gnu: curl: Update to 7.76.0 [security fixes].

Fixes CVE-2021-22876 and CVE-2021-22890.

* gnu/packages/curl.scm (curl/fixed): New variable.
(curl)[replacement]: New field.
* gnu/packages/patches/curl-7.76-use-ssl-cert-env.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.

gnu/local.mk

@@ -920,6 +920,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/clucene-contribs-lib.patch               \
   %D%/packages/patches/cube-nocheck.patch			\
   %D%/packages/patches/curl-use-ssl-cert-env.patch		\
+  %D%/packages/patches/curl-7.76-use-ssl-cert-env.patch	\
   %D%/packages/patches/cursynth-wave-rand.patch			\
   %D%/packages/patches/cvs-CVE-2017-12836.patch		\
   %D%/packages/patches/cyrus-sasl-ac-try-run-fix.patch		\

gnu/packages/curl.scm

@@ -62,6 +62,7 @@
               (base32
                "12w7gskrglg6qrmp822j37fmbr0icrcxv7rib1fy5xiw80n5z7cr"))
              (patches (search-patches "curl-use-ssl-cert-env.patch"))))
+   (replacement curl/fixed)
    (build-system gnu-build-system)
    (outputs '("out"
               "doc"))                             ;1.2 MiB of man3 pages
@@ -151,6 +152,20 @@ tunneling, and so on.")
     (name "curl-minimal")
     (inputs (alist-delete "openldap" (package-inputs curl))))))
 
+(define-public curl/fixed
+  (package
+    (inherit curl)
+    (version "7.76.0")
+    (source
+     (origin
+       (inherit (package-source curl))
+       (uri (string-append "https://curl.haxx.se/download/curl-"
+                           version ".tar.xz"))
+       (patches (search-patches "curl-7.76-use-ssl-cert-env.patch"))
+       (sha256
+        (base32
+         "1j2g04m6als6hmqzvddv84c31m0x90bfgyz3bjrwdkarbkby40k3"))))))
+
 (define-public kurly
   (package
     (name "kurly")

gnu/packages/patches/curl-7.76-use-ssl-cert-env.patch

@@ -0,0 +1,64 @@
+Make libcurl respect the SSL_CERT_{DIR,FILE} variables by default. The variables
+are fetched during initialization to preserve thread-safety (curl_global_init(3)
+must be called when no other threads exist).
+
+This fixes network functionality in rust:cargo, and probably removes the need
+for other future workarounds.
+===================================================================
+--- curl-7.66.0.orig/lib/easy.c	2020-01-02 15:43:11.883921171 +0100
++++ curl-7.66.0/lib/easy.c	2020-01-02 16:18:54.691882797 +0100
+@@ -134,6 +134,9 @@
+ #  pragma warning(default:4232) /* MSVC extension, dllimport identity */
+ #endif
+ 
++char * Curl_ssl_cert_dir = NULL;
++char * Curl_ssl_cert_file = NULL;
++
+ /**
+  * curl_global_init() globally initializes curl given a bitwise set of the
+  * different features of what to initialize.
+@@ -155,6 +158,9 @@
+ #endif
+   }
+ 
++  Curl_ssl_cert_dir = curl_getenv("SSL_CERT_DIR");
++  Curl_ssl_cert_file = curl_getenv("SSL_CERT_FILE");
++
+   if(!Curl_ssl_init()) {
+     DEBUGF(fprintf(stderr, "Error: Curl_ssl_init failed\n"));
+     return CURLE_FAILED_INIT;
+@@ -260,6 +266,9 @@
+   Curl_ssl_cleanup();
+   Curl_resolver_global_cleanup();
+ 
++  free(Curl_ssl_cert_dir);
++  free(Curl_ssl_cert_file);
++
+ #ifdef WIN32
+   Curl_win32_cleanup(init_flags);
+ #endif
+diff -ur curl-7.66.0.orig/lib/url.c curl-7.66.0/lib/url.c
+--- curl-7.66.0.orig/lib/url.c	2020-01-02 15:43:11.883921171 +0100
++++ curl-7.66.0/lib/url.c	2020-01-02 16:21:11.563880346 +0100
+@@ -524,6 +524,21 @@
+     if(result)
+       return result;
+ #endif
++    extern char * Curl_ssl_cert_dir;
++    extern char * Curl_ssl_cert_file;
++    if(Curl_ssl_cert_dir) {
++        if(result = Curl_setstropt(&set->str[STRING_SSL_CAPATH], Curl_ssl_cert_dir))
++            return result;
++        if(result = Curl_setstropt(&set->str[STRING_SSL_CAPATH_PROXY], Curl_ssl_cert_dir))
++            return result;
++    }
++
++    if(Curl_ssl_cert_file) {
++        if(result = Curl_setstropt(&set->str[STRING_SSL_CAFILE], Curl_ssl_cert_file))
++            return result;
++        if(result = Curl_setstropt(&set->str[STRING_SSL_CAFILE_PROXY], Curl_ssl_cert_file))
++            return result;
++    }
+   }
+ 
+   set->wildcard_enabled = FALSE;