DragonFly On-Line Manual Pages
TLS(2) DragonFly System Calls Manual TLS(2)
NAME
set_tls_area, get_tls_area -- kernel TLS (thread local storage) support
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/tls.h>
int
set_tls_area(int which, struct tls_info *info, size_t infosize);
int
get_tls_area(int which, struct tls_info *info, size_t infosize);
DESCRIPTION
The set_tls_area() system call creates an entry for the TLS facility
which representing thread local storage as specified by the info
structure. A descriptor representing the facility is returned, or -1 if
an error occurred. The facility may be cleared by specifying a NULL
pointer and an infosize of 0. The get_tls_area() system call retrieves
the requested TLS facility. A descriptor representing the facility is
returned, or -1 if an error occurred. If you simply want the descriptor
you may specify a NULL pointer and an infosize of 0.
The returned descriptor and the TLS mechanism is machine-dependent. On
IA32 three global segment descriptors are supported (0, 1, and 2) and
the %gs load value is returned.
The tls_info structure passed to set_tls_area() should first be zerod (to
remain compatible with future extensions) and then initialized.
struct tls_info {
void *base; /* base address of TLS area */
int size; /* size of TLS area in bytes */
};
The actual implementation of the area is machine-dependent. If the
kernel is unable to accommodate the supplied size it may create a larger
area. If the kernel is unable to accommodate the supplied base address
an error will be returned.
RETURN VALUES
A return value of 0 is returned on success, -1 on error.
EXAMPLES
/*
* Pseudo example showing how the TLS system calls work on IA32.
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/tls.h>
int X;
static int getdata(int offset);
int
main(int ac, char **av)
{
int i;
int gs;
struct tls_info info;
info.base = &X;
info.size = sizeof(X);
if ((gs = set_tls_area(0, &info, sizeof(info))) < 0) {
perror("setarea");
exit(1);
}
printf("gs = %04x\n", gs);
__asm __volatile("mov %0,%%gs" : : "g" (gs) );
if (get_tls_area(0, &info, sizeof(info)) < 0) {
perror("getarea");
exit(1);
}
printf("%p/%d\n", info.base, info.size);
X = 1;
printf("should be 1: %d\n", getdata(0));
X = 2;
printf("should be 2: %d\n", getdata(0));
printf("this should fault:\n");
fflush(stdout);
getdata(4);
return(0);
}
static int
getdata(int offset)
{
int rv;
__asm __volatile("movl %%gs:(%0),%%eax; movl %%eax,%1" : "+r" (offset) : "m"
(rv) : "ax");
return (rv);
}
ERRORS
[ERANGE] The specified facility index, which, is not supported.
[EINVAL] An invalid parameter has been specified.
[ENOENT] (get_tls_area) The specified facility has not been
initialized with sys_set_tls_area().
SEE ALSO
umtx(2)
HISTORY
The set_tls_area(), and get_tls_area() function calls first appeared in
DragonFly 1.1.
DragonFly 5.5 February 21, 2005 DragonFly 5.5
TLS_CONFIG_SET_PRO... DragonFly Library Functions Manual TLS_CONFIG_SET_PRO...
NAME
tls_config_set_protocols, tls_config_parse_protocols,
tls_config_set_alpn, tls_config_set_ciphers, tls_config_set_dheparams,
tls_config_set_ecdhecurves, tls_config_prefer_ciphers_client,
tls_config_prefer_ciphers_server -- TLS protocol and cipher selection
SYNOPSIS
#include <tls.h>
int
tls_config_set_protocols(struct tls_config *config, uint32_t protocols);
int
tls_config_parse_protocols(uint32_t *protocols, const char *protostr);
int
tls_config_set_alpn(struct tls_config *config, const char *alpn);
int
tls_config_set_ciphers(struct tls_config *config, const char *ciphers);
int
tls_config_set_dheparams(struct tls_config *config, const char *params);
int
tls_config_set_ecdhecurves(struct tls_config *config,
const char *curves);
void
tls_config_prefer_ciphers_client(struct tls_config *config);
void
tls_config_prefer_ciphers_server(struct tls_config *config);
DESCRIPTION
These functions modify a configuration by setting parameters. The con-
figuration options apply to both clients and servers, unless noted other-
wise.
tls_config_set_protocols() specifies which versions of the TLS protocol
may be used. Possible values are the bitwise OR of:
TLS_PROTOCOL_TLSv1_0
TLS_PROTOCOL_TLSv1_1
TLS_PROTOCOL_TLSv1_2
Additionally, the values TLS_PROTOCOL_TLSv1 (TLSv1.0, TLSv1.1 and
TLSv1.2), TLS_PROTOCOLS_ALL (all supported protocols) and
TLS_PROTOCOLS_DEFAULT (TLSv1.2 only) may be used.
The tls_config_parse_protocols() utility function parses a protocol
string and returns the corresponding value via the protocols argument.
This value can then be passed to the tls_config_set_protocols() function.
The protocol string is a comma or colon separated list of keywords.
Valid keywords are tlsv1.0, tlsv1.1, tlsv1.2, all (all supported proto-
cols), default (an alias for secure), legacy (an alias for all) and
secure (currently TLSv1.2 only). If a value has a negative prefix (in
the form of a leading exclamation mark) then it is removed from the list
of available protocols, rather than being added to it.
tls_config_set_alpn() sets the ALPN protocols that are supported. The
alpn string is a comma separated list of protocols, in order of prefer-
ence.
tls_config_set_ciphers() sets the list of ciphers that may be used.
Lists of ciphers are specified by name, and the permitted names are:
secure (or alias default)
compat
legacy
insecure (or alias all)
Alternatively, libssl cipher strings can be specified. See the CIPHERS
section of openssl(1) for further information.
tls_config_set_dheparams() specifies the parameters that will be used
during Diffie-Hellman Ephemeral (DHE) key exchange. Possible values are
"none", "auto" and "legacy". In "auto" mode, the key size for the
ephemeral key is automatically selected based on the size of the private
key being used for signing. In "legacy" mode, 1024 bit ephemeral keys
are used. The default value is "none", which disables DHE key exchange.
tls_config_set_ecdhecurves() specifies the names of the elliptic curves
that may be used during Elliptic Curve Diffie-Hellman Ephemeral (ECDHE)
key exchange. This is a comma separated list, given in order of prefer-
ence. The special value of "default" will use the default curves (cur-
rently X25519, P-256 and P-384). This function replaces
tls_config_set_ecdhecurve(), which is deprecated.
tls_config_prefer_ciphers_client() prefers ciphers in the client's cipher
list when selecting a cipher suite (server only). This is considered to
be less secure than preferring the server's list.
tls_config_prefer_ciphers_server() prefers ciphers in the server's cipher
list when selecting a cipher suite (server only). This is considered to
be more secure than preferring the client's list and is the default.
RETURN VALUES
These functions return 0 on success or -1 on error.
SEE ALSO
tls_config_ocsp_require_stapling(3), tls_config_set_session_id(3),
tls_config_verify(3), tls_init(3), tls_load_file(3)
HISTORY
tls_config_set_ciphers() appeared in OpenBSD 5.6 and got its final name
in OpenBSD 5.7.
tls_config_set_protocols(), tls_config_parse_protocols(),
tls_config_set_dheparams(), and tls_config_set_ecdhecurve() appeared in
OpenBSD 5.7, tls_config_prefer_ciphers_client() and
tls_config_prefer_ciphers_server() in OpenBSD 5.9, and
tls_config_set_alpn() in OpenBSD 6.1.
AUTHORS
Joel Sing <jsing@openbsd.org> with contributions from
Ted Unangst <tedu@openbsd.org> (tls_config_set_ciphers()) and
Reyk Floeter <reyk@openbsd.org> (tls_config_set_ecdhecurve())
DragonFly 5.5 August 12, 2017 DragonFly 5.5