send_creds_unix_sock(int sock, const void *buf, size_t len)
        struct msghdr msg;
        struct iovec iov[1];
        ssize_t ret = -1;
-#ifdef __linux__
+#if defined(__linux__) || defined(__CYGWIN__)
        struct cmsghdr *cmptr;
        size_t sizeof_cred = sizeof(lttng_sock_cred);
        char anc_buf[CMSG_SPACE(sizeof_cred)];
        lttng_sock_cred *creds;
 
        memset(anc_buf, 0, CMSG_SPACE(sizeof_cred) * sizeof(char));
-#endif /* __linux__ */
+#endif /* __linux__, __CYGWIN__ */
 
        memset(&msg, 0, sizeof(msg));
 
@@ -1012,7 +1012,7 @@ ssize_t lttcomm_send_creds_unix_sock(int sock, const void *buf, size_t len)
        msg.msg_iov = iov;
        msg.msg_iovlen = 1;
 
-#ifdef __linux__
+#if defined(__linux__) || defined(__CYGWIN__)
        msg.msg_control = (caddr_t) anc_buf;
        msg.msg_controllen = CMSG_LEN(sizeof_cred);
 
@@ -1029,7 +1029,7 @@ ssize_t lttcomm_send_creds_unix_sock(int sock, const void *buf, size_t len)
        LTTNG_SOCK_SET_UID_CRED(creds, geteuid());
        LTTNG_SOCK_SET_GID_CRED(creds, getegid());
        LTTNG_SOCK_SET_PID_CRED(creds, getpid());
-#endif /* __linux__ */
+#endif /* __linux__, __CYGWIN__ */
 
        do {
                ret = sendmsg(sock, &msg, 0);
@@ -1059,11 +1059,11 @@ ssize_t lttcomm_recv_creds_unix_sock(int sock, void *buf, size_t len,
        struct iovec iov[1];
        ssize_t ret;
        size_t len_last;
-#ifdef __linux__
+#if defined(__linux__) || defined(__CYGWIN__)
        struct cmsghdr *cmptr;
        size_t sizeof_cred = sizeof(lttng_sock_cred);
        char anc_buf[CMSG_SPACE(sizeof_cred)];
-#endif /* __linux__ */
+#endif /* __linux__, __CYGWIN__ */
 
        assert(sock);
        assert(buf);
@@ -1078,10 +1078,10 @@ ssize_t lttcomm_recv_creds_unix_sock(int sock, void *buf, size_t len,
        msg.msg_iov = iov;
        msg.msg_iovlen = 1;
 
-#ifdef __linux__
+#if defined(__linux__) || defined(__CYGWIN__)
        msg.msg_control = anc_buf;
        msg.msg_controllen = sizeof(anc_buf);
-#endif /* __linux__ */
+#endif /* __linux__, __CYGWIN__ */
 
        do {
                len_last = iov[0].iov_len;
@@ -1100,7 +1100,7 @@ ssize_t lttcomm_recv_creds_unix_sock(int sock, void *buf, size_t len,
        }
        /* Else ret = 0 meaning an orderly shutdown. */
 
-#ifdef __linux__
+#if defined(__linux__) || defined(__CYGWIN__)
        if (msg.msg_flags & MSG_CTRUNC) {
                fprintf(stderr, "Error: Control message truncated.\n");
                ret = -1;
@@ -1129,18 +1129,15 @@ ssize_t lttcomm_recv_creds_unix_sock(int sock, void *buf, size_t len,
        }
 
        memcpy(creds, CMSG_DATA(cmptr), sizeof_cred);
-#elif (defined(__FreeBSD__) || defined(__CYGWIN__) || defined(__sun__) || defined(__APPLE__))
-       {
-               int peer_ret;
-
-               peer_ret = getpeereid(sock, &creds->uid, &creds->gid, &creds->pid);
-               if (peer_ret != 0) {
-                       return peer_ret;
-               }
+#elif (defined(__FreeBSD__) || defined(__sun__) || defined(__APPLE__))
+       if (lttng_get_unix_socket_peer_creds(sock, creds)) {
+               fprintf(stderr, "ARG\n");
+               ret = -1;
+               goto end;
        }
 #else
 #error "Please implement credential support for your OS."
-#endif /* __linux__ */
+#endif /* __linux__, __CYGWIN__ */
 
 end:
        return ret;
@@ -1149,7 +1146,7 @@ end:
 /*
  * Set socket option to use credentials passing.
  */
-#ifdef __linux__
+#if defined(__linux__) || defined(__CYGWIN__)
 LTTNG_HIDDEN
 int lttcomm_setsockopt_creds_unix_sock(int sock)
 {
@@ -1162,7 +1159,7 @@ int lttcomm_setsockopt_creds_unix_sock(int sock)
        }
        return ret;
 }
-#elif (defined(__FreeBSD__) || defined(__CYGWIN__) || defined(__sun__) || defined(__APPLE__))
+#elif (defined(__FreeBSD__) || defined(__sun__) || defined(__APPLE__))
 LTTNG_HIDDEN
 int lttcomm_setsockopt_creds_unix_sock(int sock)
 {